Forelimb Osteology

What are the functions of the Skeleton

Provides a frame for the body, acts as an attachment site for muscles-allows movement. Protection of, vital organs , source of minerals - calcium + phosphorus, hematopoiesis.

What are the 3 parts of the skeleton

Axial, Appendicular, Heterotopic

How many vertebrae in the vertebral column in dogs and cats

7 Cervical, 13 Thoracic, 7 Lumbar, 3 Sacral, 20-23 caudal. Total of ~50.

What are the types of bones based on shape

Long, Short, Flat, Irregular, Sesamoid, Pneumatic, Visceral/Heterotopic

What are examples of forelimb long bones

Radius, ulna

What are examples of forelimb short bones

Carpals

What are examples of flat bones in the forelimb

Scapula

What are examples of sesamoid bones in the forelimb

Palmar and dorsal sesamoids

Fovea

Smaller depression or hollow area

Fossa

Depression or hollow area, bigger than fovea

Foramen

Hole

Meatus

Hole

Hiatus

Hole

Ostium

Hole

Lacuna

Hole

Aperture

Hole

Tubercle

Protuberance or elevation, smaller than tuberosity and tuber

Tuberosity

Protuberance or elevation, bigger than tubercle but smaller than tuber

Tuber

Protuberance or elevation, bigger than tuberosity and tubercle

Process

Projection

What are the types of bone based on composition

Woven, Lamellar, Cortical/Compact, Cancellous/Trabecular

Woven bone

Arrangement of immature bone, found in developing or juvenile bones and early fracture repair

Lamellar bone

Highly ordered arrangement of bone, comes from woven bone

Cortical/compact bone

Dense outer layers of lamellar bone, think cortex

Cancellus/trabecular bone

Lattice arrangement of bony spicules deep to cortical bone.

Cancellous=lattice, Trabecula=small beam

Medullary Cavity

Cancellous bone interspersed throughout with either red or yellow marrow

Red marrow

Lots of hematopoietic tissue, highly vascularized. Red due to hemoglobin in erythroid cells. Main marrow of young animals, present in ribs, sternum, ilium, femur, and humerus of adults

Yellow Marrow

Main marrow in adults, lots of adipose tissue. Color is due to carotenoids in fat cells. In times of need (lots of blood loss), yellow marrow can be converted into red

Where can intraosteous access be found on the humerus

Proximal lateral humerus, just distal to the greater tubercle

What are the types of bone linings

Hyaline, Periosteum, Endosteum

Hyaline cartilage

Lines the superficial surface of subchondral bones - articular surfaces of joints

Periosteum

Lines the superficial surface of non-articular areas

Endosteum

Lines the deep surface of compact bone

What are the general regions of long bones

Epiphysis, Body/diaphysis, Metaphysis, Physis/growth plate/epiphyseal plate, nutrient foramen

Epiphysis

Enlarged region of long bone on proximal and distal plates, “upon the growth plate”

Body/Diaphysis

Elongated central region of long bones, contains marrow cavity

Metaphysis

Between epiphysis and diaphysis

Physis

Growth plate/epiphyseal plate of long bones, after closure of Physis an ossified epiphyseal line remains

Nutrient foramen

Hole which nerves and vessels pass through, all bones have at least one

Physes of the scapula

Supraglenoid

Physes of the humerus

Proximal, distal, mid-condyle, medial and lateral epicondyle

Physes of the radius

Proximal and distal physes

Physes of the Ulna

Olecranon tuber, anconeal process, distal

Types of Ossification/osteogenesis

Two ways: intramembranous or endochondral

Intramembranous ossification

No cartilage intermediate. 4 steps: mesenchymal cells group into clusters and ossification center forms, secreted osteoids trap osteoblast that then become osteocytes, trabecular matrix and periosteum forms, compact bone develops superficial to the trabecular bone and crowded blood vessels condense into red marrow. Occurs in skull, mandible, and bony clavicle

Endochondral ossification

Mesenchymal cells form from a cartilage model which acts as scaffolding that is progressively calcified, resorted, and replaced by osteoid, then mineralized bone (woven —> lamellar or trabecular). Occurs in majority of bones. Growth plates used this model for longitudinal growth