Canine Musculoskeletal Anatomy, Physiology, and Conditions

Comprehensive vocabulary flashcards covering canine skeletal anatomy, bone histology, muscular physiology, muscle classifications, and common musculoskeletal disorders.

Os / Osteo

Prefixes and root terms referring specifically to bone.

Compact Bone

Heavy, dense bone tissue organized into tightly packed cylinders called Haversian systems; forms the rigid exterior layer of all bones and the shafts (diaphyses) of long bones.

Spongy Bone (Cancellous Bone)

Lightweight, porous bone consisting of randomly arranged microscopic plates called spicules; provides strength without excessive weight and houses bone marrow.

Haversian System

The structural cylinder of compact bone consisting of concentric layers of ossified matrix surrounding a central Haversian canal that contains blood vessels, lymph vessels, and nerves.

Red Bone Marrow

Hematopoietic marrow tissue responsible for blood cell production; it is the predominant marrow type in young animals and resides in the spaces between bone spicules.

Yellow Bone Marrow

Marrow composed primarily of adipose connective tissue; it is the most common form in adult animals, does not generate blood cells under normal conditions, but can revert to red marrow if needed.

Axial Skeleton

The division of the skeleton that forms the central axis of the body, including the skull, spinal column, vertebrae, ribs, and sternum.

Appendicular Skeleton

The division of the skeleton composed of the limbs and their supporting girdles, including the thoracic limb bones, pelvic limb bones, and pelvis.

Canine Vertebral Formula

The anatomical distribution of vertebrae in the dog: $7$ Cervical ($C1\text{--}C7$), $13$ Thoracic ($T1\text{--}T13$), $7$ Lumbar ($L1\text{--}L7$), $3$ fused Sacral ($S1\text{--}S3$), and $6\text{--}23$ Caudal (tail) vertebrae.

Vertebral Foramen

The central canal formed between the vertebral body and arch that encloses and protects the spinal cord.

Manubrium

The cranialmost segment of the sternum where the first pair of ribs articulate.

Xiphoid Process

The caudalmost bony element of the sternum that terminates in the xiphoid cartilage.

Sternebra

One of the individual bony segments that align to form the sternum.

Costochondral Junction

The articulation point where the rigid bony dorsal rib connects to the ventral costal cartilage.

Acetabulum

The deep, cup-like socket on the lateral pelvis formed by the convergence of the ilium, ischium, and pubis that receives the head of the femur.

Obturator Foramen

The large paired opening on the ventral floor of the pelvis bounded by the pubis and ischium.

Synarthrosis

An immovable fibrous joint, exemplified by the sutures between skull bones.

Amphiarthrosis

A slightly movable cartilaginous joint, such as the intervertebral disks or the pubic symphysis.

Diarthrosis

A freely movable synovial joint containing a joint capsule and synovial fluid, such as the shoulder or hip joint.

Epimysium

The fibrous outer connective tissue sheath that encircles the entire skeletal muscle body.

Tendon

A tough, dense, cord-like band of fibrous connective tissue connecting a muscle directly to a bone.

Aponeurosis

A broad, flattened sheet of dense fibrous connective tissue that attaches muscle to bone or to other muscles, such as the linea alba.

Agonist (Prime Mover)

A muscle that directly initiates and performs a specific desired joint movement upon contraction.

Antagonist

A muscle whose mechanical action directly opposes the movement produced by an agonist (prime mover).

Synergist

A muscle that contracts at the same time as a prime mover to assist, steady, and streamline the movement.

Fixator

A muscle that stabilizes proximal joints and anchors bony origins so that another muscle can exert force effectively.

All-or-None Principle

The physiological rule establishing that an individual skeletal muscle fiber either contracts completely to its fullest capacity when stimulated or does not contract at all.

Intercalated Discs

Specialized intercellular junctions in cardiac muscle tissue that enable rapid electrical conduction from cell to cell so contractions occur in a coordinated, wavelike manner.

Visceral Smooth Muscle

Smooth muscle found in the walls of large internal hollow organs, organized into broad continuous sheets that contract in large, rhythmic waves without conscious control.

Multi-Unit Smooth Muscle

Smooth muscle organized into small, discrete cell clusters that execute fine, delicate contractions, such as around small blood vessels and within the iris of the eye.

Cutaneous Muscles

Thin, broad, superficial muscles situated within fascia beneath the skin with little or no bony attachment, functioning primarily to twitch the skin.

Muscles of Respiration

A functional group of thoracic and abdominal muscles that alter the volume of the chest cavity to move air during breathing.

Lameness

An alteration or disturbance in normal gait and locomotion resulting from pain, injury, or mechanical dysfunction.

Hip Dysplasia

A malformation of the coxofemoral joint wherein a misshapen femoral head and shallow acetabulum prevent a proper ball-and-socket fit, resulting in joint laxity and degeneration.

Patellar Luxation

A condition in which the patella (kneecap) slips out of its normal anatomical position within the femoral trochlear groove, frequently associated with a shallow groove or displaced tibial attachment.

Sprain

A traumatic injury involving the stretching or tearing of ligaments around a joint.

Strain

A traumatic injury involving the stretching or tearing of a muscle or tendon at a point located between two joints.

Dislocation

An injury in which the articular surfaces of a joint are completely displaced, causing a bone to pop out of its socket or joint cavity.

Fracture

A structural break in a bone, classified as open (compound, where bone breaches the skin) or closed (simple, where skin integrity remains intact).