📝 STANDARD DESCRIPTION:
Type: Intrinsic, Forearm (Caudomedial/Flexor Group)
Origin: Medial epicondyle of humerus
Insertion: Palmar aspect of proximal metacarpus (Mc III)
Function: Flexes the carpus (primary flexor).
📚 DETAILED DESCRIPTION:
THE CARPAL FLEXOR LEADER
The most cranial of the caudal (flexor) group muscles, lying directly medial on the forearm deep to the pectoral retinacula.
STRAIGHT LINE PULL: Originates from the medial epicondyle and runs straight down the medial forearm to insert on the palmar aspect of the proximal cannon bone (Mc III). This direct line provides maximum mechanical advantage for carpal flexion.
CARPAL CANAL RELATIONSHIP: Passes over the palmar carpus but outside the carpal canal proper (which contains the digital flexors). Covered by the flexor retinaculum at the carpus.
FUNCTIONAL DUALITY: While primarily a flexor, it provides active check against hyperextension during the weight-bearing phase, working in concert with the passive stay apparatus.
MEDIAN NERVE RELATIONSHIP: The median nerve runs deep to this muscle in the proximal forearm; the muscle serves as a landmark for median nerve blocks (inject just cranial to FCR tendon at carpus).
// COMPARATIVE ANALYSIS
| HORSE |
Similar position and function; larger for support. |
| DOG |
Splits into superficial and deep parts in some breeds. |
CLINICAL RELEVANCE
Median Nerve Block: Landmark for 'High Volar' block—inject just distal to elbow, cranial to palpable FCR tendon. Carpal Hyperextension: Transection allows carpal over-flexion.
