|Year : 2015 | Volume
| Issue : 1 | Page : 39-41
Presence of communication between radial and ulnar nerve at high humeral level and its distribution to triceps brachii muscle
Ravindra S Swamy, Naveen Kumar, Satheesha B Nayak, Surekha D Shetty, Ashwini Aithal
Department of Anatomy, Melaka Manipal Medical College (Manipal Campus), Manipal University, Manipal, Karnataka, India
|Date of Web Publication||13-Jan-2015|
Department of Anatomy, Melaka Manipal Medical College (Manipal Campus), Manipal University, Manipal - 576 104, Karnataka
Source of Support: None, Conflict of Interest: None
Unusual communications between the branches of brachial plexus is not uncommon phenomenon. But among these, aberrant interconnection between radial and ulnar nerve is seldom reported. We present a case of persistence of well established abnormal communication between radial and ulnar nerves and its distribution to medial head of the triceps brachii muscle. Due to this, the triceps brachii which is normally innervated by radial nerve received additional innervations from the twigs of ulnar nerve through this communication. Aberrant communicating nervous channels when persist are vulnerable to iatrogenic injuries during surgical procedures as well as might results in entrapment neuropathic syndromes.
Keywords: Communication, entrapment neuropathy, radial nerve, triceps brachii, ulnar nerve
|How to cite this article:|
Swamy RS, Kumar N, Nayak SB, Shetty SD, Aithal A. Presence of communication between radial and ulnar nerve at high humeral level and its distribution to triceps brachii muscle. Int J Health Allied Sci 2015;4:39-41
|How to cite this URL:|
Swamy RS, Kumar N, Nayak SB, Shetty SD, Aithal A. Presence of communication between radial and ulnar nerve at high humeral level and its distribution to triceps brachii muscle. Int J Health Allied Sci [serial online] 2015 [cited 2020 Feb 21];4:39-41. Available from: http://www.ijhas.in/text.asp?2015/4/1/39/149259
| Introduction|| |
For anesthesia of upper extremity during surgery, brachial plexus blockade is effectively utilized.  Variant interconnections between the major nerves in high humeral region of upper limb may pose a difficulty during nerve blockade.  Brachial plexus is a major nerve plexus of the upper limb. Among the branches of the brachial plexus, the median, ulnar, and radial nerve provide chief contribution both in terms of sensory and motor innervation to upper limb structures. Following their formations from respective cords of brachial plexus, they lie in close relation to the axillary artery. The posterior cord of brachial plexus gives rise to radial nerve which passes through the lower triangular space of scapular region and then through radial groove along with the profunda brachii artery and gives branches to three heads of triceps brachii muscle, while the medial cord of the brachial plexus gives rise to ulnar nerve.  Triceps brachii is a three-headed muscle having lateral, long, and medial heads and occupies the posterior compartment of the arm. This muscle is the extensor of the elbow joint and is supplied by branches of radial nerve. 
| Case report|| |
During routine dissection of axilla and arm for the medical undergraduate students, we observed a prominent communication between radial and ulnar nerve at humeral level on left side of the arm. This communication was about 4.5 cm long and descended obliquely downward and medially to join the ulnar nerve. A twig (B1) from this communication was found to be innervating the medial head of triceps brachii muscle (MHTBM) [Figure 1]. Another nerve branch (B2) from the ulnar nerve originated just distal to the termination of communicating nerve (CN) and supplied the long head of triceps brachii muscle (LHTBM) [Figure 1]. Thus, the MHTBM received additional innervations derived from CN through B1 as well as from ulnar nerve through B2 nerve. The origin and course of both radial and ulnar nerve and their subsequent branching pattern were otherwise normal. This aberrant communicating branch was observed unilaterally on the left upper extremity of an elderly male cadaver of South Indian origin, aged about 60 years.
|Figure 1: Dissection of left arm showing the radial nerve (RN) giving rise to communicating nerve (CN) which joins with the ulnar nerve (UN). A branch (B1) from CN supplies to medial head of triceps brachii muscle (MHTBM) and another branch from ulnar nerve (B2) supplying the long head of triceps brachii muscle (LHTBM). MN: Median nerve, MCNF : Medial cutaneous nerve of forearm, BBM: Biceps brachii muscle, LDM: Latissimus dorsi muscle|
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| Discussion|| |
Transcommunications between the branches of brachial plexus are well-documented. These communications may persist at the level of arm, forearm, and wrist areas of the upper extremities. Communication between radial and ulnar nerve is rare. Even though Bergman et al., mentioned that the radial nerve may communicate with the ulnar nerve in the arm,  there are only three reported cases of communication between the radial and ulnar nerve in the arm so far to the best to our knowledge. Based on the topographical location of the communication and or nerves involved in the communication, the different types of nomenclature of anastomosis are identified as Martin-Gruber anastomosis, Marinacci communication, and Berretini anastomosis. 
In the available literature, sufficient reports on communication between median and ulnar nerve with the prevalence of 20% and between median and musculocutaneous nerve with the incidence of 46% have been reported.  Sensory communication between ulnar and radial nerve in dorsum of the hand was reported by Loukas et al., (2008). This study reported the prevalence of this communication on the dorsum of the hand in 60% of cases. 
The motor communication between ulnar and radial nerve is seldom reported. In the present case, such communication was observed at the medial side of the left arm. Aberrant communication between ulnar and radial nerve at arm has been reported in a Turkish population by Ozguner et al., (2010).  Australian population by Arachchi et al., (2013)  and in Indian population by Monika et al., (2014).  But none of the reports mentioned about the distribution of this communicating branch to the neighboring structures. Thus, the motor twig from CN and another motor twig from the ulnar nerve supplying the MHTBM is a unique feature of this report.
Nevertheless, the consequences of unusual communication between the radial and ulnar nerves, has not been well-documented in the literature. Thus it necessitates discussing possible clinical complications that might be encountered due to aberrant communication between ulnar and radial nerves in the arm region. Awareness of these unusual communications becomes important during nerve blockade procedures. Failure to recognize variant communications between the branches of brachial plexus may lead to blockade of unexpected regions during anesthetic procedures, which in turn might result in diagnostic impairment in assessment of severity of nerve injury.  Persistence of variant nerve communication as reported in the present case can lead to partial paralysis of MHTBM in case of accidental or iatrogenic trauma to the CN or the ulnar nerve proximal to the attachment of CN in addition to other structures, even though the radial nerve is not disturbed.
| Conclusion|| |
Presence of rare and abnormal CN between radial and ulnar nerves as reported here should be known to the clinicians, orthopedic surgeons, and anesthesiologists; as these might encounter with accidental iatrogenic injuries during surgical procedures as well as might result in entrapment neuropathic syndromes.
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