5 functions of bones?
Support Protection Movement Storage RBC production
What is the axial skeleton? Name them.
Bones on or attached to midline of the body
Skull, vertebral column, sternum, ribs
Vertebral regions..?
Cervical, Thoracic, Lumbar, Sacral, Caudal
What is the appendicular skeleton?
Bones of the front & hind limbs + pectoral & pelvic girdle
Name the front (thoracic) limbs
Thoracic girdle, brachium, antebrachium, carpus, metacarpus, phalanges
Name the hind (pelvic) limbs
Pelvic girdle, thigh, crus, tarsus, metatarsus, phalanges (digit)
Define compact bone
hard layer covering most bones (covers most of shaft on long bones) - cortex
Define cancellous bone
Spongy bone - composed of spicules forming porous network (inside long bone)
Define medullary cavity
Space filled with marrow
Red marrow in young animals
Yellow (fatty) marrow as animal ages
Define epiphysis
Either end of long bone (proximal/distal)
Define diaphysis
Cylindrical shaft between two epiphyses (in long bone)
Define metaphysis
In mature bone - flared area adjacent to epiphysis (widest part of bone)
Define epiphyseal cartilage/disk/plate
Layer of hyaline cartilage separating epiphysis & diaphysis in immature bone
Define articular
Relating to joints
Define articular cartilage
Thin hyaline layer covering articular surface of bone - reduces friction
Define periosteum
fibrous membrane covering surface of bone except where articular cartilage is
Define endosteum
Tough, fibrous membrane lining marrow cavity & osteonal canals of bone
What does compact bone surround?
Cortex surrounding marrow
Bones can receive how much blood supply?
Up to 10% CO
Nerves in bone do what?
Influence blood vessels & sensory
Properties of osteocytes
Maintain protein & mineral content of matrix & involved in bone repair
Can not divide
Properties of osteoblasts
Increase [calcium phosphate] -> Ca deposition -> bone growth
Properties of osteoclasts
Breakdown of bone
Important in Ca & PO4 (phosphate) regulation
Define endochondral
When bone replaces cartilaginous model (long bone)
Define intramembranous
Develops in connective tissue without connective bone (flat bones of skull)
Define ossification
Process of laying down new bone by osteoblasts
Describe steps in bone growth & dev…
- Formation of collar around hyaline cartilage model
- Cavitation of hyaline cartilage
- Invasion of internal cavities by periosteal bud, blood vessels & spongy bone formation.
- Formation of medullary cavity. Appearance of secondary ossification centres in epiphyses
- Ossification of epiphyses. When complete -> hyaline cartilage remains only in epiphyseal plates, and articular cartilages.
Role of epiphyseal plates?
promote longitudinal growth until young adulthood
Describe long bone growth…
- Chondrocytes produce new cartilage in epiphyseal plate
- Epiphyseal plate widens -> bone lengthens
- Chondrocytes die
- Osteoblasts replace chondrocytes & lay down bone
- Epiphyseal plate closure (puberty, hormone-regulated, no further increase in length)
Rate of bone growth determined by…?
Matrix prod.
hypertrophic chondrocytes enlargement
proliferative kinetics
Hormones & growth factors involved in bone growth?
GH (somatotropin)
Sex hormones (oestrogen/testosterone)
Thyroxine
Bone morphogenic proteins (BMPs)
Bone remodelling involves…?
organic & mineral continuously recycled & renewed
calcium homeostasis
constant diet source of Ca & PO4 (phosphate) salts
Hormones (calcitriol, calcitonin, PTH)
3 major hormones involved with bone remodelling?
- Calcitriol (1,25-dihydroxy vitamin D3)
- Calcitonin
- PTH
Role of calcitriol?
kidneys -> Ca & PO4 absorption -> ++ blood [Ca]
Role of calcitonin?
From thyroid -> kidney -> Ca & PO4 homeostasis -> decreases blood [Ca] by inhibiting osteoclast activity & excretion from kidney
Role of PTH?
Ca & PO4 homeostasis -> stimulate osteoclast activity + increased absorption of Ca + decrease Ca excretion (kidney)
Describe steps in bone fractures…?
- broken bone -> ruptured blood vessels -> haematoma
- New capillaries grow -> nutrition, growth factors, phagocytes. Connective tissue -> fibrocartilaginous callus formation
- More bone cells recruited to area -> spongy bone -> bony callus formation
- Remodelling of bony callus -> healed fracture
Articular cartilage properties…?
formed at joints
no sensory nerves
no blood supply (nutrients by diffusion)
Define fontanel…
soft connective tissue on infant skulls to aid in child birth
Define sutures…?
immovable fibrous joints that connect cranium bones together
Define synchondroses
immovable
Define symphyses…?
fibrocartilage between bone
Synovial joints contain…?
periosteum, ligament, joint cavity (synovial fluid), articular (hyaline) cartilage, fibrous capsule, synovial membrane
Different types of synovial joints & one eg. of each…?
Gliding/Plane - vertebrocostal (hoolahoop action) Hinge - elbow, knee Pivot - atlas, axis Ellipsoidal - radiocarpal Saddle - 1st carpometacarpal (thumb) Ball & socket - hip, shoulder
Define circumduction
moving arm in loop
Define pronation
turning dorsal palm up
Define supination
turning palm up
Ligaments & their role…?
Bone to bone
support synovial joints
Name some joint problems & eg’s…?
Bursitis - inflamm. of synovial membrane sac
Dislocation/luxation - bone forced out of normal position
Sprain - Damage or tear to ligaments/tendons
Arthritis - inflamm. or degenerative disease damaging joints
Acute arthritis - bacterial invasion (treat with AB’s)
Osteoarthritis…?
Degenerative condition in older animals
Spurs of bone develop
Rheumatoid arthritis…?
chronic inflamm. disorder -> immune sys attempts to destroy joints