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!