Skeletal System
1. axial skeleton
- bones of the head and torso
2. appendicular skeleton
- bones of the arms and legs
・bone numbers
a. adult — 206 bones
b. infant — ~300 bones
- Coccyx — 4 bones that fused into 1
- sacrum — 5 bones that fused into 1
・spine
a. 7 cervical vertebrae
b. 12 thoracic vertebrae
c. 5 lumbar vertebrae
- job: protect your spinal cord
・ ribs
a. 7 true
b. 5 false
- 2 floating
- 12 total ribs on each side
・ pelvis
- male and female pelvis are slightly different
- female pelvis is more rounded
- more of an open angle to the coccyx for childbirth
- more cartilage at the front of the pelvis (pubic symphysis) to allow for expansion and contraction
during childbirth
・ functions of skeletal system
a. support
b. protection
c. movement
d. storage (ca, phosphorous, fat)
e. blood cell formation (hematopoiesis)
・ classification of bone shapes
1. long bones — ex. femur, humorous
2. short bones — ex. wrist, ankle
3. flat bones — ex. skull
4. irregular bones — ex. vertebrae
・shapes of bones
- the external layer of bone is called compact bone
- the internal layer is called spongy bone
・cellular bone terms
a. osteoblasts — bone forming cells
b. osteoclasts — bone-destroying cells (when bones wear out)
c. osteocytes — mature bone cells
- the osteoblasts and the osteoclasts are found in the periosteum and the endosteum
・compact bone make-up
- circular structures called osteons
・bone structures (long bones)
a. diaphysis — long shaft of the bone
b. medullary cavity — inside the diaphysis which houses bone marrow
c. epiphyses — ends of the bone
d. periosteum — outer most covering, makes the bone shiny
e. endosteum — lines medullary cavity
・structure of long bones
- there is both red marrow and yellow marrow. yellow marrow is yellow due to a high number of fat
cells
- as infants all marrow is red marrow
- in adults there is about 50/50 yellow/red marrow. the yellow marrow can revert to red marrow if
needed
・red vs. yellow
- adults have on average about 5.7lbs of bone marrow, with about half of it being red
- red marrow is mainly in the flat bones such as hip bone, skull, ribs, vertebrae, and shoulder blades,
and in the ends of the long bones femur and humorous
・bone fracturs
- simple — doesn’t penetrate the skin, bone is broken into 2 pieces
- closed reduction — nonsurgical realignment
- compound/open — does penetrate the skin, usually bone becomes infected and requires heavy
antibiotics
- comminuted — bone fragments into many pieces (usually happens in brittle bones)
- impacted — broken bone ends are forced into each other (shoulder, hip)
- spiral — twisting force applied to bone (common sports injury)
- greenstick — incomplete break (common in children)
- depressed — broken bone portion is pressed inward (skull)
・healing of fracturs
- normally healing takes 8-12 weeks (longer in elderly)
- stages of healing
1. fracture hematoma
- broken vessels form a blood clot
2. granulation tissue (soft callus)
- fibrous tissue formed by fibroblasts & infiltrated by capillaries
3. callus formation
- soft callus of fibrocartilage replaced by hard callus of bone in 6 weeks
4. remodeling
- occurs over next 6 months as spongy bone is replaced with compact bone
・bone conditions
a. osteoporosis
- depletion of the bone tissue
- typically, a result of hormonal changes, or deficiency of calcium of vitamin D
- bone becomes more porous and less compact
- elderly more affected
b. rickets
- rickets is the softening and weakening of bones in children, usually because of an extreme and
prolonged vitamin D deficiency
- most visible sign is bowed legs
c. scoliosis
- lateral curvature of the spine
- more common in young girls
- unknown cause
- can be treated with surgery or various braces depending on the severity of the curvature
d. kyphosis
- hunchback, curvature of the spine in a bent over position
- commonly found in women with osteoporosis
e. lordosis
- swayback, curvature of the spine where the hips protrude forward
- commonly found in pregnant women or men with potbellies
- can be permanent or temporary
f. arthritis
- usually involves the degeneration of bone
- there are more than 100 different types of arthritis
- can be crippling and very painful
g. osteoarthritis
- most common of all types of arthritis, 50% of all cases
- degenerative joint disease
- sometimes due to aging or can be from cartilage destruction (some sports injuries)
- can be treated with drugs
1. vioxx
2. celebrex
h. rheumatoid arthritis
- common in men and women aged 40-50
- joint stiffness and tenderness
- occurs bilaterally
- synovial joint swelling
・joints
a. arthrology is the study of joints
b. kinesiology is the study of musculoskeletal movement
- joints are classified by their freedom of movement
a. diarthrosis — freely moveable
b. amphiarthrosis — slightly moveable
c. synarthrosis — little or no movement
- 3 classes of joints
1. fibrous joints — bone ends/parts are united by collagen fibers
- 3 types
a. suture — between the bones in the skull (immobile)
b. gomphosis — teeth (immobile)
c. syndesmosis — between radius/ulna, connected by tendon or ligament and CT
(slightly mobile)
2. cartilaginous joints — bone ends are united by cartilage
- 2 types
a. synchondroses — connect ribs to sternum (immobile)
b. symphysis — vertebrae (slightly mobile)
3. synovial joints — bone ends are covered with articular cartilage, and lined with synovial fluid
- 6 types
a. plane — between carpals and tarsals (gliding movements)
b. hinge — knee and elbow
c. pivot joints — first bone rotates on its longitudinal axis relative to the other
(head on top of the vertebral column)
d. condyloid — knuckles, hands and fingers
e. ball and socket — shoulder and hit
f. saddle — thumb
- joint problems
a. dislocation — bones are forced out of the normal positions at a joint
b. bursitis — inflammation of bursa sac (usually from falling directly on elbow or knee)
c. tendonitis — inflammation of tendon sheath usually caused by overuse
・achondroplasia dwarfism
- short stature but normal-sized head and trunk
- long bones of the limbs stop growing in childhood but other bones are unaffected
- about 80% of people with achondroplasia have average-sized parents; these cases result from new
mutations
- individuals who inherit two altered copies of this gene typically have a severe form of achondroplasia
・pituitary dwarfism
- pituitary dwarf has lack of growth hormone from the pituitary gland
- short stature with normal proportions
- the condition begins in childhood, but becomes more evident during puberty
- causes
a. genetic mutations
b. tumors
c. trauma
d. leukemia
e. idiopathic — the cause of pituitary dwarfism is unknown