Skeletal System

•Made up of bones•In an adult there are 206 bones

Functions of the Bone

1.Framework: support body’s muscles, fat, and skin

• 2. Protectiona. surrounds vital organs to protect them

• examples: skull surrounding brain; ribs to protect heart • 3. Levers: attach to muscles to help provide

movement• 4. Production of blood cells: red and white

blood cells and platelets

Formation of bones

• Initially collagen fibers secreted by fibroblasts then cartilage deposits between fibers• Skeleton fully formed

by 2nd month of fetal development – all cartilage

Formation continued…

• 8th week of fetal development – ossification begins - which is mineral matter being deposited and cartilage is replaced

Formation continued…• During childhood and adolescence, ossification exceeds

bone loss• During adulthood and middle age, ossification equals

bone loss• After age 35, bone loss exceeds ossification

Bone Growth• Grows in

length at the epiphyseal line• Grows in

width by addition of bone to the surface

•Controlled by anterior pituitary gland (growth hormone)

Four major types of bones

•long•short•flat•irregular

Two sections of skeleton

•Axial – forms main trunk of body; composed of the skull, spinal column, ribs, and sternum

•Appendicular - forms extremities (arms and legs); composed of shoulder girdle, arm bones, pelvic girdle, and leg bones

Axial skeleton•Skull• Composed of cranial and

facial bones• Cranium• Surrounds and protects

the brain• Made of eight bones• Frontal• Two parietal• Two temporal• Occipital• Ethmoid• Sphenoid

• At birth the cranium is not solid bone• Spaces called

fontanels or “soft spots” allow for enlargement of skull as brain growth occurs• Fontanels are

made of membrane and cartilage• Turn into solid

bone by about 18 months of age

Facial Bones• Fourteen facial bones 1). Main bones

a). Mandible: lower jawb). Maxilla: two bones forming upper jawc). Zygomatic: two cheek bonesd). Nasal: five bones in upper part of nosee). Lacrimal: two bones at inner aspect of eyesf). Palatine: two bones of hard palate or roof of mouth

Sutures• areas where

cranial bones have joined together

Sinuses• a. Air spaces in the

bones of the skull• b. Provide strength

with less weight• c. Act as resonating

chambers for the voice• d. Lined with

mucous membranes

Foramina

• a. Openings in bones•b. Allow

nerves and blood vessels to enter or leave bone

Vertebrae• Spinal column

made of 26 bones called vertebrae•Protect the spinal

cord•Provide support

for head and trunk

Main sections:

• Cervical: 7 neck vertebrae• Thoracic: 12 vertebrae in

back of chest, attach to ribs• Lumbar: 5 vertebrae by

waist• Sacrum: 5 fused bones,

triangular in shape, forms dorsal part of pelvis• Coccyx: 3-4 fused bones,

called tailbone, slightly moveable

Intervertebral Disks•1) Pads of

cartilage tissue that separate vertebrae•2) Act as shock

absorbers•3) Permit bending

and twisting movements of vertebral column

Ribs• 1) 12 pairs of long slender bones• 2) Attach to thoracic vertebrae on dorsal

surface of body• a) True ribs: First 7 pairs of ribs; Attach directly

to sternum on front of body• b) False ribs: Next 5 pairs of ribs; first 3 pairs

attach to cartilage of rib above• c) Floating ribs: last two pairs of false ribs;

no attachment on front of body

Ribs continued…

Sternum• Breastbone 1) Consists of three parts

a) Manubrium: upper region b) Gladiolus: body or center

area c) Xiphoid process: small piece of cartilage at bottom2. Two clavicles attach to the manubrium by ligaments3.Ribs attach to sternum with costal cartilages to form a cage that protects the heart and lungs

Appendicular Skeleton

Shoulder Girdle (aka Pectoral Girdle)

•Two clavicles•Two scapula's (scapulae)

Upper Extremities• Humorous: upper

arm• Radius: thumb side of

forearm• Ulna: Little finger side

of forearm• Carpals (8): wrist

bones• Metacarpals (5):

hand bones• Phalanges (14): finger

bones

Pelvic Girdle• Two os coxae:

contains the acetabulum (hip socket)• Join with sacrum on

dorsal part of body• Join together at a joint

called the pubic symphysis on ventral part of body

•Each os coxae made of three bones that are fused or joined• Ilium• Ischium• Pubis

Obturator foramen• 1) Opening

between the ischium and pubis• 2) Allows for

passage of nerves and blood vessels to and from the legs

Lower Extremities• Femur: thigh bone• Patella: kneecap• Tibia: medial bone in lower

leg, shin bone• Fibula: Lateral bone of lower

leg, small than tibia• Tarsals (7): ankle bones

(calcaneous is heel bone)• Metatarsals (5): bones forming

instep of foot• Phalanges (14): toe bones

Joints (a.k.a. Articulations)• Synarthrotic

• Immovable• Cranium

• Amphiarthrotic• 1)Limited movement• 2)pubic symphysis, vertebral joints, sacroiliac joint• Diarthrotic• Freely movable

• Gliding: wrist• Pivot: between radius and ulna• Ball and socket: hip, shoulder• Hinge: elbow

Bone Composition, Shape & Bone Marrow

Types of Bone Based on Composition

1. Compact Bone•Very dense• Stress bearing• Femur, tibia,

humorous

2. Cancellous Bone• Light, spongy.• Low stress areas where

weight of bone would be a problem.• Found at ends of long

bones, ribs, sternum, hips, vertebrae, cranium.

Classification of Bones According to Shape

Long Bones (extremities): levers1. Parts of long bones:• Epiphysis: at ends, cancellous bone• Diaphysis: shaft, compact bone• Medullary Canal:• Cavity in diaphysis• Filled with yellow marrow

4. Endosteum:•Membrane that lines

medullary canal• Keeps yellow marrow

intact• Produces some bone

growth

5. Periosteum:• Tough membrane

covering outside of bones• Contains blood and

lymph vessels• Contains osteoblasts:

special cells that form new bone tissue• Necessary for bone

growth, repair, and nutrition

6. Articular cartilage:• Thin layer

covers the epiphysis• Acts as a shock

absorber when two bones meet to form a joint

7. Long bones include:

Femur FibulaTibia

Humorous

Ulna Radius Clavicle

Short Bones

•Cubed shaped•Allow flexible

movement•Cancellous bone

covered by compact bone

Short Bones include:

Flat Bones•Flat plates•Protect vital organs •Provide broad surface area for muscle attachment

Flat bones include:Facial Bones

Scapula

Cranial Bones

Sternum

Irregular Bones• Peculiarly shaped to provide support & protection• Allows flexibility

Ear bones

RibsVertebra

Hyoid bone

Hip bones

Sesamoid Bone• Extra bones found in certain tendons.

Patella

Bone Growth• Grow in length at epiphyseal line• Grow in width by addition of bone to surface• Controlled by anterior pituitary (growth

hormone)

Growth Hormone Dysfunction

• Dwarfism: hypofunction• Giantism: hyperfunction• Acromegaly: hyperfunction after puberty;

enlarges bones of hands, feet, and face.

Bone Marrow• Yellow Marrow• Inside

medullary canal•Mainly fat cells

Bone Marrow continued…• Red Marrow

1. Found in certain bones such as:1. Vertebrae2. Ribs3. Sternum4. Cranium5. Proximal ends of humorous & femur

2. Produces RBC, platelets & some WBC3. Important in the manufacture of blood & is involved with the body’s immune response4. Used in diagnosing blood diseases5. Given as transplants to people with defective immune systems

Diseases & Disorders of the Skeletal System

Arthritis

• Inflammation of the bones at the joints; usually with pain and changes in bone structure.

Two Main Types of Arthritis:• Osteoarthritis• Rheumatoid Arthritis

Osteoarthritis• Chronic disease that

occurs with aging• Symptoms: joint pain,

stiffness, aching, limited ROM• Rx: Rest, heat/cold

applications, aspirin, anti-inflammatory medications, steroid injections, special exercises

Rheumatoid Arthritis• Chronic inflammatory disease of connective tissues and joints• Three times more common in women• Often begins between ages 35-45• Progressive attacks cause scar tissue formation and atrophy of

bone and muscle tissue resulting in permanent deformity and immobility• Rx: Rest and prescribed exercise• Anti-inflammatory medications: aspirin and steroids• Surgery or arthroplasty to replace damaged joints such as hips

or knees

Bursitis• Inflammation of bursae (small fluid-filled

sacs surrounding joints)• Frequently affects shoulders, elbows, hips,

or knees• Symptoms: severe pain, limited

movement, accumulation of fluid in joint• Rx: • Pain medications and rest• Injections of steroids and anesthetics

into joint• Aspiration (withdrawal of fluid with a

needle) of joint• Physical Therapy to preserve joint

motion

Fractures

•Involve a crack or break in a bone•Several Types of Fractures

Fractures--Greenstick Bone is bent and splits causing a crack or incomplete break; common in children

Fractures-Simple

Complete break with no damage to skin

Fractures--CompoundBreak in bone that ruptures through skin; increased chance of infection

Fractures--Impacted

Broken bone ends jam into each other

Fractures-Comminuted

Bone fragments or splinters into more than two pieces

Fractures-SpiralSevere twisting of a bone causes one or more breaks; common in skiing and skating accidents

Fractures-DepressedBroken piece of skull bone moves inward; common with severe head injuries

Fracture-CollesBreaking and dislocation of the distal radius that causes a characteristic bulge at the wrist; caused by falling on an outstretched hand

Reduction:•Process by which bone is put back into proper alignment• Closed reduction: position bone in

alignment, usually with traction, and apply cast or splint to maintain position• Open reduction: surgical repair of

bone, and sometimes the insertion of pins, plates, and other devices

 Dislocation

• Bone is forcibly displaced from a joint• Frequently occurs in shoulders, fingers,

knees, and hips• Reduced and immobilized with splint, cast,

or traction

Sprain• Twisting action tears

ligaments at a joint• Common sites are wrists

and ankles• Symptoms: pain, swelling,

discoloration, limited movement• Rx: Rest and elevation• Immobilization with elastic

bandage or splint• Cold applications

Osteomyelitis• Inflammation of bone usually

caused by pathogenic organism• Pathogen causes formation of

abscess within bone and accumulation of pus in medullary canal• Symptoms: pain at site,

swelling, chills, fever• Rx: antibiotics for infection

Osteoporosis• Metabolic disorder with increased porosity or

softening of bones• Etiology• Deficiency of hormones, especially estrogen in females• Prolonged lack of calcium in diet • Sedentary lifestyle

• Loss of calcium and phosphate causes bones to become porous, brittle, and prone to fracture• Bone density tests lead to early detection and

preventative treatment• Rx:• Increased intake of calcium and vitamin D• Exercise• Medications to increase bone mass• Estrogen replacement

Ruptured Disk• Also called a herniated or slipped disk• Intervertebral disk ruptures or protrudes out of

place and causes pressure on the spinal nerve• Most common site is lumbar-sacral area; can occur

anywhere on spinal column• Symptoms: severe pain, muscle spasm, impaired

movement and/or numbness• Rx:• Pain, anti-inflammatory, and muscle relaxant medications• Rest and traction• Physical therapy and massage therapy• Chiropractic treatment• Heat or cold applications• Laminectomy: surgical removal of the protruding disk for

severe cases

Spina Bifida• Congenital defect in which the vertebrae fail

to unite in midline•May require surgery • Severity may cause paralysis

Abnormal curvatures of spinal column

• Kyphosis: “hunchback” or rounded bowing of the back at the thoracic area• Scoliosis: side-to-side or lateral curvature of spine• Lordosis: “swayback”: or abnormal inward curvature

of lumbar vertebrae

Causes or abnormal curvatures:• poor posture• congenital defects• structural defects of vertebrae• malnutrition• degeneration of vertebrae• Rx:• Therapeutic exercises, firm

mattresses and braces• Surgical repair for severe

deformities

Growth Hormone Disorders

• Dwarfism: hypofunction• Gigantism:

hyperfunction

Acromegaly: hyperfunction after puberty; enlarges bones of hands, feet, face