📝 STANDARD DESCRIPTION:
Type: Extrinsic, Deep Layer
Origin: Funicular nuchal ligament [Cervicis]; Spinous processes T2-T7 [Thoracis]
Insertion: Medial surface of dorsal scapular cartilage
Function: Elevates scapula and draws it medially toward trunk; stabilizes dorsal apex during stance phase.
📚 DETAILED DESCRIPTION:
THE SCAPULAR ANCHOR
Lying deep to the trapezius, the rhomboideus provides the medial stabilizing force for the scapular girdle, anchoring the dorsal border to the axial skeleton.
SUBDIVISIONS:
• Rhomboideus Cervicis: Arises from the funicular nuchal ligament (larmier)
• Rhomboideus Thoracis: Arises from spinous processes of cranial thoracic vertebrae (T2-T7)
• Rhomboideus Capitis: ABSENT or vestigial in ox (critical distinction from carnivores where it reaches the occiput)
INSERTION SPECIFICS: Muscle inserts on the medial surface of the dorsal scapular cartilage (cartilago scapulae), amplifying the surface area for thoracic attachment and shock dissipation.
BIOMECHANICAL ROLE: Presses the cartilage against the trunk, preventing lateral deviation of the scapula during the stance phase. This medial pull is vital for maintaining the rigid column needed for weight support, counteracting the lateral abduction forces generated during weight bearing.
// COMPARATIVE ANALYSIS
| DOG |
Possesses prominent rhomboideus capitis attaching to occiput; absent in ox. |
| HORSE |
Similar division but attaches more extensively to cervical vertebrae. |
CLINICAL RELEVANCE
Atrophy Indicators: Wasting creates instability at the shoulder dorsal angle, contributing to lateral 'popping' in conjunction with sweeney.
