THE THE SKELETAL SKELETAL SYSTEMSYSTEM
I. BONE STRUCTURE & FUNCTIONA.A. There are 206 bones in There are 206 bones in
the body.the body.
A.A. FUNCTIONFUNCTION1.Support2.Protection3.Movement due to muscles
4.Blood formation aka hematopoesis
5.Electrolyte Balance stores and releases calcium and phosphate
6.Acid Base Balance Buffers blood by storing and releasing alkaline
salts
Skeletal system is divided Into 2 parts:
A. blood by storing and releasing alkaline salts
Parts of the skeletal Parts of the skeletal system include: system include: bones (skeleton); bones (skeleton); joints, joints, cartilage, cartilage, & ligaments& ligaments
Axial SkeletonAppendicular Skeleton
IV. The SkeletonA.A.OrganizationOrganization
1.1. Axial SkeletonAxial Skeleton
– SkullSkull
– Vertebral Column Vertebral Column
– VertebraeVertebrae
– RibsRibs
2.2. Appendicular SkeletonAppendicular Skeleton
– limbslimbs
– girdlesgirdles
Spongy Spongy (cancellous)(cancellous)
Compact Compact BoneBone
Two types of Two types of BoneBone
3.3.Mature BoneMature Bone
Osseous Osseous TissueTissue
B. Microscopic AnatomyB. Microscopic Anatomy
• Called Lamellar Lamellar bonebone•Two kinds of bone
CompactCompact Spongy Spongy (cancellous)(cancellous)
3. Mature 3. Mature BoneBone
• Spongy Spongy (cancellous)(cancellous)
• contains contains trabeculaetrabeculae
• contains spacescontains spaces
• Dense, few Dense, few spacesspaces• Haversian canalsHaversian canals• Concentric Concentric LamellaeLamellae
Compact Compact BoneBone
3. Mature 3. Mature BoneBone
Osseous Vocabulary & Anatomy• Osteon (Haversian System) is a unit of bone.
• Central (Haversian) Canal is an opening in the center of an osteon that carries bloodvessels & nerves.
Osseous Vocabulary & Anatomy• Perforating (Volkman’s) Canal runs perpendicular
to the central canal & carries blood vessels & nerves.
Osseous Vocabulary & Anatomy• Lacunae are cavities
holding the mature bone cells (osteocytes). Arranged in concentric rings..
• Lamella are the concentric rings around the central canal that holds the lacunae
Osseous Vocabulary & Anatomy• Canaliculi are the tiny
canals radiating perpendicularly from the central canal through the lamella creating a transport system from nutrients.
Osseous Vocabulary & Anatomy• Osteoblasts are young
bone forming cells that cause the hard extracellular matrix to form.
• Osteoclasts are bone dissolving cells
• Osteocytes are mature bone cells.
Osteoblasts
Osteocytes
Osteoclasts
OsteoblastsOsteoclasts
Osteocytes
Name C, D & EName C, D & E
D = OsteoblastE = Osteocytes
C = Osteoclast
I. BONE STRUCTURE & FUNCTION4 Shapes of Bone:4 Shapes of Bone:–Long bones Have a shaft
with heads at both ends & Contain mostly compact bone.
–Short bones Generally cube-shape & contains mostly spongy bone.
–Flat bones thin, flattened, usually curved & has thin layer of compact bone surrounding spongy bone.
–Irregular bones Do not fit into other bone classification categories
Long bones Short bones
Flat bones
Irregular bones
Classify the bone types to the left
B. StructureB. StructureParts of Long Parts of Long
BoneBone
– Epiphyses Epiphyses AKA: headAKA: head
• Contains red bone marrow
• Spongy bone and compact bone
B.B. Parts of a Long BoneParts of a Long BoneDiaphysis:Diaphysis:
• Shaft of bone
• Contains yellow bone marrow w/in medullary cavity
• Spongy and compact bone
Diaphysis of Long Bone
•Medullary cavity contains yellow marrow (fat & minerals) in adults.
B.B. Parts of a long boneParts of a long boneEpiphyseal plateEpiphyseal plate Allows for growth in Allows for growth in
bone bone Found only in childrenFound only in children
Articular Cartilage:Articular Cartilage:Covers the epiphysesCovers the epiphyses
Made of hyaline Made of hyaline cartilagecartilage
Decreases Friction @ Decreases Friction @ joint surfacesjoint surfaces
B.B. Parts of a long boneParts of a long bonePeriosteum: Periosteum: outer outer
covering of covering of diaphysisdiaphysis
Fibrous connective Fibrous connective tissue membranetissue membrane
Sharpey’s Fibers: Sharpey’s Fibers: Secure periosteum Secure periosteum to underlying boneto underlying bone
Arteries: Arteries: Supply bone cells Supply bone cells
w/nutrientsw/nutrients
D. MembranesD. Membranes1.1. PeriosteumPeriosteum:
a.The external covering of bone
2. endosteum: a. Found on internal
bone surfaceb. covers trabeculae of
spongy bone c. in marrow cavities
II. BONE GROWTH & DEVELOPMENTA.A.Two Patterns of Bone Two Patterns of Bone
FormationFormation1.1. Intramembranous Intramembranous bones bones
– originate between originate between sheet-like sheet-like layers of layers of connective connective tissues tissues
II. BONE GROWTH & DEVELOPMENTA.A.Two Patterns of Bone Two Patterns of Bone
FormationFormation 2.2. Endochondral Endochondral bones bones
– begin as masses begin as masses of hyaline of hyaline cartilage that cartilage that bone tissue later bone tissue later replaces. replaces.
II. BONE GROWTH & DEVELOPMENTB.B.Growth in Long BonesGrowth in Long Bones
1.1. grow by interstitial growth at grow by interstitial growth at epiphyseal platesepiphyseal plates
a.a. rate of cartilage growth is rate of cartilage growth is balanced by replacement with balanced by replacement with bone bone
b.b. end of growth as cartilage end of growth as cartilage cells slow down division cells slow down division
Bone Growth in Long Bones
II. BONE GROWTH & DEVELOPMENTB.B.Growth in Long BonesGrowth in Long Bones
2. bones grow in width by 2. bones grow in width by appositional growthappositional growth
a.a. Osteoblasts in periosteum: Osteoblasts in periosteum: secretes bone matrix secretes bone matrix
b.b. Osteoclasts in endosteum: Osteoclasts in endosteum: removes bone matrix (a little removes bone matrix (a little slower) slower)
Appositional Growth Appositional Growth
– New bone forms at ridges around New bone forms at ridges around blood vessels blood vessels
– Periosteum becomes endosteumPeriosteum becomes endosteum
– New lamella formedNew lamella formed
– More bone added forming osteonMore bone added forming osteon
Appositional Growth Appositional Growth
II. BONE GROWTH & DEVELOPMENTC.C.HormonesHormones
1. growth hormone from pituitary: 1. growth hormone from pituitary: stimulates growth in childhood stimulates growth in childhood
a.a. Gigantism:Gigantism: excessive growth excessive growth hormone hormone
b.b. dwarfism:dwarfism: not enough growth not enough growth hormone or thyroid hormones hormone or thyroid hormones
II. BONE GROWTH & DEVELOPMENTC.C.HormonesHormones
2. 2. thyroid:thyroid: regulates activity of regulates activity of growth hormone growth hormone
3. 3. sex hormones:sex hormones: promote growth promote growth spurt, induce epiphyseal plate spurt, induce epiphyseal plate closure closure
estrogenestrogen: maintains bone : maintains bone densitydensity
III. Bone Maintenance & RepairA.Bone remodeling: 1. Life long process
2. Local areas of bone are destroyed and rebuilt
3. Repairs microdamage caused by normal wear and tear
B.Fractures 1. Simple1. Simple
bone breaks cleanly, does not break through skin
B.Fractures 2. Compound2. Compound
broken ends protrude through the skin, risk of bone infection
B.Fractures 3. Greenstick3. Greenstick
Greenstick: Greenstick: (children)
Does not break completely
Impact Fx of distal radius & ulna @ Epiphyseal Line
Facial Comminuted Fx
Tibial Oblique Fx
C. RepairC. Repair1. Hematoma formsHematoma forms 2. Spongy bone forms in area of 2. Spongy bone forms in area of
hematomahematoma forming a soft callusforming a soft callus
III. Remodeling and Repair
C. RepairC. Repair3. Osteoblasts lay down new bone Osteoblasts lay down new bone
matrix matrix converting the soft callus into a hard callus of spongy bone
4. The boney callus is remodeled to 4. The boney callus is remodeled to form a permanent patchform a permanent patch
• Bone healing occurs in stages: – fracture–granulation–callus– lamellar bone–normal contour
III. Types of Bone Repair
III. Calcium HomeostasisA.A.Blood CaBlood Ca2+2+ Level Level
1.1. Has a very narrow range Has a very narrow range
2.2. CaCa2+2+ Required forRequired for
– For normal muscle contractionFor normal muscle contraction
– Nerve impusesNerve impuses
III. Calcium HomeostasisA.A.Blood CaBlood Ca2+2+ Level Level
3.3. Abnormal levelsAbnormal levels
– HypocalcemiaHypocalcemia
causes marked jitteriness and causes marked jitteriness and convulsive seizures convulsive seizures
III. Calcium HomeostasisA.A.Blood CaBlood Ca2+2+ Level Level
3.3. Abnormal levelsAbnormal levels
– HypercalcemiaHypercalcemia
the most common life-the most common life-threatening metabolic disorder threatening metabolic disorder associated with cancerassociated with cancer
III. Calcium HomeostasisB.B.Bone’s Role Bone’s Role
1.1. Major storage site for calcium Major storage site for calcium
2.2. Calcium movesCalcium moves
– Into bone as osteoblasts build Into bone as osteoblasts build new bone new bone
– Out of bone as osteoclasts Out of bone as osteoclasts break down bone break down bone
III. Calcium HomeostasisC.C.Bone, Calcium and Bone, Calcium and
Hormones Hormones 1.1.Parathyroid Hormone –Parathyroid Hormone – Increases blood CaIncreases blood Ca2+2+ levels levels
2.2. CalcitoninCalcitonin
Decreases blood CaDecreases blood Ca2+2+ levels levels
D. Homeostatic Imbalances
• Osteopenia Osteopenia – Inadequate ossification
• Osteoporosis Osteoporosis – Bone absorption outpaces deposition – Fractures common – More common in elderly women
III. Calcium Homeostasis
• RicketsRickets – Lack of vitamin D or
calcium during growth – Bowed legs – Deformed pelvis
D. Homeostatic Imbalances
Rickets
•Osteosarcoma – Bone cancer – Usually between ages 10-25 – Survival rate is about 50% with amputation
D. Homeostatic ImbalancesD. Homeostatic Imbalances
•Bone spurBone spur – Abnormal projection at one site of bone due to
overgrowth – Common in aging bones
D. Homeostatic Imbalances
Bone Markings• Bony markings are the surface features of a bone.
• They are sites of attachments for muscles, tendons & ligaments.
• They can serve as passage ways for nerves & blood vessels.
• There are 2 Categories of Bony Markings – Projections & processes – outward growths on
the bone surface.– Depressions or cavities – indentations on the
surface of the bone.
C.C.Bone Markings –Bone Markings –
1. Kinds
For muscle attachment
For formation of a joint
To allow blood vessels or nerves to pass through
• Articulating Surfaces
•Openings
• Depressions & Enlargements 1. Kinds
C.C.Bone Markings –Bone Markings –
2. Articulating surfaces
A rounded projection set off from the body of a bone by a constriction (the neck) ex. head of femur
Head
C.C.Bone Markings –Bone Markings –
2. Articulating surfaces
Condyle
Any large articulating surface, may be concave or convex
C.C.Bone Markings –Bone Markings –
2. Articulating surfaces
A smooth, flat surface, generally small
Facet
C.C.Bone Markings –Bone Markings –
2. Articulating surfaces
A shallow depression
Fossa
C.C.Bone Markings –Bone Markings –
3. Enlargements & Processes
generic term for bone projection that serves as a point for attachment of other structures
Process
C.C.Bone Markings –Bone Markings –
3. Enlargements
projection or swelling to the side of or above a condyle
Epicondyle
C.C.Bone Markings –Bone Markings –
Spine
a sharp, slender projecting process
3. Enlargements
C.C.Bone Markings –Bone Markings –
a small rounded projection
Tubercle
3. Enlargements
C.C.Bone Markings –Bone Markings –
a large rounded roughened projection
3. Enlargements
Turberosity
C.C.Bone Markings –Bone Markings –
3. Enlargements
Trochantera large blunt projection
C.C.Bone Markings –Bone Markings –
3. Enlargements
a prominent border or ridge
Crest
C.C.Bone Markings –Bone Markings –
3. Enlargements A major branch or division off of the main body of a bone
Ramus
C.C.Bone Markings –Bone Markings –
4. Openings
C.C.Bone Markings –Bone Markings –
4. Openings
Canal like opening
Meatus
C.C.Bone Markings –Bone Markings –
5. Depressions
A shallow groove
Sulcus
C.C.Bone Markings –Bone Markings –
5. Depressions
A very shallow groove
Fovea
C.C.Bone Markings –Bone Markings –
5. Depressions
A deep groove
Fissure
Axial Skeleton
• Forms the longitudinal part of the skeleton.
• Divided into 3 parts:
• Skull
• Vertebral Column
• Bony Thorax
The Skull
• The skull is divided into 2 parts:
• Cranium
• Facial Bones
• The cranial bone joints are called sutures.
• Only the mandible is attached by a freely movable joint.
Lateral view of the Skull
Frontal view of the Skull
Transvers section of Inferior, Internal Skull
Inferior, External view of Skull
SinusesThe sinuses are hollow portions of bone within the skull surrounding the nasal cavity. They lighten the face/skull, act as resonance chambers & amplify the voice.
The Hyoid BoneThe only bone
in the body that does not articulate w/another bone.
It serves as a moveable base for the tongue.
The Fetal Skull• The fetal skull is large
compared to the infant’s total body length.
• Fontanels are fibrous membranes connecting the cranial bones
• The fontanels allows the brain to grow.
• The fontanels converts to bone within 24 months after birth.
The Vertebral Column
The Vertebrae are separated by intervertebral discs made of fibrocartilage, connective tissue.
The spine has a normal “S” curvature.
Each vertebrae is given a name according to its location.
Bony Thorax
Made of 3 parts: Sternum Ribs Thoracic vertebrae
The bony thorax forms the rib cage that protects the thoracic internal organs.
The Appendicular Skeleton
Includes the: Appendages (limbs)Pectoral GirdlePelvic Girdle
Pectoral – Shoulder Girdle
Made of 2 bones:Clavicle aka collarboneScapula aka shoulder blade
The pectoral girdle allows the upper limb to have free range of movement
Pectoral – Shoulder Girdle
Pectoral Girdle – Posterior View
Upper Extremity Bones
Includes the:Humerus (upper arm bone)Radius (thumb side of forearm)Ulna (pinki side of forearm)& the Hand
Anterior Humerus
Posterior Humerus
Upper Extremity Bones
The distal head of the radius is larger than the proximal
The proximal head of the Ulna is larger than the distal.
Upper Extremity Bones
The Hand includes:Carpals – short bones of the wrist.Metacarpals – long bones of the palm of the hand.Phalanges (Digits) – Proximal, Middle, Distal fingers.
Pelvic Girdle
Made of the Coxal Bone (hip) which is 3 bones fused together: Ilium Ischium Pubic Bone
The total weight of the upper body sits on the pelvis.
The pelvis protects the reproductive organs, urinary bladder, & part of the large intestine
Lateral View of Pelvis
B. Male vs. Female Skeleton - B. Male vs. Female Skeleton - PelvisPelvis
a. spines farther apart in male
b. hole in ischium: smaller and triangular in female
c. angle across pubic symphysis = pubic arch: less than 90° and more sharply angled in male
d. distance between ischia larger in female
Male & Female Pelvic Differences
Lower Extremity
Anterior Femur View
Posterior Femur View
The lower extremity is made of:PelvisFemur (thigh)Tibia (shin)FibulaFoot
Lower ExtremityThe flat superior portion of the tibia is called the Tibial Plateau.
The distal head of the tibia is called the medial malleolus while the distal head of the fibula is called the lateral malleolus
Lower ExtremityThe Foot is made up of the :Tarsals – short bones of footMetatarsals – long bones of footPhalanges (Digits)- long bones of the toes
The ArchesThe bones of the foot make up 3 arches. The 2 long arches are the lateral & medial longitudinal arches. The arch across the foot is the transverse arch.
JointsJoints are where 2 or more bones come together. Joint Functions: Holds bones together. Allows for mobility.Classified either Functionally or Structurally.
Joint Functional Classification
Synarthrosis – immovable joints These joints permit no movement. Certain fibrous joints fall into this category.
Amphiarthrosis – slightly moveable joints. These joints permit only a little bit of movement. Some cartilaginous and fibrous joints are in this category.
Diarthroses – freely movable joints. These joints permit a variety of movements. Synovial joints fall into this category.
Joint Structural Classification
Fibrous Joints – immovable joints. Formed by dense fibrous connective tissue
Cartilaginous Joints – slightly moveable joints. Formed by cartilage
Synovial Joints – freely movable joints. Formed by a synovial capsule
Joint Structural Classification
Fibrous Joints Exaples:Sutures of SkullSyndemoses – Allows slightly more movement than suturesMedial MallelousLateral Mallelous
Joint Structural Classification
Cartilaginous Joints Examples: Pubic Symphysis Intervertbral joints
Joint Structural ClassificationSynovial Joints: Bones are separated by a joint cavity & surrounded by a fibrous capsule.Synovial fluid fills the joint cavity/capsule.Ends of bones covered w/hyaline cartilage.Ligaments reinforce these joints.
Structures associated w/ Synovial Joints
Bursa – flattened fibrous sacs filled w/synovial fluid. Tendon Sheath – Elongated bursa/membrane that wraps around a tendon to hold it together & protection.
Types of Synovial JointsBall-and-socket joint
Hinge joint
Pivot joint
Gliding or Plane joint
Saddle joint
Condyloid or Ellipsoid joint
Types of Synovial JointsGliding or Plane joint –allows a wide range of side-to-side movements. Ex. Carpals & Tarsals
Hinge joint - permit an angular motion along one plane, which is similar to the opening and closing of a door. Ex. Knee, elbow, PIP, MIP, DIP joints.
Pivot joint – This allows a rotation similar to the turning of a dial. Ex. Radius pivots w/ulna.
Types of Synovial JointsBall-and-socket joint –produce a wide array of movements. Ex. Hip & shoulderSaddle joint – joints resemble a saddle in which one bone’s articular surface rocks back and forth upon another. Ex. Metacarpal & carpal or Metattarsal & tarsal.Condyloid or ellipsoid joint –a ball-like articular surface rests against the curve-shaped end of another articular surface. This articulation allows a circular or elliptical pattern of motion. EX. Metacarpal & phalange
Joint Homeostatic ImbalancesBursitis – inflammation of the bursa usually due to trauma or friction
Tendonitis – inflammation of the tendon usually due to overuse.
Joint Homeostatic Imbalances
Arthritis – inflammation or degeneration of a joint. It’s the most widespread & crippling disease in the US. There are over 100 different types.
Osteoarthritis - Most common type, due mostly to aging.
Joint Homeostatic ImbalancesRheumatoid Arthritis – an autoimmune disease where the body sees it’s joints as a foreign threat & will try to destroy them. Symptoms are bilateral joint pain & can lead to deformities.
Gouty Arthritis – inflammation caused by deposits of uric crystals from the blood. Typically occurs in big toe. Usually due to diet.
That’s All Folks!