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Lecture 8: Introduction to Bones

Cartilage Location and basic structure

o Found throughout adult bodyo Ear and epiglottiso Articular cartilage and coastal cartilageo Intervertebral discs and pubic symphysis

Where do you find each type of cartilage? o Is abundant in embryoo Is surrounded by perichondriumo Consists primarily of watero Resilient tissue springs back to original shape.

Types Hyaline cartilage (glassy)

o Most abundant cartilageo Provides support through flexibility

Elastic cartilage o Contains many elastic fiberso Able to tolerate repeated bending

Fibrocartilage o Resists strong compression and strong tensiono An intermediate between hyaline and elastic cartilage.

Growth of Cartilage Appositional growth

o Chondroblasts in surroundingo Perichondrium produce new cartilage

Interstitial growth o Chondrocytes within cartilage divide and secrete new matrix

Tissue in Bone Bones contain several types of tissues Dominated by bone connective tissue Contains nervous tissue and blood connective tissue Contain cartilage in articular cartilages Contains epithelial lining blood vessels

Functions of Bone Support – provides hard framework Movement – skeletal muscles use bones as levers Protections from underlying organs Mineral storage – reservoir for important minerals Blood-cell formation – bone contains red marrow.

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Classification Long bones – longer than wide, a shaft plus ends Short bones – roughly cube-shaped Flat bones – thin and flattened, usually curved Irregular bones – various shapes, do not fit into other categories Give an example of each type of bones

Gross Anatomy of Bones Compact bone – dense outer layer of bone Spongy (cancellous) bone – internal network of bones

Structure Typical of Long Bones Diaphysis – “shaft” of bone Epiphysis – ends of a bone Blood vessels – well vascularized Medullary cavity – hollow cavity filled yellow marrow Membranes

o Periosteum, perforating fibers (Sharpery’s fiber), and endosteum

Structure Typical of Flat Bones Flat bones, short bones, and irregular bones Contain bone marrow but no marrow cavity Diploe

o Internal spongy bone of flat bones

Bone Design and Stress Anatomy of a bone reflects stresses Compression and tension greatest at external surfaces

Bone Markings Pg 132, study, study, study

Chemical Composition of Bones 35% organic components

o Composed of cells, fibers, and organic substanceo Collagen – abundant

65% inorganic mineral saltso Primarily calcium phosphateo Resists compression

Bone Development Ossification (osteogenesis) – bone tissue formation

o Membrane bones formed directly from mesenchyme Intramembraneous ossification

o Other bone – develop initially from hyaline

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Endochondral Ossification

Endochondral Ossification All bones except some bones of the skull and clavicles Bones are modeled in hyaline cartilage Begins forming late in the 2nd month of embryonic development Continues forming until early adult hood.

Anatomy of Epiphyseal Growth Areas Older chondrocytes signal surrounding matrix to calcify Older chondrocytes then die and disintegrate

o Leaves long trabeculae (spicules) of calcified cartilage on diaphysis sideo Trabeculae are partly eroded by osteoblasts.

Osteoblasts then cover trabeculae with bone tissue Trabeculae finally eaten away from their tips by osteoblasts.

Lecture 9: Introduction to Bones (continued)

Anatomy of Epiphyseal Growth Areas In epiphyseal plates of growing bones

o Cartilage is organized for quick, efficient growtho Cartilage cells form tall stacks o Chondroblasts at the top of stacks divide quickly

Pushes the epiphysis away from the diaphysis Lengthens the entire long bone Older chondrocytes signal surrounding matrix to calcify Older chondrocytes then die and disintegrate

o Trabeculae are partly eroded by osteoclasts.o Osteoblasts then cover trabeculae with bone tissueo Trabeculae finally eaten away from their tips by osteoclasts.

Postnatal Growth of Endochondral Bones During childhood and adolescence

o Bones lengthen entirely by growth of the epiphyseal plates.o Cartilage is replaced with bone connective tissue as quickly as it grows.o Epiphyseal plate maintains constant thicknesso Whole bone lengthens

Hormonal Regulation of Bone Growth Growth hormone – produced by the pituitary gland.

o Stimulates epiphyseal plates. Thyroid hormone – ensures that the skeleton retains proper proportions Sex hormones (estrogen and testosterone)

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o Promotes bone growth o Later induces closure of epiphyseal plates.

Postnatal Growth of Endochondral Bones As adolescence draws to an end

o Chondroblasts divide less ofteno Epiphyseal plate becomes thinner

Cartilage stops growing Replaced by bone tissue

o Long bones stop lengthening when diaphysis and epiphysis fuse.

Bone Remodeling Bone is dynamic living tissue 500mg of calcium may enter or leave the adult skeleton each day. Cancellous bone of the skeleton is replaced every 3-4 years. Compact bone is replaced every 10 years.

Postnatal Growth of Endochondral Bones Growing bones widen as they lengthen Osteoblasts – add bone tissue to the external surface of the diaphysis Osteoclasts – remove bone from the internal surface of the diaphysis. Appositional growth – growth of a bone by addition of bone tissue to it’s surface.

Bone Remodeling Bone deposit and removal

o Occurs at periosteal and endosteal surfaces. Peri – around Endo – in

Bone Remodeling o Bone deposition – accomplished by osteoblastso Reabsorption – accomplished by the osteoclasts.

Osteoblast Against cell with many nuclei Crawls along bone surfaces Breaks down bone tissue

o Secretes concentrated HClo Lysosomal enzymes are released.

Repair of Bone Fractures Simple and compound fractures Treatment by reduction

o Closed reduction – without use of surgery.o Open reduction – includes surgery and they use traction.

Fracture Classifications

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Simple – still remain under the skin. Compound – protrudes skin Overcompression will break bones.

Healing Hematoma Fibrocartilginous

o Blood vessels come into heal bone hyaline cartilage reforms. Osteoblasts start to reform the bone and start forming Last part…

Types of Fractures Comminuted – old bones fractures into more than 2 parts. Compressed – under pressure which cracks open bones, especially with

osteoporosis. Spiral – twist bone with a lot of force. Epiphyseal – epiphyseal plate no more fresh cells, dying. Depressed – flat bones goes deep and goes down into tissue.

o Hit head the skull would go in instead of out. Green stick – seen in children

Disorders of Bones Osteoporosis

o Characterized by low bone masso Bone reabsorption outpaces bone depositiono Occurs most often in women after menopause.o Common in women

Menopause – after bone tissue formation slows down and weakenso Men less common

Less active males don’t use the bones so they get weak, lose fluid and then they don’t calcify as much, use them and then they get stronger.

Osteomalacia o Occurs in adults o Bones are inadequately mineralized

Rickets o Occurs in children-analogous to osteomalaciao Malformed bones

Paget’s disease o Characterized by excessive rate of bone deposition

Osteosarcoma o A form of bone cancer.

Lecture 10: The Skeleton

Skeleton consists of Bones, cartilage, joints, and ligaments

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Composed of 206 named bones grouped into two divisionso Axial skeleton (80)o Appendicular (126)

Axial Skeleton Formed from 80 named bones Consists of the skull, vertebral column, and bony thorax

Bone Markings Projections that provide attachment for muscles and ligaments Projections that help form joints Depression and openings for passage of nerves

Skull Formed by the cranial facial bones

Cranium Serves to

o Enclose the braino Provide attachment sites for some head and neck muscles.

The Face Facial bones serves to

o Form framework of the faceo Form cavities for the sense organs of sight, taste, and smello Provide openings for the passage of air and foodo Hold the teeth in placeo Anchor muscles of the face.

Skull Geography Facial bones form anterior aspect Cranium is divided into cranial vault and the base Internally, prominent bony ridges

Skull contains smaller cavities Middle and inner ear cavity – in lateral aspect of the cranial base Nasal cavity – lies in and posterior to the nose Orbits – house the eyeballs Air-filled sinuses – occur in several bones around the nasal cavity.

The Skull contains approximately 85 named openings Foramina, canals, fissures Provide openings for important structures

o Spinal cordo Blood vessels serving braino 12 pairs of cranial nerves

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Cranial Bones Paired bones include

o Temporal baseso Parietal bases

Unpaired bones o Frontal, occipital, sphenoid, ethmoid

Frontal Bones Forms the forehead and roofs of the orbits Forms supercilliary arches Internally it contributes to the anterior cranial fossa Contains frontal sinuses

Parietal Bones Parietal bone form superior and lateral parts of the skull Four sutures of the cranium

o Coronal suture – runs in the coronal plane Located where parietal bones meet the frontal bones

o Squamous suture – occurs where each parietal bone meets a temporal bone inferiorly

o Sagittal suture – occurs where right and left parietal bones meet superiorly

o Lambdoid suture – occurs when the parietal bones meet the occipital bone posteriorly

Sutural Bones Small bones that occur within sutures Irregular in shape, size, and location Not all people have sutural bones

Occipital Bones Forms the posterior portion of the cranium and cranial base Articulates with the temporal bones and parietal bones Forms the posterior cranial fossa. Foramen magnum located at its basale Features and Structures

o Occipital condyleso Hypoglossal forameno External occipital protuberanceo Superior nuchal lineso Inferior nuchal lines

Temporal Bones Lie inferior to the parietal bones Form the inferior and lateral portion of the skull

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Term “temporal”o Comes from Latin word for time

Specific regions of temporal boneso Squamous o Temporalo Petrouso Mastoid process

The Sphenoid Bone Spans the width of the cranial floor Resemble a butterfly or bat Consists of a body and three pairs of processes Contains 5 important openings

Ethmoid Bones Lies between nasal and sphenoid bones Forms most of the medial bony region between the nasal cavity and orbits

Facial Bones Unpaired Bones

o Mandible, vomer Paird bones

o Maxillae, zymphatic bones, nasal bones, lacrimal bones, palantine bones, inferior nasal conchae

Mandible The lower jawbone is the largest and strongest facial bone Composed of 2 main parts

o Horizontal bodyo 2 upright rami

Maxillary Bones Articulate with all of the facial bones except the mandible Contains maxillary sinuses – largest paranasal sinuses Forms part of the inferior formal fissures

Other Bones Zymphatic bones – form lateral wall of orbits Nasal bones – form bridge of nose Lacrimal bones – complete the posterior part of the hand palate Vomer – forms the inferior part of the nasal septum Inferior nasal conchae – thin, curved bones that project medially from the lateral

walls of the nasal cavity

Sinuses – to reduce weight.

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Lecture 11: The Axial Skeleton (continued)

Paranasal Sinuses Air-filled sinuses are located within

o Frontal boneo Ethmoid boneso Sphenoid boneso Maxillary bones

Lined with mucous membranes Serve to lighten the skull

The Hyoid Bone Lies inferior to the mandible The only bone with no direct articulation with any other bone Acts as a movable base for the tongue

Vertebral Column Formed from 26 bones in the adult Transmits weight of trunk to the lower limbs Surrounds and protects the spinal cord Serves as attachment sites for muscles of the neck and back Held in place by ligaments Anterior and posterior longitudal ligaments

o Ligamentum flavum

Intervertebral Discs Cushion – like pads between vertebrae Acts as shock absorbers Compose about 25% of height of the vertebral column

o Composed of Nucleus pulpous and annulus fibrosis The gelatinous inner sphere of intervertebral discs Enables spine to absorb compressive stresses

Annulus Fibrosis An outer collar of ligaments and fibrocartilage Contains the nucleus pulpous Functions to bind vertebrae together to resist tension on the spine, and absorb

compression forces.

Herniated Disc

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May be caused by trauma to the spine Aging is also a contributing factor Nucleus pulpous loses cushioning properties Annulus fibrosis weakens

Regions and Normal Curvatures Vertebral column is about 70cm (28 inches) Vertebral column is divided into 5 major regions

o Cervical vertebrae 7 vertebrae of the neck region

o Thoracic vertebrae 12 vertebrae of the thoracic region

o Lumbar vertebrae 5 vertebrae of the lower back

o Sacrum Inferior to the lumbar vertebrae Articulates with coxal bones

o Coccyx Most inferior region of the vertebral column

4 distinct curvatures give vertebral column an S-shape o Cervical and lumbar curvature

Are concave posteriorly “(“o Thoracic and sacral curvatures

Are convex posteriorly “)”o Curvatures increase the resilience of the spine

Go to page 171 table 7.2 and the first 4 rows.

Specific Regions of the Spine perform specific functions Types of movement that occur between vertebrae

o Flexion and extensiono Lateral flexion

Cervical Vertebrae The Atlas

o C(1) is termed the atlaso Lacks a body and spinous processo Supports the skullo Superior articular facets receive the occipital condyles. o Allow flexion and extension of the neck

Nodding the head yes Axis

o Has a body and spinous processo Dens

(odontid process) projects superiorly

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o Formed from fusion of the body of the atlas with the axiso Acts as a point of rotation of the atlas and skullo Participates in rotating the head from side to side.

Thoracic Costal facets connect to rib

Lumbar Heavier Vertebral foramen triangular Transverse process is thinner.

Sacrum Shapes the posterior wall of the pelvis Formed from 5 fused vertebrae Superior surface articulates with L(5) Inferiorly articulates with the coccyx Sacral promontory

o Where the first sacral vertebrae bulges into pelvic cavity Center of gravity is 1cm posterior to sacral promontory

Sacral Foramina Ventral foramina

o Passage for ventral rami of sacral spinal nerves Dorsal foramina

o Passage for dorsal rami of sacral spinal nerves

Coccyx Is the “tail bone” Formed from 3-5 fused vertebrae Offers only slight support to pelvic organs

Bony Thorax Forms framework of the chest Components of the bony thorax

o Thoracic vertebrae – posteriorlyo Ribs – laterallyo Sternum and costal cartilage – anteriorly

Projects thoracic organs Supports shoulder girdle and upper limbs Provides attachment sites for muscles

Ribs True ribs – (1-7) – directly attached to the sternum False ribs – (8-12) Floating – 11, 12

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Sternum Formed from 3 sections

o Manubrium – superior section Articulates with the medial end of the clavicles

o Body – bulk of sternum Sides are notched at articulations for costal cartilage of ribs 2-7

o Xiphoid process – inferior to end of sternum Anatomical landmarks

o Jugular notch Central indentation at superior border of the manubrium

o Sternal angle Horizontal ridge where the manubrium joins the body

Ribs All ribs attach to vertebral column posteriorly True ribs – superior seven pairs of ribs

o Attach to sternum by costal cartilage False ribs – inferior five pairs of the ribs Ribs 11, 12 are known as floating ribs

Disorders of the Axial Skeleton Abnormal spinal curvatures

o Scoliosis – abnormal lateral curvatureso Kyphosis – an exaggerated thoracic curvatureo Lordosis – an accelerated lumbar curvature sway backo Stenosis – of the lumbar spine

Narrowing of the vertebral canal Membrane bones to ossify in second month of development Bone tissue grows outward from ossification centers Fontanels

o Unossified remnants of membraneso Anterior and posterior fontanels on skulls

Takes 2 years to harden where structures are.

Lecture 12: Appendicular Skeleton

Appendicular Pectoral Girdle

o Attaches the upper limbs to the trunk Pelvic Girdle

o Attaches to the lower limbs to the trunks

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Upper limbs and lower differ in functiono Share the same structural plan.

Pectoral Girdle Consists of the clavicle and the scapula Pectoral girdles do not quite encircle the body completely. Provides attachment for many muscles that move the upper limb Girdle is very light and upper limbs are mobile

o Only clavicle and upper limbs are mobileo Socket of the shoulder joint glenoid cavity is shallow.o Good for flexibility but bad for stability.

Clavicles Extend horizontally across the superior thorax. Sternal end articulates with the manubrium. Acromial end articulates with the scapula. Provide attachment for muscles. Hold the scapulae and arms laterally Transmit compression forces from the upper limbs to the axial skeleton.

Scapulae Lie on the dorsal surface of the rib cage. Located between ribs 2-7 Have 3 borders

o Superioro Medial (vertebral)o Lateral (axillary)

Have 3 angles o Lateral, superior, and inferior

Upper Limb 30 bones form each upper limb Grouped into the bones of the

o Armo Forearm – 2o Hand

Arm Region of the upper limb between the shoulder and elbow Humerus

o The only bone of the armo Longest and strongest bone of the upper limbo Articulates with the scapula at the shouldero Articulates with the radius and ulna at the elbow.

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Humerus Many structures of the humerus provide sites for muscle attachment Other structures of the humerus provide articulation sites for other bones. Capitulum – half bone Trochlea – locks into the elbow.

Forearm Formed from the radius and ulna Proximal ends articulate with the humerus Distal ends articulate with carpals. Radius and ulna articulate with each other. At the proximal and distal radioulnar joints. The interosseous membrane.

o Interconnects radius and ulna In anatomical position

o The radius is lateral and the ulna is medial.

Ulna Main bone responsible for forming the elbow joint with the humerus Hinge joint allows forearm to bend on arm Distal end is separated from carpals by fibrocartilage Plays little to no role in hand movement.

Radius Superior surface of the had of the radius articulates with the capitulum. Medially – the head of the radius articulates with the radial notch of the ulna. Contributes heavily to the wrist joint Distal radius articulates with the capral bones. When radius moves the hand moves with it.

Hand Includes the following bones

o Carpus – wristo Metacarpals – palmo Phalanges – fingers.

Carpus Forms the true wrist – the proximal region of the hand. Gliding movements occur between carpals Composed of 8 marble sized bones.

Carpal bones Are arranged in 2 irregular rows. Proximal row from lateral to medial

o Scaphoid, lunate, triquetral, and pisiform Distal from lateral to medial

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o Trapezium, trapezoid, capitate, and hamate A mnemonic to help remember the carpals.

o Sally left the party to take Carmen home.

Metacarpus 5 metacarpals radiate distally from the wrist. Metacarpals form the palm Numbered 1-5 beginning with the pollex (thumb) ‘ Articulate proximally with the distal row of carpals Articulates distally with the proximal phalanges.

Phalanges of the Hand Numbered 1-5 beginning with the pollex (thumb) Except for the thumb each finger has 3 phalanges

o Proximal, middle, and distal.

Pelvic Girdle Attaches lower limbs to the spine Supports visceral organs Attaches to the axial skeleton by strong ligaments Acetabulum is a deep cut that holds the head of the femur. Lower limbs have less freedom of movement

o Are more stable than the arm. Consists of paired hip bones (coxal bones or coxae) Hip bones unite anteriorly with each other. Articulates posteriorly with the sacrum.

Bony Pelvis A deep basin like structure Formed by

o Coxal bones, sacrum, and coccyx.

Coxal Bones Consists of 3 separate bones in childhood

o Ilium, ischium, and pubis. Bones fuse – retain separate names to regions of coxal bones Acetabulum

o A deep hemispherical socket on lateral pelvic surface.

Ilium Large flaring bone Forms the superior region of the coxal bones. Site for attachment for many muscles. Articulation with the sacrum forms sacroiliac joint.

Ischium

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Forms posteroinferior region of the coxal bone Anteriorly joints the pubis Ischial tuberositiies

o Are the strongest part of the hip bones.

Pubis Forms the anterior region of the coxal bone Lies horizontally in anatomical position Pubis symphysis

o 2 pubic bones are joined by fibrocartilage at the midline

True and False Pelves Bony pelvis is divided into 2 regions. False (greater) pelvis – bounded by alae of the iliac bones. True (lesser) pelvis – inferior to pelvic brim

o Forms a bowl containing the pelvic organs.

The Lower Limb Carries the entire weight of the erect body Bones of lower limb are thicker and stronger than those of the upper limbs. Divided into 3 segments

o Thigh, leg, foot

Thigh The region of the lower limb between the hip and the knee Femur – single bone of the thigh Longest and strongest bone of the body Ball shaped head articulates with the acetabulum.

Patella Triangular sesmoid bone Imbedded in the tendon that secures the quadriceps muscles. Protects the knees anteriorly Improves leverage of the thigh muscles across the knee.

Leg Refers to the region of the lower limb between the knee and ankle. Composed of the tibia and fibula Tibia – more massive medial bone of the leg.

o Receives weight of the body from the femur. Fibula – stick-like lateral bone of the leg. Interosseous membrane

o Connects the tibia and fibula Tibia articulates with the femur at the superior end.

o Forms the knee joint Tibia articulates with the talus at the inferior end.

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o Forms the ankle joint Fibula doesn’t contribute to the knee joint

o Stabilizes the ankle joint

The foot The foot is composed of

o Tarsus, metatarsals, and the phalanges. Important functions

o Supports body weighto Acts as a lever to propel body forward when walking

Segmentation makes foot pliable and adapted to uneven ground.

Tarsus Makes up the posterior half of the foot Contains 7 bones called tarsals Body weight is primarily borne by the talus and the calcaneous

Metatarsus Consists of 5 small long bones called metatarsals Numbered 1-5 beginning with the hallux (great toe) First metatarsal supports body weight.

Phalanges of the foot 14 phalanges of the toe Smaller and less nimble than those of the fingers. Structure and arrangement are similar to phalanges of the fingers. Except for the great toe, each toe has 3 phalanges

o Proximal, middle, and distal.

Arches of the foot Foot has 3 important roles

o Medial and lateral longitudinal archo Transverse arch

Arches are maintained byo Interlocking shapes of tarsals, ligaments, and tendons

Lecture 13: Joints

Joints Rigid elements of the skeleton meet at joints or articulations Articulations can be

o Bone to boneo Bone to cartilageo Teeth in bony sockets

Structure of joints o Enables resistance to crushing, tearing, and other forces.

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Classifications Joints can be classified by function or structure Functional Classifications

o Based on amount of movemento Synarthroses – immovable, common to axial skeletono Amphiarthroses – slightly movable, common to axial skeletono Diarthroses – freely movable, common in appendicular skeleton, and all

synovial joints. Structural Classifications based on

o Material that binds togethero Pressure or absence of a joint cavityo Structural classifications include

Fibrous Cartilaginous Synovial

Fibrous Joints Bones are connected by fibrous connective tissue. Do not have joint cavity Most are immovable or slightly movable Types

o Sutureso Syndesmoseso Gomphoses

Sutures Bones are tightly bound by a minimal amount of fibrous tissue Only occur between the bones of the skull Allow bone growth so the skull can expand with brain during childhood Fibrous tissue ossifies in middle age Synostoses – closed sutures.

Syndesmoses Bones are connected exclusively by ligaments Amount of movement depends on length of fibers. Tibiofibular joint – immovable synarthorsis Interosseous membrane – between radius and ulna

o Freely movable diarthrosis

Gomphoses Tooth in a socket Connecting ligament – the periodontal ligament

o Short, no movement.

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Cartilaginous Joints Bones are united by cartilage Lack a joint cavity Two types

o Synchondroseso Symphyses

Synchondroses Hyaline cartilage unites bones Epiphyseal plates

o Hyaline Joint between the first rib and manubrium

Sympheses Fibrocartilage unites bones – resists tension and compression Slightly moveable joints that provide strength with flexibility Hyaline present which lines the surfaces of the bones. Intervertebral discs Pubic symphysis Hyaline cartilage – also present as articular cartilage.

Synovial Joints Most movable type of joint All are diarthroses which allow movements in all directions. Each contain a fluid-filled joint cavity.

General Structure Articular Cartilage

o Ends of opposing bones are covered with hyaline cartilageo Absorbs compression

Joint Cavity (synovial cavity) o Unique to synovial cavityo Cavity is a potential space that holds a small amount of synovial fluid.

Articular Capsule Joint cavity is enclosed in a 2 layered capsule Fibrous capsule – dense irregular connective tissue which strengthens the joint Synovial membrane – loose connective tissue

o Lines joint capsule and covers internal joint surface.o Is a blood filtrate o Functions to make synovial fluido Glycoprotein makes it slippery.

Synovial Fluid A viscous fluid similar to raw egg white

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o A filtrate of bloodo Arises from capillaries in synovial membrane

Contains glycoprotein molecules secreted by the fibroblasts.

Reinforcing Ligaments Often are thickened parts of the fibrous capsule Sometimes are extracapsular ligaments

o Located outside the capsule Sometimes are intracapsular ligaments

o Located inside the capsule. Richly supplied with sensory nerves Detect pain Most monitor how much the capsule is being stretched. Have a rich blood supply

o Most supply the synovial membraneo Extensive capillary beds produce basis of synovial fluido Branches of several major nerves and blood vessels.

Synovial Joins with Articular Discs Some synovial joints contain an articular disc Occur in the temporomandibular joint and at the knee Occur in joints whose articulating bones have somewhat different shapes.

How Synovial Joints Function Synovial joints are lubricating devices Friction could overheat and destroy joint tissue Are subjected to compressive forces

o Fluid is squeezed out as opposing cartilages toucho Cartilages ride on the slippery film

Bursae and Tendon Sheath Bursae – is a sac. Bursae and tendon sheath are not synovial joints (doesn’t have to connect to bone) Closed bags of lubricant Reduce friction between body elements. Bursae – a flattened fibrous sac lined by a synovial membrane Tendon sheath – are elongated bursa that wraps around a tendon.

Fractures Influencing Joint Stability Articular surfaces – seldom play a major role in joint stability

o The elbow, knee, and the hip do provide stability Ligaments – the more ligaments in a joint the stronger it is. Muscle tone – the most important factor in joint stability

o Keeps tension on muscle tendonso (Continuous contraction).

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Movements Allowed by Synovial Joints Refer to page 213-216, Tables 9.3 and 9.4 3 basic types of movement

o Gliding – one bone across the surface of another.o Angular movement – movements change the angle between bones.o Rotation – movement around a bone’s long axis.

Gliding Joints Flat surfaces of 2 bones slip across each other. Gliding occurs between

o Carpals, tarsals, articular process of vertebrae.

Angular Movement Increases or decreases angle between bones Movement involves

o Flexion and extensiono Abduction and adductiono Circumduction

Rotation Involves turning movement of a bone around its long axis The only movement allowed between atlas and axis vertebrae Occurs at the hip and shoulder joints.

Special Movements Supination – forearm rotates laterally, palm faces anterior Pronation – forearm rotates medially, palm faces posterior Dorsiflexion – lifting the foot so the superior surfaces approaches the shin Plantar flexion – depressing the foot, pointing the toes. Inversion – turning the sole medially Eversion – turning the sole laterally. Protraction – nonangular movement of jutting out the jaw. Retraction – opposite movement to protraction Elevation – lifting a body superiorly Depression – moving elevated part inferiorly. Opposition – movement of the thumb to touch the tip of the other fingers.

Classified by Shape

Plane joint Articular surfaces are flat planes Short gliding movements are allowed Intertarsal and intercarpal joints Movements are nonaxial Gliding doesn’t involve rotation around any axis.

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Hinge joints Cylindrical end of one bone fits into another bone. Angular movement is allowed in one plane Elbow, ankle, and joints between phalanges Movement in uniaxial – allows movement around axis only.

Pivot Joints Classified as uniaxial rotating bone only turns around its long axis. Examples

o Proximal radioulnar jointo Joint between atlas and axis

Condyloid joints Allow moving bone to travel Side to side – abduction and adduction Back and forth – flexion and extension. Classified as biaxial-movement Occurs around two axes

Saddle Joints Each articular surface has concave and convex surfaces. Classified as biaxial joints.

Ball and Socket Joints Spherical head of one bone fits into round socket of another. Classified as multiaxial – allow movement in all axes

o Shoulder and hip joints.

Disorders of Joints Disorders of joints make them prone to traumatic stress Function of joints makes them subject to friction and wearing Affected by inflammatory and degenerative processes.

Joint Injuries Sprains – ligaments of a reinforcing joint are stretched or torn. Dislocation – occurs when the bones of a joint are forced out of alignment Torn cartilage – common injury to meniscus (cartilage of the knee) of knee joint. Bursitis – inflammation of a bursa due to injury or friction. Tendonitis – inflammation of a tendon sheath Arthritis – describes over 100 kinds of joint damaging diseases.

o Osteoarthritis – most common type of “wear and tear” arthritiso Rheumatoid arthritis – a chronic inflammation disorder.o Gouty arthritis (gout) – uric acid build up causes pain in jointso Lyme disease – inflammatory disease often resulting in joint pain.

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Lecture 14: Muscle Tissue

General: Tendon – muscle to bone

Muscles Muscle is the primary tissue in the heart (cardiac muscle tissue) Walls of hollow organs (smooth muscle tissue) Skeletal muscle

o Makes up nearly half the body’s mass.

Overview of Muscle Tissue

Functions of Muscle Tissue Movement

o Skeletal muscles – attach to skeleton Moves body by moving the bones

o Smooth muscle – squeezes fluids and other substances through hollow membranes.

Maintenance of posture – enables the body to remain sitting or standing Joint stabilization Heat generation

o Muscle contractions produce heato Helps maintain normal body temperatures

Functional Features of Muscles Functional Features

o Contractility Long cells shorten and generate pulling forces.

o Excitability Electrical nerve impulse stimulates the muscle cells to contract

o ?

Types of Muscle Tissue 3 Types

o Skeletal Muscle Tissue Packaged into skeletal muscles. Makes up 40% of body weight. Specific banding pattern with light and dark.

o Cardiac Muscle Tissue Occurs only in the walls of the heart

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Branching and striations Intercalated discs.

o Smooth Muscle Tissue Cells lack striations One nucleus Nonstriated.

Similarities of Muscle Tissue Cells of muscles

o Are known as fibers Muscle contraction

o Depends on two types of myofilaments (contractile proteins) One type contains actin (thin) Another type contains myosin (thick)

These 2 proteins generate contractile forces. Plasma membrane is called a sarcolemma (outside covering) Cytoplasm is called the sarcoplasm (inside).

Skeletal Muscle Each muscle is an organ

o Contained mostly of muscle tissueo Skeletal muscle also contains

Blood tissue Nerves Connective tissue

Basic Features of Skeletal Muscle Connective tissue and fasicles

o Connective tissue sheaths bind a skeletal muscle and its fibers together. Epimysium – dense irregular connective tissue surrounding entire

muscle. Perimysium – surrounds each fasicle (group of muscle fibers) Endonysium – a fine sheath of connective tissue wrapping each

muscle cell.o Helpful

Epi – outside Peri – around fasicles (several bundles of fibers) (group of fibers) Endo – inside (individual)

o Connective tissue sheaths are continuous with tendons.

Nerves and Blood Vessels Each smooth muscle supplied by branches of

o One nerveo One artery (remember: blood out to system)o One or more veins

Nerves and blood vessels branch repeatedly

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Smallest nerve branches serveo Individual muscle fiberso Neuromuscular junction – signals the muscle to contract.

Muscle Attachments Most skeletal muscles run from one bone to another One bone will move and the other bone remains fixed.

o Origin – less movable attachment Usually proximal

o Insertion – more movable Usually distal.

Muscle attaches to origins and insertions by connective tissueo Fleshy attachments – connective tissue fibers are short.o Indirect attachments – connective tissue forms a tendon or aponeurosis

Bone markings present where tendons meet boneso Tubercles, trochanters, and crests.

Microscopic and Functional Anatomy of Smooth Muscle Tissue The skeletal muscle fibers

o Fibers are long and cylindrical o Are huge cells – diameter is 10-100um o Length – several centimeters to dozens of centimeters

Each cell formed by fusion of embryonic cells Cells are multinucleate Nuclei are peripherally located.

Myofibrils and Sarcomeres Striations result from internal structure of myofibrils Myofibrils

o Long rods within cytoplasmo Make up 80% of the cytoplasmo Are a specialized contractile organelle found in muscle tissueo A long row of repeating segments called sarcomeres (functional unit of

smooth muscle tissue. Sarcomeres

o Basic unit of contraction of skeletal muscleo 2 disc (line) – boundaries of each sarcomeres o Thin (actin) – filaments external from the 2 disco Thick (myosin) filaments – located in the center of the sarcomeres

Overlap inner ends of the thin filaments Contain ATPase enzymes.

Sarcomere Structure A bands – full length of the thick filament

o Includes inner end of thin filaments

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H zone – center part of A band where no thin filaments occur. M line – in center of H zone.

o Contains tiny rod that holds thick filaments together. I band – region with only thin filaments

o Lies within 2 adjacent sarcomeres.

Sarcoplasmic Reticulum and the T Tubules Sarcoplasmic Reticulum

o A specialized smooth ERo Interconnecting tubules surround each myofibrilo Some tubules form cross channels called terminal cisternae. o Cisternae occur in pairs on either side of a T Tubuleo Contains calcium ions – released when muscle is stimulated to contracto Calcium ions diffuse through cytoplasm

Trigger the sliding filaments mechanism.

Mechanism of Contraction Sliding filament theory

o Myosin heads attach to actin in the thin filamentso Then pivot to pull in thin filaments inward the center of the sarcomeres.

Muscle Extension Muscle is stretched by a movement opposite that which contracts it. Muscle fiber length and force of contraction

o Greatest force produced when a fiber starts out slightly stretched.o Myosin heads can pull along the entire length of the thin filaments.

Role of Titin Titin – a spring-like molecule in sarcomeres

o Resists overstretchingo Holds thick filaments in place.o Unfolds when muscle is stretched.

Sarcoretic T Tube Muscle contraction

o Ultimately controlled by nerve-generated impulse o Impulse travels along the sarcolemma of the muscle cells

Impulses further conducted by T Tubules T Tubule – a deep invagination of the sarcolemma

Innervation of Smooth Muscle Motor neurons innervate skeletal muscle tissue Neuromuscular junction – is the point where nerve ending and muscle fibers

meet.

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Types of Smooth Muscle Fibers Skeletal muscle fibers are categorized according to

o How they manufacture energy (ATP)o How quickly they contract

Skeletal Muscle Fibers Are divided into 3 classes

o Slow oxidative fibers (Type I) Red slow twitch Resist fatigue Postural Go very slow.

o Fast glycolytic fibers (Type IIx) White fast twitch Myoglobin holds oxygen for longer period of time Fast bursts and tired right away Anaerobic (meaning without oxygen) Upperlimbs

o Fast oxidative fibers (Type IIa) Intermediate fibers Requires oxygen Lower limb

Disorders of Muscle Tissue Muscle Dystrophy

o A group of inherited muscle destroying diseaseso Affected enlarge with fat and connective tissueo Muscle degenerateo What happens

Fat replaces muscle fibers and continue to lose the muscles and they become weak.

Lecture 15: Muscles of the Body

Skeletal Muscles Produce movements

o Blinking of eye, standing on tiptoe, swallowing food, etc. General principle of leverage Muscles act with or against each other Criteria used in naming muscles.

Lever Systems: Bone Muscle Relations Movement of skeletal muscles involve leverage

o Lever – a rigid bar that moves.o Fulcrum – a fixed point.o Effort – applied force.

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o Load – resistance.

Equation on Board Effort x Distance = Load x Distance

Lever Systems: Bone Muscle Relations Bones – act as levers Joints – act as fulcrums Muscle contraction – provides effort.

o Applies force where muscle attaches to bone. Load – bone, overlying tissue, and anything lifted. Levers allow a given effort to

o Move a heavier loado Move a load farther

Mechanical advantage o Move a large load over small distances

Mechanical Disadvantage o Allow a load to be moved over a large distance.

First-class Lever Effort applied at one end Load is at the opposite end. Fulcrum is located between load and effort Equation

o Effort Fulcrum Load = Mechanical Advantage Examples :

o See saw, scissors, and lifting your head off your chest.

Second-class Lever Effort applied at one end Fulcrum is at the opposite end Load is between the effort and fulcrum Examples

o Wheelbarrow, or standing on tiptoe Uncommon type of lever in body Work at mechanical advantage Equation

o E L F = MA

Third-class Lever Effort is applied between load and the fulcrum. Work speedily Most common type Always at the mechanical disadvantage of the human body Equation

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o L E F = Mechanical Disadvantage. Most skeletal muscles are third class Examples – biceps brachii,

o Fulcrum – the elbow joint. o Force – exerted on the proximal region of the radius.o Load – distal part of the forearm.

Arrangement of Fasicles in Muscles Skeletal muscles – consist of fasicles Fasicles – arranged in different patterns Fasicles arrangement – tells about action of muscle.

Types of Fasicle Arrangement Parallel

o fasicles run parallel to the long axis of the muscleso Strap-like – sternocleidomastoido Fusiform – biceps brachii

Convergent o Origin of the muscle is broado Fasicles converge toward the tendon of insertiono Example

Pectoralis major Pennate

o Unipennate – fasicles insert into one side of the tendono Bipennate – fasicles insert into the tendon from both sides

Example: rectus femoruso Mutlipennate – fasicles insert into one large tendon from all sides

Example: deltoid of the shoulder. Circular

o Fasicles – are arranged in concentric rings. Surrounded external body openings Sphincter – general name for a circular muscle.

o Example Orbicularis oris (mouth) Bicularis oculi (eyes).

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Interactions of Smooth Muscle in the Body A muscle cannot reserve the movement it produces Another muscle must undo the action Muscles with opposite actions lie on opposite sides of a joint.

Muscle Classified into Several Functional Groups

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Prime mover (agonist) o Has major responsibility for a certain movement

Antagonist o Opposes or reverses a movement

Synergist o Helps the prime mover

By adding extra force By reducing undesirable movements.

o Fixator A type of synergist that holds a bone firmly in place.

Muscle Compartments of the Limbs Dense fibrous connective tissue divides limb muscles into compartments Muscles in opposing compartments are

o Agonist and antagonist pairs. Each compartment is innervated by a single nerve.

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Naming Smooth Muscle Location

o Example – the brachialis is located on the arm Shape

o Example – the deltoid (shoulder) is triangular Relative Size

o Maximus, minimus, and longus indicate size.o Example: gluteus maximus, and gluteus minimus

Direction o Direction of fasicles and muscle fibers.o Name tells direction in which fibers runo Example – rectus abdominis and transervus abdominis

Location o Location of attachments – name reveals point of origin and insertiono Example – brachioradialis

Number of origins o Two, three, or four origins.o Indicated by the words biceps, triceps, and quadriceps.

Action o The action is part of the muscle’s nameo Indicates type of muscles movemento Flexor, extensor, adductor, abductor

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Refer to pages 273 and 274