An anomalous muscle in the hand that can cause carpal · carpal tunnel, resulting in carpal tun -...
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Page 1 of 3 Case report Licensee OA Publishing London 2013. Creative Commons Attribution License (CC-BY) For citation purposes: Shetty P, Nayak SB, D’Souza MR, Thangarajan R, Prabhu GS. An anomalous muscle in the hand that can cause carpal tunnel syndrome: A case report. OA Case Reports 2013 Sep 10;2(10):100. Compeng interests: none declared. Conflict of interests: none declared. All authors contributed to concepon and design, manuscript preparaon, read and approved the final manuscript. All authors abide by the Associaon for Medical Ethics (AME) ethical rules of disclosure. Anatomy An anomalous muscle in the hand that can cause carpal tunnel syndrome: A case report P Shetty, SB Nayak*, MR D’Souza, R Thangarajan, GS Prabhu Abstract Introduction Intrinsic and extrinsic muscles of the hand show frequent variations. Knowledge of these muscle varia- tions is important during diagnosis and treatment of carpal tunnel syn- drome, hand surgery and some plas- tic surgery procedures. We report here the presence of an anomalous muscle in the hand between the first and second lumbricals. Case report The flexor digitorum superficialis had five tendons and the two later- al-most tendons among them gave origin to this abnormal muscle of the hand. The fleshy belly of the mus- cle was supplied by a branch of the median nerve. Distally the tendon of the anomalous muscle and most of the lateral tendon of the flexor digitorum superficialis muscle mer- ged with the second tendon of the flexor digitorum superficialis muscle. The common tendon was inserted to the base of the middle phalanx of the index finger. Further, the first lumbri- cal had two heads: a lateral head and a medial head. The lateral head took its origin from the lateral-most ten- don of the flexor digitorum profun- dus muscle and the medial head took origin from the lateral part of the fleshy belly of the abnormal muscle. Its insertion and nerve supply were normal. Conclusion The abnormal muscle can produce a bulge in the palm and it might compress the median nerve in the carpal tunnel, resulting in carpal tun- nel syndrome. Introduction Wide ranges of accessory muscles of the forearm have been described in anatomical, surgical and radiological literature. In most of the cases, these additional muscles are asymptomatic but in some cases, they produce clini- cal symptoms. They may occur as a palpable soft swelling near or in the carpal tunnel with or without symp- toms of neurovascular compression. In symptomatic cases, recognition and careful evaluation of the acces- sory muscle with electromyographic examination may help in diagnosis and proper planning of the treatment. Anomalies of the flexor digitorum su- perficialis muscle are extremely rare and were first reported by MacAlister in 1868 and subsequently by Graper in 1917 and Mainland in 1927 1 .The anomalous bellies arising from flexor digitorum superficialis might show a tender mass in the palm. Magnetic Resonance Imaging (MRI) may be of great use in knowing the extent and exact nature of the muscle 2 . Partial or complete surgical resection of such muscles can reduce the symptoms 3 . We report an anomalous muscle bel- ly arising from the flexor digitorum superficialis that could be a potential source of carpal tunnel syndrome. Case report During routine dissection classes for medical undergraduates, we found an anomalous muscle between the first and second lumbricals of the right hand of an adult male cadaver, aged approximately 60 years (Figure 1). The flexor digitorum superficialis muscle had five tendons and the two most lateral tendons gave origin to this abnormal muscle of the hand (Figure 2). The fleshy belly of the muscle was supplied by a branch of the median nerve. Distally the ten- don of the abnormal muscle and the lateral-most tendon of the flexor dig- itorum superficialis muscle merged with the second tendon (tendon going to index finger) of the flexor digitorum superficialis muscle. The common tendon was inserted to the base of the middle phalanx of the in- dex finger. Further, the first lumbrical had two heads: a lateral head and a medial head. The lateral head took its origin from the lateral-most ten- don of the flexor digitorum profun- dus muscle and the medial head took origin from the lateral part of the fleshy belly of the abnormal muscle (Figure 3). Its insertion and nerve supply were normal. Discussion It is very important for clinicians to be aware of the anomalous mus- cles in the forearm and hand. These muscles may simulate a ganglion or a soft tissue tumour 4–7 . When they are closely related to the nerves, they may result in carpal tunnel syn- drome or pressure neuritis 8 . Many such anomalous symptomatic mus- cles have been reported. Stephens et al. 9 have reported the presence of a symptomatic anomalous flexor digi- torum superficialis. The symptoms were relieved by surgically debulk- ing the muscle 9 . An unusual muscle belly originating as a continuation of flexor digitorum superficialis tendon in the carpal tunnel and inserting normally into the middle phalanx has been reported by D’Costa et al. 10 . The * Corresponding Author E-mail: [email protected] Melaka Manipal Medical College (Manipal Campus), Manipal University, Manipal, Karnataka State, India. 567104
Transcript of An anomalous muscle in the hand that can cause carpal · carpal tunnel, resulting in carpal tun -...
Page 1 of 3
Case report
Licensee OA Publishing London 2013. Creative Commons Attribution License (CC-BY)
For citation purposes: Shetty P, Nayak SB, D’Souza MR, Thangarajan R, Prabhu GS. An anomalous muscle in the hand that can cause carpal tunnel syndrome: A case report. OA Case Reports 2013 Sep 10;2(10):100. Co
mpe
ting
inte
rest
s: n
one
decl
ared
. Con
flict
of i
nter
ests
: non
e de
clar
ed.
All
auth
ors
cont
ribut
ed to
con
cepti
on a
nd d
esig
n, m
anus
crip
t pre
para
tion,
read
and
app
rove
d th
e fin
al m
anus
crip
t.A
ll au
thor
s ab
ide
by th
e A
ssoc
iatio
n fo
r Med
ical
Eth
ics
(AM
E) e
thic
al ru
les
of d
iscl
osur
e.
Ana
tom
y
An anomalous muscle in the hand that can cause carpal tunnel syndrome: A case report
P Shetty, SB Nayak*, MR D’Souza, R Thangarajan, GS Prabhu
AbstractIntroduction Intrinsic and extrinsic muscles of the hand show frequent variations. Knowledge of these muscle varia-tions is important during diagnosis and treatment of carpal tunnel syn-drome, hand surgery and some plas-tic surgery procedures. We report here the presence of an anomalous muscle in the hand between the first and second lumbricals. Case report The flexor digitorum superficialis had five tendons and the two later-al-most tendons among them gave origin to this abnormal muscle of the hand. The fleshy belly of the mus-cle was supplied by a branch of the median nerve. Distally the tendon of the anomalous muscle and most of the lateral tendon of the flexor digitorum superficialis muscle mer-ged with the second tendon of the flexor digitorum superficialis muscle. The common tendon was inserted to the base of the middle phalanx of the index finger. Further, the first lumbri-cal had two heads: a lateral head and a medial head. The lateral head took its origin from the lateral-most ten-don of the flexor digitorum profun-dus muscle and the medial head took origin from the lateral part of the fleshy belly of the abnormal muscle. Its insertion and nerve supply were normal. Conclusion The abnormal muscle can produce a bulge in the palm and it might
compress the median nerve in the carpal tunnel, resulting in carpal tun-nel syndrome.
IntroductionWide ranges of accessory muscles of the forearm have been described in anatomical, surgical and radiological literature. In most of the cases, these additional muscles are asymptomatic but in some cases, they produce clini-cal symptoms. They may occur as a palpable soft swelling near or in the carpal tunnel with or without symp-toms of neurovascular compression. In symptomatic cases, recognition and careful evaluation of the acces-sory muscle with electromyographic examination may help in diagnosis and proper planning of the treatment. Anomalies of the flexor digitorum su-perficialis muscle are extremely rare and were first reported by MacAlister in 1868 and subsequently by Graper in 1917 and Mainland in 19271.The anomalous bellies arising from flexor digitorum superficialis might show a tender mass in the palm. Magnetic Resonance Imaging (MRI) may be of great use in knowing the extent and exact nature of the muscle2. Partial or complete surgical resection of such muscles can reduce the symptoms3. We report an anomalous muscle bel-ly arising from the flexor digitorum superficialis that could be a potential source of carpal tunnel syndrome.
Case reportDuring routine dissection classes for medical undergraduates, we found an anomalous muscle between the first and second lumbricals of the right hand of an adult male cadaver, aged approximately 60 years (Figure 1). The flexor digitorum superficialis
muscle had five tendons and the two most lateral tendons gave origin to this abnormal muscle of the hand (Figure 2). The fleshy belly of the muscle was supplied by a branch of the median nerve. Distally the ten-don of the abnormal muscle and the lateral-most tendon of the flexor dig-itorum superficialis muscle merged with the second tendon (tendon going to index finger) of the flexor digitorum superficialis muscle. The common tendon was inserted to the base of the middle phalanx of the in-dex finger. Further, the first lumbrical had two heads: a lateral head and a medial head. The lateral head took its origin from the lateral-most ten-don of the flexor digitorum profun-dus muscle and the medial head took origin from the lateral part of the fleshy belly of the abnormal muscle (Figure 3). Its insertion and nerve supply were normal.
DiscussionIt is very important for clinicians to be aware of the anomalous mus-cles in the forearm and hand. These muscles may simulate a ganglion or a soft tissue tumour4–7. When they are closely related to the nerves, they may result in carpal tunnel syn-drome or pressure neuritis8. Many such anomalous symptomatic mus-cles have been reported. Stephens et al.9 have reported the presence of a symptomatic anomalous flexor digi-torum superficialis. The symptoms were relieved by surgically debulk-ing the muscle9. An unusual muscle belly originating as a continuation of flexor digitorum superficialis tendon in the carpal tunnel and inserting normally into the middle phalanx has been reported by D’Costa et al.10. The
* Corresponding Author E-mail: [email protected]
Melaka Manipal Medical College (Manipal Campus), Manipal University, Manipal, Karnataka State, India. 567104
Page 2 of 3
Case report
Licensee OA Publishing London 2013. Creative Commons Attribution License (CC-BY)
For citation purposes: Shetty P, Nayak SB, D’Souza MR, Thangarajan R, Prabhu GS. An anomalous muscle in the hand that can cause carpal tunnel syndrome: A case report. OA Case Reports 2013 Sep 10;2(10):100. Co
mpe
ting
inte
rest
s: n
one
decl
ared
. Con
flict
of i
nter
ests
: non
e de
clar
ed.
All
auth
ors
cont
ribut
ed to
con
cepti
on a
nd d
esig
n, m
anus
crip
t pre
para
tion,
read
and
app
rove
d th
e fin
al m
anus
crip
t.A
ll au
thor
s ab
ide
by th
e A
ssoc
iatio
n fo
r Med
ical
Eth
ics
(AM
E) e
thic
al ru
les
of d
iscl
osur
e.
the muscle belly was in close proxim-ity with the median nerve, there are chances for it to compress the me-dian nerve in the carpal tunnel and produce the symptoms of carpal tun-nel syndrome.
Lumbricals of the hand are peculiar muscles in the sense that they connect the flexor tendons with the extensor tendons. Variations in the attachment of lumbricals are common. In a study conducted by Mehta and Gardner11, the lumbricals had an occasional origin in the forearm, from a metacarpal or from the flexor digitorum superficialis, instead of the deep flexor tendons and that the third and fourth lumbricals originated from a single tendon in-stead of two11. Roy et al.12 have report-ed a bipennate first lumbrical in which the accessory head arose from the ten-don of flexor digitorum superficialis of the index finger and the other main belly took origin, as usual, from flexor digitorum profundus12. Nayak et al.13 also have reported a similar case. The bipennate first lumbrical observed in the current case is quite different from the previous reports because its acces-sory head arose from the anomalous muscle in the palm.
tendon and two lateral-most tendons gave origin to the anomalous muscle. Its origin was in the forearm and it traversed the carpal tunnel. Since
anomalous muscle in the current case is totally different from this be cause, in the current case, the flexor digito-rum superficialis had an addi tional
Figure 2: Dissection of the palm showing the origin of the abnormal muscle. (1, 2, 3, 4 – lumbricals; AM – anomalous muscle; MN – median nerve; A, B, C, D, E – 5 tendons of the flexor digitorum superficialis muscle).
Figure 3: Dissection of the palm showing the bipennate first lumbrical muscle. (LH – lateral head of the first lum-brical; MH – medial head of the first lumbrical; AM – anom-alous muscle; MN – median nerve; TM – thenar muscles).
Figure 1: Dissection of the palm showing the abnormal muscle. (1, 2, 3, 4 – lumbricals; AM – anomalous muscle; MN – digital branches of the median nerve; TM – thenar muscles; UA – ulnar artery).
Page 3 of 3
Case report
Licensee OA Publishing London 2013. Creative Commons Attribution License (CC-BY)
For citation purposes: Shetty P, Nayak SB, D’Souza MR, Thangarajan R, Prabhu GS. An anomalous muscle in the hand that can cause carpal tunnel syndrome: A case report. OA Case Reports 2013 Sep 10;2(10):100. Co
mpe
ting
inte
rest
s: n
one
decl
ared
. Con
flict
of i
nter
ests
: non
e de
clar
ed.
All
auth
ors
cont
ribut
ed to
con
cepti
on a
nd d
esig
n, m
anus
crip
t pre
para
tion,
read
and
app
rove
d th
e fin
al m
anus
crip
t.A
ll au
thor
s ab
ide
by th
e A
ssoc
iatio
n fo
r Med
ical
Eth
ics
(AM
E) e
thic
al ru
les
of d
iscl
osur
e.
8. Ashby BS. Hypertrophy of the palmaris longus muscle; Report of a case. J Bone Joint Surg Br. 1964 May; 46:230–2.9. Stephens N, Marques E, Livingston C. Anomalous flexor digitorum superfi-cialis muscle belly presenting as a mass within the palm. Can J Plast Surg. 2007 Spring;15(1):44–6.10. D’Costa S, Jiji, Nayak SR, Sivanadan R, Abhishek. Anomalous muscle belly to the index finger. Ann Anat. 2006 Sep;188(5):473–5.11. Mehta, HJ, Gardner WU. A study of lumbrical muscles in the human hand. Am J Anat. 1961 Nov;109:227–38.12. Roy S, Mehta V, Arora J, Dhuria R, Suri R, Rath G, et al. An unusual bifid origin of 1st lumbrical muscle of hand: anatomi-cal and clinical perspectives. Clin Ter. 2011;162(3):249–50.13. Nayak SR, Rathan R, Chauhan R, Krishnamurthy A, Prabhu LV. An addi-tional muscle belly of the first lumbrical muscle. Cases J. 2008 Aug 18;1(1):103.
2. Sanger JR, Krasniak CL, Matloub HS, Yousif NJ, Kneeland JB. Diagnosis of an anomalous superficialis muscle in the palm by magnetic resonance imaging. J Hand Surg Am. 1991 Jan;16(1):98–101.3. Coenen L, Biltjes I. Pseudotumor of the palm due to an anomalous flexor digi-torum superficialis muscle belly. J Hand Surg Am. 1991 Nov;16(6):1046–51.4. Jones BV. An anomalous extensor in-dicis muscle. J Bone Joint Surg Br. 1959 Nov;41-B:763–5.5. Thomas CG Jr. Clinical manifestations of an accessory palmaris muscle. J Bone Joint Surg Am. 1958 Jul; 40-A(4):929–30.6. Lipscomb PR. Duplication of hypoth-enar muscles simulating soft-tissue tu-mour of the hand. Report of a case. J Bone Joint Surg Am. 1960;42:1058–61.7. Dunn AW. Anomalous muscles simu-lating soft-tissue tumors in the lower extremities. Report of three cases. J Bone Joint Surg Am. 1965 Oct;47(7): 1379–400.
ConclusionThe current case is a combination of two variant muscles in the hand. The anomalous muscle that took origin from the additional tendon of the flexor digitorum superficialis might compress the median nerve in the carpal tunnel. The bipennate origin of the first lumbrical may not cause any clinical symptoms but what makes the case interesting is that the accessory head of the first lumbrical took origin from the anomalous mus-cle. Knowledge of these variations is important for plastic surgeons, hand surgeons and clinicians, in general.
References1. Elias LS, Schulter-Ellis FP. Anomalous flexor superficialis indicis: two case re-ports and literature review. J Hand Surg Am. 1985 Mar;10(2):296–9.
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