Case Report
BILATERAL M ULTIPLE VARIATIONS IN THE UPPER EXTREM ITY OF
A HUM AN CADAVER: A CASE REPORT
Soniya A Gupta
1, Saiprasad P Bhavsar *
2, M edha V Ambiye
3, Seema N Khambatta
4.
ABSTRACT
Address for Correspondence: Dr Saiprasad P Bhavsar, 323, Above CGHS Dispensary, CGS Colony, Sect or- C, Bhandup East , M umbai, M aharasht ra-400042, India. E-M ail: [email protected]
Background: A rare case of bilat eral m ult iple anat om ical variat ions in t he upper ext rem it y, w as found in a m ale cadaver, dur ing rout ine dissect ion in t he Anat omy depar t m ent at TN M edical College, M um bai.
Observation:The variat ions included absence of M usculocut aneous ner ve of right ar m and com m unicat ion of M usculocut aneous nerve w it h m edian nerve in t he left arm , bilat eral t hr ee heads of Biceps Brachii m uscle and bilat eral m ult iple t endons of Abduct or Pollicis Longus m uscle in bot h t he ar m s.
Conclusion: M edical significance of an absent M usculocut aneous nerve and t he presence of t hree heads of Biceps Brachii lies in t he fact t hat it can cause t raum at ic nerve com pressions or com plicat ions in anaest het ic block et c. Anat om ic variat ions of t endons of abduct or pollicis longus are signif icant in assessm ent of hand injuries and surgeons perform ing hand reconst ruct ive surgery.
KEYW ORDS:Abduct or pollicis longus, Biceps brachii, M edian ner ve, M usculocut aneous ner ve.
INTRODUCTION
Int ernat ional Journal of Anatomy and Research, Int J Anat Res 2015, Vol 3(4):1655-59. ISSN 2321- 4287 DOI: ht t p:/ / dx.doi.org/10.16965/ ijar.2015.307
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Received: 30 Oct 2015 Accept ed: 24 Nov 2015 Peer Review : 30 Oct 2015 Published (O): 31 Dec 2015 Revised: None Published (P): 31 Dec 2015
Int ernat ional Journal of Anat omy and Research ISSN 2321-4287
ww w.ijmhr.org/ ijar.htm
DOI: 10.16965/ ijar.2015.307
1 Assistant Professor, Anat omy Depart ment , M ayo Inst it ute of M edical sciences, Gadia, Barabanki,
UP, India.
* 2 Junior Resident , Depart ment of prevent ive and social medicine, TNM C, M umbai, India.
3 HOD, Anat omy Depart ment , TNM C, M umbai, India.
4Associate Professor, Anat omy Depart ment , TNM C, M umbai, India.
Anat omic variat ions of upper limb are common but coexist ence of bilat eral mult iple variat ions are rare. Since, several spinal nerves unit e and divide t o form the Brachial plexus, variat ions are com mon. Normally M usculocut aneous nerve (C5,6,7) arises from t he lat eral cord of brachial plexus, pier ces coracobrachialis m uscle and supplies muscles of flexor compart ment of arm.
frequent ly not ed variat ion among t he branches of t he brachial plexus [1]. Nakat ani et al (1997) [2] observed t hat t he branches from t he lat eral cord direct ly supplied t he ant erior compart ment m uscles of t he upper arm and t here w as no musculocutaneous nerve arising from the lat eral cord of t he brachial plexus.
Su per n um er ar y heads ar e co nf using f or a sur geon and ar e liable f or com pr ession of neurovascular st ruct ures in upper limb [4].
The t endon of abduct or pollicis longus muscle normally takes origin from t he posterior surface of radius, ulna and int erosseus membrane and is inser t ed as a single t en don on t he f ir st met acarpal. The variat ions of t endon have been not ed by many researchers.
CASE REPORT
During t he rout ine dissect ion of a male cadaver in Anat omy depart ment of TN M edical College, M um bai, w e obser ved int er est ing bilat eral m ul t i pl e var i at i on s of sup er i or ext rem i t y. Specimen w as dissect ed, cleaned and paint ed carefully. Phot ographs w ere taken.
OBSERVATIONS
A case of m ult iple, bilat eral var iat ions w as observed during rout ine dissect ion of superior ext remit y of a male cadaver.
In t h e r i ght ar m as sh ow n in f igu r e 1, musculocut aneous nerve w as absent and t he lat eral cord cont inued as t he lat eral root of
median nerve. Before joining t he medial root , 2 small t w igs w ere given– one t o coracobrachialis and the ot her as a proximal communicat ion w it h t he m edial root . The ot her m uscles of flexor compart ment w ere supplied by branches from t he median nerve as show n in figure 2 and one of t hem cont inued as lat eral cut aneous nerve of t he forearm.
How ever, in t he left arm as show n in figure 3, t he musculocut aneous nerve w as present and about t he middle of arm, it communicat ed by a small t w ig w it h t he median nerve.
In t he same cadaver, as show n in figure 4, biceps brachii had t hree heads of origin, bilaterally. The long and short heads arose normally, w hile t he accessory t hird head arose from t he midshaft of hum er u s, near t he inser t ion o f cor aco-brachialis muscle.
We also found three tendons of Abductor pollicis longus muscle near it s insert ion. Of t hese, t w o w ere insert ed on t he base of first met acarpal and one cont inued w it h t he belly of the abductor pollicis brevis muscle, as show n in figure 5.
Fig. 1:Diagram show ing
absent M usculo Cut ane-ous Ner ve in right arm .
Fig. 2:diagram show ing
Fig. 3:Diagram show ing t he co m m u n i cat i o n b et w een M CN (m u scu l o cu t an e o u s n er v e) an d M N ( m e d i an nerve) in left arm .
Fig. 4:Diagram show ing
3rd head of biceps brachii.
Fig. 5: Di agr am sh o w i n g m ult iple t endons of abduct or p o l l i ci s l o n gu s ( APL) , ext ensor pollicis longus(EPL), ext ensor pollicis brevis(EPB), abduct or pollicis brevis (APB) .
DISCUSSION
com m unicat ion t o t he point of ent ry of t he musculocut aneous int o coracobrachialis muscle. In si x o u t o f 54 d issect i o n s, w her e t h e musculocut aneous w as present , t he nerve did not pierce t he coracobrachialis muscle. In t w o cases, t he musculocut aneous nerve w as absent and in one case t he musculocut aneous and t he median nerve had a dist al origin [6].
Le M inor (1992) (as cit ed by Sachdeva, Singla Var iat ions of m usculocut aneous ner ve are
Type 2: t he fibers of medial root of median nerve pass t hrough t he musculocut aneous nerve and join t he median nerve in t he middle of t he arm.
Type 3: fibers of t he lateral root of t he median nerve pass through t he musculocutaneous nerve and aft er some dist ance leave it t o form lat eral root of median nerve.
Type 4: t he musculocut aneous fibers join t he lat eral root of t he median nerve and aft er some dist ance it arise from t he median nerve.
Type 5: The musculocutaneous nerve is absent and t he ent ire fibers of musculocut aneous pass t hrough lat eral root of median nerve and fibers t o t he muscles supplied by musculocut aneous nerve branch out directly from median nerve. In t his t ype t he musculocut aneous does not pierce t he coracobrachialis muscle [7].
Our case report show s t he t ype 5 variat ion in t he right arm.
In t he previous st udies, Biceps Brachii is know n t o present a wide variety of variations. The most com mon is presence of t hird head. This t hird head may have it s orgin from coracoid process/ pect oralis m inor t endon or proxim al head of humerus. The one arising from humerus, know n as t he humeral head of biceps brachii muscle is m ost com m on. According t o Hit endra et al (2008) pr esence of hum eral head var ies in d i f f er en t po p u lat i on n am el y Ch i nese 8%, Eu r o p ean w hi t e 10%, Af r i can b l ack 12%, Japanese 18%, Sout h African Blacks 20.55% and 37.5% in Columbians [8]. In t he present case, t hird head arises from t he shaft of humerus, close t o t he insert ion of coracobrachialis on bot h t he sides. Presence of t his t hird head of biceps br achii m uscle is liable for com pr ession of m usculocut aneous or m edian nerve [9]. As biceps act s during flexion of elbow joint and rapid supinat ion of forear m in a m id-flexed posit ion, an addit ional biceps head may increase t he pow er of flexion and supinat ion [8].
Abduct or pollicis longus m uscle is t he m ost important muscle of hand, required for everyday sk il l f ul m ov em en t s. Kn o w l ed ge abo u t i t s v ar i at i o n i s necessar y f o r r eco n st r u ct i v e surgeries. Though w e found only 3 t endons, a maximum of 9 t endons have been report ed by M ansure et al (2010) [ 10] . Dur ing surger y, exist ence of mult iple t endons can confuse t he
surgeon. Abduct or pollicis longus is know n t o have split insert ions in chimpanjees, gorillas and gibbons [11]. As report ed by Rayan and M ustafa (1989), one of t he slip of abductor pollicis longus had it s inser t ion int o an anom alous t henar muscle [12]. M any t imes, t here is inadequat e su rgi cal d eco m pr essi o n of De Qu er vain ’s Syndr om e because of def icient anat om ical know ledge. Presence of such variat ions also r ev eals ant hr opolo gical im po r t ance. Ext r a t endons of Abductor pollicis longus may increase t he force component [10]. Addit ional t endons may also be used for reconst ruct ive surgeries.
CONCLUSION
Various anomalies are common in upper limb, but presence of mult iple anomalies in t he same cadaver is not only rare, but of considerable medical significance.
Conflicts of Interests: None
LIST OF ABBREVIATIONS:
M CN - M usculocut aneous nerve M N - M edian Nerve
APL - Abduct or pollicis longus EPL - Ext ensor pollicis longus EPB - Ext ensor pollicis brevis APB - Abduct or pollicis brevis
I t hank head of depar t m ent , t eacher s, col-leagues and st aff members for t heir guidance and support . No grant or funding was taken for t he research.
ACKNOW LEDGEM ENTS
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