Skeletal System Chapter 5

carpals metacarpals sternum mandible humerus cranium

Functions of the Bone Support  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 (but five different types) 1. Long bones – longer than they are wide

Classification of Bones (cont.) 2. Short bones – cube-shaped and contain mostly spongy bone

Classification of Bones (cont.) 3. Flat bones – thin, flattened, and usually curved

Classification of Bones (cont.) 4. Irregular bones – bones that don’t fit one of the preceding categories

Classification of Bones (cont.)  Seismoid bone - usually short or irregular bones, imbedded in a tendon

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

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.

Vomer

Skull Anatomy Tutorial Website ull/skulltt.htm ull/skulltt.htm

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  7 vertebrae  C 1 – C 7 Thoracic – chest  12 vertebrae  T 1 – T 12 Lumbar – lower back  5 vertebrate  L 1 – L 5 Sacrum  5 fused vertebrae Coccyx – tail bone  4 fused vertebrae

Vertebral Column Atlas – C 1  Supports weight of the skull Axis – C 2  allows the head to turn

Vertebral Column Vertebral foramen – canal through which the spinal cord passes  Body – Weight-bearing part of the vertebra that contains a disk  Foramen – an opening, or orifice, in a bone

Vertebral Column

Spinal problems  Bulging disk - extends outside the space it should normally occupy  Herniated disk - results when a disk ruptures