Human Skeletal System Axial Skeleton Skull Appendicular Skeleton

Human Skeletal System Axial Skeleton ÞSkull Appendicular Skeleton => Pectoral Girdle & Upper Limbs (31 bones/structures) ÞVertebral Column (11 bones/structures) (44 bones/structures) => Pelvic Girdle & Lower Limbs (36 bones/structures) ÞThorax Þ(8 bones/structures) Total = 130 bones/markings that you are required to know There is a total of 206 bones in the human skeleton

Body Framework I. Functions of Bone A. Support B. Movement – due to articulations (joints) C. Storage – Ca and P D. Blood Cell Production (rbc, wbc) E. Protection – of internal organs, brain, spinal cord F. Leverage/Site of muscle attachment

II. Major Features of Bone (Long Bones; Tibia, Femur) A. Epiphysis - “head” or expanded ends of long bones - - contains spongy (or cancellous) bone - - Trabeculae - struts, plates in spongy bone

Normal Trabeculae with Osteoporosis

B. Diaphysis - tubular shaft of long bones - made of compact bone; provides strength

C. Medullary canal (cavity) – Marrow cavity in diaphysis 1. Red Marrow - production of blood cells - found in spongy bone of vertebrae, ribs, breastbone, long bones 2. Yellow Marrow - found in center of long bones - made of adipose and connective tissue

D. Endosteum - cellular lining of marrow cavity, connective tissue E. Periosteum - outer surface of bone; made of tough connective tissue - Contains osteoblasts: form Osteocytes

III. Bone Shapes and Sizes A. Long Bones – Longer than they are wide Ex. Femur, Humerus, Tibia, Fibula, Radius, Ulna B. Short Bones – About as broad as they are long Ex. Carpals, Tarsals C. Flat Bones – Thin, parallel surfaces of compact bone with spongy bone in between Ex. Roof of skull, Sternum, Ribs, Scapula

D. Irregular Bones – complex shapes; short, flat, notched, ridged surfaces Ex. Vertebrae E. Sesamoid Bones - small, round, flat bones; usually near knee, hands, and feet Ex. Patella

IV. Bone Markings – surfaces of bones are not smooth A. Process - bump, projecting portion of bone B. Fossa – depression (hole that doesn’t go all the way through) C. Foramen - hole D. Condyle - rounded process (bump) at bone articulation

E. Epicondyle - raised area or bump on condyle F. Crest - narrow ridge, ex. Iliac crest G. Spine - sharp, slender process H. Sinus - hollow or cavity inside bone I. Sulcus - groove

J. Head and Neck - found in ball and socket joint 1. 1. Head - ball part 2. 2. Neck - supports ball

V. The skeleton is often divided into 2 major divisions A. Axial Skeleton – includes skull, vertebral column, bones of thorax and hyoid bone B. Appendicular Skeleton – includes bones of upper extremeties, shoulder, lower extremities, and pelvis