S KELETAL UNIT BONE INTRODUCTION NOTES MMHS Anatomy and Physiology

S KELETON DESIGN Human Skeleton has 206 Bones. Humans have endoskeletons (=internal) Arthropods have exoskeletons (=external) Humans must rely on nervous system and sensory organs for protection *oncoming car *hot stove

S KELETAL DIVISIONS 2 Main Divisions of the Skeleton 1. Axial skeleton (body’s central frame ) 2. Appendicular skeleton (body’s lateral frame) Axial (forms the midline of the body) Includes the following parts  cranium, rib cage, vertebral column, sacrum, coccyx Appendicular (think “appendages”) Includes the following parts  pectoral girdle (shoulder), pelvic girdle (hips), arms to hands, legs to feet.

A XIAL VS APPENDICULAR SKELETON

F UNCTION OF SKELETON 1. [Protection] of vital internal organs protects a) Skull protects brain. b) Rib cage protects heart and lungs c) Pelvis protects reproductive organs. 2. [Support] provides framework for tissues to hang on. 3. [Movement] muscles attached via tendons. 4. [Storage] of minerals like calcium (Ca) and phosphorous (P) 5. [Production] of Erythrocytes (RBC’s) from red marrow.

B ONE CLASSIFICATION BY SHAPE Bone ShapeLocation in Body 1. Long BonesFemur, humerus, tibia, fibula 2. Short BonesCarpals and tarsal 3. Flat BonesClavicle, ribs, cranial plates, scapula 4. Irregular BonesVertebrae

B ONE CLASSIFICATION a. long b. irregular c. flat d. irregular e. short

B ONE A NATOMY 1. Epiphysis = ends of bone (covered in hyaline cart) Epiphyses form RBC’s 2. Diaphysis = narrow shaft of bone 3. Periosteum = layer of connective tissue outside of bone. Contains blood vessels and nerves. 4. Medullary Cavity = Hollow center of the bone. Contains major blood vessels and marrow.

A NATOMY OF BONE

C OMPACT BONE 1. Calcified matrix ( Canaliculi ) contain lacunae which hold osteocytes. 2. Osteocytes are connected to each other by canaliculi. Receive nutrients Get rid of wastes 3. Blood vessels and nerves that travel the length of the bone do so through Haversian Canals.

C ANCELLOUS “ SPONGY ” BONE 1. Trabeculae (interconnecting rods of bone) create the “spongy” appearance. 2. Located in epiphyses of bones (close to joints) a) Joints bear greater amounts of stress from many directions. b) Cancellous bone channels stress into direction of compact bone (= more strength)

C ANCELLOUS BONE

G ENDER DIFFERENCES IN SKELETONS Male skeletons tend to be heavier to bear greater muscle attachment. Coxa bones (hips) are narrower and more upright Female skeletons have fewer markings on the skeleton Female skeletons are better designed for childbirth. 1. Enlarged pelvic outlet / inlet 2. Less curvature of the sacrum and coccyx. 3. Broader = Iliac bones stick out more laterally but not as high as in males.

M ALE VS FEMALE