The Skeleton

The Human Skeleton Learn major bones and markings on handout. 206 bones of human skeleton divided into: axial skeleton appendicular skeleton

Axial Skeleton skull and trunk vertebral column and rib cage

Appendicular Skeleton arms and legs includes pectoral and pelvic girdles

Bone Markings sites of muscle, ligament, and tendon attachment points of articulation pathways for blood vessels and nerves Projections grow outward Depressions and Openings for blood and nerve supply

Projections Crest - narrow ridge ilium Head - bony expansion humerus, ribs Condyle – rounded lower humerus, mandible articular projection Process - lump elbow- olecranon process Spine - sharp, slender vertebra pointed

Depressions and Openings Meatus - canal-like auditory Sinus - air filled cavity paranasal Fossa - shallow depression iliac Foramen – round/ oval opening vertebrae Fissure - slit-like, cleft eye socket

How to Identify the Sex of a Skeleton

Male and Female Pelvis female modified for childbearing wider, shallower, lighter, rounder, tilted forward

Developmental Aspects of the Skeleton

Fontanels At birth fontanels (still fibrous areas of cranium) accommodate future brain growth. - “soft spot” - by age 2 skull is 3/4 adult size - by age 11 skull is full size and face is starting to grow out

Spinal Curvatures 6 months Lift head Cervical curvature develops Walking Wight over center of gravity Develops lumbar curvature Spinal curve at birth No curvature

Natural Spinal Curvatures

Disorders: normal curves become exaggerated Scoliosis lateral bend in thoracic region one leg shorter, congenital, poor posture, muscle paralysis on one side

Kyphosis hunch back, “rounded shoulder” exaggeration of thoracic curve poor posture, degeneration of discs, rickets

Lordosis sway back exaggeration of lumbar curve increase wt. in abdomen, pregnancy, poor posture

After birth, legs grow more rapidly than trunk. With age, all bones lose some mass.