Skeletal System Chapter 5

cranium mandible sternum humerus carpals metacarpals

Functions of the Bone Support Protection Movement Storage Form the internal framework for the body Protection Protect soft body organs Example – Ribs and skull Movement Skeletal muscles, attach to skeleton by tendons, use the bones to move the body Storage Fat and calcium is stored in bones Blood cell formation Occurs in bone marrow

Classification of Bones Adult skeleton has 206 bones. Compact bone – dense and looks smooth and homogenous Spongy bone – Composed of small needlelike pieces of bone and lots of open spaces

Classification of Bones (cont.) Four different shapes of bone Long bones – longer than they are wide

Classification of Bones (cont.) Short bones – cube-shaped and contain mostly spongy bone

Classification of Bones (cont.) Flat bones – thin, flattened, and usually curved

Classification of Bones (cont.) Irregular bones – bones that don’t fit one of the preceding categories

Classification of Bones (cont.) Skeleton system is divided into two categories Axial skeleton – bones that form the longitudinal axis of the body Cranium and vertebral column Appendicular skeleton – bones of the limbs

Structure of a Long Bone Diaphysis – shaft of bone Made of compact bone Periosteum – covers the diaphysis Epiphysis – the ends of the long bone Filled with spongy bone Articular cartilage – covers the external surface of the epiphysis

Structure of a Long Bone (cont.) Epiphyseal plate – cause the lengthwise growth of the long bone Epiphyseal line – replaces the epiphyseal plate after puberty

Structure of a Long Bone (cont.) Yellow marrow stores adipose tissue Found in the diaphysis Made of compact bone Red marrow produces blood Found in the epiphysis Made of spongy bone

Bone Fractures Simple or closed Compound or open Bone breaks clearly but does not penetrate the skin Compound or open Broken ends of the bone protrude through soft tissues and the skin

Simple Fracture or Compound Fracture?

Bone Fractures (cont.) Comminuted Bone breaks into many fragments Common in geriatrics with brittle bones

Bone Fractures (cont.) Compression Bone is crushed

Bone Fractures (cont.) Depression Broken bone portion is pressed inward Common fracture in skull

Bone Fractures (cont.) Impacted Broken bone ends are forced into each other

Bone Fractures (cont.) Spiral Excessive twisting forces bone to break Common sports fracture

Bone Fractures (cont.) Greenstick Bone breaks incompletely, much in the way a green twig breaks Common in children

Repairing Bone Fractures Week 1 Blood vessels are ruptured when bone breaks. Hematoma is formed Blood-filled swelling

Repairing Bone Fractures (cont.) Weeks 2-3 New blood vessels form. Hematoma hardens forming fibrocartilage callus (or soft callus). Fibrocartilage callus (made of some bone and cartilage) forms over the break.

Repairing Bone Fractures (cont.) Weeks 4-16 The fibrocartilage callus ossifies (or hardens) becoming spongy bone. This forms a bony callus (or hard callus).

Repairing Bone Fractures (cont.) Weeks 17 and more Bony callus is remodeled so that it forms a “patch” over the break. The “fixed” part of the bone will be the strongest part.

Infant Skull Fontanel – soft spot Skull is cartilaginous and hardens as an infant ages As an individual grows, fontanels fuse to form sutures

Vertebral Column Cervical – neck Thoracic – chest Lumbar – lower back 7 vertebrae C1 – C7 Thoracic – chest 12 vertebrae T1 – T12 Lumbar – lower back 5 vertebrate L1 – L5 Sacrum 5 fused vertebrae Coccyx – tail bone 4 fused vertebrae

Vertebral Column Atlas – C1 Axis – C2 Supports weight of the skull allows the head to turn

Vertebral Column Spinal problems Bulging disk - extends outside the space it should normally occupy Herniated disk - results when a disk ruptures http://www.mayoclinic.com/health/bulging-disk/AN00272