Palmaris Brevis Research Articles

Effects of Kin Ball Initiation: Pre- and Post-Pandemic Impact on Palmar Muscle Strength, Endurance, and Coordination in Non-Athlete Participants.

A retrospective, case-control study with a focus on four distinct research groups. The research was conducted in a camp setting, situated in the mountainous region of Bughea de Sus, Romania. The study included 94 students, comprising 54 boys and 40 girls, with an overall average age of 20.85 ± 2 years. All participants were classified as non-athletes based on their level of sports practice. The Kin Ball initiation program, a key component of the study, comprised 20 training sessions conducted in 10-day stages, systematically evaluating participants' motor skills. The study assessed palmar muscle strength, endurance, and co-ordination function. Statistical analyses, including the Kolmogorov-Smirnov test, revealed notable differences in the initiation process and significant variations (p < 0.05) in all measurements performed in 2022. In 2019, the tests recorded both significant and statistically insignificant differences, as indicated by the calculation of Cohen's d indicator. The study underscored the influence of reduced movement during the pandemic on motor skills and highlighted Kin Ball's potential as an alternative sport within physical education curricula. Despite lower baseline motor capacities observed in 2022, participants exhibited significant progress, emphasizing Kin Ball's capacity to improve physical skills. These findings underscore the importance of alternative sports such as Kin Ball in fostering holistic personal development and mitigating the impact of pandemic-induced disruptions on motor skills.

Palmaris brevis spasm syndrome: The treatable hypothenar dimpling

Abstract Palmaris brevis spasm syndrome is a rare disorder, mostly reported with occupational overuse of a computer keyboard, mouse, pipette, and vibratory tools or after the use of arm braces. Rarely, it can be spontaneous. It is clinically characterized by spontaneous contraction of the palmaris brevis muscle over the hypothenar eminence. Here, we report a patient with long-standing, spontaneous, and bilateral palmaris brevis spasm syndrome without any occupational exposure who demonstrated excellent response to botulinum toxin therapy. Clinicians should be aware of this rare but treatable entity in patients presenting with hypothenar spasms.

Transfer of the palmaris brevis motor branch to the thenar motor branch: A cadaveric preliminary study

ObjectiveHigh median nerve injuries can lead to poor distal recovery, especially poor functioning of median innervated thenar muscles involved in thumb opposition and palmar abduction. The palmaris brevis (PB) is a small subcutaneous muscle innervated by ulnar nerve. Innervation of the PB is in most of cases provided by the ulnar digital nerve to the little finger. The purpose of this study is to assess the feasibility of transferring the PB motor branch (PBMB) to the median nerve thenar motor branch (TMB), in order to allow for early restoration of thumb palmar abduction and opposition, through a preliminary cadaveric study. MethodsTwenty-five cadaver upper limbs were dissected under magnification. The length of the PBMB and TMB, and their origin were recorded. Nerve transfer from PBMB to TMB was conducted, and evaluated on 2 parameters: surgical feasibility, and distance from the coaptation site to the recipient nerve muscle entry point. The PBMB and TMB were harvested, fixated in formalin, then embedded in paraffin. They were sectioned transversely, and stained with a combination of hematoxylin–eosin and Luxol fast blue. Myelinated axons were counted in each specimen and the donor-to-recipient axon ratio was recorded. ResultsThe PBMB was constant and originated from the ulnar digital nerve of the little finger in all cases. The transfer from PBMB to TMB was feasible in all cases. Mean myelinated axon counts of PBMB and TMB were 253±142 and 356±198, respectively (p=0.06). The donor-to-recipient axon ratio was 1:1.41. The mean distance from coaptation of the PBMB to the recipient thenar muscles was 23.1±3.0mm. ConclusionsBased on our results, PBMB to TMB transfer is feasible. The PBMB has the advantage over other distal nerve transfer donors to be constant and superficial, allowing for an easier harvest. Moreover, this procedure does not sacrifice any intrinsic function of the hand, and the proximity of the PBMB with the carpal tunnel allows for a single incision procedure. Therefore, early restoration of the median innervated thenar muscles may be feasible by the PBMB to TMB transfer in cases of high median nerve lesions. Level of evidenceIV.

An aberrant palmaris brevis causing ulnar nerve compression at guyon’s canal: An anatomic case report and literature review

There have been reports of ulnar nerve compression due to anatomic variations at Guyon’s canal. Knowledge of certain variations at Guyon’s canal may help hand surgeons identify possible unconventional compression sites of the ulnar nerve. We present a case report of a patient with an aberrant palmaris brevis muscle belly that was found to cross over the proximal aspect of the ulnar tunnel neurovascular bundle potentially causing ulnar nerve symptoms. Surgical interventions with the release of the palmaris brevis muscle belly and transposition to the flexor carpi ulnaris tendon at the level of Guyon’s canal helped provide relief of the patient’s ulnar nerve symptoms.

An Anatomical Study of the Palmaris Brevis, Transverse Carpal Ligament, and the Recurrent Motor Branch of the Median Nerve.

Background: The anatomical structures in relation to the carpal tunnel release are the palmaris brevis muscle (PBM), transverse carpal ligament (TCL), and the recurrent motor branch of the median nerve (RMBMN). Our aim is to describe the gross morphology in the Korean population of the PBM, TCL, and RMBMN specifically looking for anomalies, and to determine the muscles encountered during a standard carpal tunnel release. Material and Methods: A total of 30 cadaveric hands were dissected. A longitudinal line drawn from the third web space to the midpoint of the distal wrist crease served as the reference line (RL). The PBM and TCL were classified according to its shape and location. The length, width, and thickness of the TCL were measured. The ratio of the lengths of PBM and TCL to RL was calculated. The course of the RMBMN was dissected specifically looking for anomalies. We also looked at the muscle fibers encountered during a standard carpal tunnel release to identify the muscle. Results: PBM was classified into three different types based on the shape. The average thickness of the PBM and TCL were 0.89 ± 0.16 mm and 1.43 ± 0.40 mm, respectively. The distal border of the TCL was thicker than the proximal border. The average ratio of the length of the PBM to the RL was 25.65 ± 8.62% and TCL to the RL was 24.00 ± 3.37%. The distribution of the RMBMN was classified into three different types. A few accessory branches of the RMBMN were also noted. And 36 muscle fibers were noted within the TCL in line with the RL. Conclusion: We clarified findings and added quantitative information about the anatomical structures surrounding carpal tunnel. A thorough knowledge of the anatomy and anomalies around the carpal tunnel is helpful for surgeons to ensure optimal surgical results.

Hand and foot musculature of Sooglossoidea: synapomorphies, convergences and hind limb digging behaviour in anurans

Abstract We describe the hand and foot musculature of the fossorial Indian purple frog, Nasikabatrachus sahyadrensis, and compare it to other members of Sooglossoidea: the Seychellean sooglossid genera Sechellophryne and Sooglossus. Due to the key phylogenetic position of Sooglossoidea, we compare its members with the diversity of Anura and define 52 characters from the hand and foot musculature, among which 26 are novel hypotheses of homology. We found several synapomorphies for Sooglossus, Sooglossidae, Nasikabatrachidae and Sooglossoidea. Additionally, we (1) propose synapomorphies for diverse anuran clades at different taxonomic levels, (2) re-evaluate the identity of some conflicting plantar and palmar muscles in the context of Batrachia and (3) discuss putative adaptations to hind limb digging behaviour resulting from morphological convergences. The lack of a clear pattern of convergences among hind limb digging species suggests the occurrence of a phenomenon of many-to-one mapping from form to function.

Anatomical work-up of an individual with multiple muscular variants on both forearms

Muscular variants of the forearm are common and frequently cause neurovascular compression syndromes, especially when interfering with the compact topography of the carpal tunnel or the Canalis ulnaris. Here, we report on a male body donor with multiple muscular normal variations on both forearms. The two main findings are (1) an accessory variant muscle (AVM) on the right forearm originating from the M. brachioradialis, the distal radius, and the M. flexor pollicis longus. It spanned the wrist beneath the Fascia antebrachia and inserted at the proximal phalanx of the digitus minimus. (2) Moreover, we found a three-headed palmaris longus variant on the left arm with proximal origin tendon and a distal, trifurcated muscle belly, with separated insertions at the palmar aponeurosis, the flexor retinaculum, and, in analogy to the accessory muscle on the contralateral arm, at the base of the proximal phalanx of the digitus minimus. We found a considerable thickening of the left-hand median nerve right before entering the carpal tunnel indicative of a possible chronic compression syndrome adding clinical relevance to this anatomical case. We also discuss the notion that both, the AVM and the contralateral three-headed palmaris variant are developmental descendants of the M. palmaris longus. Additionally, we found a previously not recorded variant of the M. palmaris brevis on the left hand.

In the human, true myocutaneous junctions of skeletal muscle fibers are limited to the face.

Within the panniculus carnosus‐associated skeletal muscles in the human, the palmaris brevis and the platysma showed myotendinous/myofascial junctions with clear distance to the corium and the specific connection collagen type XXII. The orbicularis oris muscle, in contrast, contained bundles of striated muscle fibers reaching the corium at two distinct levels: the predominant inner ending was connected to the elastic network of the inner corium and the outer ending was within the more superficial collagen network. At both locations, the striated muscle fibers showed brush‐like cytoplasmic protrusions connecting a network which was not oriented toward the muscle fibers. Collagen type XXII was not present.

Fractional CO2 laser-assisted Botulinum toxin type A delivery for the treatment of primary palmar hyperhidrosis.

Intradermal injections of botulinum toxin type A (BTX-A) have been used successfully to treat patients with primary palmoplantar hyperhidrosis (PPH). However, problems with local injections of BTX-A for palmar hyperhidrosis include injection pain and reduced palmar muscle strength. This case series describes three patients with PPH. Patients were followed up for 3months and assessed using the minor iodine starch test and the visual analog scale (VAS). Over two sessions within a 2-week interval, all patients received treatment on one palm, while the other palm served as the untreated control. Treated palms received fractional CO2 laser therapy and immediate post-operative topical application of BTX-A solution for a total of 50units. Sweat production was assessed based on the size of the sweat-producing area (measured by the minor iodine starch test) and subjective assessment of sweat production using the visual analog scale (VAS) at baseline, 2weeks after the first treatment, and 1, 2, and 3months after the second treatment. In the BTX-A-treated palm, the decrease in the mean sweat production was 51.6% at 2weeks after the first treatment, and 88.5%, 67.8%, and 52.9%, at 1, 2, and 3months after the final treatment when compared to the baseline. In the untreated palms, the decrease in the mean sweat production was 2% on all follow-ups when compared to the baseline. No adverse effect was observed in any patient. Fractional CO2 laser is a safe technique for BTX-A delivery on the palm area and is demonstrated to be safe and effective in decreasing sweat secretion of hyperhidrosis palm.

Panniculus Carnosus of Anterior Abdominal Wall—a Case Report

Panniculus carnosus (PC) is a subcutaneous muscle system usually well developed in mammals. In humans, it is limited to the facial muscles, dartos and palmaris brevis. We report a case of subcutaneous sheet of muscle in the anterior abdominal wall that is a part of PC system. This is a rare presentation and will be of interest to the surgeons managing the anterior abdominal wall hernias.

An anatomical study of extensor expansion of thumb

Introduction The presence of extensor expansion of the thumb has been reported in the literature and its mode of formation and contribution from the palmar muscles has been studied earlier. Yet, some authors deny its presence in the thumb. Objective This article evaluates the presence of the extensor expansion of thumb (EET) and its formation and contributions from palmar muscles. Methods Dissection was carried on the dorsum of the hand on 80 free upper limbs. The dorsum of thumb was carefully cleaned to look for the presence of extensor expansion. When present, its mode of formation and the contributing muscles were looked into. The mode of insertion of the extensor tendons onto the phalanges was also observed. Results In all specimens, EET had tendons of extensor pollicis longus (EPL) and extensor pollicis brevis (EPB) along its central axis. It received expansion from abductor pollicis brevis (APB; 100%) and flexor pollicis brevis (FPB; 41.2%) on the lateral side, and adductor pollicis (AP; 100%) and first palmar interosseous (PI; 50%) on the medial side. Attachment of EPL to distal phalanx (DP) was seen in 45%, and to both phalanges in 55%. EPB insertion onto proximal phalanx alone, DP alone, and both phalanges was in 46.2, 25, and 23.75%, respectively. Conclusion Extensor expansion was noted in all limbs studied. It is formed by the extensor tendons of the thumb with expansions from APB and AP on its margins. Contribution from the first PI and FPB was found to be variable. Differences in insertion of EPL and EPB to the phalanges were also noted.

Characterization of afferent corpuscular sensors of the human palmaris brevis muscle.

The palmaris brevis muscle contains numerous muscle spindles to control changes of the muscle length but is devoid of tendon‐associated neuronal elements (e.g. Golgi tendon organs or Ruffini‐like corpuscles) controlling changes in muscle strength. Pacinian bodies, frequently seen in the palm of the hand, show no direct association to the muscle bundles. The observed innervation pattern of the palmaris brevis muscle points to a specific type of neuronal regulation, present in skeletal muscles with no skeletal connection.

Electrophysiological responsiveness and clinical outcomes of local corticosteroid injection in the treatment of carpal tunnel syndrome.

Carpal tunnel syndrome (CTS) is the most common mononeuropathy caused by entrapment of the median nerve at the wrist. Common treatment options for CTS include oral analgesics, splinting, hand therapy, local injections with steroids or surgery. OBJECTIVE The aim of the present study was to assess the short-term clinical and electrophysiological outcomes of local corticosteroid injection (LCI) in patients with symptomatic CTS. METHODS Electrophysiological parameters were evaluated before and three months after LCI. Moreover, the Numeric Rating Scale (NRS), the Boston Symptom Severity Scale (SSS) and the Functional Status Scale (FSS) were administered before and after the injection. A mixture of 1 mL (40 mg) of methylprednisolone and 1 mL of 0.5% bupivacaine were injected blindly on the volar side of the forearm between the tendons of the radial carpal flexor muscle and long palmar muscle. RESULTS A total of 25 patients (45 hands) were enrolled in the study. Twenty women and five men with a mean age of 49.28 ± 11.37 years were included. A statistically significant difference was noted for improvement of sensory conduction velocities, sensory peak latency, and motor distal latency (p = 0.001) after LCI. A significant difference was recorded between pre- and post-injection for NRS, SSS and FSS scores (p = 0.000). CONCLUSION Local corticosteroid injection for CTS provides a short-term improvement in neurophysiological and clinical outcomes such as pain intensity, symptom severity and functional ability.

Anatomical Description of the Forelimb Muscles of the Brown-Throated Sloth (Bradypus variegatus)

Background: Brown-throated sloths are mammals of the order Xenarthra, suborder Pilosa, family Bradypodidae. These folivorous and arboreal animals, which possess a peculiar type of arboreal quadrupedalism, move through the forest canopy by means of suspensory locomotion. On the ground, their extremely slow movements make them easy targets for road accidents, often leading to serious injury or even death. This paper describes the forelimb muscles of the brown-throated sloth (Bradypus variegatus), updating the literature on the subject to help veterinarians in clinical and surgical interventions on this species, and to provide data for comparative animal anatomy.Materials, Methods &amp; Results: Five brown-throated sloths (Bradypus variegatus Schinz, 1825), two adults and three babies were dissected. The animals were donated by the Arruda Câmara Zoo and Botanical Park in João Pessoa, state of Paraíba, Brazil, where they were thawed and fixed in 10% formalin. The sloths’ forelimbs were dissected by lifting and folding over a skin flap to expose, identify and describe the underlying musculature. The dissection revealed the following muscles: supraspinatus, infraspinatus, deltoideus, teres major, subscapularis, coracobrachialis, brachialis, biceps brachii, triceps brachii, anconeus epitrochlearis, dorsoepitrochlearis, brachioradialis, supinator, pronator teres, pronator quadratus, extensor carpi radialis, extensor carpi ulnaris, extensor carpi obliquus, flexor carpi radialis, flexor carpi ulnaris, extensor digitorum communis, extensor digitorum lateralis, palmaris longus, flexor digitorum superficialis, flexor digitorum profundus, extensor indicis longus second finger, extensor indicis brevis second finger, extensor digitorum third finger, abductor digitorum second finger, abductor digitorum third finger, palmaris brevis, and interosseous muscles. Characteristics found in this species revealed differences in the muscular development of the upper forelimb, whose muscles are less developed than those of the lower forelimb, which are visibly more developed with greater muscle density. An interesting feature of this musculature is the presence of three flexor tendons, short and thick, originating from the flexor muscles, which give the hand of the brown-throated sloth a hook-like aspect.Discussion: Our observations indicate that some of the muscles are very similar to those of other animals of this order and also of domestic mammals. However, the most relevant characteristics resemble those of arboreal animals and humans, since the forearm and hand pronation and supination muscles are essential for their arboreal habits. Therefore, all the pronator and supinator muscles of the brown-throated sloth are well developed. Due to the functional adaptations of the species of the family Bradypodidae, the shoulder muscles, especially the deltoideus, are more developed, providing greater support to the shoulder joint, and their origin and insertion assist in faster and easier movements, albeit exerting less force. The group of flexor muscles in this species gives the forearm stronger and more concentrated action than the extensor muscles. This study enabled us not only to produce a more precise description of the muscles of the forelimb of this species but also to update the literature, since there are few relevant studies on the subject and the terms in the literature are outdated and no longer in use. Keywords: sloth, Bradypodidae, morph

Structural and functional anatomy of the palmaris brevis: grasping for answers.

The palmaris brevis (PB) is a small cutaneous hand muscle that has been described as the most mysterious muscle from a functional and developmental perspective [Kaplan () Kaplan's Functional and Surgical Anatomy of the Hand]. Functionally, the PB is considered to deepen the hollow of the palm and to protect the neurovasculature of the ulnar canal. Although the function of the PB has been inferred from cadaveric observations, the electromyographic (EMG) activity of this muscle has not been explored systematically during specific movements of the hand. The purpose of this study was to record PB intramuscular EMG activity during dynamic grasping tasks, and to quantify the change in PB muscle length (ML ) and thickness (MT ) incurred during maximal contraction using ultrasound imaging. Intramuscular EMG was recorded from the PB in the dominant hands of 12 healthy participants (11 males, one female; age: 27 ± 4 years) during maximal abduction, flexion and opposition of the 5th digit, and two grasping tasks. Abduction of the 5th digit yielded the greatest EMG activity in most individuals (seven out of 11), and produced significantly less PB EMG activity when compared with grasping a cylindrical-shaped object (P = 0.003) but not a spherical-shaped object (P=0.130). During maximal abduction of the 5th digit, PB ML decreased in both the left (28±11%; P=0.002) and right (32±5%; P=0.002) hands. Similarly, a concomitant increase in PB MT was observed in the left (68±30%; P=0.002) and right (85±44%; P=0.002) hands during the same contraction. These EMG results indicate that the PB is voluntarily activated during prehensile and non-prehensile movements of the hand with significant changes in muscle architecture. The study supports the preservation of the PB in surgical procedures based on its proposed protective role as a muscular barrier to the neurovasculature within the ulnar canal.

Pattern of Variations in Superficial Palmar Arch and its Clinical Importance

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; Superficial palmar arch (SPA) is an important arterial anastomotic arcade which is the dominant vascular supply to the majority of the palmar muscles.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Objectives:&lt;/strong&gt; Keeping the importance of these variations in mind this study was designed to find out the pattern of superficial palmar arterial arches.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Materials and Methods:&lt;/strong&gt; A total of 40 adults upper limbs of unknown sex were observed for the variations in the pattern of superficial palmar arches on right and left side and were compared with the previous data.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results:&lt;/strong&gt; A complete superficial palmar arch was encountered in 72.5% (n=29/40) of specimens and an incomplete SPA was observed in 27.5% (n=11/40) of specimens.&lt;/p&gt;&lt;p&gt;&lt;strong&gt; Conclusion:&lt;/strong&gt; Knowledge of the variations in the arterial supply of hand is essential in advent of microvascular surgery for revascularisation, replantation and composite tissue transfers.&lt;/p&gt;

Pattern of Variations in Superficial Palmar Arch and its Clinical Importance

Background: Superficial palmar arch (SPA) is an important arterial anastomotic arcade which is the dominant vascular supply to the majority of the palmar muscles. Objectives: Keeping the importance of these variations in mind this study was designed to find out the pattern of superficial palmar arterial arches. Materials and Methods: A total of 40 adults upper limbs of unknown sex were observed for the variations in the pattern of superficial palmar arches on right and left side and were compared with the previous data. Results: A complete superficial palmar arch was encountered in 72.5% (n=29/40) of specimens and an incomplete SPA was observed in 27.5% (n=11/40) of specimens. Conclusion: Knowledge of the variations in the arterial supply of hand is essential in advent of microvascular surgery for revascularisation, replantation and composite tissue transfers.

Fiber type composition of the palmaris brevis muscle: implications for palmar function.

The palmaris brevis (PB) is a small muscle of variant morphology located on the ulnar aspect of the palm, superficial to the hypothenar eminence. Functionally, the PB has been proposed to protect the neurovasculature of the ulnar canal from compressive forces during repetitive or intermittent trauma associated with grasping. Although PB function has been inferred from cadaveric observations, it is unknown whether it has the contractile capacity and fatigue-resistance necessary to withstand these functional demands. Insight into the functional specialization of the PB can be provided through investigating the proportions of type I and type II muscle fibers by staining for myosin heavy chain (MHC) isoforms using immunohistochemical methods. Therefore, the purpose of this study was to quantify the proportion of type I and type II muscle fibers to provide insight into the role of the PB in palmar function based on its gross histological structure. Sixteen PB specimens were harvested from the hands (eight right, eight left) of eight formalin-embalmed cadavers (mean age: 75±14years; three males, five females). PB muscle composition was determined by labeling serial cross-sections with MHC type I and type II monoclonal antibodies. The results indicate that the PB is primarily composed of type I muscle fibers (72.2±13.7%), with no significant differences between left and right hands. Given the predominance of type I muscle fibers, our findings indicate the PB may be fatigue-resistant and thus, capable of contracting for prolonged durations. This supports cadaveric observations indicating that the PB functions to protect the ulnar neurovasculature of the palm by providing a muscular barrier in addition to serving as a functional anchor to the hypothenar fat pad when objects are firmly compressed into the palm.

Does Palmaris Brevis Structure Allow for Protection Against Prolonged Overlying Compression? An Ultrasound and Immunohistochemical Investigation

IntroductionThe palmaris brevis (PB) is small hand muscle located superficial to the hypothenar eminence in the medial palm. Although this muscle may have variant morphology, its complete absence is considered rare (&lt;3%) compared to its counterpart, the palmaris longus, whose absence is more frequent (14%). From cadaveric studies, PB function has been postulated to protect the neurovasculature of the ulnar tunnel from prolonged overlying compression; however, it is unknown whether the PB has the gross histological structure and fatigue resistance necessary for prolonged contraction. Therefore, the initial objective was to determine the fiber‐type composition of the PB by staining for myosin heavy chain (MHC) type I (slow‐twitch) and type II (fast‐twitch) isoforms in cadaveric specimens.When the PB contracts, it has the potential to create a muscular barrier to protect the neurovasculature of the ulnar tunnel; however, the extent of change in PB dimensions from rest to maximal contraction remains unknown. Previous PB electromyographic investigations recorded the greatest muscle activity during maximal abduction of the 5th digit, but it is unknown whether significant changes in muscle architecture (length and thickness) occur during this contraction. Thus, the second objective was to investigate and quantify the dynamic changes in PB morphology using ultrasound imaging in young participants.MethodsTo date, fiber‐type proportions have been quantified from 5μm cross‐sections of 4 PB muscles (3 left and 1 right) from 3 cadaveric specimens (2 Females, 1 Male; age: 80 ± 1 y) using immunohistochemistry by staining for MHC type I and MHC type II. Type I and type II fibers were manually counted using ImageJ software from 3 sites per slide from each specimen. Architectural changes in PB muscle length and thickness were investigated in the left and right hands of 8 male participants (age: 27 ± 4 y). Ultrasound images were taken at rest and during maximal abduction of the 5th digit.ResultsThe cadaveric PB specimens displayed a homogenous fiber‐type distribution with a mean fiber ratio of 71% slow‐type (range: 62–82%) to 29% fast‐type (range: 18–38%). Upon PB muscle contraction, a 26% and 28% decrease in mean muscle length was observed in the left and right hands, respectively. A concomitant increase in mean PB muscle thickness of 40% and 48% was also observed in the left and right hands respectively.ConclusionThe preponderance of MHC slow‐type isoform relative to fast‐type in the PB render the whole muscle with fatigue resistant contractile properties that would allow the muscle to remain contracted during prolonged grasping tasks. Considering the muscle fiber type proportions along with the significant changes in muscle length and thickness observed with ultrasound imaging supports the supposition that the PB is capable of acting as a thick muscular barrier to the contents of the ulnar tunnel during a movement known to elicit the greatest EMG activity.Support or Funding InformationSupported by NSERC

Anatomical insights of the palmaris brevis muscle for clinical procedures of the hand.

The purpose of the present study is to provide useful data for anatomists and clinicians by describing the topography of the palmaris brevis muscle, taking particular note of its morphology and distribution pattern of the nerve and artery. Forty-nine hands from Korean adult cadavers were used in this study. Parameters with respect to the size, scale, and location of the muscle were measured using a ultrasonography system, digital caliper, and surgical microscope. Histologic sections were obtained to clarify the positional relationship with surrounding tissues. The branches of the ulnar nerve and artery, which supply the muscle, were observed. The minimum and maximum depths in which the palmaris brevis muscle can be existed, including the thickness of the skin (1.9 mm), were 3.7 and 6.9 mm, respectively. It was inserted into the hypothenar fascia and the dermis. The main trunk of the ulnar nerve and artery were positioned under the lateral side of the muscle. The richest arborization of perforating branches of the ulnar nerve and artery was mostly confined to the distal section of the lateral side of the muscle. Our findings provide theoretical evidence of the palmaris brevis muscle for clinical procedures of the hand, such as botulinum toxin injection. Clinicians should pay attention not to injure the ulnar artery under the lateral side of the muscle. Botulinum toxin should be injected at a depth of between approximately 2 and 7 mm, considering the range of depth of the muscle. Clin. Anat. 30:397-403, 2017. © 2017 Wiley Periodicals, Inc.