The Skeletal System No Bones About It!

Major Functions Support Support Protection Protection –Indirect & direct Aid in movement Aid in movement Blood cell formation Blood cell formation Storage Storage

Types of Bone Long Long Short Short –Sesamoid Flat Flat Irregular Irregular

Parts of a Long Bone

1 - Diaphysis (shaft) 1 - Diaphysis (shaft) 2 - Epiphysis (ends with articular cartilage) 2 - Epiphysis (ends with articular cartilage)

Parts of a Long Bone 3 - Periosteum – covers entire bone except articulations 3 - Periosteum – covers entire bone except articulations 4 - Compact bone 4 - Compact bone 5 - Spongy bone 5 - Spongy bone

Parts of a Long Bone 6 - Red marrow – within spaces of spongy bone 6 - Red marrow – within spaces of spongy bone 7 - Medullary cavity in diaphysis 7 - Medullary cavity in diaphysis –Lined with 8 - endosteum –Filled with 9 - yellow marrow

Bone Cells Osteoblasts – produce matrix Osteoblasts – produce matrix Osteoclasts – dissolve matrix Osteoclasts – dissolve matrix Osteocytes – stationary blasts Osteocytes – stationary blasts

Bone Development & Growth Osteogenesis Osteogenesis Begins around Week 8 prenatal Begins around Week 8 prenatal Precursor cells develop one of two ways… Precursor cells develop one of two ways… –Intramembranous –Endochondral

Intramembranous Development Cells develop between sheets of tissue Cells develop between sheets of tissue Skulls, clavicles Skulls, clavicles

Endochondral Development Chondral = cartilage Chondral = cartilage From template of cartilage From template of cartilage Ossification – secretion of bone matrix Ossification – secretion of bone matrix Long bones Long bones

Endochondral Development of a Long Bone Primary ossification center = diaphysis Primary ossification center = diaphysis –Blood vessels penetrate –Chondroblasts die –Cartilage destroyed –Spaces for osteoblasts to move in

Endochondral Development of a Long Bone Secondary ossification center = epiphysis Secondary ossification center = epiphysis –Leaves Epiphyseal Plate – band of cartilage

Epiphyseal Plate

Endochondral Growth Interstitial Growth Interstitial Growth –Lengthwise –Chondroblasts active near epiphysis –Osteoblasts active near diaphysis

Endochondral Growth Appositional Appositional –Widthwise –Osteoblasts active in periosteum –Osteoclasts in medullary cavity –UNEQUAL PROCESS!

Axial Skeleton vs. Appendicular Skeleton

Joints (Articulations) Fibrous – connective tissue Fibrous – connective tissue –Little to no movement –Sutures, Syndesmoses, Teeth

Joints (Articulations) Cartilaginous – cartilage Cartilaginous – cartilage –Slightly moveable –Costal cartilage, intervertebral discs, symphysis pubis

Joints (Articulations) Synovial – fluid-filled space Synovial – fluid-filled space –Freely moveable –Lots of variety

Synovial Joints Gliding Gliding Hinge Hinge Pivot Pivot Ellipsoid Ellipsoid Saddle Saddle Ball & socket Ball & socket

Movements at Synovial Joints Flexion/extension/hyperextension Flexion/extension/hyperextension Abduction/adduction Abduction/adduction Horizontal abduction/horizontal adduction Horizontal abduction/horizontal adduction Rotation Rotation Pronation/supination Pronation/supination Eversion/inversion Eversion/inversion Plantar flexion/Dorsiflexion Plantar flexion/Dorsiflexion