Clinical relevance of palmaris longus agenesis: common anatomical aberration

Palmaris longus muscle, although of little functional use to the human upper limb, assumes great importance when used as a donor tendon for transfer or transplant. The variability in the prevalence of palmaris longus agenesis among various ethnic groups has been established, and the surgeon's awareness of the prevalence in a population or ethnic group is desirable. The prevalence of palmaris longus agenesis has, to the best of the authors' knowledge, not been reported in Indian patients. Five hundred Indian patients were examined for the presence or absence of palmaris longus tendon, using the conventional test for presence of palmaris longus. The prevalence and pattern of palmaris longus agenesis was analyzed statistically and any difference in prevalence or pattern of palmaris longus agenesis with regard to body side or sex was looked for. All statistical analysis was done using SPSS (version 12). chi2 test was used to analyze the association of agenesis with limb laterality and sex. The prevalence of palmaris longus agenesis was found to be 17.2% (8% bilateral and 9.2% unilateral). The prevalence of agenesis was significantly more common on the left side. Male subjects had a greater likelihood of unilateral agenesis, while female subjects were more likely to have bilateral agenesis. That prevalence of palmaris longus agenesis is race dependent is reaffirmed in the present study. Although the prevalence of palmaris longus agenesis in Indian patients was found to be much higher than the reported average prevalence in an Asian population, this tendon can still be counted on by surgeons treating Indian patients for use as a donor tendon, which will be present in a vast majority of Indian patients.     

Prevalence of the palmaris longus through clinical evaluation

Purpose  

Most standard textbooks of hand surgery report on the rate of palmaris longus muscle absence of 15%. The aim of the study was to determine the absence of palmaris longus and to correlate it with age, sex and body side.     

Degenerative trends of the palmaris longus muscle in a South African population

The literature reports that the palmaris longus muscle (PL) is only found in mammals in which the forelimbs are weight‐bearing extremities. It is suggested that the function of this muscle has been taken over by the other flexors in the forearm. Terms used in the literature to describe the diminishing of this muscle include retrogressive or phylogenetic degenerative trends. The aims of this study were to determine the prevalence of PL in a South African population and whether a phylogenetic degenerative trend for the PL exists. To determine the prevalence of the PL, five groups, representing different age intervals (Years 0–20, 21–40, 41–60, 61–80, and 81–99) were used. A sample of 706 participants of various ages was randomly selected. Statistical analysis included comparisons of the prevalence of the muscle between males and females and left and right sides, using a student t‐test. A Chi‐squared test was used to determine a possible phylogenetic degenerative trend of PL within the five groups. The sample yielded a bilateral absence of the PL in 11.9% of the cases. The muscle was unilaterally absent on the left side in 7.65% and 6.94% on the right side. The Chi‐squared tests revealed a P‐value of 0.27 for the left arm and 0.39 for the right arm. No obvious trend could be established for the phylogenetic degeneration of the PL in this study. It would appear that the PL muscle should not be considered as a phylogenetically degenerating muscle in a South African population. Clin. Anat. 27:222–226, 2014. © 2013 Wiley Periodicals, Inc.     

A Case of the Bilateral Duplicate Palmaris Longus Muscles Coupled with the Palmaris Profundus Muscle

The palmaris longus muscle is one of the most variable muscles in human anatomy. During a routine anatomical dissection for medical students at Tottori University, we found duplicate palmaris longus muscles in the bilateral forearms together with the palmaris profundus muscle in the right forearm. The bilateral aberrant palmaris longus muscles were observed at the ulnar side of the palmaris longus muscle and their distal tendons were attached to the flexor retinaculum. The palmaris profundus muscle found in the right forearm was located at the radial side of the flexor digitorum superficialis muscle. The proximal tendon was originated from the anterior surface in the middle of the radius, while the distal tendon coursed radial to the median nerve through the carpal tunnel, finally inserting into the distal part of the flexor retinaculum. Both the palmaris longus and aberrant palmaris longus muscles were innervated by the median nerve. The palmaris profundus muscle was presumably supplied by the median nerve.     

A case of an accessory palmaris longus muscle and a duplicate palmaris longus muscle with special reference to their nerve supply--morphologic significance of a common innervation trunk

During a dissection of the forearm and hand, a duplicate palmaris longus muscle with an accessory palmaris longus muscle was observed on the right side of a 73-year-old Japanese male cadaver. Duplications of the palmaris longus muscle have been reported by many authors. Humphry (1872) suggested the presence of radial, intermediate, and ulnar sectors in the superficial layers of the forearm flexor muscular angulus, based on a comparison of fore- and hind limbs and comparative anatomical theory. The palmaris longus muscle usually differentiates from the intermediate sector but differentiation from the other two sectors may also be possible. Some authors have asserted that a common innervation trunk is critical for determining an ontogenetic relation between the muscles (Fuchino, 1960; Honma, 1980; Yamada, 1986). We examined the nerve supply in addition to scrutinize these anomalous palmaris longus muscles. In our case, the ramification of the innervating nerves was specific. The branches to the second palmaris longus muscle and the flexor carpi radialis arose as a common trunk from the median nerve. The branches to the first palmaris longus muscle and the accessory palmaris longus muscle originated as another common trunk from the median nerve. From these observations, we speculated that the second palmaris longus muscle has differentiated from the flexor carpi radialis, while the accessory palmaris longus muscle has differentiated from the first palmaris longus muscle, based on Humphry's suggestion.     

Clinical prevalence of palmaris longus agenesis: A systematic review and meta‐analysis

We report a systematic review and a proportion meta‐analysis of prevalence studies evaluating the prevalence of palmaris longus agenesis (PLA) in the literature. The overall PLA rate was defined to be the primary outcome. Secondary outcomes were rates of PLA in relation to ethnicity, laterality, side, gender, age, and hand dominance. We identified 26 articles which met the inclusion criteria. Meta‐analyses showed an overall PLA pooled rate of 20.25%, higher than the commonly reported overall rate of 15%. Our results also showed significantly lower pooled rates in Africans (11.3%) and East Asians (4.5%) when compared to Arab Middle Eastern population (41.7%). A subgroup analysis of the African group showed a pooled rate of 2.71%, the lowest, in the East and South East African population. The pooled rate was 26.3% among Caucasians, 26.16% among South and Southeast Asians and 34.13% among Turkish. In discordance with the literature, PLA was statistically more predominant on the right side. No significant differences in PLA rates were found for laterality, gender, the combination of gender and side or the combination of gender and laterality. The lowest rate of PLA found in East and South East African populations might be indicative of the subsequent phylogenetic degeneration of the palmaris longus muscle in modern humans after the “Out of Africa” migration. Clin. Anat. 26:709–718, 2013. © 2013 Wiley Periodicals, Inc.     

Three-headed reversed palmaris longus muscle and its clinical significance

The palmaris longus muscle originates from the medial epicondyle of the humerus. After a short distance, almost in the middle of the forearm, the muscle belly is toggled into a broad tendon which is inserted into the flexor retinaculum and the palmar aponeurosis. After dissection of the left forearm of a 73-year-old female cadaver we found a reversed palmaris longus muscle. This means that the palmaris longus muscle was tendinous in its upper part and muscular in its lower part. Additionally, the muscle belly was triple, thus our finding was characterized as "three-headed reversed palmaris longus muscle". Rarely is the palmaris longus muscle double, whereas the three-headed reversed palmaris longus muscle is mentioned only once in the literature as a surgical finding, in a patient who suffered from edema and pain in the wrist [Yildiz, M., Sener, M., Aynaci, O., 2000. Three-headed reversed palmaris longus muscle: a case report and review of the literature. Surg. Radiol. Anat. 22, 217-219]. The overuse of the reversed palmaris longus muscle can lead to the muscle's local hypertrophy. According to the literature a reversed palmaris longus muscle may cause a compartment syndrome with pain and edema in the wrist's area, the carpal tunnel syndrome and Guyon's syndrome. The described variation is also useful to the hand surgeon, as the palmaris longus muscle is an anatomical landmark for operations at this area.     

Prevalence of the palmaris longus in relation to the hand dominance

Purpose  

The incidence of left-handedness in the general population is between 8 and 15%. There is a presumption that the prevalence of palmaris longus muscle differ between right-handed and left-handed people. This prospective study was conducted to determine the prevalence of the palmaris longus in relation to the hand dominance.     

The clinical surface anatomy anomalies of the palmaris longus muscle in the Black African population of Zimbabwe and a proposed new testing technique

The presence of the palmaris longus muscle (PLM) is highly variable. Rates of absence vary from 0.6% in the Korean population to as high as 63.9% in the Turkish population. The tendon of PLM may be absent on one or both forearms, may have duplicated tendons on one forearm or may be laterally shifted to the extent that the tendon of the PLM lies superficial to that of flexor carpi radialis muscle. Among Black American populations, in which there is usually mixed ancestry, rates of absence are 3.5%. Only two studies have been performed on Black African populations: in Republic of Congo and Uganda, and each showed widely differing rates of absence of 3.0% and 14.6%, respectively. In this study, a total of 890 Black Zimbabwean subjects in Harare aged between 8 and 13 years, were examined for clinical surface anatomy anomalies of the tendon of PLM. The results showed that the tendon of the PLM was absent unilaterally in 0.9% of the population, and bilaterally absent in 0.6% with an overall rate of absence of 1.5%. Other variations noted were a laterally shifted PLM in 1.1% of subjects and duplicated tendons on one forearm, which was the least prevalent anomaly, in 0.2% of subjects. The author proposes a new technique to test the tendon of PLM, which combines resisted thumb abduction and resisted wrist flexion. The proposed technique capitalizes on the role of the PLM as an important abductor of the thumb. Clin. Anat. 22:230–235, 2009. © 2009 Wiley‐Liss, Inc.     

Asymmetry of the active nonweightbearing foot and ankle range of motion for dorsiflexion-plantar flexion and its coupled movements in adults

Asymmetries in ankle range of motion (ROM) have been reported, but often the uninvolved limb is used as a reference in clinical practice. The study wanted to quantify the intraindividual asymmetries in dorsi-plantar flexion foot and ankle ROM and its coupled foot movements. Active triplanar nonweightbearing ROM of the foot and ankle was recorded in young healthy adults (30 male volunteers, mean age 22.8 years; 35 female volunteers, mean age 23.8 years) using an optoelectronic set-up. The sagittal plane movement (mean ROM female subjects right side 71.3 degrees, left side 71.4 degrees, P > 0.05; mean ROM male subjects right side 69 degrees , left side 68.9 degrees, P > 0.05; sex difference, P < 0.001) was coupled with frontal (mean ROM female subjects right side 16.6 degrees, left side 14.8 degrees, P > 0.05; male subjects right side 17 degrees, left side 15.3 degrees; P > 0.05; no sex difference) and horizontal (mean ROM female subjects right side 19.6 degrees, left side 18.8 degrees, P < 0.001; male subjects right side 17.6 degrees, left side 16.2 degrees, P < 0.001; sex < 0.001) plane motions. Individual fluctuating asymmetries up to 15 degrees (principal movement), and up to 29 degrees (associated movements) were measured. Overall, 20% of female and 34% of male subjects had principal plane asymmetries >5 degrees, and 50% of the subjects had asymmetries >5 degrees in the associated movements. In young adults, individual asymmetries in ankle joint complex dorsi-plantar flexion should be taken into account when using the uninvolved, contralateral limb as a reference for clinical examination.     

The contribution of the palmaris longus muscle to the strength of thumb abduction

The palmaris longus muscle (PLM) is described as a weak flexor of the wrist and a tensor of the palmar aponeurosis, but not a thumb abductor. The PLM is believed to aid thumb abduction through its insertion onto the thenar eminence. Two groups, both right hand dominant, were selected from 1,200 sampled participants. The first group comprised of 38 subjects with unilateral presence of the PLM and was used to determine the strength of thumb abduction. The second group comprised of 30 subjects, with bilateral presence of the PLM, and it was used to calculate the effects of hand dominance. A significant number of subjects with bilateral absence of the PLM were observed and undocumented. Using a dynamometer in subjects with unilateral presence of the PLM, the force of thumb abduction was significantly greater on the hand with a PLM than the one without it (P = 0.014), irrespective of hand dominance. In the second sample with bilateral PLM, thumb abduction on the dominant hand was 10% stronger than on the nondominant hand and was similar to the universally accepted average of 10% increase in grip strength of the dominant hand. Thus, 10% was deducted from all the dominant hands, and the force of thumb abduction remained greater on the hand with PLM than the hand without it (P = 0.049). The results of this study demonstrated the PLM to be involved in thumb abduction, and the authors therefore recommend that this action of the muscle be universally accepted by anatomists and hand surgeons. Clin. Anat. 23:431–436, 2010. © 2010 Wiley‐Liss, Inc.     

Clinical Assessment of Absence of Palmaris Longus Muscle and its Association with Gender,Body Sides,Handedness and Other Neighboring Anomalies in a Population of Central India

The palmaris longus (PL) is a vestigial or degenerating superficial muscle in the anterior compartment of forearm. It is variable in its structure, attachments and presence or absence in different individuals in various populations and even in one population among individuals. It is well known that individuals may have unilateral or bilateral absence of PL. The aims of this study were to determine the incidence of absence of PL and its association with gender, body sides, handedness and other neighboring anomalies like the absence of flexor digitorum superficialis (FDS) muscle to little finger, the incomplete superficial palmar arch (SPA) etc. in a population of central India; and to correlate the same with the other related studies. We examined 400 Caucasian subjects (200males and 200 females of a population of central India) aged 18–55 years. Total 65 (16.25%) subjects had overall absence of PL, out of which 25 (6.25%) presented bilateral absence and 40 (10%) presented unilateral absence so statistically unilateral absence was little more common than bilateral absence. Overall absence and unilateral absence of PL were little more common in males (M:8.5%,17:7.75% and M:5.75%,17:4.25% respectively) whereas bilateral absence was little more common in females (17:3.5%,M:2.75) however these associations with gender were not statistically significant. In unilateral PL absence, the right and the left sides were more or less equally affected (RT: 5.25%, LT: 4.75%) and no statistical significance was evident for this association with body sides. Out of 65 subjects with absence of PL only 5 were left handed and rest right handed so this association with handedness was also statistically insignificant. No correlation was evident between PL absence and other neighboring anomalies like absence of FDS to little finger, incomplete SPA etc. So the present study concluded with (i) The unilateral absence is statistically little more common than the bilateral absence (ii) There is no statistical association between the PL absence and gender, body sides, handedness and other neighboring anomalies like absence of FDS to little finger, incomplete SPA etc. in a population of central India.     

Association of the absence of palmaris longus tendon with an anomalous superficial palmar arch in the human hand

The normal arterial supply to the human hand is via the ulnar and radial arteries which unite mid-palm to form a complete arch called the superficial palmar arch (SPA). From the SPA blood vessels pass anteriorly to supply the thumb and digits, and deeply to complete the deep palmar arch. Previous reports have documented anomalies of the SPA formation, and this may change the normal blood distribution to the thumb and the digits. There have also been reports of the absence of the palmaris longus tendon. A total of 47 embalmed cadaveric hands (some paired, some single) were dissected and the presence of an anomalous SPA was more frequently observed when the palmaris longus tendon was absent. This may be significant when considering the suitability of patients for hand surgery which involves interruption to the vascular supply to the hand, e.g. harvesting upper limb vessels for coronary artery grafting. The current techniques for assessing the vascular supply to the hand (Aliens test and/or Doppler ultrasounding) are unreliable. Demonstration of a palmaris longus tendon in the living arm is easy and the use of this in combination with the other techniques may improve overall reliability.     

Frequency of palmaris longus absence and its association with other anatomical variations in the egyptian population

The palmaris longus (PL) is one of the most variable muscles in the human body. Racial differences in its variation have been documented. Several studies have attempted to correlate PL absence with other anatomical variations. This study was conducted to determine the prevalence of absence of PL, correlate it with gender and body side and to determine its association with other anatomical variations in the Egyptian population. The presence of PL was clinically determined in 386 Egyptians using the standard technique. All subjects were examined for the presence of the flexor digitorum superficialis (FDS) to the fifth finger. Allen's test was done to assess the completeness of the superficial palmar arch (SPA). The overall prevalence of absence of the PL in Egyptian subjects was 50.8%. There was no significant difference in PL absence with regard to the body side but a significant difference was seen as regards gender and when bilateral absence of PL was compared to its unilateral absence. Absence of FDS tendon to the fifth finger was seen in 1.3% subjects. There was no association between the absence of the FDS tendon to the fifth finger and either presence or absence of PL and also between the absence of PL and the incompleteness of SPA in both genders. In conclusion, the prevalence of absence of PL in the Egyptian population represents one of the highest rates of absence to be reported for this muscle, which is significantly different from that in other ethnic groups. Clin. Anat. 26:572–577, 2013. © 2013 Wiley Periodicals, Inc.     

掌长肌内神经血管的解剖学观察及其临床意义

目的：观察掌长肌肌内神经血管解剖分布,探讨该肌肉能否被分割为若干个功能单位,以提供新的功能性骨骼肌游离移植供区.方法：解剖10具10%福尔马林固定的成人尸体共20侧掌长肌,观察其肌外神经血管的分布形式.10具新鲜成人尸体标本共20侧掌长肌,一侧的掌长肌完整剥离后用Sihler＇s染色法行肌内神经的染色,另一侧掌长肌用30%硫酸钡、乳胶混悬液血管灌注并行X线钼靶摄片.而后对照观察神经、血管在肌内分布及其关系.结果：掌长肌血供多为尺侧返动脉和尺动脉肌支,4侧出现肱动脉肌支.其神经支配来自正中神经发出的神经支.该支在进入肌肉前多为1支,有动脉伴行,构成神经血管束.尺侧返动脉肌支和正中神经分支在肌内的分布区域大致吻合.结论：根据掌长肌肌内神经血管在肌内分布的不同情况,可将其分为一个近端和两个远端的3个功能单位,供节段性游离肌肉移植.     

Muscle variations and abnormal branching and course of the ulnar nerve in the forearm and hand

During dissection of the right forearm of a 27-year-old female cadaver, variations in the form and insertion of the palmaris longus muscle were observed. The tendon of the palmaris longus muscle, which demonstrated a centrally placed belly, split into two tendons: one inserted into the palmar aponeurosis and the other into the proximal part of the flexor retinaculum. Additionally, we found an accessory muscle extending between the flexor retinaculum and the tendon of the abductor digiti minimi muscle. This accessory muscle was located deep to the ulnar artery but superficial to the superficial and deep branches of the ulnar nerve at the wrist. Finally, an aberrant branch of the ulnar nerve was identified in the forearm; it traveled distally alongside the ulnar artery and in the palm demonstrated communications with common palmar digital nerves from the ulnar and the median nerves. No variations were observed in the contralateral upper limb.     

锥状肌及耻骨前韧带的解剖学观测

目的 探究锥状肌及耻骨前韧带的毗邻关系,为进一步了解维持耻骨联合稳定的机制提供解剖学依据。 方法 选用24具标本（男19具,女5具）,观测锥状肌的长、宽、厚及其与邻近的腹直肌、长收肌和耻骨前韧带之间的毗邻关系。 结果 95.8%大体标本双侧存在锥状肌（23/24,男性19例,女性4例）,4.2%右侧缺如（1/24,女性1例）。测得锥状肌长度,右侧：男（70.64±13.48）mm,女（71.81±11.27）mm,左侧：男（69.60±12.01）mm,女（64.25±19.79）mm;宽度,右侧：男（20.68±4.12）mm,女（20.65±2.04）mm,左侧：男（20.02±2.99）mm,女（18.23±4.77）mm;厚度,右侧：男（2.50±1.61）mm,女（1.49±0.40）mm,左侧：男（2.19±1.06）mm,女（1.50±0.56）mm,左、右侧锥状肌的长、宽和厚未见统计学差异（P>0.05）。测得耻骨前韧带宽度,右侧：男（5.96±1.55）mm,女（6.60±1.10）mm,左侧：男（6.35±1.58）mm,女（6.16±0.69）mm。锥状肌以腱性纤维起于耻骨前面及耻骨联合前的纤维性韧带;腹直肌肌腱、长收肌肌腱、腹股沟韧带以及锥状肌起点在耻骨嵴处交织毗邻,形成层次鲜明的耻骨前韧带。 结论 锥状肌起于耻骨前韧带,与腹股沟韧带和长收肌肌腱一同构成耻骨前韧带;同时以耻骨前韧带为中心,毗邻结构共同构成一个复合体,为耻骨联合的稳定提供重要的支撑。     

Analysis of the gross anatomical variations found in four cases of trisomy 13

The variations and defects observed during detailed gross anatomical dissections of four cases of trisomy 13 are described. Emphasis is on the muscular system where previously undocumented variations, absences, and supernumerary elements were observed. A muscle phenotype which includes absence of palmaris longus, palmaris brevis, plantaris, and peroneus tertius, the presence of pectorodorsalis muscles and muscles from the central tendon of the diaphragm to the pericardium near the pulmonary veins, and variations in the extensor indicis, extensor carpi radialis longus and brevis, biceps, and suprahyoid muscles is discussed. The brain defects which include absent olfactory bulbs and tracts and hypoplastic commissures are compared to those defects seen in cases of alobar holoprosencephaly wherein severe defects of the ethmoid bone are concomitants. Previously well-documented defects of the viscera are included.     

Analysis of the gross anatomical variations found in four cases of trisomy 13.

The variations and defects observed during detailed gross anatomical dissections of four cases of trisomy 13 are described. Emphasis is on the muscular system where previously undocumented variations, absences, and supernumerary elements were observed. A muscle phenotype which includes absence of palmaris longus, palmaris brevis, plantaris, and peroneus tertius, the presence of pectorodorsalis muscles and muscles from the central tendon of the diaphragm to the pericardium near the pulmonary veins, and variations in the extensor indicis, extensor carpi radialis longus and brevis, biceps, and suprahyoid muscles is discussed. The brain defects which include absent olfactory bulbs and tracts and hypoplastic commissures are compared to those defects seen in cases of alobar holoprosencephaly wherein severe defects of the ethmoid bone are concomitants. Previously well-documented defects of the viscera are included.     

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.