An unusual supernumerary head of biceps brachii muscle

Variation of the supernumerary head of the biceps brachii muscle: two case reports and literature review

“…1,3,[7][8][9][10][11] Supernumerary heads of the biceps brachii muscle have been described as part of either a three, four, or fiveheaded biceps brachii muscle. 2,6,8,[12][13][14][15][16][17][18][19][20] Recently, Rodriguez-Niedenfuhr et al 1 The presence of supernumerary heads of the biceps brachii muscle has been associated with variations of the musculocutaneous nerve. 6,14 The musculocutaneous nerve or its connection with the median nerve usually passed deep to the supernumerary head but may also pass superficial to it or have no relationship to it at all.…”

Unusual origin of three headed biceps brachii muscle

“…[2,3,6,7,9,10,[12][13][14][15][16][17][18][19][20] Other origins can include the tendons or fascia of the neighboring muscles (deltoid, pectoralis major, pronator teres, brachioradialis and medial triceps), the intermuscular septum, the shoulder capsule itself, the neck, lesser tuberosity or the anteromedial surface of the humerus. [4,6,[8][9][10]14,[16][17][18][20][21][22][23][24][25][26][27][28][29] The insertion of these accessory heads can be just as variable as their origins. The current literature reports them inserting into the individual muscle bellies of the normal long and short heads, into a common muscle belly, the common tendon or onto the bicipital aponeurosis.…”

“…The current literature reports them inserting into the individual muscle bellies of the normal long and short heads, into a common muscle belly, the common tendon or onto the bicipital aponeurosis. [2,3,[6][7][8][9][10]12,[14][15][16][18][19][20]22,23,26,28,30,31] There have been multiple population based studies which attempt to determine the prevalence of supernumerary heads. The overall prevalence has traditionally been reported as 10% in white Europeans, 12% in black Africans, 8% in Chinese and 18% in Japanese populations.…”

“…[6,32,33] The incidence of bilaterally symmetric supernumerary heads is also variable between studies and has been reported to be between 3.3% and 29.3%. [9,17,19,22,32,34,35] All reported supernumerary heads of the biceps brachii are innervated by the musculocutaneous nerve, [10,12,13,16,22,23,28,30,[33][34][35] with the rare exceptions where accessory heads are innervated by the median nerve. [24,36] However, the presence of supernumerary head of the biceps are also frequently associated with musculocutaneous nerve variations which include anything from the absence of the nerve, to unique branching patterns, to duplication.…”