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

Abstract

The aim of this study is to demonstrate the relationship between the proximal attachment of the coracobrachialis muscle and the short head of the biceps brachii and the distal attachment of the pectoralis minor. Their correlation with the bifurcated coracoid process (CP) will be also assessed. On the basis of these observations, a new classification of structures attached to the coracoid process is proposed. Classical anatomical dissection was performed on one hundred forty-five upper limbs. Three types of relationship between the coracobrachialis muscle and the short head of the biceps brachii were observed in the cadavers. In type I (occurring in 54%), the coracobrachialis and the short head of the biceps brachii created a common junction attached to a single CP. Type II was divided into two subtypes (a and b). Subtype IIa (frequency 10%) was represented by independent proximal attachments of the short head of the biceps brachii and the coracobrachialis muscles to the CP. In subtype IIb (frequency 5%), the coracobrachialis muscle was two-headed (the first head located under the second) and not connected to the short head of the biceps brachii; all heads were attached to a single CP. Type III (frequency 31%) was characterized by a two-headed coracobrachialis muscle, the first head originating from a bifurcated CP laterally to the short head of the biceps brachii and the second medially to this structure. Different variations connected with the mentioned structures could be problematic for surgeons during operations, so detailed knowledge of them could contribute to more efficient procedures.

An unreported innervation of the coracobrachialis longus by the radial nerve: a potential pitfall for clinicians

“…It is no different in case we observed. The relationship between the origins of the shBB and CBM is also variable [ 33 ]. This case represents the most common combination of their origins (54%) and represents type I in the classification presented by Zielinska et al [ 33 ] (one head of the CBM and the shBB creating a common junction originating from the coracoid process).…”

Subscapularis tendon tears: A narrative review

“…The axillary artery and vein, long thoracic nerve, and brachial plexus are located nearby (52). Furthermore, one may see the presence of compound tendons originating from the short head of the biceps and coracobrachialis, together with the attachment of the pectoralis minor muscle (53). Burkhart suggests that in cases of partial tear of the subscapularis muscle, coracoplasty can be performed by establishing a window in the rotator interval.…”

Anatomical Variations in the Pectoralis Minor Muscle Origin and Insertion: A Systematic Review

“…To conduct the quality assessment of the identified studies, the Quality in Prognostic Studies Tool16’s four scales, including reporting and statistical analysis, study participation, outcome measurement, prognostic factor measurement, and confounding. Further, for each scale, a subscale was developed to enable the authors to grade the studies as low quality (0), intermediate quality [ 1 ], and high quality [ 2 ]. The quality assessment approach has been widely used by authors who have conducted systematic reviews and meta-analyses of variations of arteries and different body muscles [ 16 ].…”

“…The pectoralis minor anatomically offers the landmark to the much deeper structures that include the medial pectoral nerves, the axillary arteries, and the brachial plexus cords. Several anatomy studies and literature have reported variations with regard to the pectoralis minor muscle attachment points [1][2][3].…”