Three-headed biceps brachii muscle associated with duplicated musculocutaneous nerve.
ABSTRACT A unilateral three-headed biceps brachii muscle coinciding with an unusual variant of the musculocutaneous nerve was found during routine dissection of a 79-year-old male cadaver. The supernumerary bicipital head originated from the antero-medial surface of the humerus just beyond the insertion of the coracobrachialis, and inserted into the conjoined tendon of biceps brachii. Associated with this muscular variant was a duplicated musculocutaneous nerve. The proximal musculocutaneous nerve conformed to the normal pattern only in its proximal part, and terminated after innervating the coracobrachialis and biceps brachii muscles. The distal musculocutaneous nerve arose from the median nerve in the lower arm, then passed laterally between the supernumerary bicipital head and the brachialis muscles, supplying both and terminating as the lateral cutaneous nerve of the forearm. The supernumerary bicipital head and the accompanying anomaly of the musculocutaneous nerve seem to be unique in literature.
Article: Four-headed biceps brachii, three-headed coracobrachialis muscles associated with arterial and nervous anomalies in the upper limb.[show abstract] [hide abstract]
ABSTRACT: A four-headed biceps brachii muscle and three-headed coracobrachialis muscle, high-originated radial artery and communication between the median and musculocutaneous nerves have been well documented in the available literature. However co-existence of these variations is rare. In this study we aimed to describe multiple variations in the upper limb and discuss their co-existence from clinical and embryological points of view.Anatomy & cell biology 06/2012; 45(2):136-9.
[show abstract] [hide abstract]
ABSTRACT: The arterial and muscular variations of the upper limbs are common but important with regard to surgical approaches. Even though anomalies of the coracobrachialis muscle are rare, anatomical variations of the biceps brachii, existence of the accessory muscles in the forearm and persistent median artery are known and well documented. During routine dissection, we observed some important anatomical variations in a 50-year-old male cadaver. The variations were unilateral. The anomalies were: third head for biceps brachii muscle, an accessory belly for coracobrachialis muscle crossing the median nerve and brachial vessels and continuing with the medial head of triceps brachii muscle to be inserted to the olecranon process (coracoulnaris), a persistent median artery and an additional muscle in the anterior compartment of forearm. Although there are individual reports about these variations, the combination of these variations in one cadaver has not previously been described in the literature. Awareness of these variations is necessary to avoid complications during radiodiagnostic procedures or surgeries in the upper limb.Singapore medical journal 10/2008; 49(9):e254-8. · 0.73 Impact Factor
Article: The biceps brachii muscle and its distal insertion: observations of surgical and evolutionary relevance.[show abstract] [hide abstract]
ABSTRACT: A sound understanding of the anatomy of the biceps brachii and possible anatomical variants is necessary to manage distal biceps injury. The present study was performed to define the anatomy of the biceps brachii with particular focus on the conformation of the distal biceps tendon, and its relationship of the two heads of the biceps brachii. Twenty cadaver specimens were dissected and both qualitative and quantitative observations were made of a series of features relating to the biceps muscle and its tendon. The investigation revealed anatomical variations including supernumerary heads (20%) and 'fusion' of the muscle proximal to tendon formation and a spiralling arrangement of the tendon in its approach to the radial tuberosity. The data from the present study was reviewed in the context of previous studies on the anatomy of this muscle and speculation on the evolutionary basis of the variations and their clinical implications are discussed.Anatomia Clinica 10/2009; 32(4):371-5. · 0.93 Impact Factor
Three-Headed Biceps Brachii Muscle Associated
With Duplicated Musculocutaneous Nerve
MARWAN F. ABU-HIJLEH*
Department of Anatomy, College of Medicine and Medical Sciences, Arabian Gulf University,
Manama, Kingdom of Bahrain
A unilateral three-headed biceps brachii muscle coinciding with an unusual variant of the
musculocutaneous nerve was found during routine dissection of a 79-year-old male cadaver.
The supernumerary bicipital head originated from the antero-medial surface of the humerus
just beyond the insertion of the coracobrachialis, and inserted into the conjoined tendon of
biceps brachii. Associated with this muscular variant was a duplicated musculocutaneous
nerve. The proximal musculocutaneous nerve conformed to the normal pattern only in its
proximal part, and terminated after innervating the coracobrachialis and biceps brachii
muscles. The distal musculocutaneous nerve arose from the median nerve in the lower arm,
then passed laterally between the supernumerary bicipital head and the brachialis muscles,
supplying both and terminating as the lateral cutaneous nerve of the forearm. The super-
numerary bicipital head and the accompanying anomaly of the musculocutaneous nerve
seem to be unique in literature. Clin. Anat. 18:376–379, 2005.
C2005 Wiley-Liss, Inc.
Key words: biceps brachii; musculocutaneous nerve; neuro-muscular anoma-
lies; anatomical variations
Neuromuscular anomalies are common in the upper
limbs. Such variations may present clinically or be
detected at cadaveric dissection, autopsy, and surgery
(Abu-Hijleh, 1993). In terms of the number and mor-
phology of its heads, the biceps brachii is one of the
most variable muscles in the human body (Bergman
et al., 1988; Nakatani et al., 1998). Although absence
of the entire muscle or one of its heads (Greig et al.,
1952; Rodriguez-Niedenfuhr et al., 2003) and varia-
tions of the insertion seem to be uncommon (Greig
et al., 1952; Reina-de la Torre et al., 1994), supernum-
erary heads of the biceps brachii are relatively fre-
quent (Greig et al., 1952; Kosugi et al., 1992; Asvat
et al., 1993; Nakatani et al., 1998; Rodriguez-Nieden-
fuhr et al., 2003).
Variations in the course and distribution of the
musculocutaneous nerve have been reported previ-
ously (Schafer et al., 1909; Bergman et al., 1988; Saeed
and Rufai, 2003). Although a communicating branch
from the musculocutaneous nerve to the median nerve
in the arm is common (Le Minor, 1990; Eglseder and
Goldman, 1997; Venieratos and Anagnostopoulou,
1998; Choi et al., 2002), a branch in the opposite
direction or complete absence of the musculocutane-
ous nerve, with its muscular branches arising from the
median nerve or lateral cord of the brachial plexus,
are less frequent (Schafer et al., 1909; Nakatani et al.,
1997; Gumusburun and Adiguzel, 2000).
During routine dissection of the upper limbs of a
79-year-old male embalmed cadaver, a unilateral
*Correspondence to: Dr. Marwan F. Abu-Hijleh, MD, PhD,
Medicine and Medical Sciences, Arabian Gulf University, PO
Box 22979, Manama, Kingdom of Bahrain.
E-mail: marwanah@ agu.edu.bh
ofAnatomy, College of
Received 31 October 2004; Accepted 4 November 2004
Published online in Wiley InterScience (www.interscience.wiley.com).
C2005 Wiley-Liss, Inc.
Clinical Anatomy 18:376–379 (2005)
three-headed biceps brachii was discovered in the
right arm. The supernumerary head (Fig. 1) was a
flat muscular belly (1.5 cm wide ? 9.5 cm long) that
originated from the antero-medial surface of the
humerus between the insertion of the coracobrachia-
lis and the origin of the brachialis. The belly contin-
ued infero-medial to the bulk of the biceps brachii
and anterior to the brachialis muscle and lay lateral
to the brachial artery and median nerve. It inserted
into the proximal part of the common biceps tendon
(Fig. 1). The nerve supply to this third head was
from a branch of an aberrant musculocutaneous
nerve and the blood supply was from a branch of the
brachial artery. Careful dissection under 2? magnifi-
cation to identify the nerve supply to this accessory
bicipital head showed a duplicated musculocutane-
ous nerve (Fig. 1). The proximal musculocutaneous
nerve followed a normal course only as far as the
biceps brachii where it terminated. It originated
from the lateral cord of brachial plexus and pierced
coracobrachialis and, after supplying it, terminated as
branches to both normal heads of the biceps brachii
muscle. The nerve was thus purely muscular.
The distal aberrant musculocutaneous nerve arose
from the median nerve in the lower third of the arm
(at a distance of about 23.5 cm from the coracoid
process and 11 cm from the origin of the median
nerve). It crossed laterally over the brachial artery
and passed between and supplied the supernumerary
bicipital head and the brachialis muscle before
emerging lateral to the bicipital tendon as the lateral
cutaneous nerve of the forearm (Fig. 1). Cords and
other terminal branches from the brachial plexus
were found to have normal origins, courses, and dis-
(B) of the dissected right axilla, arm and the cubital fossa. It demon-
strates the presence of a supernumerary head of biceps brachii (*) asso-
ciated with a duplicated musculocutaneous nerve (2,6). Abbreviations:
1, lateral cord of brachial plexus; 2, proximal musculocutaneous
nerve; 3, lateral root of median nerve; 4, medial root of median nerve;
5, median nerve; 6, distal musculocutaneous nerve; 7, axillary artery;
Photograph (A) and corresponding schematic drawing
8, brachial artery; 9, lateral cutaneous nerve of forearm; 10, coraco-
brachialis, attached to the coracoid process (star, shown only in the
prosection photograph for orientation); 11, biceps brachii (displaced
laterally); 12, conjoined bicipital tendon; 13, brachialis; 14, pectoralis
major (reflected and displaced laterally); 15, subscapularis; 16, ulnar
nerve (shown only in the drawing, in the prosection photograph it is
concealed by the median nerve).
377Variant Biceps Brachii and Musculocutaneous Nerve
tributions. No additional muscular, neural, or vascu-
lar anomalies were found in the remainder of the
right upper limb or in the left upper limb of the
The most frequent variation of the biceps brachii
muscle is in the number of muscle heads with a
prevalence range of 9.1–22.9% (Greig et al., 1952;
Bergman et al., 1988; Kosugi et al., 1992; Nakatani
et al., 1998; Kopuz et al., 1999; Rodriguez-Nieden-
fuhr et al., 2003). Although supernumerary bicipital
heads have been described as part of either a three-,
four-, five- or seven-headed biceps brachii, the
three-headed variant represents the most common
type that has been reported with a prevalence rang-
ing from 7.5–18.3% and with no clear racial or gen-
der differences (Greig et al., 1952; Kosugi et al.,
1992; Asvat et al., 1993; Nakatani et al., 1998; Neto
et al., 1998; Kopuz et al., 1999; Rodriguez-Nieden-
fuhr et al., 2003). Bilateral occurrence of supernum-
erary heads in the biceps brachii muscles is rela-
tively rare (Greig et al., 1952; Kosugi et al., 1992;
Nakatani et al., 1998).
Recently, Rodriguez-Niedenfuhr et al. (2003) clas-
sified the supernumerary bicipital heads based on
their origin and location. Taking into account all
studies and cases reported previously, they defined
three different types: superior, infero-medial, and
infero-lateral humeral heads. They observed the
presence of a third head in 23 of 175 (13.1%) cadav-
ers or in 27 of 350 (7.7%) arms. In 26 arms, the
supernumerary head was represented by the infero-
medial humeral head and in one arm by an infero-
lateral humeral head. In the present case, the super-
numerary bicipital head corresponds to the infero-
medial type. It originated from the antero-medial
surface of the humerus distal to the insertion of the
coracobrachialis, passed infero-medial to the main
biceps brachii and anterior to the brachialis muscle,
and inserted into the medial side of the common
biceps tendon. The development of the third head
may have influenced the course or branching pattern
of the variant musculocutaneous nerve, or vice versa,
and could explain the coexistence of such a neuro-
The most frequent variation of the musculocuta-
neous nerve is the presence of a communicating
branch from the nerve to the median nerve (Le
Minor, 1990; Eglseder and Goldman, 1997; Veniera-
tos and Anagnostopoulou, 1998; Choi et al., 2002). A
branch in the opposite direction is less common
(Schafer et al., 1909; Bergman et al., 1988; Nakatani
et al., 1997). Very occasionally, the musculocutaneous
nerve fails to separate from the median nerve, and
the latter therefore gives off the branches that should
arise from the musculocutaneous. In a similar fashion,
the musculocutaneous has been reported to go only
to the muscles of the arm, whereas the lateral cutane-
ous nerve of the forearm arose from the median
(Schafer et al., 1909; Kosugi et al., 1992). Kosugi
et al. (1992) studied the branching pattern of the
musculocutaneous nerve and found variations in 75
of 546 limbs (13.5%). They divided the variations
into five groups according to the manner of communi-
cation with the median nerve: in Group I there were
no communications (32 of 75 limbs); in Group II
there was a communicating branch from the musculo-
cutaneous nerve to the median nerve (24 of 75
limbs); in Group III a branch ran from the median
nerve to the musculocutaneous nerve (12 of 75
limbs); in Group IV the above two communications
were present (5 of 75 limbs); in Group V there were
various other patterns (2 of 75 limbs). In the present
study, the musculocutaneous nerve seemed to be
duplicated; the proximal division (purely muscular)
had a normal origin from the lateral cord of the bra-
chial plexus and pierced the coracobrachialis muscle,
but the more distal aberrant division (muscular and
cutaneous) arose from the median nerve in the lower
arm and terminated as the definitive lateral cutaneous
nerve of the forearm. The course and distribution of
the duplicated musculocutaneous nerve seen in this
case, and the manner of connection of its distal divi-
sion with the median nerve, did not correspond with
any of those described in detail by previous authors.
Awareness of anatomic, neurological, and muscu-
lar variations of the types reported in the present
case can be helpful in explaining unusual clinical
signs and symptoms. For example, the very close
relationship of the variant distal musculocutaneous
nerve to the brachial artery (it crossed the artery
after leaving the median nerve) may result in arterial
compression (Saeed and Rufai, 2003) or the natural
beating of the artery could cause irritative neurologic
symptoms in certain positions and movements of the
arm or shoulder. Variant nerves having an abnormal
origin, course, and distribution may be more prone
to accidental injuries and entrapment neuropathies
(Roberts, 1992). Injury to the segment of the median
nerve in the mid-arm containing the more distal
anomalous musculocutaneous nerve may cause para-
lysis of the supernumerary head of biceps brachii
and brachialis muscles and anesthesia on the lateral
aspect of the forearm, in addition to motor and sen-
sory deficits that would have been expected from
such a lesion of the median nerve. Lack of aware-
ness of such variations in the median and musculo-
cutaneous nerves might thus complicate surgical
repair of the nerves. Variations of the heads of the
biceps brachii also have clinical importance as they
may cause compression of neurovascular structures
or confuse a surgeon during surgical procedures
(Warner et al., 1992).
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379Variant Biceps Brachii and Musculocutaneous Nerve