A proposal for a new classification of the Coracobrachialis longus: A rare case or a new, distinct muscle?

Nicol Zielinska; Fabrice Duparc; Michał Polguj; Andrzej Borowski; Łukasz Olewnik

doi:10.1016/j.aanat.2021.151825

A proposal for a new classification of the Coracobrachialis longus: A rare case or a new, distinct muscle?

Ann Anat. 2022 Jan:239:151825. doi: 10.1016/j.aanat.2021.151825. Epub 2021 Sep 3.

Authors

Nicol Zielinska¹, Fabrice Duparc², Michał Polguj³, Andrzej Borowski⁴, Łukasz Olewnik¹

Affiliations

¹ Department of Anatomical Dissection and Donation, Medical University of Lodz, Poland.
² Laboratory of Anatomy, Faculty of Medicine, Rouen University, France.
³ Department of Normal and Clinical Anatomy, Medical University of Lodz, Poland.
⁴ Orthopaedics and Pediatric Orthopaedics Department, Medical University of Lodz, Poland.

PMID: 34481938
DOI: 10.1016/j.aanat.2021.151825

Abstract

Background: The coracobrachialis muscle, along with the brachialis and biceps brachii muscles, belong to the anterior group of the brachial region. It is characterized by high level of morphological variabilities, with a common variation being the coracobrachialis longus (CBL) muscle. The CBL may be recognized as a distal part of the coracobrachialis muscle, originating from the anteromedial surface of the humerus, however, the two muscles are distinct from each other, and the distal attachment of the CBL is longer and located closer to the elbow joint. The CBL muscle may also be inserted on to various structures. The aim of the present study was to determine the frequency of the CBL muscle among a studied population, and to prepare a classification based on its morphological features.

Material and methods: Classical anatomical dissection was performed on 100 upper limbs from fifty human cadavers (30 female and 20 male) fixed in 10% formalin solution.

Results: The coracobrachialis muscle was found in all individuals, and the CBL muscle was present in 11%, i.e. 11 upper limbs: four women, and seven men; five left and six right. Significantly, in all cadavers in which the coracobrachialis longus was found, its presence was unilateral (five left and six right). A new classification of the CBL can be proposed based on its insertion: Type I characterized by a distal attachment located on the medial epicondyle (73% of all cases of the CBL) and Type II by an insertion into the olecranon (27% of all cases of the CBL).

Conclusion: The CBL muscle is morphologically variable. More studies focused on the course of this muscle among various populations are needed. Nevertheless, our findings indicate that the CBL muscle could be classified as a distinct muscle.

Keywords: Anatomical variation; Coracobrachialis longus; Coracobrachialis muscle; Median nerve; Musculocutaneous nerve; New classification; Ulnar nerve compression.

Publication types

Case Reports

MeSH terms

Arm*
Cadaver
Dissection
Female
Humans
Male
Muscle, Skeletal*