A & P Ch. 7, Part 2 Notes

I. Vertebral ColumnA. Extends from the skull to the

pelvis; forms the vertical axis of skeleton

B. Vertebrae are separated by intervertebral discs.

C. Protects the spinal cordD. Sacrum formed by five fused

vertebraeE. Coccyx formed by four fused

vertebraeF. Four curvatures: thoracic, pelvic, cervical, and lumbar

G. Typical Vertebra

1. Body of a vertebra forms thick, anterior portion of bone

2. Intervertebral discs are fastened to upper and lower surfaces of the vertebral bodies; cushion and soften forces caused by walking and jumping movements

3. Intervertebral foramina provide passageways for spinal nerves

H. Vertebral curves1. There are 7 cervical vertebrae; atlas is the 1st cervical

vertebra & supports the head; axis is the 2nd cervical vertebra; as the head turns side to side, the atlas pivots around a process that projects upward (dens)

2. 12 thoracic vertebrae; articulate with ribs; bodies adapted to bear increasing loads of body weight

3. 5 lumbar vertebrae; located in the small of the back; bodies are larger and stronger than the superior vertebrae

4. Sacrum is triangular & forms posterior wall of the pelvis; foramina provide passageways for nerves and blood vessels; Coccyx is lowest part of vertebral column; sitting presses on coccyx & it moves forward, acting like a shock absorber

II. Thoracic cageA. Includes the ribs, thoracic vertebrae, the sternum, &

costal cartilages that attach ribs to sternum; supports shoulder girdle & upper limb & protects internal organs

B. Usually 24 ribs; true ribs are 1st 7 pairs; false ribs are last 5 pairs; floating ribs are last 2 pairs of false ribs; costal cartilages attached to anterior ends of a rib

C. Sternum located along the midline in anterior of thoracic cage; 3 parts of sternum are manubrium, body, & xiphoid process (xiphoid process projects downward, manubrium articulates w/ clavicles, manubrium & body articulate w/ ribs)

III. Pectoral girdleA. Consists of 2 clavicles & 2

scapulae; supports upper limbs & is an attachment for muscles that move the arm

B. Clavicles run between sternum & shoulders

C. Scapula (shoulder blades) are shaped like triangles & located in posterior part of girdle; connects to humerus & clavicle

IV. Upper limbA. Form framework for arm, forearm,

wrist & hand; humerus, radius, ulna, carpals, metacarpals, & phalanges

B. Humerus extends from scapula to elbow; largest bone of arm; provides attachment for many muscles

C. Radius located on thumb side of the forearm; extends from elbow to wrist & crosses over ulna when hand is turned so that palm faces backward

D. Ulna forms hinge joint w/humerus; on medial side of forearm; proximal end is commonly called elbow

V. Wrist & handA. Wrist is at junction of forearm and

hand; bones called carpals; anterior surface of is concave for passage of tendons & nerves into palms

B. Hand composed of palm & 5 fingers; metacarpals form framework of palm; distal metacarpals form knuckles of clenched fist; metacarpal of thumb is numbered 1

C. Finger bones are phalanges; each finger has 3 phalanges & thumb has 2 phalanges

VI. Pelvic girdleA. Formed by the sacrum, coccyx, and pelvic girdle (2 coxae-

hipbones); supports trunk of body; provides attachments for lower limbs & protects urinary bladder, distal end of large intestine, & internal reproductive organs; body’s weight transmitted through pelvic girdle to lower limbs, then onto ground

B. Coxae also called hipbones; three parts: an ilium, an ischium, & a pubis

C. Differences Between Male and Female PelvisFemale iliac bones more flared & smaller; female hips usually wider; angle of female pubic arch may be greater than male; female pelvic cavity usually wider; female pelvis is lighter and less evidence of muscle attachments

VII. Lower limbA. Thigh, leg, ankle, & foot (femur, tibia, fibula, patella,

tarsals, metatarsals, & phalanges)B. Femur extends from hip to knee; provide attachments

for muscles and ligamentsC. Patella is sesamoid bone located in a tendon over kneeD. Shinbone is the tibia; located on medial sideE. Fibula is on lateral side of tibiaF. Ankle & foot consist of a tarsus, a metatarsus, &

phalanges; heads at distal ends of metatarsals form ball of foot; arch of the foot formed by arrangements of tarsals & metatarsals; bones of toes called phalanges; toes have 3 phalanges except big toe because it lacks middle phalynx

VIII. Life span changesA. Decrease in height begins at about age 30.B. As calcium levels fall, bones become brittle & prone to

fracture.C. Gradually, osteoclasts come to outnumber osteoblasts.D. By age 35 all adults start to lose bone mass.E. Most common fractures in elderly are vertebral

compression fractures, hip fractures, wrist fractures, leg fractures, & pelvis fractures

J. Preserving skeletal health may involve avoiding falls, taking calcium supplements, getting enough vitamin D, avoiding carbonated beverages, & getting regular exercise.