📝 STANDARD DESCRIPTION:
Type: Intrinsic, Forearm (Caudomedial/Ulnar Group)
Heads: Humeral head (medial epicondyle) & Ulnar head (olecranon)
Insertion: Accessory carpal bone
Function: Flexes carpus (ulnar aspect).
📚 DETAILED DESCRIPTION:
THE ULNAR CARPAL FLEXOR
Located caudal/medial in the forearm, providing ulnar-sided flexion and stabilization.
DUAL-HEADED ORIGIN: Unique among flexors in having two origins:
• Humeral Head: Arises from medial epicondyle (with other flexors)
• Ulnar Head: Arises from medial surface of the olecranon (ulna), giving it origin from the forearm itself
ACCESSORY CARPAL INSERTION: Inserts on the prominent accessory carpal bone on the caudolateral carpus—the same bone receiving the Ulnaris Lateralis but from the flexor side.
ULNAR STABILITY: Provides the flexor counterbalance to the Ulnaris Lateralis, creating a force couple stabilizing the carpus in the frontal plane during weight bearing. Prevents excessive abduction/adduction of the carpus.
ULNAR NERVE BLOCK LANDMARK: Forms the medial border of the groove (with Ulnaris Lateralis forming the lateral border) used for ulnar nerve blocks.
// COMPARATIVE ANALYSIS
| HORSE |
Similar dual heads; ulnar head larger in horse. |
| DOG |
Ulnar head may be absent or fused in some individuals. |
CLINICAL RELEVANCE
Ulnar Nerve Block Landmark: Palpate groove between FCU (medial) and Ulnaris Lateralis (lateral) ~10cm proximal to accessory carpal bone. Carpal Valgus/Varus: Asymmetry between left/right FCU tone contributes to angular limb deformities.
