Equine Anatomy, Physiology, and Kinesiology
This domain tests whether you can connect palpable anatomy and tissue physiology to movement, injury risk, and safe technique. Expect questions on forelimb and hindlimb supporting structures, tendon anatomy, muscle fiber recruitment, and cardiovascular and respiratory responses to exercise.
Core rules and concepts
- The forelimb has no clavicle; the scapula is attached largely by muscle (synsarcosis), which affects shoulder movement and palpation.
- The hindlimb stay apparatus locks the stifle via the patellar mechanism, letting horses stand with minimal muscle activity; the forelimb check apparatus limits fetlock overextension.
- The SDFT lies palmar or plantar and superficial to the DDFT; the suspensory ligament sits between the flexor tendons and the cannon bone. Tendon mid-substance and intrasynovial regions heal slowly because of limited vascularity.
- Muscle fibers: type I (slow, oxidative, postural), IIA (fast, oxidative-glycolytic), and IIX (fast, glycolytic). Recruitment is orderly, so fatigue can alter gait before overt lameness appears.
- Exercise physiology: splenic contraction raises packed cell volume; heart rate can exceed 200 beats/min; sweating is protein-rich and evaporation-dependent, so hot humid conditions impair heat loss.
Worked example
A horse has a painful, warm swelling on the palmar aspect of the proximal cannon bone. Palpation shows the swelling is superficial to a deeper, firmer band. Reasoning: the superficial structure is the SDFT, which flexes the distal limb and supports the fetlock through its check ligament. The deeper band is the DDFT. A core lesion on ultrasound in the SDFT fits the anatomy and explains fetlock hyperextension during weight-bearing.
Traps
Confusing SDFT and DDFT positions; ignoring the hindlimb stay apparatus; assuming a tendon injury is healed when swelling subsides; and interpreting a high heart rate after exercise without considering fitness and heat.