Is it the coracobrachialis superior muscle, or is it an unidentified rare variant of coracobrachialis muscle?

Abstract

The coracobrachialis muscle (CBM) originates from the apex of the coracoid process, in common with the short head of the biceps brachii muscle, and from the intermuscular septum. The CBM demonstrates variability in both the proximal and distal attachment, with some extremely rare varieties, such as the coracobrachialis superior, coracobrachialis longus and coracocapsularis muscle. This case report describes an extremely rare variant of the coracobrachialis superior muscle, or a very rare variant of the CBM. Our findings highlight the importance of muscle variants in the shoulder region, especially the coracoid region, and are significant for radiologists, anatomists, physiotherapists and surgeons specializing in the shoulder joint.

An unreported infraspinatus muscle variation—two-headed infraspinatus minor muscle and three-headed fusion with the teres minor muscle

“…Only a few variants of the infraspinatus muscle have been described previously. Macalister [ 15 ] described an infraspinatus muscle split into two laminae, which did not completely overlay each other Query[ 15 ]. The infraspinatus muscle fascia derived from the deltoid muscle to the infraspinatus muscle, and in the reverse direction from the infraspinatus to the deltoid [ 15 ].…”

“…The shoulder girdle region is characterized by muscle variations. For example, the deltoid muscle can lack its acromial part [ 15 ]. It can create fusions with the pectoralis major, trapezius, infraspinatus or latissimus dorsi muscles [ 15 ].…”

“…For example, the deltoid muscle can lack its acromial part [ 15 ]. It can create fusions with the pectoralis major, trapezius, infraspinatus or latissimus dorsi muscles [ 15 ]. The number of bellies of the subscapularis muscle ranges from one to nine.…”

“…Accessory subscapularis muscles have been described in the literature. The infraspinatus muscle can be fused with the deltoid or teres minor muscles [ 15 , 18 ]. Additional infraspinatus muscles such as the infraspinatus minor, infraspinatus superficialis and accessory infraspinatus have been found [ 14 , 15 ].…”

Relationships among Coracobrachialis, Biceps Brachii, and Pectoralis Minor Muscles and Their Correlation with Bifurcated Coracoid Process

“…Proximal or distal attachments sites can also differ [ 5 ]. There are cases featuring an accessory muscle connected with one of these muscles, such as the coracobrachialis superior [ 17 ], the coracobrachialis longus [ 15 ], or the accessory pectoralis muscle [ 18 ].…”