Anatomy and innervation of the infraspinatus muscle
There is ongoing debate on the anatomical arrangement and pattern of innervation of the infraspinatus. More specifically, it remains unclear whether the muscle is bipennate, multipennate or composed of two separate compartments and if the suprascapular nerve branches into two or more motor branches in the infraspinous fossa.
48 muscle-scapula complexes were derived from 24 cadavers and then examined using standard dissection techniques. Fascial divisions or muscle compartments were determined by visual inspection before and after removal of the muscle from the cadaver. The number of nerve branches from the suprascapular nerve was determined by visual inspection.
The infraspinatus muscle was found to be composed of three partitions: a superior, middle and inferior part were present in all muscles. In 62.5% of the muscles, full compartmentalization was established (i.e. a separate nerve branch entered all three partitions). It can be speculated that the different neuromuscular partitions correspond to different biomechanical functions of the infraspinatus.
> From: Fabrizio & Clemente, J Bodyw Mov Ther 18 (2015) 228-232. All rights reserved to Elsevier Ltd. Click here for the Pubmed summary.