The research paper published by IJSER journal is about An accessory head of the coracobrachialis muscle - a case report. 1
ISSN 2229-5518
An accessory head of the coracobrachialis muscle - a case report.
Dr. Sharadkumar Pralhad Sawant1, Dr. Shaguphta T. Shaikh2, Dr. Rakhi M. More3
Abstract - During routine dissection for Ist MBBS students on 65 year old donated embalmed male cadaver in the Department of Anatomy, K.J.Somaiya Medical College, Sion, Mumbai, India, we observed an accessory head of the coracobrachialis muscle in the left ar m. It extended downwards and medially from the middle part of the medial border of the humerus in front of the median nerve and brachial
artery and finally was inserted on the anteromedial aspect of the medial epicondyle of the humerus. The length of the ligame nt was 15 cm
and the diameter was 0.2 cm. The photographs were taken for proper documentation. The existence of accessory head of the coracobrachialis muscle should be kept in mind by surgeons operating on patients with high median nerve palsy and brachial ar tery compression and radiologists while doing scans of the arm.
Key words - Coracobrachialis Muscle, Median Nerve, Brachial Artery, Medial Epicondyle of Humerus, Orthopaedic Surgeons, Physiotherapists, Radiologists.
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HE coracobrachialis muscle shows several interesting morphological and anatomical characteristics. It is the counterpart in the arm of the adductors (longus, brevis, magnus) of the thigh. It arises from the apex of the coracoid process, where it is fused with the medial side of the short head of biceps. The tendon is continued into a muscular belly of varying development which is inserted into the medial bor- der of the humerus. The lower extent of the insertion is marked by the nutrient foramen of the humerus, for the nutri- ent branch of the brachial artery runs along the lower border of the muscle. The upward extent of the insertion cannot be seen on most bones, the muscle usually leaving no impression. The musculocutaneous nerve passes through the muscle and supplies it. Compared to the morphological interest of this muscle its action is negligible. It is a weak adductor of the shoulder joint, the main adductors of which are pectoralis ma- jor and latissimus dorsi (1,2) In some animals the coraco- brachialis muscle has three heads (3), in man two have fused, trapping the nerve between them, and the third part has be- come suppressed. The occasional supratrochlear spur (on the anteromedial aspect of the lower humerus) may be continuous with a ligament (of Struthers) which passes to the medial epi- condyle and represents the remains of the third head (4). The median nerve or brachial artery or both may run beneath it
and be subjected to compression.
During routine dissection for Ist MBBS students on a 65 years donated embalmed male cadaver in the Department of Anat- omy, K.J.Somaiya Medical College, we observed an accessory head of the coracobrachialis muscle on the left side. It extend- ed downwards and medially from the middle part of the me- dial border of the humerus in front of the median nerve and brachial artery and finally was inserted on the anteromedial aspect of the medial epicondyle of the humerus. The length of the ligament was 15 cm and the diameter was 0.2 cm. The pho- tographs were taken for proper documentation and ready ref- erence. There were no associated neurovascular variations found in the same specimen. The right upper limb of the same cadaver was normal.
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Full name of Authors : Dr. Sharadkumar Pralhad Sawant1, Dr. Shaguphta T. Shaikh2, Dr. Rakhi M. More3
Institution : 1,2,3Department of Anatomy, K. J. Somaiya Medical College, Somaiya Ayurvihar, Eastern Express Highway, Sion, Mumbai-400 022.
Telephone no. : 9322061220, 022-22936867
E-mail : dr.sharadsawant@yahoo.com
Photographic presentation of an accessory head of the coraco- brachialis muscle crossing the median nerve and the brachial artery and finally was inserted on the anteromedial aspect of the medial epicondyle of the humerus in left upper limb.
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The research paper published by IJSER journal is about An accessory head of the coracobrachialis muscle - a case report. 2
ISSN 2229-5518
Photographic presentation of the origin of the accessory head of the coracobrachialis muscle from the middle part of the medial border of the humerus and the nerve supply from the musculocutaneus nerve.
Photographic presentation of Ligament of Struther’ attached to the anteromedial aspect of the medial epicondyle of the humerus.
The accessory head of coracobrachialis muscle may be at- tached to the lesser tubercle, medial epicondyle or medial in- termusculur septum (2). The clinical implication of the acces- sory head of coracobrachialis is that it has the potential to cause median nerve entrapment and brachial artery compres- sion. Various studies have described the compression of medi- an nerve and brachial artery with anomalous muscles (5, 6, 7,
3 cm muscle belly and 15 cm tendinous band. It extended downwards and medially in front of the median nerve and brachial artery and finally got inserted on the anteromedial aspect of the medial epicondyle of the humerus. The accessory
head of the coracobrachialis muscle reported in this case may be explained on the basis of the embryogenesis of the muscles of the arm. An important finding in our case is a passage for the brachial artery and median nerve formed by the tendinous band of the accessory head of the coracobrachialis muscle. This tendinous band forming the tunnel is called as Ligament of Struther’s. Other openings, however, have been described for the passage of the median nerve and brachial artery, the most common being the tunnel formed beneath the ligament of Struthers (4).The neurovascular bundle of the arm may un- dergo active or passive compression by ligament of Struthers leading to neurovascular disorders. It may lead to wasting or ischaemic contraction of flexors of the forearm. This variation is important during the active use of coracobrachialis as a transposition flap in deformities of infraclavicular and axillary areas and in postmastectomy reconstruction (11), during sur- gical intervention of the anterior compartment of the arm, such as trauma, tumour, neurovascular disease; while using conjoint tendon for stabilisation treatment for recurrent dislo- cation and subluxation of the shoulder joint (12), while using coracobrachialis as a vascularised muscle for transfer in the treatment of longstanding facial paralysis (9) during evalua- tion of computed tomography (CT) and magnetic resonance imaging (MRI) . As the coracobrachialis is also a guide to the axillary artery during surgery and anaesthesia, knowledge of this abnormal insertion may prove significant. Accessory mus- cles in the arm and forearm may lead to confusion during sur- gical procedures or cause compression of neurovascular struc- tures. To avoid clinical complications, during radiodiagnostic procedures e.g. CT, MRI or surgical approach of these regions, awareness of such variations must be borne in mind. These types of variations are interesting not only to anatomists, but also to orthopaedic surgeons, physiotherapists and radiolo- gists.
During development, the limb bud mesenchyme of the lateral plate differentiates into intrinsic muscles of the upper limb. A single muscle mass is formed by fusion of the muscle primor- dia within the different layers of the arm at certain stages of development; thereafter, some muscle primordia disappears through cell death. The morphological variations of the cora- cobrachialis muscle may be due to failure of muscle primordia to disappear during embryological development (10).
The existence of such variation of the coracobrachialis muscle should be kept in mind by the surgeons operating on patients with high median nerve palsy and brachial artery compres- sion, by the orthopaedicians dealing with fracture of the hu- merus, the radiologists while doing radiodiagnostic proce- dures e.g.CT scan, MRI of the arm and angiographic studies and also by the physiotherapists. These accessory fibres of coracobrachialis may be used as a transposition flap in de- formities of infraclavicular and axillary areas and in postmas- tectomy reconstruction. The accessory fibres of coracobrachial-
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The research paper published by IJSER journal is about An accessory head of the coracobrachialis muscle - a case report. 3
ISSN 2229-5518
is may prove significant and lead to confusion during surgical procedures or cause compression of neurovascular structures.
The authors declare that they have no competing interest.
SPS wrote the case report, performed the literature review & obtained the photograph for the study. RMM performed the literature search and assisted with writing the paper. STS con- ceived the study and helped to draft the manuscript. All au- thors have read and approved the final version manuscript.
All the authors wish to convey thanks to Dr. Arif A. Faruqui for his valuable support. We are also thankful to Mr. M. Murugan. Authors also acknowledge the immense help re- ceived from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors / editors / publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed.
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