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1. INTERNATIONAL JOURNAL OF MEDICAL AND APPLIED SCIENCES
E‐ISSN:2320‐3137
218 www.earthjournals.org Volume 3, Issue 3, 2014
Research Article
CORACOBRACHIALIS NOT PIERCED BY
MUSCULOCUTANEOUS NERVE : A CADAVERIC STUDY
Dr. Yadav Abhijeet 1*
, Dr. Yadav Mukul2
, Dr.Dixit Asha 3
1*
Assistant Professor, Department of Anatomy, Bundelkhand Medical College,Sagar(M.P.)
2
Prof. & Head , Department of Anatomy, Bundelkhand Medical College,Sagar(M.P.)
3
Ex- Prof. & Head, Department of Anatomy, Gandhi Medical College,Bhopal(M.P.)
Corresponding Author: Dr. DR.ABHIJEET YADAV,Q. NO. 8, BLOCK 9,BMC CAMPUS,TILI
ROAD,SHIVAJI WARD,SAGAR(M.P.),mobile: 09827586326
ABSTRACT
Introduction:-Variation in musculocutaneous nerve are common. They may be in origin, branching pattern,
course or termination .A rare variation of this nerve was therefore studied for a period of four long years on 52
upper limbs in the department of anatomy of Gandhi Medical College ,Bhopal and Bundelkhand Medical
College,Sagar, that variation is musculocutaneous nerve not piercing coracobrachialis muscle. Its an important
variation for anatomist, clinicians and surgeons to avoid unexpected complication. Material & method:-
Dissecting instruments, measuring tape, thread, labels and clean cloth were used for routine dissection procedure
of pectoral region and arm for all 52 upper limbs. Nerve was carefully traced throughout its course and
distribution .Result – Musulocutaneous nerve did not pierce coracobrachialis muscle in 7% of all the 52
specimens under study. Importance of this finding lies in the fact that this variation ranges from 1.7% to 9.3% in
individuals according to different authors. The nerve supplied brachialis and biceps brachii by its muscular
branches. Whole nerve from its origin to termination was studied thoroughly. Conclusion:- It is
phylogenetically a very important finding. The knowledge of this variation is important for anatomists,
morphologists, surgeons, physicians particularly neurologists.
Key Words: coracobrachialis,Lateral Cord, Musculocutaneous Nerve, Variations
INTRODUCTION
Musculocutaneous nerve arises from the lateral cord (C5-7)and normally pierces
coracobrachialis. It supplies coracobrachialis, biceps and brachialis muscle. Just below the
elbow it pierces the deep fascia and continues as the lateral cutaneous nerve of the forearm.
The branch to coracobrachialis is given off before the musculocutaneous nerve enters the
muscle: its fibres are from the seventh cervical ramus and may branch directly from the
lateral cord. Branches to biceps and brachialis leave after the musculocutaneous has pierced
coracobrachialis: the branch to brachialis also supplies the elbow joint[1]. Nakatani et al[2]
and other authors reported cases in which musculocutaneous nerve did not pierce
corachobrachialis .
MATERIAL AND METHODS:
52 upper limbs dissected for study during period of four long years in the department of
anatomy of Gandhi Medical College ,Bhopal and Bundelkhand Medical College,Sagar. The
pectoral region, axilla and arm dissected carefully. Complete course of musculocutaneous
nerve was studied in each specimen.

2. INTERNATIONAL JOURNAL OF MEDICAL AND APPLIED SCIENCES
E‐ISSN:2320‐3137
219 www.earthjournals.org Volume 3, Issue 3, 2014
OBSERVATION & RESULTS:
Of the many variations that we came across in our study,we have tried to restrict ourselves to
the much less reported researched topic of coracobrachialis not pierced by musculocutaneous
nerve. In our study we found only two specimens(3.8%) in which musculocutaneous nerve
did not pierce coracobrachialis unilaterally . But there was a cadaver in which this nerve
didn’t pierce the muscle under study bilaterally(1.9%). Thus , in a total of 4 cases out of 52
(7.6%) musculocutaneous nerve didn’t pierce coracobrachialis .
FIG 1. CORACOBRACHIALIS NOT PIERCED BY MUSCULOCUTANEOUS
NERVE BILATERALLY
FIG 2: MUSCULOCUTANEOUS NERVE NOT PIERCING CORACOBRACHIALIS
UNILATERALLY

3. INTERNATIONAL JOURNAL OF MEDICAL AND APPLIED SCIENCES
E‐ISSN:2320‐3137
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DISCUSSION:-
Jamuna et al[3] Gomusburun, E. and Adiguzel, E.[4] and Chitra et al[5] reported that
musculocutaneous nerve does not pierce the coracobrachialis and only muscular branch
pierce the coracobrachialis and nerve passes behind or between coracobrachialis and biceps.
Hollinshed[6] referring Rao et al. has described that in 9.3% cases.Sachdeva K et al[7]
observed that musculocutaneous nerve instead of piercing coracobrachialis giving one
muscular branch to it and in further course giving one communicating branch to median
nerve and then supply biceps and brachialis and continue as lateral cutaneous nerve of
forearm bilaterally. Similar finding was observed by us. Venieratos and Anagnostopoulou[8]
described 3 types of communication between Musculocutaneous and Median nerve in
relation to Coracobrachialis; Type 1: communication between Musculocutaneous and Median
nerve is proximal to the entrance of Musculocutaneous into Coracobrachialis. Type 2:
communication between the two nerves is distal to the muscle. Type 3: neither the nerve nor
its communicating branch pierced the muscle. Iwata et al[9] explained that human brachial
plexus appeared as single radicular cone in upper limb bud, ventral and dorsal segment form
after division of upper limb bud. The ventral division give roots to ulnar and median nerve.
Musculocutaneous nerve arises from median nerve. Disturbances in this process lead to
anatomical variation.
In human being forelimb muscles develops from mesenchyme of paraxial
mesoderm in the fifth week of intrauterine life [11]. Regional expression of five Hox D (Hox
D 1 to Hox D 5) genes is responsible for upper limb development [12]. The motor axons
arrive at the base of limb bud; they mix to form brachial plexus in upper limb. The growth
cones of axons continue in the limb bud [11].As the guidance of the developing axons is
regulated by the expression of chemo-attractants and chemo-repulsants in a highly
coordinated site specific fashion any alterations in signalling between mesenchymal cells and
neuronal growth cones can lead to significant variations[13].Studies of comparative anatomy
have observed the existence of such connections in monkeys and in some apes; the
connections may represent the primitive nerve supply of the anterior arm muscles[10].
CONCLUSION:
By this study , a rare variation is brought to light of anatomists. Morphology of
coracobrachialisis revisited.Knowledge about this variation should be known to neurologists,
surgeons and orthropaedicians as deficit of this knowledge to them can result in faulty
diagnosis and treatment.
Conflict of interest: none
Source of funding : none
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