Int J Anat Res 2017, 5(1):3461-63. ISSN 2321-4287 3461

Case Report

A RARE VARIATION IN THE DISTAL ATTACHMENT OF AN EXTRAHEAD OF BICEPS BRACHI MUSCLEAfil M Alex *1, Uma B Gopal 2.

ABSTRACT

Address for Correspondence: Dr. Afil .M. Alex, Assistant Professor (on contract), Department ofRachana Sharira (Anatomy), Govt. Ayurveda College, Pariyaram, Kannur, Kerala 670503, India.Ph.9400585242, E-Mail: afilmalex@gmail.com

This paper presents and highlights the anatomical variation in the insertion of supernumerary heads of bicepsbrachi muscle. The variation was noted in one of the cadaver in the department of Rachana Sharira (Anatomy) atSDM College of Ayurveda, Hassan, Karnataka (India). During routine dissection of a male cadaver (65 yearsage),in the anterior compartment of arms bilaterally, it was noticed extra heads for biceps brachi muscle witha separate insertion. Extra head origin and insertion was compared to the normal muscle origin and insertion asper Anatomical literature. The findings were compared with different possible variations of the muscle reportedin the various literatures. The clinical importance of this variation has been discussed.KEY WORDS: Anatomical variation, Biceps brachi Muscle, Biceps tendon, Bicipital aponeurosis.

INTRODUCTION

International Journal of Anatomy and Research,Int J Anat Res 2017, Vol 5(1):3461-63. ISSN 2321-4287

DOI: https://dx.doi.org/10.16965/ijar.2016.503

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*1 Assistant Professor (on contract), Department of Rachana Sharira (Anatomy),Govt.AyurvedaCollege, Pariyaram, Kannur, Kerala, India.2 Associate Professor and HOD, Department of Rachana Sharira (Anatomy),Sri DharmasthalaManjunatheswara College Of Ayurveda &Hospital, Hassan-573201, Karnataka, India.

Received: 07 Dec 2016Peer Review: 07 Dec 2016Revised: None

Accepted: 04 Jan 2017Published (O): 31 Jan 2017Published (P): 31 Jan 2017

which lie side by side and do not join until about7 cm above the elbow joint, where a flat tendonis formed. The tendon passes through thecubital fossa, undergoes twisting so that theanterior surface becomes lateral and is insertedinto the posterior part of the radial tuberosity; abursa seperates the tendon from the anteriorpart of the tuberosity. Before insertion, themedial border of the tendon presents a fibrousexpansion, the bicipital aponeurosis, whichextends downward and medially across thebrachial artery and is attached to the upper partof the subcutaneous posterior border of the ulnaby way of deep fascia of the fore-arm [3].Nerve supply: Musculocutaneous nerve (C5, C6)

Biceps brachi (biceps=two heads of origin,brachi=arm) is a muscle with usually two heads,a long head and a short head which lies in theanterior compartment of arm between shoulderand elbow. Although the biceps is located in theanterior compartment of the arm, it has noattachment to the humerus [1].Origin: The long head originates from the supraglenoidtubercle of scapula and from the glenoi-dal labrum and the tendon is intracapsular.Theshort head originates from the tip of coracoidprocess of the scapula along with the origin ofcorachobrachialis [2].Insertion: both heads expand into fusiform

Int J Anat Res 2017, 5(1):3461-63. ISSN 2321-4287 3462

Afil M Alex, Uma B Gopal. A RARE VARIATION IN THE DISTAL ATTACHMENT OF AN EXTRA HEAD OF BICEPS BRACHI MUSCLE.

[2] which is a branch of lateral cord of brachialplexus with separate branches passing to eachbelly.Blood supply: Brachial artery; anterior circum-flex humeral artery [4].Actions: Muscle crosses three joints (“three jointmuscles”) viz: shoulder, elbow and superiorradio-ulnar joint [5]. It can therefore act on allof them. Biceps is a strong supinator when thefore arm is flexed. All the screwing movementsare done with it. It is a flexor of the elbow. Theshort head is a flexor of the arm and the longhead prevents upward displacement of the headof the humerus. In short biceps flexes thefore-arm at elbow joint, supinates fore-arm atradio-ulnar joints, and flexes arm at shoulderjoint.

During our routine dissection in the departmentof Rachana Sharira at SDM College of AyurvedaHassan, an Anatomical variation anatomicalvariation in the insertion of a supernumeraryhead of biceps brachi muscle was observed inboth hands (bilaterally) of the 65 years old malecadaver. In the dissection of the anteriorcompartment of theleft arm the main muscleBiceps brachi we noticed an extra third headwhich has origin from the antero lateral surfaceof the shaft of humerus just below the ‘V’shaped deltoid tuberosity into which the deltoidmuscle is inserted. Also the short head ofbiceps originates by two slips from the tip ofcoracoid process. The extra head is innervatedby a separate branch from the musculocutane-ous nerve. We also noticed that the the inser-tion of the extra head is also by an aponeurosisand a separate tendon (fig.1). The extra tendonlies lateral to the original biceps tendon and itis the most lateral content of cubital fossa. Theaponeurosis joins with the bicipital aponeuro-sis and is attached to the upper part of thesubcutaneous posterior border of the ulna byway of deep fascia of the fore-arm. Theseparate tendon goes medially and downwardsand expanded to blend with the inter osseousmembrane between the radius and ulna (fig.2).In the right hand the extra head takes origin fromthe antero-medial surface of the shaft ofhumerus just below the anterior lip of deltoid

CASE REPORT

tuberosity, which continues as a narrowtendinous slip and is inserted into the radialtuberosity just lateral to the insertion of thebiceps tendon. This head is also supplied by aseparate branch from musculo cutaneous nerve.Fig. 1: Showing the Insertion of additional head by anaponeurosis and a separate tendon.

Fig. 2: Showing the Course of the tendon in betweenradius and ulna.

DISCUSSIONNormal variations - additional heads may bepresent for biceps muscle. Approximately 10%of people have a third head to the biceps. A thirdhead may arise from the upper and medial partof the brachialis, passes behind the brachialartery, and is inserted on the bicipital aponeuro-sis and the medial side of the bicipital tendon.A fourth head may arise from the lateral side ofthe humerus; or from inter tubercular sulcus.This case is a rare condition of variation in theinsertion of biceps brachi muscle. Bicipitalaponeorosis attaches indirectly by means of thefascia (deep fascia covering the flexor musclesin the medial side of the fore-arm) to thesubcutaneous border of the ulna [6]. In one of

Int J Anat Res 2017, 5(1):3461-63. ISSN 2321-4287 3463

Afil M Alex, Uma B Gopal. A RARE VARIATION IN THE DISTAL ATTACHMENT OF AN EXTRA HEAD OF BICEPS BRACHI MUSCLE.

the articles an extra tendon of insertion ofbiceps has been mentioned where it is insertedinto the radial tuberosity distal to the insertionof common tendon [7].Surgical and clinical importance: Damage tothe musculo cutaneous nerve causes paralysisof the biceps brachi muscle resulting in loss offlexion of the elbow [8]. Bicipital aponeurosishelps lessen the pressure of the biceps tendonon the radial tuberosity during pronation andsupination of the fore-arm [6]. Variations in theheads of biceps brachi muscle have beenreported to cause compression of surroundingneuro-vascular structures and lead to erroneousinterpretation during routine surgeries [9].Branching pattern of musculocutaneous nerve,while innervating short head and third head isclinically important [10] as the nerve is subjectedto compression by the bulky third head. Any vari-ant nerve having the abnormal origin, course anddistribution may be prone to accidental injuriesand impairments [9].In literatures variation in the insertion patternof extra head of biceps muscle is very rare [11].This knowledge is essential in various surgicalinterventions done in these areas. Variations ofthe heads of the biceps brachii muscle haveclinical importance. Supernumerary heads mayconfuse surgeons during shoulder operations orcause compression of neurovascular structures.Knowledge of the accessory tendon of thebiceps is crucial while performing tendonreconstruction and repair [7]. Therefore,surgeons should be aware of this anatomicalvariation in surgical procedures [12]. Such varia-tions become relevant during surgical interven-tion of the arm especially after humeralfracture with subsequent unusual bone displace-ments [13].

CONCLUSION

forearm. It can be argued that the presence ofsupernumerary heads of biceps brachii muscleincrease its kinematics. Therefore, fromanatomical standpoint of view it can bepresumed the power of flexion and supinationof the forearm. In addition to allowing theelbow flexion irrespective of the shoulder jointposition, the supernumerary head of bicepsbrachii may enhance the strength of elbowflexion.

These muscles should not be mistaken fortumors on magnetic resonance imaging of thearm. The biceps brachii are known for itspowerful elbow flexion and supination of the

Conflicts of Interests: None

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[11]. PavalJ,Mathew GJ. A rare variation of the bicepsbrachi muscle. Indian Journal of Plastic Sur-gery.2006; 39(1): 65-67.

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How to cite this article:Afil M Alex, Uma B Gopal. A RARE VARIATION IN THE DISTAL ATTACHMENT OF AN EXTRAHEAD OF BICEPS BRACHI MUSCLE. Int J Anat Res 2017;5(1):3461-3463. DOI: 10.16965/ijar.2016.503