page 89 chapter #3 - the skeletal system: the …

CHAPTER #3 - THE SKELETAL SYSTEM: THE APPENDICULAR SKELETON

APENDICULAR SKELETON - consists of the bones of the pectoral

(shoulder) and pelvis (hip) girdles and extremities.

I. PECTORAL (SHOULDER) GIRDLE - attach the bones of the upper

extremities to the axial skeleton. They have no articulation

with the vertebral column. The shoulder Joints are not very

stable, but are freely movable and thus allow movement in

many directions. Each of the two pectoral girdles consists

of two bones.

A.) CLAVICLE - (collarbones) - is the anterior component

and articulates with the sternum at the

sternoclavicular joint. They are long, slender bones

with a double curvature. The two bones lie

horizontally in the superior and anterior part of

the thorax, superior to the first rib.

1.) STERNAL EXTREMITY - is the medial end of the clavicle, it is rounded and articulates with

the sternum.

2.) ACROMIAL EXTEMITY - is the broad, flat, lateral end and articulates with the acromion of the

scapula.

3.) ACROMIOCLACICULAR JOINT - Is created when the acromial extremity articulates with the

acromion of the scapula.

4.) CONOID TUBERCLE - is on the inferior surface of the lateral end of the bones serves as a point

of attachment for a ligament.

5.) COSTAL TUBEROSITY - is on the inferior surface

of the medial end and serves as a point of

attachment for a ligament.

B.) SCAPULA - (shoulder blades) - is the posterior

component of the scapula which is positioned

freely by complex muscle attachments, articulates

with the clavicle and humerus. They are large,

triangular, flat bones situated in the dorsal

part of the thorax between the levels of the

second and seventh ribs. Their medial borders are

located about 5 cm. (2") from the vertebral

column.

1.) SPINE - is a sharp ridge that runs diagonally across the dorsal surface of the body.

2.) BODY - is the flattened, triangular portion. 3.) ACROMION - is the end of the where the spine

protects as a flattened, expanded process. It

articulates with the clavicle.

4.) GLENOID CAVITY - is the depression inferior to the acromion. It articulates with the head of

the humerus to form the shoulder Joint.

5.) MEDIAL (VERTEBRAL) BORDER -is the thin edge of the body near the vertebral column.

6.) LATERAL (AXILLARY) BORDER - is the thick edge closer to the arm.

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7.) INFERIOR ANGLE - is where the medial

and lateral borders join.

8.) SUPERIOR BORDER - is the superior edge of the

scapular body.

9.) SUPERIOR ANGLE - is where the superior border and the vertebral border join.

10.) SCAPULAR NOTCH - is a prominent indention along the superior border near the caracoid process;

it permits passage of the suprascapular nerve.

11.) CORACOID PROCESS - Is the projection at the lateral end of the superior border of the

anterior surface, to which muscles attach.

12.) SUPRASPINOUS FOSSA and INFRASPINOUS FOSSA - are above and below the spine, respectively.

Both serve as surfaces of attachment for

shoulder muscles.

13.) SUBSCAPULAR FOSSA - is the lightly hollow-

out area on the ventral (costal) surface, it

is a surface of attachment for should

muscles.

II. UPPER EXTREMITY - consists of 60 bones. It contains the

following:

A.) HUMERUS - (arm bone) - is the longest and

largest bone of the upper extremity. It

articulates

proximally with the scapula and distally at

the elbow with both ulna and radius.

1.) PROXIMAL END consists of :

a.) HEAD - It articulates with the glenoid cavity of the scapula.

b.) ANATOMICAL, NECK - it is an oblique

groove just distal to the head.

c.) GREATER TUBERCLE - Is a lateral projection distal to the neck.

d.) LESSER TUBERCLE - is an anterior projection to the neck.

e.) INTERTUBERCULAR SULCUS (BICIPITAL GROOVE) is between the greater and lesser tubercle

f.) SURGICAL NECK - i s a constricted portion Just distal to the tubercles; it is named

because of its liability to fracture.

2.) BODY (SHAFT) - is cylindrical at its

proximal end and gradually becomes

triangular and is flattened and broad at

its distal end.

a.) DELTOID TUBEROSITY - is the roughened,

V-shaped area along the middle portion

of the shaft.

3.) DISTAL END - contains the following:

a.) CAPITULUM - is a rounded knob that articulates with the head of the radius.

b.) RADIAL FOSSA - Is a depression that receives the head of the radius when the

forearm is flexed.

c.) TROCHLEA - is a pullylike surface

that articulates with the ulna.

d.) CORONOID FOSSA - is an anterior depression

that receives part of the ulna when the

forearm is flexed.

e.) OLECRANON FOSSA - is a posterior depression that receives the olecranon of the ulna when the

forearm is extended.

f.) MEDIAL AND LATERAL EPICONDYLE - are rough

projections on either side of the distal end.

B.) ULNA - is the medial bones of the forearm. It is

located at the little finger side.

1.) OLECRANON (OLECORANON PROCESS) - is the proximal end of the ulna, which forms the prominence of

the elbow.

2.) CORONOID PROCESS - is anterior projection that, together with the olecranon, receives the trochle of

the humerus.

3.) TROCHLEAR (SEMILUNAR) NOTCH - is a curved area between the olecranon and the coronoid process. The trochlea of

the humerus fits into this notch.

4.) RADIAL NOTCH, - is a depression located laterally

and inferiorly to the trochlear notch. It

receives the head of the radius.

5.) HEAD - is at the distal end of the ulna, it is

separated from the wrist by a fibrocartilage disc.

6.) STYLOID PROCESS - is on the posterior side of the

distal end.

C.) RADIUS - is the lateral bone of the forearm,that is

situated on the thumb side.

1.) HEAD - is the disc-shaped proximal end of the radius. It articulates with the capitulum of the

humerus and radial notch of the ulna.

2.) RADIAL RUBEROSITY - is the raised, roughened area on the medial side. It is a point of attachment

for the biceps muscles.

3.) Shaft of the radius widens distally to form a concave inferior surface that articulates with two

bones of the wrist called the lunate and scaphoid

bones.

4.) STYLOID PROCESS - is at the distal end on the lateral side, it articulates with the distal end of

the ulna, with the ulnar notch.

5.) ULNAR NOTCH - is at the distal end on the medial side, it is convace, it articulates with

the distal end of the ulna, with the styloid

process.

D.) CARPUS (WRIST) - consists of eight small bones.

The carpals, unites to each other by ligament. The bones

are arranged in two transverse rows, with four bones in each row.

1.) PROXIMAL ROW - from lateral to medial position

consists of:

a.) SCAPHOID -70% of cases Involving carpal

fractures only involve the scaphoid.

b.) LUNATE

c.) TRIQUETRAL

d.) PISIFORM

2.) DISTAL ROW - from the lateral to

medial position consists of:

a.) TRAPEZIUM

b.) TRAPEZOID

c.) CAPITATE

d.) HAMATE

E.) METACRPUS - has five bones and constitute the

palm of the hand. They are numbered I to V,

starting with the lateral bone.

1.) BASE - is proximal, it articulates

with the distal row of carpal bones

and with one another.

2.) SHAFT

3.) HEAD, - (knuckles) - is distal, it articulates

with the proximal phalanges of the fingers. The

heads are commonly called the "knuckles" and

are readily visible when the fist is clenched.

F.) PHALANGES - (bones of the fingers and toes) -

number 14 in each hand. A single bone of the

finger (or toe) is referred to as a PHALANX.

Each consists of a proximal BASE, a SHAFT,

and a distal HEAD. There are two phlanges in

the first digit, called the thumb (POLLEX),

and three phalanges In each of the remaining

four digits,(commonly referred to as : index

finger, middle finger, ring finger, and

little finger). There are three rows:

1.) PROXIMAL ROW - the first row of

phalanges, articulates with the

metacarpal bones and second row of

phalanges.

2.) MIDDLE ROW - the second row of phalanges,

articulate with the proximal row and the

third row.

3.) DISTAL ROW - the third row of

phalanges, articulate with the

middle row.

NOTE: The thumb has no middle phalanx.

III. PELVIC (HIP) GIRDLE - consist of the two COXAL

BONES, commonly called the pelvic, innominate, or

hipbones. It provides a strong and stable support

for lower extremities on which the weight of the

body is carried. The coxal bones are united to

each other anteriorly at the SYMPHYSIS PUBIS. They

unite posteriorly to the sacrum.

A.) PELVIS, - is the basin-like structure formed

by the sacrum and the coccyx, the two bones of

the pelvic girdle. It is divided into a

greater and lesser pelvis by an oblique plane

that passes through sacral promontory

(posterior), iliopectineal lines (lateral) and

sysphysis pubis (anteriorly).

1.) BRIM OF THE PELVIS - is the

circumference of the oblique plane.

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2.) GREATER (FALSE) PELVIS - is the expanded portion

situated superior to the brim of the pelvis. It

consists laterally of the superior portions of

the illa and posteriorly of the superior portion

of the sacrum. There is no bony component in the

anterior aspect of the greater pelvis. The front

is formed by the walls on the abdomen.

3.) LESSER (TRUE) PELVIS - is inferior and posterior to

the brim of the pelvis. It is formed by the

inferior portions of the ilia and sacrum, the

coccyx and the pubes.

a.) PELVIC INLET - is the superior opening of the lesser pelvis.

b.) PELVIC OUTLET - is the inferior opening of the

lesser pelvis.

4.) ACETABULUM - is the deep, lateral fossa, the area

of fusion where the three components of each of

the two coal bones of the newborn; superior ilium,

an inferior and anterior pubis and an inferior and

posterior ischium. It is commonly to discuss the

bones as if they still consisted of three bones.

It is the socket for the head of the femur. Two-

fifths of it is formed by the ilium, two-fifths by

the ischium and one-fifth by the pubis.

a.) ILIUM - is the largest of the three

subdivisions of the coxal bone.

1.) ILIAC CREST - Is the superior border. 2.) ANTERIOR SUPERIOR ILIAC SPINE - where

the iliac crest ends anteriorly. It

serves as a point of attachment for

muscles of the abdominal wall.

3.) POSTERIOR SUPERIOR ILIAC SPINE - where the iliac crest ends

posteriorly. It serves as a point of

attachment for muscles of the abdominal

wall.

4.) GREATER SCIATIC NOTCH - is inferior to

the posterior superior iliac spine.

5.) ILIAC FOSSA - is the internal surface of the ilium seen from the medial side. It is

a concavity where the illacus muscles

attaches.

6.) AURICULAR SURFACE - is posterior to the

iliac fossa, it articulates with the

sacrum.

b.) ISCHIUM - is the inferior, posterior

portion of the coxal bone.

1.) ISCHIAL SPINE - it is prominent. 2.) LESSER SCIATIC NOTCH - i s below the

spine.

3.) ISCHIAL TUBEROSITY -

4.) RAMUS - Is the rest of the ischium,

it Joins with the pubis and together

they surround the OBTURATOR FORAMEN.

c.) PUBIS - is the anterior and inferior part

of the coxal bone.

1.) SUPERIOR RAMUS -together with the Inferior

ramus and body to form the SYMPHYSIS PUBIX .

2.) INFERIOR RAMUS - see superior ramus

3.) BODY - see superior ramus

B.) SYMPHYSIS PUBIS - is the joint between the two coxal bones.

It consists of fibrocartilage.

IV. LOWER EXTREMITIES - are composed of 60 bones.

A.) FEMUR - or thighbone - is the longest and heaviest bone In

the body. Its proximal end articulates with the coxal bone.

Its distal end articulates with the tibia. The shaft of the

femur bows medially so that it approaches the femur of the

opposite thigh. As a result of this convergence, the knee

Joints are brought nearer to the body's line of gravity. The

degree of convergence is greater in the female because the

female pelvis is broader.

1.) HEAD - Is the proximal end, it articulates with the acetabulum of the coxal bone.

2.) NECK - is a constricted region distal to the head. 3.)GREATER TROCHANTER - is one of the protections that serves

as points of attachment for some the thigh and buttock

muscles.

4.)LESSER TROCHANTER - is one of the protections that serves

as points of attachment for some the thigh and buttock

muscles.

5.)LINEAN ASPERA - is a rough vertical ridge on

the posterior surface of the shaft. It serves for the

attachment of several thigh muscles.

6.)MEDIAL CONDYLE - Is the expanded distal end, it articulates

with the tibia

7.) LATERAL CONDYLE, - is the expanded distal end, it articulates with the tibia.

8.) MEDIAL EPICONDYLE – is superior to the condyles 9.) LATERAL EPICONDYLE – is superior to the condyles 10.) INTERCONDYLAR FOSSA – is the depressed area between the

condyles on the posterior surface.

11.) PATELLAR SURFACE – is located between the condyles on the anterior surface

B.) PATELLA - or kneecap - is a small, triangular bone anterior

to the knee joint. It is a sesamoid bone

that develops in the tendon of the quadriceps femoris

muscle.

1.) BASE – is the broad superior end. 2.) APEX – is the pointed inferior end. 3.) ARTICULAR FACETS(2) – is the posterior

surface, one is for the medial condyle and the

other is for the lateral condyle of the femur.

C.) TIBIA -or shinbone - Is the larger, medial bone of

the leg. It bears the major portion of the weight of the

leg. It articulates at its proximal end with the femur and

fibula, and at its distal end with the fibula of the leg

and talus of the ankle.

1.) LATERAL CONDYLE - is expanded proximal end of the tibia. The inferior surface of it

articulates with the head of the fibula.

2.) MEDIAL CONDYLE - is the expanded proximal end of the tibia.

3.) INTERCONDYLAR EMINENCE -is the upward projection that separates the slightly

concave condyles.

4.) TIBIAL TUBEROSITY - is on the anterior surface and is a point of attachment for the patellar ligament.

5.) MEDIAL MALLEOLUS - is the medial surface of the distal end of the tibia. It articulates with the talus bone

of the ankle and forms the prominence that can be

felt on the medial surface of the ankle.

6.) FIBULAR NOTCH - is the prominence that can be felt on the medial surface of the ankle, it articulates

with the fibula.

D.) FIBULA - is parallel and lateral to the tibia. It is

considerably smaller.

1.) HEAD - Is the proximal end and articulates with the inferior surface of the lateral condyle of the tibia

below the level of the knee joint.

2.) LATERAL MALLEOLUS - is the projection on the distal end, it articulates with the talus bone of the ankle.

This forms the prominence on the lateral surface of

the ankle. The inferior portion of the fibula also

articulates with the tibia at the fibular notch.

a.) POTT'S FRACTURE - is a fracture of the lower end

of the fibula with injury to the tibial

articulation.

E.) TARSUS - is a collective designation for the seven

bones of the ankle called TARSALS, A BROAD, FLAT

SURFACE.

1.) TALUS - is located on the posterior part of the foot.

It is only bone that articulates with the fibula and

tibia. It is surrounded on one side by the medial

malleolus of the tibia and on the other side by the

lateral malleolus of the fibula. During walking, the

talus initially bears the entire weight of the body.

About half the weight is then transmitted to the

calcaneus and the remainder is transmitted to the

other tarsal bones.

2.) CALCANEUS - or heel bone - is located on the

posterior part of the foot. It Is the largest

and strongest tarsal bone.

3.) CUBOID - Is located on the anterior.

1.) NAVICULAR - is located on the anterior.

5.) CUNEIFORM BONES - there are three, and are

located on the anterior.

a.) FIRST (MEDIAL) CUNEIFORM b.) SECOND (INTERMEDIATE) CUNEIFORM c.) THIRD (LATERAL) CUNEIFORM

F.) METATARSUS - consists of five metatarsal bones

numbered I to V from the medial to lateral position.

It articulates proximally with the first, second, and

third cuneiform bones and with the cuboid. Distally,

it articulates with the proximal row of phalanges.

The first metatarsal is thicker than the others

because it bears more weight.

1.) BASE - proximal 2.) SHAFT 3.) HEAD - distal

C.) PHALANGES - resembles those of the hand both in

number and arrangement. The great (big) toe or

hallux, has two large, heavy phalanges called

PROXIMAL and DISTAL phalanges. The other four toes

each have three phalanges - PROXIMAL, MIDDLE AND

DISTAL.

1.) BASE - proximal 2.) SHAFT - middle 3.) HEAD - distal

H.) ARCHES OF THE FOOT - The bones of the foot are

arranged in two arches. These arches enable the foot

to support the weight of the body and provide

leverage while walking. The arches are not rigid.

They yield as weight is applied and spring back when

the weight is lifted.

1.) LONGITUDINAL ARCH - has two parts, both consist

of tarsal and metatarsal bones arranged to form

an arch from the anterior to the posterior part

of the foot.

a.) MEDIAL - inner - part originates at the

calcaeus. It rises to the talus and

descends through the navicular, the three

cuneiforms, and the three medial

metatarsals. The talus is the keystone of

this arch.

b.) LATERAL - outer - part begins at the

calcaneus. It rises at the cuboid and

descends to the two lateral metatarsals.

The cubold is the keystone of this arch.

2.) TRANSVERSE ARCH - is formed by the calcaneus,

navicular, cuboid, and the posterior parts of

the five metatarsals.

V. FEMALE AND MALE SKELETONS - The female pelvis is adapted for pregnancy and

childbirth. (See 8-1) Male bones are

7

generally larger and heavier than female bones and

have more prominent markings f o r muscle attachment.

CHAPTER #9 - ARTICULATIONS

ARTICULATION - (JOINT) - is a point of contact between bones or between

cartilage or bones.

ARTHOLOGY - the scientific study of Joints.

Some joints permit no movement, others permit slight movement,

and still other afford considerable movement. In general, the closer

the fit at the point of contact, the stronger the joint. At tightly

f i t t e d joints, however, movement is r e s t r i c t e d. The looser the f i t ,

the g r e a t e r the movement. Movement at joints is also determined by the

flexibility of the connective tissue that binds the bones together and

by the position of ligaments, muscles, and tendons.

I. CLASSIFICATION

A.) FUNCTIONAL - Joints are c l a s s i f i e d functionally in three

categories.

1.) SYNARTHROSES - are immovable joints 2.) AMPHIARTHROSES - are slightly movable joints. 3.) DIARTHROSES - are f r e e l y movable joints.

B.) STRUCTURAL - this c l a s s i f i ca t i o n of Joints is based on the

presence or absence of a Joint c a v i t y (a space between the

articulating bones) and the kind of connective tissue that

binds the bones together.

1.) FIBROUS - are joints in which no joint c avity and the bones are held together by fibrous

connective tissue.

2.) CARTILAGE - are joints in which there is no Joint cavity and the bones' are held together by cartilage.

3.) SYNOVIAL - are joints in which there is a Joint cavity and the bones forming the joint are united by a surrounding

articular capsule and frequently by a c c e s s o r y ligaments.

II. FIBROUS JOINTS - lack a joint c a v i t y , and the

articulating bones are held very close together by fibrous

connective tissue. They permit l i t t l e or no movement. There

are three types:

A.) SUTURES - are found between bones of the skull. The bones are

united by a thin layer of dense fibrous connective tissue.

Their ir regular structure gives them added strength, and

d e c r e a s e s their chances of fractures. They are immovable.

Functionally they are classified as synarthroses . Some sutures

a r e replaced by bone in the adult, they are called synostoses,

or bony joints - which are complete fusion of bone' across the

suture line.

EXAMPLE: Lambdoidal suture between occipital and parietal

bones.

B.) SYNDESMOSIS - Is a fibrous Joint in which the uniting

fibrous connective tissue is present in a

much g r e a t e r amount than in a suture, but the fit

between the bones is not quite as tight. The

fibrous connective tissue forms an inter osseous

membrane or ligament. It is slightly moveable

and some flexibility is permitted by the

interosseous membrane or ligament. Functionally

it is cl assified as amphiarthrotic.

EXAMPLE: Distal ends of tibia and fibula.

C.) GOMPHOSIS - is a fibrous Joint in which a

cone-shaped peg fits into a socket. The

intervening substance is the periodontal

ligament. It is functionally classified as

synarthrotic.

EXAMPLE_: Roots of teeth in alve oli

(sockets).

II. CARTILAGINOUS JOINTS - have no joint cavity

and the articulating bones are tightly connected

by cartilage. They allow l i t t l e or no movement.

There are two types:

A.) SYNCHONDROSIS - is a joint in which the

connecting material is hyaline cartilage . The

most common type is the EPIPHYSEAL PLATE. It is

found between the epiphysis and diaphysis of a

growing bone and is immovable. Classified as

synarthrotic. It is eventually replaced by bone

when growth ceases, the joint is temporary. It

is replaced by a synostosis. Another example is

the Joint between the f i r s t rib and the sternum.

The c a r t i l a g e undergoes ossification during

adult l i f e .

B.) SYMPHYSIS - is a joint which the connecting

material Is a broad, flat disc of

fibrocartilage. It is found between bodies of

vertebrae. A portion of the int ervertebral disc

is cartilaginous material. The symphysis pubis

between the anterior surface of the coxal bone

is another example. These joints are slightly

movable or amphiarthrotic.

IV. SYNOVIAL JOINTS - is a joint in which there is a

space between articulating bones. They are f r e e l y

movable, functionally classified as diarthrotic.

A.) STRUCTURE:

1.) SYNOVIAL , (JOINT) CAVITY - is the space

between the articulating bones.

2.) ARTICULAR CARTILAGE - covers the surface of the articulating bones, but does not bind the

bone.: together. It is hyaline c artilage.

3.) ARTICULAR CAPSULE - is s ieve - like capsule the encloses the synovial c a v i t y and unites

the articulating bones. It has two types of

l a y e r s :

a.) FIBROUS CAPSULE - is the outer layer and

consists of dense connective (collagenous)

tissue. It is attached to the periosteum

of the articulating bones at a variable

distance from the edge of the articular

cartilage. The flexibility of the fibrous

capsule permits movement at a Joint,

whereas its great tensile strength r e s i s t s

dislocation. Some fibrous capsules have

fibers arranged in parallel bundles,

called ligaments. They resist recurrent

strain, and their strength is one of the

principal factors in holding hone to bone.

b.) SYNOVIAL MEMBRANE - is the inner layer, it is

composed of loose connective tissue with elastic

f i b e r s and a variable amount of adipose tissue. It

secretes SYNOVIAL FLUID which lubricates the joint

and provides nourishment for the articular

cartilage. It removes microbes and debris winch

results from wear and tear in the joint. It

consists of hyaluronic acid and an interstitial

fluid formed from blood plasma and is similar in

appearance and consistency to egg white. When there

is no joint movement, the fluid becomes VISCOUS but

as movement increases, the fluid becomes less

viscous. The amount present in each joint is

sufficient only to form a thin film over the

surfaces within an articular capsule.

4.) ACCESSORY LIGAMENTS - are of two types.

a.) EXTRACAPSULAR LIGAMENTS - are outside of the articular capsule.

EXAMPLE: Fibular collateral ligament of

the knee joint

b.) INTRACAPSULAR LIGAMENTS - occur within the articular capsule, but are excluded from the

synovial cavity by reflections of the

synovial membrane.

EXAMPLE: Cruciate ligaments of the knee Joint.

5.) ARTICULAR DISCS (MENISCI - are the pads of

fibrocartilage (inside some synovial Joints)

that lie between the articular surfaces of the

hones and are attached by their margins to the

fibrous capsule. They are usually subdivide the

synovial cavity into two separate spaces. They

allow two bones of different shapes to fit

tightly; they modify the shape of the joint

surfaces of the articulating bones. They also

help to maintain the stability of the joint and

direct the flow of the synovial fluid to areas of

greatest friction.

6.) BURSAE - are sac-like structures situated in the

body of tissues. The sacs resemble Joints in that

their walls consist of connective tissue lined by a

synovial membrane. Also, filled with a fluid

similar to synovial fluid. They are located

between the skin and bone in places where akin rubs

over hone, and also between tendons and bones,

muscles and bone, and

ligaments and bones. They cushion the

movement of one part of the body over

another. BURSITIS is an inflammation of a

bursa.

7.) FACTORS that keep Joints in contact with

each other.

a.) FIT of articulating bones. (hip joint)

b.) STRENGTH of Joint ligaments. (hip Joint)

c.) TENSION of the muscles around the joint. (the fibrous capsule of the knee Joint Is

formed principally from tendinous

expansions by muscles acting on the

joint.

B.) MOVEMENTS - permitted at synovial joints are

limited by several factors.

1.) APPOSITION OF SOFT PARTS - during the bending of the elbow, the anterior surface of the

forearm is pressed against the an t e r i o r

surface of the arm. Thus it limits movement.

2.) TENSION OF LIGAMENT - the different components of a fibrous capsule a r e tense only when the joint

is in certain p os i t i o n s. Tense ligaments not

only r e s t r i c t the range of movement but also

direct the movement of the articulating bones

with respect to each other.

EXAMPLE: Knee Joint the major ligaments are

lax when the knee is bent, but tense when the

knee is straightened. Also, when the knee is

straightened, the surfaces of the

articulating bones are in fullest contact

with each other.

3.) MUSCLE TENSION - which re i n f o r ce s the restraint placed on a joint by ligaments.

EXAMPLE: Hip Joint

4.) STRUCTURE OF THE ARTICULATING BONES 5.) SPECIFIC MOVEMENTS

a.) GLIDING - one s u r f a c e moves back and

forth and from side to side over another

surface without angular or r o ta ry motion.

b.) ANGULAR - there is an increase or

decrease at the angle between bones.

1.) FLEXION - usually involves a decrease in the angle between the

anterior surfaces of articulating

bones.

2.) EXTENSION - usually involves an increase in the angle between

the anterior s u r f a c e s of

articulating bones.

3.) HYPEREXTENSION - continuation of extension beyond the

anatomical position.

4.) ABDUCTION - movement of a bone away the midline.

5.) ADDUCTION - movement of a bone toward the midline.

c.) ROTATION - movement of a bone around its

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longitudinal axis; may be medial or

lateral.

d.) CIRCUMDUCTION - a movement in which the distal end of a bone moves in a circle

while the proximal end remains stable.

e.) SPECIAL - occurs at specific Joints. 1.) INVERSION - movement of the sole of

the foot inward at the ankle Joint.

2.) EVERSION - movement of the sole of the foot outward at the ankle joint.

3.) DORSIFLEXION - flexion of the foot at the ankle Joint.

4.) PLANTAR FLEXION -- extension of the foot at the ankle Joint.

5.) PROTRACTION - movement of the mandible or clavicle forward on a

plane parallel to the ground.

6.) RETRACTION - movement of the protracted part backward on a plane

parallel to the ground.

7.) SUPINATION - movement of the forearm

in which the palm is turned anterior

or superior.

3.) PRONATION - movement of the flexed

forearm in which the palm is

posterior or Inferior.

9.) ELEVATION - movement of a part of the body upward.

10.) DEPRESSION - movement of a part of the body downward.

C.) TYPES - all synovial joints are similar in

structure, variations exist in the shape of the

articulating surfaces. They are six subtypes:

1.) GLIDING - articulating surfaces usually flat. MOVEMENT: nonaxial

EXAMPLE: lntercarpal and intertarsal Joints

2.) HINGE - s p o o l - l i k e surface fits into a concave surface.

MOVEMENT: monaxial (flexion-extension)

EXAMPLE: elbow, ankle, and interphalanges

joints

3.) PIVOT - rounded, pointed, or concave surface fits into a ring formed partly by bone and

partly by a ligament.

MOVEMENT: monaxial (rotation)

EXAMPLE: atlantoaxial and rodioulnar joints

4.) ELLIPSOIDAL - oval-shaped condyle fits into an elliptical cavity.

MOVEMENT: biaxial (flexion-extension,

abduction-adduction)

EXAMPLE: radiocarpal Joint

5.) SADDLE - articular surfaces concave in one

direction and convex in opposite direction.

MOVEMENT: biaxial (flexion-extension,

abduction-adduction)

EXAMPLE: carpometacarpal joint of thumb

6.) BALL-AND-SOCKET - ball-like surface fits into a

cuplike depression.

MOVEMENT: triaxial (flexion-extension,

abduction-adduction, rotation)

EXAMPLE: shoulder and hip joints

V. SUMMARY OF JOINTS - based on movement:

A.) SYNARTHROSES - immovable joints

1.) SUTURE 2.) SYNCHONDROSIS 3.) GOMPHOSIS

B.) AMPHIARTHROSES - slightly movable joints

1.) SYNDESMOSIS 2.) SYNPHYSIS

C.) DIARTHROSES - freely movable Joints

1.) GLIDING 2.) HINGE 3.) PIVOT 4.) ELLIPSOIDAL the most freely moveable joint 5.) SADDLE 6.) BALL-AND-SOCKET

VI. HUMEROSCAPULAR (SHOULDER) JOINT - is formed by the head

If the humerus and the glenoid cavity of the scapula. It

is a ball-and-socket (spheroid) Joint. Its anatomical

components are:

A.) ARTICULAR CAPSULE - Loose sac that completely envelops the joint, extending from the circumference of the

glenoid cavity to the anatomical neck of the humerus.

B.) CORACOHUMERAL LIGAMENT - Strong, broad ligament that

extends from the coracoid process of the scapula to

the greater tubercle of the humerus.

C.) GLENOHUMERAL LIGAMENTS - Three thickenings of the

articular capsule over the ventral surface of the

joint.

D.) TRANSVERSE HUMERAL LIGAMENT - Narrow sheet extending from the greater tubercle to the lesser tubercle of the

humerus.

E.) GLENOID LABRUM - Narrow rim of fibrocartilage around

the edge of the glenoid cavity.

F.) BURSAE - associated with the shoulder are: 1.) SUBSCAPULAR BURSA - between the tendon of the

subscapularis muscle and the underlying joint

capsule.

2.) SUBDELTOID BURSA - between the deltoid muscle and joint capsule.

3.) SUBACROMIAL BURSA - between the acromion and Joint capsule.

4.) SUBCORACOID BURSA - either lies between the coracoid process and Joint capsule or appears as

an extension from the subacromial bursa.

VII. COXAL (HIP) JOINT - is formed by the head of the femur

and the acetabulum of the coxal bone. It is a ball-and

socket joint. Its anatomical components are:

A.) ARTICULAR CAPSULE - Extends from the rim of the acetabulum to

the neck of the femur. One of the strongest ligaments of the

body, the capsule consists of circular and longitudinal fibers.

The circular fibers, called the ZONA ORBICULARIS, form a collar

around the neck of the femur. The longitudinal fibers are

reinforced by accessory ligaments known as the ILIOFEMORAL

LIGAMENT, PUBOFEMORAL LIGAMENT, AND ISCHIOCHANTERIC LIGAMENT.

B.) ILIOFEMORAL LIGAMENT - Thickened portion of the

articular capsule that extends from the anterior

inferior iliac spine of the coxal bones to the

tntertrochanteric line of the femur.

C.)PUBOFEMORAL LIGAMENT - Thickened portion of the articular capsule that

extends from the public part of the rim of the acetabulum to the neck of

the femur.

D.) ISCHIOFEMORAL LIGAMENT - Thickened portion of the articular capsule that extends from the Ischlal wall of the

acetabulum to the neck of the femur.

E.) LIGAMENT OF THE HEAD OF THE FEMUR - (capitate ligament) - Flat, triangular band that extends from the fossa of the

acetabulum to the head of the femur.

F.) ACETABULUM LABRUM - Fibrocartilage rim attached to the margin of the acetabulum.

G.) TRANSVERSE LIGAMENT OF THE ACETABULUM - Strong ligament that crosses over the acetabular notch, converting it to a

foramen. It supports part of the acetabulum labrum and is

connected with the ligament of the head of the femur and the

articular capsule.

VIII. TIBIOFEMORAL (KNEE) JOINT - is the largest Joint of the

body, actually consisting of three Joints:

A.) INTERMEDIATE PATELLOFEMORAL JOINT between the patella and the patellar surface of the femur. Is a gliding

(arthrodial) Joint.

B.) LATERAL TIBIOFEMORAL JOINT between the lateral condyle of the femur, lateral meniscus, and lateral condyle of the

tibia. Is a hinge (ginglymus) joint.

C.) MEDIAL TIBIOFEMORAL JOINT between the medial condyle of

the femur, medial meniscus, and medial condyle of the

tibia. Is a hinge (ginglymus) joint.

D.) ANATOMICAL COMPONENTS:

i.) ARTICULAR CAPSULE - No complete, independent capsule

unites the bones. The ligamentous sheath surrounding the

Joint consists mostly of muscle tendons or expansions of

them. There are, however, some capsule fibers connecting

the articulating bones.

2.) MEDIAL AND LATERAL PATELLAR RETINACULA - Fused tendons

of insertion of the quadriceps femoris muscle and the

fascia lata that strengthen the

anterior surface of the Joint.

3.) PATELLA LIGAMENT - Central portion of the common

tendon of Insertion of the quadriceps femoris

muscle that extends from the patella to the

tibial tuberosity. This ligament also

strengthens the anterior surface of the joint.

The posterior surface of the ligament is

separated from the synovial membrane of the

joint by and INFRAPATELLAR FAT PAD.

1.) OBLIQUE POPLITEAL LIGAMENT - Broad, flat ligament

that connects the Intercondylar fossa of the femur

to the head of the tibia. The tendon of the

semimembranosus muscle id superficial to the

ligament and passes from the medial condyle of the

tibia to the lateral condyle of the femur. The

ligament and tendon afford strength for the

posterior surface of the Joint.

5.) ARCUATE POPLITEAL LIGAMENT - Extends from the lateral condyle of the femur to the styloid

process of the head of the fibula. It

strengthens the lower lateral part of the

posterior surface of the Joint.

6.) TIBIAL COLLATERAL LIGAMENT - Broad, flat ligament on the medial surface of the Joint

that extends from the medial condyle of the

femur to the medial condyle of the tibia. The

ligament is crossed by tendons of the

sartorius, gracilis, and semitendinosus muscles,

all of which strengthen the medial aspect of the

Joint.

7.) FIBULAR COLATERAL LIGAMENT,- Strong, rounded ligament on the lateral surface of the Joint that

extends from the lateral condyle to the femur to

the lateral side of the head of the fibula. The

ligament is covered by the tendon of the biceps

femoris muscle. The tendon of the popliteal

muscle is deep to the tendon.

8.) INTRAARTICULAR LIGAMENTS - Ligaments within the capsule that connect the tibia and femur.

a.) ANTERIOR CRUCIATE LIGAMENT - Extends posteriorly and laterally from the area

anterior to the lntercondylar eminence of

the tibia to the posterior part of the

medial surface of the lateral condyle of

the femur. This ligament is stretched or

torn in about 70% of all serious knee

Injuries.

b.) POSTERIOR CRUCIATE LIGAMENT - Extends anteriorly and medially from the posterior

lntercondylar fossa of the tibia and

lateral meniscus to the anterior part of

the medial surface of the medial condyle of

the femur.

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9.) ARTICULAR DISCS - Fibrocartilage discs between

the tibial and femora condyles. They help to

compensate for the incongruence of the

articulating bones.

a.) MEDIAL MENISCUS - Semicircular piece of flbrocartilage. Its anterior end is

attached to the anterior intercondylar

fossa of the tibia, in front of the

anterior cruciate ligament. Its posterior

end is attached to the posterior

interccndylar fossa of the tibia between the

attachments of the posterior cruciate

ligament and lateral meniscus.

b.) LATERAL MENISCUC - Circular piece of fibrocartilage. Its anterior end is

attached to the intercondylar eminence of the

tibia and lateral and posterior to the

anterior cruciate ligament. Its posterior end

Is attached posterior to the

intercondylar eminence of the tibia and

anterior to the posterior end of the medial

meniscus. The medial and lateral menisci are

connected to each other by the TRANSVERSE

LIGAMENT and to the margins of the head of

the tibia by the CORONARY LIGAMENT.

10.) BURSAE - the principal bursae of the knee:

a.) ANTERIOR BURSAE

1.) PREPATELLAR BURSAE - between the patella and skin.

2.) INFRAPATELLAR BURSAE - between upper part of tibia and patellar ligament.

3.) SUPRAPATELLAR BURSAE - between lower part of tibial tuberosity and skin,

and between lower part of femur and

deep surface of quadriceps femoris

muscle.

B.) MEDIAL BURSAE

1.) Between medial head of gastrocnemius muscle and the articular capsule.

2.) Superficial t the tibial collateral ligament between the ligament and

tendons of the sartortus, gracilis,

and semitendinosus muscles.

3.) Deep to the tibial collateral ligament between the ligament and the

tendon of the semimembraosus muscle.

4.) Between the tendon of the semimembranous muscle and the head of

the tibia.

5.) Between the tendons of the semimembranosus and semitendinosus

muscles.

c.) LATERAL BURSAE

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1.) Between the lateral head of the gastrocnemius muscle and articular

capsule.

2.) Between the tendon of the biceps femoris muscle and fibular collateral

ligament.

3.) Between the tendon of the popliteal muscle and fibular collateral

ligament.

4.) Between the lateral condyle of the femur and the popliteal muscle.

IX. DISORDERS: HOMEOSTATIC IMBALANCES

A.) RHEUMATISM - is a painful state of supporting body structures such as bones, ligaments, tendons,

Joints, and muscles.

B.) ARTHRITIS - refers to several disorders characterized by inflammation of Joints, often

accompanied by stiffness of adjacent structures.

C.) RHEUMATOID ARTHRITIS (RA) - refers to inflammation of a Joint accompanied by pain, swelling, and loss

of function.

D.) OSTEOARTHRITIS - is a degenerative Joint disease characterized by deterioration of articular

cartilage and spur formation.

E.) GOUTY ARTHRITIS - is a condition in which sodium urate crystals are deposited in the soft tissues of

Joints and eventually destroy the tissues.

F.) BURSITIS - is an acute or chronic inflammation of bursae.

G.) DISLOCATION - (luxation) - is a displacement of a bone from its Joint; a partial dislocation is called

SUBLUXATION.

H.) SPRAIN - is the forcible wrenching or twisting of a Joint with partial rupture to its attachments with-

out dislocation.

I.) STRAIN, - is the stretching of a muscle.

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CHAPTER # 1 0 - MUSCLE TISSUE

Muscle tissue constitutes about 40-50% of the total body

weight and L. composed of highly specialized cells.

MYOLOGY - is the scientific study of the muscles.

I. CHARACTERISTICS - Muscle tissue has four principal

characteristics that assume key roles in maintaining

homeostasis.

A.) EXCITABILITY - is the ability of muscle tissue, to receive and respond to stimuli. A stimulus is a

change in the internal or external environment

strong enough to initiate a nerve impulse (action

potential).

B.) CONTRACTILITY - Is the ability to shorten and

thicken, or contract, when a sufficient stimulus is

received.

C.) EXTENSIBILITY - is the ability of muscle tissue to be stretched (extended). Many skeletal muscles are

arranged in opposing pairs. While one is

contracting, the other is relaxed and is undergoing

extension.

D.) ELASTICITY - Is the ability of muscle to return to its original shape after contraction or extension.

II. FUNCTIONS - through contraction, muscle performs three

important functions:

A.) MOTION - is obvious in movements involving the whole

body, such as walking and running, and in localized

movements, such as grasping a pencil or nodding the

head. All of these movements rely on the integrated

functioning of the bones, joints, and muscles

attached to the bones. Less noticeable kinds of

motion produced by muscles are the beating of the

heart, and churning of food in the stomach.

B.) MAINTAIN POSTURE - muscle tissue enables the body to

maintain posture. The contraction of skeletal muscles

holds the body in stationary positions, such as

standing and sitting.

C.) HEAT PRODUCTION - skeletal muscle contractions

produce heat and are thereby important in

maintaining normal body temperature. It has been

estimated that as much as 35% of all body heat is

generated by muscle contraction.

III. TYPES - of muscle tissue are categorized by location,

microscopic structure, and nervous control.

A.) SKELETAL MUSCLE TISSUE - which i s named for its

location, Is attached to bones and moves parts of

the skeleton. It is STRIATED muscle tissue because

striations, or bandlike structures, are visible when

the tissue id examined under a microscope. It is a

VOLUNTARY muscle tissue because it can be made to

contract by conscious control.

SUMMARY: Skeletal, striated, voluntary muscle

tissue.

B.) CARDIAC MUSCLE TISSUE - forms the bulk of the wall of

the heart. It is STRIATED and INVOLUNTARY, that is, its contractions usually not under conscious control.

SUMMARY: Cardiac, striated, involuntary muscle

tissue.

C.) SMOOTH MUSCLE TISSUE - is involved with processes

related to maintaining the internal environment. It is

located in the walls of hollow internal structures,

such as blood vessels, the stomach, and the

intestines. It is referred to as NONSTRIATED because

it lacks striations. It is INVOLUNTARY muscle tissue.

SUMMARY: Smooth, nonstriated, involuntary muscle

tissue.

IV. SKELETAL MUSCLE TISSUE,

A.) CONNECTIVE TISSUE COMPONENTS :

1.) FASCIA - is the sheet or broad band of fibrous

connective tissue beneath the skin or around

muscles and other organs of the body.

2.) SUPERFICIAL FASCIA (subcutaneous layer) - Is

immediately deep to the skin. It is composed of

adipose tissue and loose connective tissue and has

a number of important functions:

a.) Storehouse for water and particularly for

fat.

b.) It forms a layer of insulation protecting

the body form loss of heat.

c.) It provides mechanical protection from

blows.

d.) It provides a pathway for nerves and

vessels.

3.) DEEP FASCIA - is a dense connective tissue that

lines the body wall and extremities and holds

muscles together, separating them into functioning

groups. Functions:

a.) Allows free movement of muscles. b.) Carries nerves and blood vessels. c.) Fills spaces between muscles. d.) Sometimes provides the origin for muscles.

4.) EPIMYSIUM - is the substantial quantity of fibrous

connective tissue that the entire muscle is usually

wrapped with. It is an extension of deep fascia. It

is continuous with the connective tissue that

attaches the muscles to another structure, such as

bone or other muscle.

5.) FASCICULI OR FASCICLES - are the bundles of fibers

(cells), when the muscle is cut in cross section,

invaginations of the epimysium are seen to divide

the muscle Into bundles of fibers (cells).

6.) PERIMYSIUM - is the invaginations of the

epimysium. It is an extension of deep fascia. It

continuous with the connective tissue that attaches the

muscle to another structure, such as bone or other

muscle.

7.) ENDOMYSIUM - is the invaginations of the perimysium, they

penetrate into the interior of each fascicle and separate

the muscle fibers. It is an extension of deep fascia. It

is continuous with the connective tissue that attaches

the muscle to another structure, such as bone or other

muscle. g.)

TENDONS - a cord of connective tissue that attaches a

muscle to the periosteum of a bone. Epimysium,

perimysium, and endomysium may be extended beyond the

muscle cells as a tendon.

9.) APONEUROSIS TENDON - is when the connective tissue elements extend as a broad, flat layer. This structure

also attaches to the covering of a bone or another

muscle. EXAMPLE: Galea Aponeurotica

10.) TENDON SHEATHS - is the tubes of fibrous connective tissue that enclose certain tendons,

especially those of the wrist and ankle. They

are similar in structure to bursae. The inner

layer , the visceral layer, is applied to the

surface of the tendon. The outer layer, parietal

layer. And between layers is a cavity that

contains a film of synovial fluid. Tendon

sheaths permit tendons to slide easily and also

prevent tendons from slipping out of place.

B.) NERVE AND BLOOD SUPPLY - generally, an artery and one or two

veins accompany each nerve that penetrates a skeletal muscle.

The larger branches of the blood vessels accompany the nerve

branches through the connective tissue of the muscle. Microscopic blood vessels called capillaries are distributed

within the endomysium. Each muscle cell is thus in close

contact with one or more capillaries. Each skeletal muscle

fiber usually makes contact with a portion of a nerve cell

called a synaptic end bulb.

1.) Nerves convey impulses for muscular contraction. 2.) Blood provides nutrients and oxygen for

contraction.

C.) HISTOLOGY:

1.) Skeletal muscles consists of fibers (cells) covered by

a SACOLEMMA -plasma membrane. The fibers contain:

a.) SARCOPLASMA - cytoplasm which Is surrounded by the sarcolemma.

b.) NUCLEI - there are many within the sacroplasm

of a muscle fiber and lying close t the

sarcolemma.

c.) SARCOPLASMIC RETICULUM - is a network of membrane-enclosed tubules comparable to

P a g e 1 1 1

smooth endoplasmic reticulum.

d.) TRANSVERSE TUBULES - they run transversely

through the fiber and perpendicularly to the

sarcoplasmic reticulum. They are extensions

of the sarcolemma that open to the outside of

the fiber.

e.) TRIAD - consists of a transverse tubules and the segments of sarcoplasmic reticulum on

either side.

2.) Each fiber contains MYOFIBRILS (CYLINDRICAL

STRUCTURES) that consist of THIN AND THICK

MYOFILAMENTS. The myofilaments are

compartmentalized into SARCOMERES

a.) SARCOMERES -which are separated from one

another by narrow zones of dense material

called Z LINES. Certain areas can be

distinguished:

1.) ANISTROPIC or A BAND - a dark, dense

area, It represents the length of

thick myofilaments. Its sides are

darkened by the overlapping of thick

and thin myofilaments. The greater

the degree of contraction, the greater

the overlapping of thick and thin

myofilaments.

2.) ISOTROPIC BAND or I BAND - a light-

colored,less dense are, It is

composed of thin myofilaments only. The

combination of alternating dark A

bands and light I bands gives the

muscle fiber its striated appearance.

3.) H ZONE - is narrow, and only contains

thick myofilament.

4.) M LINE - is in the center of the H

zone, it is a series of fine threads

that appear to connect the middle

parts of adjacent thick myofilaments.

3.) Thin myofilaments are anchored in the Z lines

and project In both directions. They are

composed of:

a.) ACTIN - a protein b.) TROPOMYOSIN - a protein, It is involved in

the regulation of muscle contraction. It

is arranged in strands that are loosely

attached to the actin helices.

c.) TROPONIN - a protein, It is involved in the

regulation of muscle contraction. It is

located at regular intervals on the surface

of tropomyosin and is made up of three

subunits:

1.) TROPONIN I - which binds to actin. 2.) TROPONIN C - which binds to calcium

ions.

3.) TROPONIN T - which binds to

tropomyosin.

d.) TROPOMYOSIN-TROPONIN COMPLEX - is tropomyosin and

troponin together.

I.) Thick myofilament consist mostly of myosin. a.)

a.)MYOSIN - is a protein, shaped like a golf club. The tails

(handles of the golf club) are arranged parallel to each

other forming the shaft of the thick myofilament. The

heads of the golf clubs project outward from the shaft and

are arranged spirally, on the surface of the shaft.

b.) CROSS BRIDGES - is the projecting heads, and contain an

actin-binding site and an ATP-binding site.

D.) CONTRACTION - SLIDING-FILAMENT THEORY

1.) A nerve impulse travels over the sarcolemma and enters the

transverse tubules and sarcoplasmic reticulum.

2.) The nerve impulse leads to the release of calcium ions from the sarcoplasmic reticulum, trigging the contractile process.

3.) Actual contraction is brought about when the thin myofilaments of a sarcomere slide toward each other.

E.) NEUROMUSCULAR JUNCTION (MOTOR END PLATE) - for a skeletal fiber to

contract, a stimulus must be applied to it.

1.) NEURON - is the nerve cell that delivers the stimulus. 2.) AXON - (fiber) is the threadlike process on the neuron. 3.) MOTOR NEURON - is a neuron that stimulates a muscle tissue. It

transmits a nerve impulse to a skeletal muscle for contraction.

4.) NEUROMUSCULAR (MYONEURAL) JUNCTION OR MOTOR END PLATE - refers to the axon terminal of a motor neuron together with the portion of

the sacrolemma of a muscle fiber In close approximation with the

axon terminal.

5.) SYNAPTIC END BULB - is where the distal ends of are expanded into bulblike structures.

6.) SYNAPTIC VESICLES - is the membrane-enclosed

sac in the synaptic end bulbs.

7.) NEUROTRANSMITTERS - the chemicals stored in the

synaptic vesicles. These chemicals determine

whether a nerve impulse Is passed on to a muscle

gland, or another nerve cell.

8.) SYNAPTIC GUTTER (TROUGH) - is the invaginated

area of the sarcolemma under the axon terminal.

9.)SYNAPTIC CLEFT - is the space between the axon

terminal and sarcolemma.

10.)SUBNEURAL CLEFTS - is the numerous folds of

the

Sarcolemma along the synaptic gutter. It greatly increases

the surface area of the synaptic gutter.

11.) ACETYLOCHOLINE OR ACh – is the neurotransmitter released at neuromuscular junctions. Upon its

release, Ach diffuses across the sarcolemma of the

muscle fiber. This combination alters the

permeability of the sarcolemma and ultimately

results in the development of a nerve impulse that

travels along the sarcolemma, thus initiating the

events leading to contraction.

F.)MOTOR UNIT – a motor neuron and the muscle fiber it

stimulates forms a motor unit. A single motor unit may

innervate up to 500 muscle fibers. All the muscle fibers of

a motor unit that are sufficiently stimulated will contract

and relax together. The process of increasing the number of

active motor units is called RECRUITMENT and is determined

by the needs of the body at a given time. The various motor

neurons to a given muscle fore asynchronously, that is,

while some are excited, others are inhibited. Asynchronous

firing of motor neurons prevents fatigue while maintaining

contraction by allowing a brief rest for the inactive units.

G.) PHYSIOLOGY OF CONTRACTION, - Summary

1.) When a nerve impulse reaches an axon terminal, the synaptic vesicles of the terminal release

acetylcholine (ACh), which initiates a nerve

impulse in the muscle fiber sarcolemma. The

impulse then travels into the transverse tubules

and sarcoplasmic reticulum.

2.) The transmitted impulse releases calcium ions that combine with troponin, causing It to pull

on tropomyosin, thus exposing myosin-binding

sites on actin.

3.) The energy released from the breakdown of ATP causes myosin cross bridges to attach to actin,

and their movement results in the sliding of thin

myofilaments.

H.) ENERGY FOR CONTRACTION - ATP is the immediate,

direct source of energy for muscle contraction. Like

other cells of the body, muscle fibers synthesize

ATP as follows:

ADP + P + ENERGY ATP

Muscle fibers have several basic mechanisms for

generating ATP continuously.

1.) The first involves a high-energy molecule called

PHOSPHOCREATINE found in muscle fibers in

concentrations about five times that of ATP. It

can decompose to creatine and phosphate and, in

the process, large amount of energy are released:

PHOSPHOCREATINE CREATINE + PHOSPHATE + ENERGY

The released energy is used to convert ADP to

ATP. Together phosphocreatine and ATP provide

only enough energy for muscles to contract

maximally for about 15 seconds.

2.) When this is depleted, then the source of energy is derived from the breakdown of glycogen. Glycogen,

which is stored glucose, is always present in

skeletal muscles and the liver. Its breakdown

results in the resynthesis of tremendous quantities

of ATP. Sufficient ATP for maximal muscle

contraction for several minutes.

3.) If exercise continues to the point where even most of the glycogen is catabolized, then muscle fibers

can break down fats to provide energy to

resynthesize ATP. The supply of energy from fats to

resynthesize ATP is almost inexhaustible since fats

need only to be replaced at meals.

I.) MUSCLE LENGTH AND FORCE CIE CONTRACTION (TENSION), -

A muscle fiber develops its greatest tension where

there is maximum overlap between thick and thin

myofilaments. At this length, the optimal length,.

the maximum number of myosin cross bridges make

contact with thin myofilaments to bring about the

greatest force of contraction. If a muscle fiber is

stretched to 175% its optimal length, no myosin

cross bridges attach to thin myofilaments and no

contraction occurs. At lengths less than the optimum

length, the force of contraction also decreases. In

general, changes in resting muscle fiber length

above or below the optimum length rarely exceed 30%.

J.) ALL-OR-NONE PRINCIPLE - SUMMARY

1.) The weakest stimulus capable of causing contraction is a liminal (threshold) stimulus.

2.) A stimulus not capable of inducing contraction is a subliminal (subthreshold) stimulus.

3.) Muscle fibers of a motor unit contract to their fullest extent or not at all.

K.) KINDS of CONTRACTIONS - the various skeletal muscles

are capable of producing different kinds of

contractions, depending on the stimulation

frequency.

1.) TWITCH - is a rapid, jerky response to a single

stimulus. The record of muscle contraction is

called a MYOGRAM.

A.) LATENT PERIOD - is that brief period of

between application of the stimulus and

the beginning of contraction. (in frogs,

it last about 10 milliseconds (msec))

b.) CONTRACTION PERIOD - the second phase, last about 40 msec and is indicated by the upward

tracing.

c.) RELAXATION PERIOD - the third phase, last

about 50 msec and is indicated by the

downward tracing.

NOTE: The duration of these periods caries

with the muscle involved.

d.) REFRACTORY PERIOD - is the period of lost

irritability. If two stimuli are applied one

immediately after the other, the muscle will

respond to the first stimuli but not to the

second. When a muscle fiber receives enough

stimulation to contract, it temporarily loses

it irritability (refractory period) and

cannot contract again until Its

responsiveness is

regained.

2.) TETANUS - When two stimuli are applied and the

second is delayed until the refractory period is

over, skeletal muscle will respond to both

stimuli. Relaxation is either partial or does not

occur at all. Voluntary contractions, such as

contraction of the biceps brachii muscle in order

to flex the forearm, are tetanic contractions. In

fact, most of the work we do involves short-term

tetanic contractions.

a.) WAVE SUMMATION - is the phenomenon caused

if the second stimulus is applied after

the refractory period, but before the

muscle has finished relaxing, the second

contraction will be strong than the

first.

b.) INCOMPLETE (UNFUSED), TETANUS, - if a frog

muscle is stimulated at a rate of 20 to

30 stimuli per second, the muscle can

only partly relax between stimuli. As

the result, the muscle maintains a

sustained contraction called incomplete

(unfused) tetanus.

c.) COMPLETE (FUSED) TETANUS - If stimulation

at an increased rate (35 to 50 per

second) results in a sustained

contraction that lacks even partial

relaxation, complete (fused) tetanus.

3.) TREPPE - is the condition in which skeletal muscle contracts more forcefully in response to the same

strength of stimulus after it has contracted

several times, the staircase

phenomenon. It is the principle athletes use

when warming up. It is demonstrated by

stimulating an isolated muscle with a series of

stimuli at the same frequency and intensity, but

not at a rate fast enough to produce

tetanus. Time must be allowed for the muscle to

undergo Its latent period, contract, and relax.

4.) ISOTONIC AND ISOMETRIC - The two forces - contraction and stretching - applied in

opposite directions create the tension. The

tension developed In a muscle for performing any

kind of action depends of the total number of

muscle fibers contracting at a time and the

amount of tension each muscle fiber generates.

Although both isotonic and isometric training

methods are able to increase muscular strength in

relatively short periods, studies where direct

comparisons are made tend to favor isotonic

methods. The greatest advantage of isotonic

exercise is that it works all the involved

muscles over the entire range of a particular

movement. Some experiments indicate that greater

muscle enlargement (hypertrophy) and endurance

result from isotonic exercise.

1.) ISOTONIC CONTRACTIONS - are probably familiar to you. As the contraction

occurs, the muscles shortens and pulls on

another structure, such as a bone, to

produce movement. During such a

contraction, the tension remains constant

and energy is expended.

2.) ISOMETRIC CONTRACTION - there is a minimal

shortening of the muscle. It remains nearly

the same length but the tension of the

muscle Increases greatly.

L.MUSCLE TONE - is the results of a sustained partial

contraction of portions of a skeletal muscle in

response to activation of stretch receptors. Tone Is

essential for maintaining posture. The degree of tone

in a skeletal muscle is monitored by receptors in the

muscle called MUSCLE SPINDLES. They provide feedback

information on tone to the brain so that adjustments

can be made. Flaccidity, is a condition of less than

normal tone. Atrophy Is a wasting away or decrease in

size; hypertrophy is an enlargement or overgrowth.

M.) TYPES OF SKELETAL MUSCLE FIBERS - all skeletal

muscle fibers are not alike in structure or function.

They vary in color depending on their content of

MYOGLOBIN, a reddish pigment similar to hemoglobin In

blood. Myoglobin stores oxygen until needed by

mitochondria. RED MUSCLE FIBERS, have a high

myoglobin content. WHITE, MUSCLE FIBERS have a low

myoglobin content. Red muscle fibers are smaller In

diameter than white muscle fibers, and red muscle

fibers have more mitochondria and more blood

capillaries. White muscle fibers have a more

extensive sarcoplasmic reticulum than red muscle

fibers. Skeletal muscle fibers contract with

different velocities, depending on their ability to

split ATP. They vary with respect to the metabolic

processes they use to generate ATP. They differ in

term of the onset of fatigue. On the basis of various

structural and functional characteristics, skeletal

muscle fibers are classified into three types:

1.) SLOW-TWITCH RED FIBERS - these fibers contain

large amounts of myoglobin, many mitochondria, and

many blood capillaries. They have a high capacity

to generate ATP by oxidative metabolic processes.

Such fibers also spilt ATP at a slow rate and, as

a result, contraction velocity is slow. They are

resistant to fatigue.

2.) FAST-TWITCH, RED FIBER - contain very large amounts

of myoglobin, very many mitochondria, and very many

blood capillaries. They have a very high capacity

for generating ATP by oxidative metabolic

processes. They also split ATP at a very rapid rate

and as a result, contraction velocity is fast. They

are resistant to fatigue, but not quite as much as

slow-twitch red fibers.

3.) FAST-TWITCH WHITE FIBER - have a low content of myoglobin, relatively few mitochondria and

relatively few blood capillaries. They do,

however, contain large amounts of glycogen. They

are geared to generating ATP by anaerobic

metabolic processes, and the processes are not

able to supply skeletal muscle fiber continuously

with sufficient ATP. Accordingly, they fatigue

easily, but they split ATP at a fast rate so that

contraction velocity is fast.

NOTE: Most skeletal muscles of the body are a mixture of

all three types of skeletal muscle fibers, but

their proportion varies depending on the usual

action of the muscle. The different skeletal

muscle fibers in a muscle may be used in various

ways, depending on need.

a.) WEAK CONTRACTIONS - slow-twitch red fibers b.) STRONGER CONTRACTIONS - fast-twitch red fibers c.) MAXIMAL CONTRACTION - fast-twitch white fibers

Activation of various motor units is determined in

the brain and spinal cord.

V. CARDIAC MUSCLE TISSUE - SUMMARY

A.)It is only found in the heart wall. It is striated and involuntary.

B.)The cells are quadrangular and usually contain

single centrally located nucleus.

C.) Compared to skeletal muscle tissue, cardiac muscle

tissue has more sarcoplasm, more mitochondria, less

well-developed sarcoplasmic reticulum, and larger

transverse tubules located at Z lines rather than a A-

I band junction. Myofilaments are not arranged in

discrete myofibrils.

D.) The fibers branch freely and are connected via gap Junctions.

E.) Intercalated discs provide strength and aid impulse conduction (found only in cardiac muscle).

F.) Unlike skeletal muscle tissue, cardiac muscle tissue contracts and relaxes rapidly, continuously, and

rhythmically. Energy is supplied by glycogen and

fat in large, numerous mitochondria.

G.) Cardiac muscle tissue can contract without extrinsic

0t1mulation and can remain contracted longer than

skeletal muscle tissue.

H.) Cardiac muscle tissue has a lung refractory period

which prevents tetanus.

VI. SMOOTH MUSCLE TISSUE - SUMMARY

A.) Smooth muscle is nonstriated and involuntary. B.) Smooth muscle fibers contain thick and thin

myofilaments in a greater ratio than in skeletal

muscle fibers; it also contains intermediate

filaments, dense bodies (function as Z lines) and

caveolae (function as transverse tubules).

C.) Visceral (single-unit) smooth muscle is found in the

walls of ciscera. The fibers are arranged in a network.

D.) Multiunit smooth muscles found in blood vessels and the

eyes. The fibers operate singly rather than as a until.

E.) The duration of contraction and relaxation of smooth

muscle is longer than in skeletal muscle.

F.) Smooth muscle fibers contract in response to nerve

impulses, hormones, and local factors.

G.) Smooth muscle fibers can stretch considerably

without developing tension.

VII. HOMEOSTASIS - muscle tissue has a vital role in

maintaining the body's homeostasis. Two examples are

the relationship of muscle tissue to oxygen and to heat

production.

A.) OXYGEN DEBT - is the amount of oxygen needed to convert

accumulated lactic acid into carbon dioxide and water.

It occurs during strenuous exercise and is paid back by

continuing to breathe rapidly after exercising. Until it

is paid back, the homeostasis between muscular activity

and oxygen requirements is not restored. Muscle fatigue

results from diminished availability of oxygen and toxic

effects of carbon dioxide and lactic acid built up

during exercise. The significant factors that contribute

to muscle fatigue are:

1.) EXCESSIVE, EXERCISE - resulting in accumulation

of toxic products.

2.) MALNUTRITION - resulting in insufficient supplies of glucose and, therefore, ATP.

3.) CARDIOVASCULAR DISTURBANCES -that impair the delivery of useful substances to muscles and the

removal of waste products from muscles.

4.) RESPIRATORY DISTURBANCES - that interfere with

the oxygen supply and increase the oxygen debt.

B.) HEAT PRODUCTION -the production of heat by

skeletal muscles is an important homeostasis

mechanism for maintaining normal body temperature. Of

the total energy released during muscular

contraction, only a small amount is used for

mechanical work

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(CONTRACTION). As much as 85% can be released as

heat, which Is utilized to help maintain a normal

body temperature. Heat production by muscles may be

divided into two phases:

1.) INITIAL HEAT - which is produced by the contraction and relaxation of a muscle. It is independent of

oxygen and is associated with ATP breakdown.

2.) RECOVERY HEAT - which is produced after relaxation. It is associated with ATP

restoration, it includes the anaerobic breakdown

of glucose to pyruvic acid and pyruvic acid to

lactic acid. It also includes the aerobic

breakdown of pyruvic acid to carbon dioxide and

water and the aerobic conversion of lactic acid

to carbon dioxide and water.

C.) DISORDERS: HOMEOSTATIC IMBALANCES - SUMMARY

1.) Fibrosis is the formation of fibrous tissue where it normally does not exist; it frequently occurs

in damaged muscle tissue.

2.) Fibrositis is an inflammation of fibrous tissue. IF it occurs In the lumbar region, it is called

lumbago.,

3.) "Charleyhorse" refers to pain, tenderness and stiffness of Joints, muscles, and related

structures in the thigh.

4.) MUSCULAR DYSTROPHY - is a hereditary disease of muscles characterized by degeneration of

Individual muscle cells.

5.) MYASTHENIA GRAVIS (MG) - is a disease characterized by great muscular weakness and

fatigability resulting from Improper

neuromuscular transmission.

6.) Abnormal, contractions - include spasms, cramps,

convulsions, fibrillations, and tics.

VIII. AGING AND MUSCLE TISSUE - at about 30 years of age,

there is a progressive loss of skeletal muscle, which

is replaced by fat. There is also a decrease in muscle

strength and diminished muscle reflexes.

XI. DEVELOPMENTAL ANATOMY OF THE MUSCULAR SYSTEM - with few

exceptions, muscles develop from mesoderm. Skeletal

muscles of the head and extremities develop from general

mesoderm; the remainder of the skeletal muscles develop

from the mesoderm of somites.

P a g e 1 2 0

CHAPTER #11 - THE MUSCULAR SYSTEM

MUSCULAR SYSTEM - refers to the skeletal muscle system: the

skeletal muscle tissue and connective

tissue that make up individual muscle

organs, such as the biceps brachii muscle.

I. HOW SKELETAL MUSCLES PRODUCE MOVEMENT

A.) ORIGIN AND INSERTION - Skeletal muscles produce

movements by exerting force on tendons, which in turn

pull on bones. Most muscles cross at lest one joint

and are attached to the articulating bones that form

the joint. The attachment of a muscle tendon to the

stationary bone is called the ORIGIN. The attachment

of the other muscle tendon to the movable bone is the

INSERTION. The fleshy portion of the muscle between

the tendons of the origin and insertion is called the

BELLY (CASTER. The origin is usually proximal and the

insertion distal,

especially In the extremities.

B.) LEVER SYSTEMS AND LEVERAGE - 1.)LEVER -- In producing a body movement, hones act as

levers and Joints function as fulcrums of these levers, A

LEVER may be defined as a rigid rod that moves about on

some fixed point ca led a FULCRUM. A fulcrum may be

symbolized as . A lever is acted on at two different

points by two different forces: the RESISTANCE and

the EFFORT (E). The resistance may be regarded as a

force to overcome, whereas the effort is the force

exerted to overcome th

e resistance. EXAMPLE: When the

forearm is raised, the elbow is the fulcrum. The weight

of the forearm plus the weight in the hand is the

resistance. The shortening of the biceps branchii pulling

the forearm up is the effort.

Levers are categorized into three types

according to the positions of the fulcrum, the

effort, and the resistance.

a.) FIRST-CLASS LEVERS - the fulcrum is between the effort and resistance.

EXAMPLE: A seesaw; The head resting on the

vertebral column.

b.) SECOND-CLASS LEVER - have the fulcrum at one end, the effort at the opposite end,

and the resistance between them.

EXAMPLE: Is raising the body on the toes.

c.) THIRD-CLASS LEVERS - consist of the fulcrum at one end, the resistance at the opposite

end and the effort between them. They are

the most common levers in the body.

EXAMPLE: Is the flexing of the forearm at

the elbow.

LEVERAGE - the mechanical advantage gained by a

lever, is largely responsible for a muscle's

strength and range of movement. Strength of

movement depends on the placement of muscle

attachments. The muscle inserting closer to the

joint will produce the greater range of

movement. Range of movement also depends of the

placement of muscle attachment. Strength increases

with distance from the joint and range of movement

decreases, maximal strength and maximal range are

incompatible; strength and range vary inversely.

C.) ARRANGEMENT OF FASCICULI - skeletal muscle fibers are

arranged within the muscle in bundles called fasciculi

(fasicles). The muscle fibers are arranged in a parallel

fashion within each bundle, but the arrangement of the

fasciculi with respect to the tendons may take one of

four characteristic patterns. Fasciculi arrangement is

correlated with the power of a muscle and range of

movement. When a muscle fiber contracts, it shortens to

a length just slightly greater than half of its resting

length. Thus, the longer the fibers in a muscle, the

greater the range of movement It can produce.

1.) PARALLEL - the first pattern - the fasciculi are parallel with the longitudinal axis and

terminate at either end in flat tendons.

EXAMPLE: Is the stylohyoid muscle.

In a modification of the parallel arrangement,

called fusiform, the fasciculi are nearly

parallel with the longitudinal axis and

terminate at either end in flat tendons, but the

muscle tapers toward the tendons, where the

diameter is less than the belly.

EXAMPLE: Is the biceps branchii muscle.

2.) CONVERGENT - second pattern - a broad origin of fasciculi converges to a narrow, restricted

insertion. Such a pattern gives the muscle a

triangular shape.

EXAMPLE: Is the deltoid muscle.

3.) PENNATE - third pattern - the fasciculi are short In relation to the entire length of the muscle and

the tendon extends nearly the entire length of the

muscle. The fasciculi are directly obliquely toward

the tendon like the plumes of a feather. If the

fascicull are arranged on only one side of a

tendon, as in the extensor digitorum lonzus muscle,

the muscle is referred to as UNIPENNATE. If the

fasciculi are arranged on both sides of a centrally

positioned tendon, as in the rectus femoris muscle

the muscle is referred to as BIPENNATE.

4.) CIRCULAR - fourth pattern - the fasciculi are

arranged in a circular pattern and enclose an

orifice.

EXAMPLE: Is the orbicularis oris muscle.

D.) GROUP ACTIONS - most movements are coordinated

by several skeletal muscles acting in groups

rather than individually and most skeletal

muscles are arranged in opposing pairs at

joints, that is, flexors-ectensors, abductors-

abductors, and so on. A muscle that causes a

desired action is referred to as the PRIME MOVER

(AGONIST). Simultaneously with the contraction

of the prime mover, another muscle, called the

ANTAGONIST, is relaxing. The antagonist has an

effect opposite to that of the prime mover, that

is, the antagonist relaxes and yields to the

movement of the prime mover. Most movements also

involve muscles called SYNERGISTS which serve to

steady a movement, thus preventing unwanted

movements and helping the prime mover function

more efficiently. Some muscles in a group also

act as FIXATORS which stabilize the origin of

the prime mover so that the prime mover can act

more efficiently.

II. NAMING SKELETAL MUSCLES - the names of the nearly 700

skeletal muscles are based on several types of

characteristics:

A.) Muscle names may indicate the DIRECTION OF

THE MUSCLE FIBERS.

1.) RECTUS fibers usually run parallel to the midline of the body.

2.) TRANSVERSE fibers run perpendicular to the midline.

3.) OBLIQUE fibers are diagonal to the midline.

EXAMPLE: RECTUS ABDOMINIS, TRANSVERSE ABDOMINIS,

AND EXTERNAL OBLIQUE

B.) A muscle may be named according to LOCATION.

The temporalis is near the temporal bone.

The tibialls anterior is near the tibia.

C.) SIZE is another characteristic. The

term MAXIMUS means largest, MINIMUS

smallest, LONGUS long, and BREVIS short.

EXAMPLES: GLUTEUS MAXIMUS, GLUTEUS MINIMUS, ADDUCTOR

LONGUS, AND PERONEUS BREVIS

D.) Some muscles are named for the NUMBER OF

ORIGINS. The biceps branchii has two

origins, the triceps branchii three, and the

quadriceps femoris four.

E.) Other muscles are named on the basis of

SHAPE. EXAMPLES: DELTOID (meaning triangular)

and TRAPEZIUS

(meaning trapezoid)

F.) Muscles may be named after their ORIGIN and INSERTION.

The stenocleiodomastoid originates on the sterum and

clavicle and inserts at the mastoid process of the

temporal bone; the stylohyoid originates on the styloid

process of the temporal bone and inserts at the hyoid

bone.

G.) Still another characteristic of muscles used for

naming is ACTION. (See 11-1)

1.) FLEXOR - usually decreases the anterior angle

at a joint; some decrease the posterior angle.

EXAMPLE: Flexor Carpi Radialis

2.) EXTENSOR - usually increases the anterior angle at a joint; some increase the posterior angle.

EXAMPLE: Extensor Carpi Ulnaris

3.) ABDUCTOR - moves a bone away from the midline. EXAMPLE: Abductor Hallucis Longus

4.) ADDUCTOR – moves a bone closer to the midline. EXAMPLE: Adductor Longus

5.) LEVATOR – produces an upward movement. EXAMPLE: Levator Scapulae

6.) DEPRESSOR – produces a downward movement. EXAMPLE: Depressor Labii Inferioris

7.) SUPINATOR – turns the palm upward or anteriorly EXAMPLE: Supinator

8.) PRONATOR - turns the palm upward or posteriorly EXAMPLE: Pronator Teres

9.) SPHINCTER – decreases the size of an opening. EXAMPLE: External Anal Sphincter

10.) TENSOR – makes a body part more rigid.

EXAMPLE: Tensor Fasciae Latae

11.) ROTATOR – moves a bone around its longitudinal axis.

EXAMPLE: Obturator

III. PRINCIPAL SKELETAL MUSCLES –

Review bone markings, since they serve as points of origins and insertions for

muscles. The muscles are divided into groups according to the part of the body on

which they act.

THIS IS THE END OF THE MATERIAL FOR TEST #3

page 89 chapter #3 - the skeletal system: the …

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