ArticlePDF Available

A Rare Anatomical Finding of Undescribed Accessory Palmaris Longus in the Distal Forearm: A Case Report

Authors:

Abstract and Figures

Upper limb muscle anomalies and their clinical implications have been described frequently in the literature reviews. In this article, we are presenting a case of aberrant forearm muscle that had not been described before, and could be considered as a palmaris longus muscle variation. A 24-year-old man presented to the emergency department, Hamad General Hospital, Doha, Qatar, with right forearm laceration with multiple cut structures for which he was admitted for exploration and repair. Intraoperatively, flexor digitorum superficialis of the third, fourth, and fifth digits, flexor carpi radialis, and palmaris longus were injured‚ and all of them were repaired. We noticed an aberrant muscle—which was also injured—that originated from the distal third of the radius on its medial aspect to insert into the palmar fascia; pulling this muscle’s tendon resulted in tightening of palmar fascia‚ same as the palmaris longus. Along with the importance of deep knowledge of typical human anatomy, hand surgeons must be aware that an aberration from normal anatomy might be anticipated, to provide the best care to our patients.
www.PRSGlobalOpen.com 1
Disclosure: The authors have no nancial interest to declare
in relation to the content of this article.
From the *Plastic Surgery Department, Hamad General Hospital,
Hamad Medical Corporation, Doha, Qatar; †Ganga Hospital,
Coimbatore, Tamil Nadu, India; ‡DAFPRS, Rotterdam, The
Netherlands; and §Customer of Patient's Experience and Staff
Engagement (CPESE), Hamad Medical Corporation, Doha, Qatar.
Received for publication February 24, 2021; accepted January 6,
2022.
Copyright © 2022 The Authors. Published by Wolters Kluwer Health,
Inc. on behalf of The American Society of Plastic Surgeons. This
is an open-access article distributed under the terms of the Creative
Commons Attribution-Non Commercial-No Derivatives License 4.0
(CCBY-NC-ND), where it is permissible to download and share the
work provided it is properly cited. The work cannot be changed in
any way or used commercially without permission from the journal.
DOI: 10.1097/GOX.0000000000004240
Hand
INTRODUCTION
Although it is relatively uncommon in the popula-
tion, muscle anomalies of the forearm may be encoun-
tered by nearly all hand surgeons over the course of their
careers. These anomalies can be symptomatic but gener-
ally speaking‚ most of them are asymptomatic.1 Despite
its rareness, every surgeon should anticipate the aversion
from normal anatomy, as it might have signicant impact
on the patient’s outcome and quality of life. The pal-
maris longus (PL) muscle has the most common anoma-
lies described in the literature. In this article, we present
an incidental nding of an aberrant muscle in one of our
patients that was operated for right distal forearm lacera-
tion. We believe that this muscle could be considered as
one of the PL muscle variations that has not been men-
tioned in the literature reviews.
CASE PRESENTATION
A 24-year-old man, right-handed, laborer, nonsmoker,
nonalcoholic, with no past medical or surgical history, sus-
tained a deep laceration to his right distal forearm by a
glass during work. He had no hand complaint before the
trauma.
On examination‚ he had a15-cm deep laceration on
the volar aspect of theright distal forearm more on the
ulnar side, with weak exion at proximal interphalangeal
joints, weak wrist exion, normal sensory examination,
palpable radial artery, and ulnar arteries with capillary
rell less than 2 seconds. After stabilization and initiation
of antibiotics and pain killers, he was admitted for explo-
ration and repair of cut structures.
The patient was operated on the next day under
regional anesthesia and a tourniquet was applied for
60 minutes on pressure of 250 mm Hg. The wound was
extended minimally‚ proximally‚ and distally for explo-
ration, and the ndings were as follows: complete cut of
exor digitorum supercialis (FDS) of the fourth and
fth digits, partial cut FDS (60 %) of third digit, complete
cut exor carpi radialis, andcomplete cut PL, all of them
at zone 5. Along with that, we noticed an aberrant mus-
cle that was cut completely. All other muscles and their
Salim Allahham, MD*†‡
Zaki T. N. Alyazji, MD*
Ghanem Aljassem, MD*
Ruba Sada, MD, PM, CPESE§
Iqbal Rasool Wani, MD*
ABSTRACT
Summary: Upper limb muscle anomalies and their clinical implications have been
described frequently in the literature reviews. In this article, we are presenting a
case of aberrant forearm muscle that had not been described before, and could
be considered as a palmaris longus muscle variation. A 24-year-old man presented
to the emergency department, Hamad General Hospital, Doha, Qatar, with right
forearm laceration with multiple cutstructures for which he was admitted for explo-
ration and repair. Intraoperatively, exor digitorum supercialis of the third, fourth,
and fth digits, exor carpi radialis, andpalmaris longus were injured‚ and all of
them were repaired. We noticed an aberrant muscle—which was also injured—that
originated from the distal third of the radius on its medial aspect to insert into the
palmar fascia; pulling this muscle’s tendon resulted in tightening of palmar fascia‚
same as thepalmaris longus. Along with the importance of deep knowledge of typi-
cal human anatomy, hand surgeons must be aware that an aberration from normal
anatomy might be anticipated, to provide the best care to our patients.
(Plast Reconstr Surg Glob Open 2022;10:e4240; doi: 10.1097/GOX.0000000000004240;
Published online 29 April 2022.)
A Rare Anatomical Finding of Undescribed
Accessory Palmaris Longus in the Distal
Forearm: A Case Report
LWW
CASE REPORT
PRS Global Open 2022
2
tendons, nerves, and arteries were identied and were
intact. The abovementioned aberrant muscle originates
from the distal third of the radius on its medial aspect and
inserts into the palmar fascia separately from PL tendon,
pulling its tendon resulted in tightening of palmar fascia
(Figs. 1–3). All injured structures were repaired using
Ethilon 3-0 by modied Kessler technique (if complete
cut) and epitenon continuous suturing with Ethilon 5-0,
or horizontal mattress with 4-0 Ethilon (if incomplete).
Postoperatively, the patient stayed for 2 days for pain
management, and was referred to the inpatient occupa-
tional therapist to apply the proper splint and start the
rehabilitation program. The patient was discharged on
antibiotics for atotal of 7 days. He continued occupational
therapy for a period of 8 weeks with frequent clinic visits,
andafter 2 months he had full range of motionand com-
pletely healed wounds and resumed his work.
DISCUSSION
One of the most encountered muscles with aberra-
tions is thePL muscle. The normal PL originates from the
medial epicondyle with a proximal muscle belly and long
distal tendon that inserts into the palmar fascia.
However, a substantial amount of variation has been
noted, with variations reported as duplicate, reversed, cen-
trally located, bid, divided with an ulnar slip, or hypertro-
phic, in addition to variations in the muscle belly representing
50% of the anomalies of the PL reported.2 The PL can origi-
nate from the lacertus brosis, FDS, exor carpi radialis, and
exor carpi ulnaris and may insert into the antebrachial fas-
cia, thenar eminence, exor carpi ulnaris, or into the car-
pal bones. An accessory tendon may also exist at the ulnar
aspect of the main tendon distally.2 Epidemiologically‚ in a
study byReimann et al2, PL in 9% of the study population
exhibited variations with respect to form, origin, or insertion.
Another muscle anomaly is exor carpi radialis brevis
(FCRB), which has been described historically as “short
radiocarpal exor.”3 The FCRB commonly originates from
the volar aspect of the mid to distal third of the radius and
courses supercial to the pronator quadratus outside of
the carpal tunnel.1 The FCRB has been noted to insert
into the second, third, or fourth metacarpals,4,5 the trape-
zium,6 or the capitate.5 The FCRB may travel distally in the
same sheath as the exor carpi radialis.7
One more forearm muscle anomaly is thepalmaris pro-
fundus (PP). Origins and insertions may vary, but the PP is
characterized by its course through the carpal tunnel adjacent
to the median nerve and its insertion into the palmar apo-
neurosis distally. Possible origins include the radial diaphysis,
ulnar diaphysis, FDS fascia, PL, exor pollicis longus, or the
medial epicondyle. Insertion variations can include the third
metacarpal or the radial carpal bones in some instances. It has
also been found as either reversed or bitendinous.8–10
As described above, our patient had a muscle anomaly
originating from the distal third of the radius and inserted
at the palmar fascia, pulling its tendon andresulting in
tightening of palmar fascia. Our thorough search in the
literaturefound no records of such ananomaly consider-
ing the described origin and insertion.
CONCLUSIONS
Describing variations of the human anatomy is and
has always been essential for the progress of the surgical
Fig. 1. The cut PL and‚ adjacent to it‚ the aberrant muscle tendon‚
both with complete cuts.
Fig. 2. A complete cut of PL and aberrant muscle belly and tendon,
in addition to acomplete cut of the FCR tendon.
Fig. 3. The proximal and distal ends of the PL and aberrant muscle
tendons.
Allahham et al. Undescribed Accessory PL in the Distal Forearm
3
science. It helps surgeons to anticipate what to face in the
surgical eld and how to deal with it properly to get the
best patient outcomes; this encouraged us to write our
article to add this unique presentation to the spectrum of
hand muscle variations.
Zaki T. N. Alyazji, MD,
Plastic Surgery Department, Hamad General Hospital
Hamad Medical Corporation
Doha, Qatar
E-mail: Zakiyazji@gmail.com
ACKNOWLEDGMENTS
We thank the Qatar National Library for funding the open
access publication of this case report. We acknowledge the peer
reviewers for their valuable comments and feedback that led to
signicantly enhancing the manuscript.
PATIENT CONSENT
Patients provided written consent for the use of their images.
REFERENCES
1. Andring N, Kennedy SA, Iannuzzi NP. Anomalous forearm mus-
cles and their clinical relevance. J Hand Surg. 2018;43:455463.
2. Reimann AF, Daseler EH, Anson BJ, et al. The palmaris lon-
gus muscle and tendon: a study of 1600 extremities. Anat Rec.
1944;89:495505.
3. Kang L, Carter T, Wolfe SW. The exor carpi radialis brevis mus-
cle: an anomalous exor of the wrist and hand. A case report. J
Hand Surg Am. 2006;31:1511–1513.
4. Dodds SD. A exor carpi radialis brevis muscle with an
anomalous origin on the distal radius. J Hand Surg Am.
2006;31:15071510.
5. Kosiyatrakul A, Luenam S, Prachaporn S. Symptomatic exor
carpi radialis brevis: case report. J Hand Surg Am. 2010;35:633–635.
6. Peers SC, Kaplan FT. Flexor carpi radialis brevis muscle pre-
senting as a painful forearm mass: case report. J Hand Surg Am.
2008;33:1878–1881.
7. Mantovani G, Lino W Jr, Fukushima WY, et al. Anomalous pre-
sentation of exor carpi radialis brevis: a report of six cases. J
Hand Surg Eur Vol. 2010;35:234–235.
8. Jones DP. Bilateral palmaris profundus in association with bid
median nerve as a cause of failed carpal tunnel release. J Hand
Surg Am. 2006;31:741–743.
9. McClelland WB Jr, Means KR Jr. Palmaris profundus tendon pro-
hibiting endoscopic carpal tunnel release: case report. J Hand
Surg Am. 2012;37:695–698.
10. Bast BO, Winkler M, Kurz M. Reversed palmaris profundus mus-
cle variation. Int J Anat Var. 2016;9:21e24.
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
The palmaris profundus is a variant muscle in the forearm which might lead to carpal tunnel syndrome. Due to its variable origins, courses and insertions, it has been classified into subtypes previously, and its often very close relation to the median nerve has been highlighted. Dissection of a male cadaver now uncovered a new reversed variant of this muscle which does not match any of the already described subtypes because of its unique origin from the proximal ulnar shaft and its less pronounced spatial relation to the median nerve. This case shows that there are still unknown variations, which a surgeon may come across during carpal tunnel surgery or any other surgery of the forearm and which may lead to median nerve compression.
Article
Full-text available
The incidental finding of an aberrant wrist flexor is reported. This anomalous muscle was identified during surgical reconstruction for a distal radius fracture malunion. Distal and proximal dissection showed an independent, well-formed muscle belly with no interconnections to adjacent structures. A review of the literature yielded a report of these findings in cadaveric specimens; here we give a description in a living person.
Article
Despite their relatively low prevalence in the population, anomalous muscles of the forearm may be encountered by nearly all hand and wrist surgeons over the course of their careers. We discuss 6 of the more common anomalous muscles encountered by hand surgeons: the aberrant palmaris longus, anconeus epitrochlearis, palmaris profundus, flexor carpi radialis brevis, accessory head of the flexor pollicis longus, and the anomalous radial wrist extensors. We describe the epidemiology, anatomy, presentation, diagnosis, and treatment of patients presenting with an anomalous muscle. Each muscle often has multiple variations or subtypes. The presence of most anomalous muscles is difficult to diagnose based on patient history and examination alone, given that symptoms may overlap with more common pathologies. Definitive diagnosis typically requires soft tissue imaging or surgical exploration. When an anomalous muscle is present and symptomatic, it often requires surgical excision for symptom resolution.
Article
Palmaris profundus is an aberrant muscle of forearm and wrist anatomy. It has no discernible function, but its tendon has been implicated as a cause of carpal tunnel syndrome. Previously, all cases of palmaris profundus in the literature have been encountered during either open surgery or cadaveric dissection. We report a case of palmaris profundus encountered during attempted single-portal endoscopic carpal tunnel release, necessitating conversion to an open approach. There was a unique point of tendon insertion onto the undersurface of the transverse carpal ligament, more proximal than what has been previously described in the literature. There were other anomalies present as well, including a persistent median artery and bifid median nerve. Given the volar position of the structure, its proximal point of insertion, and its minimal bulk, we did not feel that this was the cause of our patient's carpal tunnel syndrome.
Article
A patient with a flexor carpi radialis brevis (FCRB) is reported. In contrast to all but one previous case, the anomalous FCRB was painful. The FCRB tendon was located in a separate compartment; the tenosynovitis in that compartment was the likely cause of pain. Release of the compartment relieved the symptoms.
Article
An anomalous presentation of flexor carpi radialis brevis (FCRB) is reported in six patients. These findings occurred in a consecutive series of 172 distal radius fracture fixations using a volar approach between 2002 and 2007. This is the first report of this anomalous muscle from a clinical series.
Article
This case report describes an anomalous muscle, the flexor carpi radialis brevis (FCRB), that presented as a painful, enlarging volar forearm mass. After magnetic resonance imaging (MRI) characterization, surgical exploration confirmed that the FCRB tendon crossed over the flexor carpi radialis (FCR) tendon and the resultant tenosynovitis was the apparent cause of the patient's symptoms.
Article
This is a case in which an anomalous tendon of the palmaris profundus was found running on the anterior surface of the median nerve, dividing the nerve into 2 branches at the wrist bilaterally. Excision of the tendon at the time of re-exploration of the carpal tunnel resulted in complete relief of carpal tunnel symptoms.
Article
This report describes an anomalous muscle on the volar aspect of the wrist alongside an underdeveloped pronator quadratus. Identified during cadaveric dissection, the longitudinally oriented muscle originated on the distal radial metaphysis, a location occupied typically by the insertion of the pronator quadratus. The aberrant muscle formed a tendon distally, which inserted along with the flexor carpi radialis tendon at the base of the index metacarpal.