The Skeletal System Chapter 7a

Skeletal System Introduction Functions of the skeleton Framework of bones The skeleton through life

Functions of the Skeleton Support Protection Movement Storage areas –Minerals –Lipids Hemopoiesis –Red marrow

Histology of Bones Bone = osseous tissue (connective tissue) Intercellular substance –Calcium phosphate crystals –Collagenous fibers

Human Anatomy, 3rd edition Prentice Hall, © 2001 Anatomy of a Long Bone Diaphysis – shaft Epiphysis – extremity of bone Articular cartilage – covers epiphysis Periosteum – covering around surface of bone Medullary cavity – marrow cavity in diaphysis Endosteum – lines medullary cavity

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Periosteum Two layers –Outer layer Fibrous connective tissue –Inner layer Osteoblasts

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Endosteum Single layer –Osteoclasts –Osteoblasts

Human Anatomy, 3rd edition Prentice Hall, © 2001 Structure of Bone Tissue Pores –Living cells –Channels for blood vessels –Decrease weight of bone Degree of porosity –Spongy bone –Compact bone

Human Anatomy, 3rd edition Prentice Hall, © 2001 Compact Bone Haversian system (Osteon) –Haversian canals –Lacunae –Canaliculi

Human Anatomy, 3rd edition Prentice Hall, © 2001 Spongy Bone Composed of trabeculae Penetrated by blood vessels from periosteum

Ossification Embryo skeleton –Begins as cartilage & membrane –Bone formation begins about 6 weeks after fertilization

Ossification 1 st stage – embryonic cells migrate into future bone sites –Become chondroblasts or –Become osteoblasts

Endochondral Ossification Occurs within a hyaline cartilage model Occurs in most bones of the body Periosteum forms at about week 8 Calcification begins in center of diaphysis –Primary ossification center Secondary ossification centers at epiphyses Medullary cavity forms

Endochondral Ossification

Fetus. 10 weeks

Fetus, 16 weeks

Remaining Cartilage Articular cartilage Epiphyseal plate –Bone grows in length

Homeostasis Remodeling –Different rates in body –Balance between osteoclasts and osteoblasts Factors affecting bone growth –Calcium & phosphorus in diet –Vitamins A, C, & D –Hormones

Fracture Repair Hematoma formation Formation of fibrocartilagenous callus Formation of bony callus Remodeling of bony callus

Fracture Repair

Disorders Vitamin deficiencies –Scurvy –Rickets Osteoporosis

Scurvy

Scurvy Blood Vessels

Rickets

Osteoporosis

Human Anatomy, 3rd edition Prentice Hall, © 2001 Organization of the Skeletal System Axial skeleton Skull Vertebral column Thoracic cage Appendicular skeleton Pectoral girdle Upper limbs Pelvic girdle Lower limbs

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Human Skeleton

Human Anatomy, 3rd edition Prentice Hall, © 2001 Skull –Cranium Protects brain –Facial bones Protect sense organs

Human Anatomy, 3rd edition Prentice Hall, © 2001 Vertebral Column –Vertebrae Cervical Thoracic Lumbar Sacral –Sacrum –Coccyx –Function Protect spinal cord and nerves

Human Anatomy, 3rd edition Prentice Hall, © 2001 Intervertebral Discs Vertebrae –Separated by intervertebral discs

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Atlas and Axis

Human Anatomy, 3rd edition Prentice Hall, © 2001 A Typical Vertebra

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Sacrum and Coccyx Sacrum –Several fused vertebrae Coccyx –Rudimentary tailbone

Human Anatomy, 3rd edition Prentice Hall, © 2001 Thoracic Cage –Ribs (12 pairs) Articulate with vertebrae –Sternum (breastbone) –Function Protect underlying organs

Human Anatomy, 3rd edition Prentice Hall, © 2001 Pectoral Girdle –Scapula (shoulder blade) –Clavicle (collar bone) –Attached to posterior ribs and sternum –Function Connects bones of arms to axial skeleton Aids in arm movements

Human Anatomy, 3rd edition Prentice Hall, © 2001 Upper Limbs –Humerus –Radius –Ulna –Carpals –Metacarpals –Phalanges

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Radius and Ulna

Human Anatomy, 3rd edition Prentice Hall, © 2001 Bones of the Wrist and Hand

Human Anatomy, 3rd edition Prentice Hall, © 2001 Pelvic Girdle –Coxal (hip) bones Ileum Ischium Pubis –Attached to sacrum and coccyx –Function Connect bones of legs to axial skeleton

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Pelvic Girdle

Human Anatomy, 3rd edition Prentice Hall, © 2001 Lower Limbs –Femur –Tibia –Fibula –Patella –Tarsals –Metatarsals –Phalanges

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Femur

Human Anatomy, 3rd edition Prentice Hall, © 2001 Bones of the Lower Leg

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Patella

Human Anatomy, 3rd edition Prentice Hall, © 2001 Bones of the Foot