skeletal system

skeletal system

1. functions

   • support - it is an internal scaffold
   • locomotion - attatchment for muscles
   • protection - protects soft parts, i.e. skull and brain
   • storage - acts as a store for calcium and phosphate
   • haemopoiesis - haemopoetic tissue forming bone marrow manufactures blood cells

2. bones

   • long bones
     • limb bones
   • flat
     • outer layer of compact bone, with spongy bone inside, e.g. scapula
   • short
     • carpal/tarsal bones
   • irregular
     • vertebrae
   • sesamoid
     • seasame seed shaped, develop with a tendon that runs over bony prminence, changes angle of tendon over the bone reducing wear and tear e.g. patella
   • pneumatic
     • contain sinuses - reduce weight of bone, e.g. maxillary and frontal bones
   • splanchnic
     • develops in soft organ, not attatched to rest of skeleton e.g os penis

3. bone development

   • ossification
     • intramembranous
     • endochondral
       • 1.cartilage model develops in embryo
       • 2. primary centers of oss appear in shaft. cartilage is replaced, osteoblasts lay down bone extending towards end of bone
       • 3. secondary centers of oss appear in ends of bone
       • 4. osteclasts remove bone from center of shaft to form marrow cavity, osteoblasts carry on laying it down the edges
       • 5. between shaft and ends growth plate (cartilage) forms allowing bone to lengthen as animal grows, when full size bone will replace it so cant grow anymore. growth plate is closed
     • osteoblasts - lay down new bone
     • osteoclasts - destroy/remodel bone

4. skeleton

   • axial
     • skull to tip of tail
       • skull shapes
         • brachioicephallic
         • mesaticephallic
         • doliocephallic
       • vertebrae; c7, t13, l7, s3, cd20+
         • 13 pairs of ribs (goes with t13)
   • appendicular
     • limbs, shoulder and pelvic gurdles
   • splachnic
     • os penis

5. joints

   • fibrous
     • immoveable e.g. skull sutures
   • cartilagenous
     • limited movement, e.g. pubic and mandibular symphisis. joined by cartilage
   • synovial
     • wide range of movement. bones separated by joint cavity, filled with synovial fluid, e.g. elbow, hip, shoulder, stifle, hock
     • plane/gliding - carpal/tarsal joints
     • hinge - elbow, stifle
     • pivot - atlantoaxial
     • condylar - hock
     • ball and socket - hip/shoulder