Educational resource developed at the Veterinary Anatomy Section, ICAR-Indian Veterinary Research Institute (ICAR-IVRI), Bareilly.
📝 STANDARD DESCRIPTION:
Type: Intrinsic, Scapulohumeral (Medial)
Origin: Subscapular fossa (entire medial scapular surface)
Insertion: Medial (lesser) tubercle of humerus
Function: Adducts arm; extends shoulder; functions as medial collateral ligament.
📚 DETAILED DESCRIPTION:
THE MEDIAL COLLATERAL LIGAMENT
A massive multipennate muscle filling the entire subscapular fossa on the medial aspect of the scapula. It is the largest and most powerful medial stabilizer of the shoulder.
PENNATE ARCHITECTURE: Multipennate structure allows for powerful contraction over short distances—ideal for stabilizing rather than sweeping movements.
FUNCTIONAL ANALOGY: Functions as the medial collateral ligament of the shoulder joint, preventing abduction (movement away from midline) while also being capable of active adduction (pulling toward midline).
MEDIAL STABILIZATION: Provides the essential counterforce to the infraspinatus laterally. Together, these muscles cradle the humeral head within the glenoid cavity during weight bearing.
NEURAL SUPPLY: Subscapular nerve.
// COMPARATIVE ANALYSIS
| HORSE |
Similar massive size and function; critical for weight bearing. |
| DOG |
Part of true 'rotator cuff' foursome. |
CLINICAL RELEVANCE
Medial Instability: Unlikely to be injured alone; usually involved in complete brachial plexus avulsions.
