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International Journal of Biological & Medical Research

Int J Biol Med Res. 2012; 3(3):1952-1954

Extensor digitorum brevis manus: a Cadaveric Study and Review

Surekha Dilip Jadhav*, B R Zambre

A R T I C L E I N F O A B S T R A C T

Keywords:

Original Article

Extensor digitorum manusAnatomyAtavisticCadaversDorsum of hand.

1. Introduction

2.Materials and Methods:

Introduction: The extensor digitorum brevis manus is an atavistic, small muscle which

rarely present on the dorsum of the hand. It is often misdiagnosed as ganglions, synovial cyst,

soft tissue tumor, giant cell tumor or carpal bosses and results in unnecessary exploratory

surgery. Aim: The aim of the present study is to observe the incidence and anatomy of extensor

digitorum brevis manus. Material and Methods: Ninety six upper limbs of adult cadavers of

unknown sex were studied to note down the incidence, nerve supply and blood supply of

extensor digitorum brevis manus. Results: This muscle was observed in 4.1% cadavers.

Conclusion: A detail Knowledge of the anatomy and incidence of extensor digitorum brevis

manus muscle is of great practical importance to prevent diagnostic errors and can be used for

tendon transfer to restore malfunctioning muscles such as a damaged extensor pollicis longus.

The Extensor Digitorum Brevis Manus (EDBM) is an anomalous,

small muscle present on the dorsum of the hand [1, 2]. Ogura et al.

[2] quoted in his paper that, EDBM was first described by Albinus in

1734 as “musculus extensor brevis digiti indicis vel medii” but

Macalister coined it as “extensor digitorum brevis manus”. Since

that, many authors have used this term. The incidence of EDBM

muscle has been reported to be from 1 % to 10 % in cadavers but in

clinical practice it is rarely found [3, 4]. It can be unilateral or

bilateral [2].

The common sites of proximal attachment of EDBM muscle are

wrist joint capsule, the dorsal radio-carpal ligament, the distal end

of the radius and carpal bones, dorsal metacarpal surface [5, 6, 7].

The most common distal attachment sites of this muscle, in order of

decreasing frequency are the extensor hood of the second digit,

extensor hood in second and third digits and may be inserted ulnar

to extensor digitorum tendon of index finger with or without

accessory slip to long finger, below the extensor digitorum tendon

of long finger [7]. These variations are similar to variations of

extensor indicis proprius muscle [8]. When EDBM muscle inserts in

the second digit that times in 50% individuals the extensor indicis

muscle and its tendon is absent. In this situation, the EDBM muscle

is the only muscle responsible for independent extension of the

second digit [9].

The EDBM muscle receives its innervation and blood supply

through posterior interossious nerve and artery respectively. The

importance of presence of this muscle lies in the fact that at times it

is often misdiagnosed as ganglions, synovial cyst, soft tissue tumor,

giant cell tumor or carpal bosses and results in unnecessary

exploratory surgery [10]. A detail Knowledge of the anatomy and

incidence of EDBM muscle is of great practical importance to

prevent diagnostic errors and to avoid surgical complications

during hand surgery [11]. Considering its importance this study

was conducted to evaluate the anatomy and incidence of it.

Ninety six upper limbs of adult cadavers of unknown sex were

studied. They were carefully inspected and those upper limbs

without any deformities, external trauma were taken for study.

The specimens were then dissected carefully to see the presence of

EDBM muscle, its proximal and distal attachments. We also noted

its nerve supply and blood supply. Appropriate photographs were

taken by Sony digital camera of 5.1 megapixels.

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Associate Professor* , Professor and HOD, Department of Anatomy, Padamshri Dr. Vithalrao Vikhe Patil Medical College, Ahmednagar, Maharashtra, India

* Corresponding Author : Dr Surekha D Jadhav

Associate Professor, Dept– Anatomy,PDVVP Medical Collage, Opp. Govt. Milk Dairy, P.O. M.I.D.C., Ahmednagar, Maharashtra, India, Pin: 414111Mob: 9923373960E.mail: , drsurekha_32@yahoo.indrsurekhadjadhav@gmail.com

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Surekha Dilip Jadhav & B R Zambre/ Int J Biol Med Res. 2012; 3(3) 1952-1954 1953

EDBM was observed (Fig. 1, 2, 3) in the hands of four out of

ninety six cadavers (4.1%). It was present on right side in two hands

and other two were on left side. The EDBM had a single belly in all

four cases. The belly extended to the midportion of the second or

third metacarpal bone. The belly was present between tendons of

the extensor digitorum to the index and middle fingers.

Three EDBM were originated deep to extensor retinaculum from

carpal joint capsule, carpal ligaments and one was arising from the

dorsal surface of the third metacarpal and carpal joint capsule (Fig.

3). They were running within the compartment for the extensor

digitorum. The tendon of all these four muscles passed medial to the

tendon of the extensor indicis and they were inserted into the

extensor hood of the index finger (Fig. 1, 2, 3). In all cases, a fine

branch of the posterior interossious nerve was providing

innervations and branch of anterior interossious artery was

supplying this muscle.

In human population, the hand is an exquisite organ for

performing various activities in day to day life and it is one of the

most frequently used parts of our body. The important fact is that,

the extensor muscles and tendons of the forearm and hand shows

great variability. Therefore, the knowledge of muscles and tendons

of hand and their variations appears to be very important especially

when surgery is planned in that area [12].

The EDBM is an atavistic muscle and a remnant from the

amphibians which controlled the digital joints and it could

represent a homologue of extensor digitorum brevis on the dorsum

of the foot1. According to Bunnel [13] and Souter [14], the EDBM

may represent a failure of proximal migration of ulnocarpal

elements of the antebrachial muscle mass in humans, which is

found normally in amphibians.

The incidence of the EDBM muscle in the present study was

almost the same previously reported by other authors (Table I).

Previous researchers reported several variations in proximal

attachments of EDBM. In our dissections we reported, the proximal

attachment of EDBM from capsule and ligament of wrist joint and in

one case it was from the dorsal surface of the third metacarpal and

carpal joint capsule (Fig. 3).

Paraskevas et al. [7] reported the incidence of EDBM occurring

bilaterally in approximately one third of cases, and no difference in

incidence between the right and left hands or between the genders

has been reported. In present study, we did not come across

bilateral presence of this muscle and we observed equal

distribution on right and left side. But Ranade et al. [18] observed

this muscle only on the left side. Generally, this muscle consists of a

single belly, but cases with two bellies with variable sizes also have

been reported by Paraskevas et al. [7] and Stith and Browne [19]. In

our dissection, we reported a single belly of EDBM in all cases.

Presence of EDBM muscle is usually asymptomatic, but

sometimes the patient may present with a painful dorsal wrist

swelling, particularly in individuals who are involved in sports such

as, tennis, golf, cricket, weight lifting were repetitive wrist

3.Results:

Table I: Incidence of EDBM in dissection studies by different

authors

Legend:

Fig. 3- EDBM- Extensor Digitorum Brevis Manus, EH- Extensor

Hood.

4.Discussion:

Legend:

Fig. 1- EDBM- Extensor Digitorum Brevis Manus, ER- Extensor

Retinaculum.

Fig. 2- EDBM- Extensor Digitorum Brevis Manus, EH- Extensor

Hood.

Percentage

3% (3/100)

2.7% (2/75)

2.4% (2/82)

3.8% (11/286)

4.2% (4/72)

4.1% (4/96)

McGregor (1926), [15]

Wagenseil (1937), [16]

Moriya (1956), [17]

Ogura et al. (1987), [2]

Ranade et al. (2008), [18]

Present study

Author

1954

movement is involved [9]. During clinical examination, this muscle

may be confused with ganglion cyst, soft tissue tumors etc.

Complementary tests can be useful for the proper diagnosis, such as

electromyography, ultrasonography and MRI [4]. Therefore,

knowledge of this muscle is of great practical importance in making

a correct diagnosis and using proper surgical procedure during

hand surgery and may be used for tendon transfer to restore

malfunctioning muscles such as a damaged extensor pollicis longus

[4, 11].

A rare variation found in the dorsum of the hand is the presence

of EDBM. One must remember it as a possible diagnosis when there

is swelling on the dorsum of the hand. Precise anatomical

knowledge of possible variants of extensor tendons of the hand is

vital for success of reconstructive procedures in this region,

assessing the traumatized or diseased hand for differential

diagnosis. Knowledge of this variation should be bared in mind by

clinicians, surgeons and academicians who manipulate this

particular site.

5.Conclusion:

6.References:

[1] Straus WL. The phylogeny of the human forearm extensors. Hum Biol 1941; 13: 203-238.

[2] Ogura T, Inoue H, Tanabe G. Anatomic and clinical studies of the extensor digitorum brevis manus. J Hand Surg Am. 1987;12: 100-107.

[3] Murakami Y, Todani K. The extensor indicis brevis muscle with an unusual ganglion. Clin Orthop. 1982; 162: 207-209.

[4] Gama C. Extensor digitorum brevis manus: A report on 38 cases and review of literature. J Hand Surg. 1983; 8: 578-582.

[5] Glasgow E F. Bilateral extensor digitorum brevis manus. Med J Aust. 1967; 2: 24-25.

[6] Watambe H, Abe M, Kunishima I. A case of extensor digitorum brevis manus. Seikei-Geka. 1972; 23: 1060-1061.

[7] Paraskevas R J, Papaziogas B, Spanidou S, Papadopoulos A. Unusual variation of the extensor digitorum brevis manus: a case report. Orthop Traumatol. 2002; 12: 123-124.

[8] Cauldwell E W, Anson B J, Wright R R. The extensor indicis proprius muscle. Quart Bull N W Univ Med School. 1943; 17: 267-279.

[9] Ouellette H, Bijoy J, Thomas, Torriani M. Using dynamic sonography to diagnose extensor digitorum brevis manus. AJR. 2003;181: 1224-1226.

[10] Gebuhr P, Klareskov B. Extensor digitorum brevis manus. Acta Orthop Scand. 1987; 58: 85-86.

[11] Ross J A, Troy C A. The clinical significance of the extensor digitorum brevis manus. J. B. J S (Br.). 1969; 51: 473- 478.

[12] Hirai Y, Yoshida K, Yamanaka K, Inoue A, Yamaki K, Yoshizuka M. An anatomic study of the extensor tendons of the human hand. J Hand Surg Am. 2001; 26 (6): 1009-1015.

[13] Bunnell S. Surgery of the intrinsic muscles of the hand other than those producing opposition of the thumb. J Bone Jt Surg. 1942; 24:1–31.

[14] Souter WA. The extensor digitorum brevis manus. Br J Surg. 1966; 53:821.

[15] McGregor A L. A contribution to the morphology of the thumb. J Anat. 1926; 60: 259-273.

[16] Wagenseil F. Untersuchungen uber die Muskulatur der . Chinesen. Z Morphol Anthropol. 1937; 36: 39-150.

[17] Moriya M. Cho-sho-kin oyobi Koyu-jishi-shinkin no inni tsuite. Tokyo Jikeikai Med J. 1956; 71: 2035-2041.

[18] Ranade A, Rai R, Prabhu L V, Rajanigandha V, Prakash, Janardhan JP, Ramnathan L, Prameeta M D. Incidence of Extensor digitorum brevis manus. Hand (N Y). 2008; 3 (4): 320-324.

[19] Stith JS, Browne PA. Extensor digitorum brevis manus: a case report and a review. Hand. 1979; 11:217–23.

Copyright 2010 BioMedSciDirect Publications IJBMR - All rights reserved.

ISSN: 0976:6685.c

Surekha Dilip Jadhav & B R Zambre/ Int J Biol Med Res. 2012; 3(3) 1952-1954