Skeletal system



Skeletal system

A. Introduction

a. Made up of bones

b. In an adult there are 206 bones

B. Function of bones

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

2. Protection

a. 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

C. Formation of bones

a. Initially collagen fibers secreted by fibroblasts then cartilage deposits between fibers

b. Skeleton fully formed by 2nd month of fetal development – all cartilage

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

d. During childhood and adolescence, ossification exceeds bone loss

e. During adulthood and middle age, ossification equals bone loss

f. After age 35, bone loss exceeds ossification

D. Bone growth

a. Grows in length at the epiphyseal line

b. Grows in width by addition of bone to the surface

c. Controlled by anterior pituitary gland (growth hormone)

E. Four major types of bones

a. long

b. short

c. flat

d. irregular

F. Two sections of skeleton

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

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

G. Axial skeleton

1. Skull

a. Composed of cranial and facial bones

b. Cranium

1) Surrounds and protects the brain

2) Made of eight bones

a) Frontal

b) Two parietal

c) Two temporal

d) Occipital

e) Ethmoid

f) Sphenoid

c. At birth the cranium is not solid bone

1) Spaces called fontanels or “soft spots” allow for enlargement of skull as brain growth occurs

2) Fontanels are made of membrane and cartilage

3) Turn into solid bone by about 18 months of age

2. Facial Bones

a. Fourteen facial bones

1). Main bones

a). Mandible: lower jaw

b). Maxilla: two bones forming upper jaw

c). Zygomatic: two cheek bones

d). Nasal: five bones in upper part of nose

e). Lacrimal: two bones at inner aspect of eyes

f). Palatine: two bones of hard palate or roof of

mouth

c. Sutures: areas where cranial bones have joined together

d. 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

e. Foramina

a. Openings in bones

b. Allow nerves and blood vessels to enter or leave bone

3. Vertebrae

a. Spinal column made of 26 bones called vertebrae

b. Protect the spinal cord

c. Provide support for head and trunk

d. Main sections:

1) Cervical: 7 neck vertebrae

2) Thoracic: 12 vertebrae in back of chest, attach to ribs

3) Lumbar: 5 vertebrae by waist

4) Sacrum: 5 fused bones, triangular in shape, forms dorsal part of pelvis

5) Coccyx: 3-4 fused bones, called tailbone, slightly moveable

e. Intervertebral Disks

1) Pads of cartilage tissue that separate vertebrae

2) Act as shock absorbers

3) Permit bending and twisting movements of vertebral column

f. 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

4.Sternum

a. Breastbone

1). Consists of three parts

a Manubrium: upper region

b) Gladiolus: body or center area

c) Xiphoid process: small piece of cartilage at bottom

b. Two clavicles attach to the manubrium by ligaments

c.Ribs attach to sternum with costal cartilages to form a cage that protects the heart and lungs

H. Appendicular skeleton

1. Shoulder Girdle (a.k.a. Pectoral girdle)

a. Two clavicles

b. Two scapulas (scapulae)

2. Upper Extremities

a. Humerus: upper arm

b. Radius: thumb side of forearm

c. Ulna: Little finger side of forearm

d. Carpals (8): wrist bones

e. Metacarpals (5): hand bones

f. Phalanges (14): finger bones

3. Pelvic Girdle

a. Two os coxae: contains the acetabulum (hip socket)

b. Join with sacrum on dorsal part of body

c. Join together at a joint called the pubic symphysis on ventral part of body

d. Each os coxae made of three bones that are fused or joined

1) Ilium

2) Ischium

3) Pubis

e. Obturator foramen

1) Opening between the ischium and pubis

2) Allows for passage of nerves and blood vessels to and from the legs

4. Lower Extremities

a. Femur: thigh bone

b. Patella: kneecap

c. Tibia: medial bone in lower leg, shin bone

d. Fibula: Lateral bone of lower leg, small than tibia

e. Tarsals (7): ankle bones (calcaneous is heel bone)

f. Metatarsals (5): bones forming instep of foot

g. Phalanges (14): toe bones

5. Joints (a.k.a. Articulations)

a. Synarthrotic

1) Immovable

2) Cranium

b. Amphiarthrotic

1)Limited movement

2)pubic symphysis, vertebral joints, sacroiliac joint

c. Diarthrotic

1) Freely movable

a) Gliding: wrist

b) Pivot: between radius and ulna

c) Ball and socket: hip, shoulder

d) Hinge: elbow

Diseases and Disorders

I. Arthritis

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

B. Two Main Types of Arthritis

1. Osteoarthritis

a. Chronic disease that occurs with aging

b. Symptoms: joint pain, stiffness, aching, limited ROM

c. Rx: Rest, heat/cold applications, aspirin, anti-inflammatory medications, steroid injections, special exercises

2. Rheumatoid Arthritis

a. Chronic inflammatory disease of connective tissues and joints

b. Three times more common in women

c. Often begins between ages 35-45

d. Progressive attacks cause scar tissue formation and atrophy of bone and muscle tissue resulting in permanent deformity and immobility

e. Rx: Rest and prescribed exercise

f. Anti-inflammatory medications: aspirin and steroids

g. Surgery or arthroplasty to replace damaged joints such as hips or knees

II. Bursitis

A. Inflammation of bursae (small fluid-filled sacs surrounding joints)

B. Frequently affects shoulders, elbows, hips, or knees

C. Symptoms: severe pain, limited movement, accumulation of fluid in joint

D. Rx:

1. Pain medications and rest

2. Injections of steroids and anesthetics into joint

3. Aspiration (withdrawal of fluid with a needle) of joint

4. Physical Therapy to preserve joint motion

III. Fractures

A. Involve a crack or break in a bone

B. Types of Fractures:

1. Greenstick: bone is bent and splits causing a crack or incomplete break; common in children

2. Simple: complete break with no damage to skin

3. Compound: break in bone that ruptures through skin; increased chance of infection

4. Impacted: broken bone ends jam into each other

5. Comminuted: bone fragments or splinters into more than two pieces

6. Spiral: severe twisting of a bone causes one or more breaks; common in skiing and skating accidents

7. Depressed: broken piece of skull bone moves inward; common with severe head injuries

8. Colles: breaking and dislocation of the distal radius that causes a characteristic bulge at the wrist; caused by falling on an outstretched hand

C. Reduction:

1. Process by which bone is put back into proper alignment

2. Closed reduction: position bone in alignment, usually with traction, and apply cast or splint to maintain position

3. Open reduction: surgical repair of bone, and sometimes the insertion of pins, plates, and other devices

IV. Dislocation

A. Bone is forcibly displaced from a joint

B. Frequently occurs in shoulders, fingers, knees, and hips

C. Reduced and immobilized with splint, cast, or traction

V. Sprain

A. Twisting action tears ligaments at a joint

B. Common sites are wrists and ankles

C. Symptoms: pain, swelling, discoloration, limited movement

D. Rx: Rest and elevation

E. Immobilization with elastic bandage or splint

F. Cold applications

VI. Osteomyelitis

A. Inflammation of bone usually caused by pathogenic organism

B. Pathogen causes formation of abscess within bone and accumulation of pus in medullary canal

C. Symptoms: pain at site, swelling, chills, fever

D. Rx: antibiotics for infection

VII. Osteoporosis

A. Metabolic disorder with increased porosity or softening of bones

B. Etiology

1. Deficiency of hormones, especially estrogen in females

2. Prolonged lack of calcium in diet

3. Sedentary lifestyle

C. Loss of calcium and phosphate causes bones to become porous, brittle, and prone to fracture

D. Bone density tests lead to early detection and preventative treatment

E. Rx:

1. Increased intake of calcium and vitamin D

2. Exercise

3. Medications to increase bone mass

4. Estrogen replacement

VI. Ruptured Disk

A. Also called a herniated or slipped disk

B. Intervertebral disk ruptures or protrudes out of place and causes pressure on the spinal nerve

C. Most common site is lumbar-sacral area; can occur anywhere on spinal column

D. Symptoms: severe pain, muscle spasm, impaired movement and/or numbness

E. Rx:

1. Pain, anti-inflammatory, and muscle relaxant medications

2. Rest and traction

3. Physical therapy and massage therapy

4. Chiropractic treatment

5. Heat or cold applications

6. Laminectomy: surgical removal of the protruding disk for severe cases

VII. Spina Bifida

A. Congenital defect in which the vertebrae fail to unite in midline

B. May require surgery

C. Severity may cause paralysis

VIII. Abnormal curvatures of spinal column

A. Kyphosis: “hunchback” or rounded bowing of the back at the thoracic area

B. Scoliosis: side-to-side or lateral curvature of spine

C. Lordosis: “swayback”: or abnormal inward curvature of lumbar vertebrae

D. Causes or abnormal curvatures:

1. poor posture

2. congenital defects

3. structural defects of vertebrae

4. malnutrition

5. degeneration of vertebrae

E. Rx:

1. Therapeutic exercises, firm mattresses and braces

2. Surgical repair for severe deformities

IX. Growth Hormone Disorders

1. Dwarfism: hypofunction

2. Giantism: hyperfunction

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

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