The Skeletal System
Function of
bones
A framework
for the body, support
Weight bearing
Protection
Levers
Attachment of
muscles
Stores calcium
and phosphate
Production
of blood cells
Divisions
Axial skeleton
- head and trunk
Appendicular
skeleton - arms, legs, shoulders
and hips
The bones
Skull (Cranium) -
Mandible, Maxilla, Frontal, Parietal, Temporal Occipital
Vertebra - 7
Cervical, 12 Thoracic, 5 Lumbar, Sacrum, Coccyx
Clavicle,
Ribs, Scapula, Sternum, Pelvis
Humerus,
Radius, Ulna, Carpals, Metacarpals, Phalanges
Femur,
Patella, Tibia, Fibula, Tarsals, Calcaneus, Metatarsals, Phalanges
Classification
of bones
Long - radius, ulna, tibia, fibula, femur, humerus
Short - carpals, metacarpals, phalanges (hand)
- tarsals, metatarsals, phalanges (foot)
Irregular -
vertebra
Flat - cranium, scapula, sternum, pelvic bones
Sesamoid -
patella
Long bone
Thick layer of
compact bone
Medullary
cavity - contain some red and yellow bone marrow
Shaft
Epiphysis
Epiphysial
plate
Articular
cartilage
Flat bones
Thin layer of
compact bone
Contain mostly
red bone marrow
Osseous tissue
A dense
connective tissue forming the skeleton
Cells ground
substance and fibres
Composed
mostly of collagen and calcium phosphate
Collagen - tensile strength
Calcium salts - compressive strength
Compact bone - hard and dense
Spongy bone -
more spaces than compact (cancellous)
Red marrow - red blood cell production
Yellow marrow -
mostly fat
Endosteum -
lines cavities inside bones
Periosteum
Covers outer
surface of bone, tough fibrous and vascular, carries blood lymph and nervous
supply. A white fibrous tissue
Osteon
The structural
unit of compact bone. A central Haversian canal contains blood and lymph
vessels and nerves. Concentric layers of bone form the lamellae. Between the
lamellae are osteocytes in spaces referred to as lacunae. Canaliculi link the
lacunae with the Haversian canal. Volkmann`s canals link the Haversian canals
with the periosteum.
Bone formation
Osteoblasts - bone
building cells, produce intercellular material (mostly collagen)
Calcium - is added, this hardens round the cells
which are then called osteocytes.
Osteoclasts - breakdown
of bone once formed.
Bone is formed
mostly from cartilage which is mostly collagen with fibrocytes and chondrocytes
In children bone growth is from the
epiphysial cartilage or growth plates. This is an area of mitosis producing
collagen which is subsequently calcified.
Skull
Cranium
Frontal bone
Parietal bone
Temporal bone
Occipital bone
Orbit
Maxilla
Mandible
Clavicle
Scapula
Sternum
Ribs 1 – 12
(Costal cartilage)
Humerus
Radius
Ulna
Carpal (wrist)
Metacarpal (hand)
Phalanges
Vertebral column (33 vertebrae)
7 cervical
12 thoracic
5 lumbar
5 Sacral
4 coccyx
Pelvis
Iliac crest
Ilium
Pubis
Acetabulum
Femur
Patella
Fibula
Calcaneus
Tarsal (ankle)
Metatarsals (foot)
Phalanges