Bilateral absence of subclavius muscles with thickened costocoracoid ligaments: a case report with the clinical-anatomical correlation

• Published in: Anatomy & cell biology Vol. 55; no. 2; pp. 255 - 258
• Main Authors: Kasapuram Dheeraj, Harisha K. Sudheer, Subhash Bhukiya, Neerja Rani, Seema Singh
• Format: Journal Article
• Language: Korean
• Published: 대한해부학회 30-06-2022; The Korean Association Of Anatomists
• Subjects: Costocoracoid ligament; Subclavius muscle
• ISSN: 2093-3665; 2093-3673

Anatomical variation is defined as normal flexibility in the topography and morphology of body structures. Such variations are not uncommon in muscles, particularly in the upper limb. Subclavius muscle (SM) has a proximal attachment to the first costochondral junction and the muscle fibers are then directed upwards and laterally to get attached distally to the subclavian groove of the clavicle. Having similar attachments as the subclavius, the costocoracoid ligament (CCL) is the thickening of the proximal part of clavipectoral fascia extending up to the coracoid process. Both SM and CCL help in the maintenance of smooth movements of the pectoral girdle and both may not always be present. Absent SM may be due to anomalous development from the muscle matrix that also forms the inferior belly of the omohyoid apart from the SMs. This anatomical variation may be associated with thickened CCLs and can be correlated to the smooth functioning of the pectoral girdle.