Proposal for a new classification of plantaris muscle origin and its potential effect on the knee joint

A bilateral gastrocnemius tertius coexisting with a unilateral two-headed plantaris muscle

The current cadaveric report aims to present a coexistence of two uncommon variants of the posterior leg compartment. The variations were detected, during classical dissection in an 84-year-old donated male cadaver. On the left lower limb, the gastrocnemius muscle was identified as having a third head that was attached to the lateral head. This variant is known as gastrocnemius tertius muscle and was bilaterally identified. The left-sided plantaris muscle had two distinct heads that fused into a common tendon that was inserted into the calcaneal tuberosity. Knowledge of these variants is important, due to their close relationship with the popliteal neurovascular bundle. Clinicians should be aware, to avoid pitfalls and take them into account in their differential diagnosis.

A three-headed plantaris muscle with a bipartite insertion of its two accessory heads

The plantaris muscle consists of a small muscular and a long tendinous part and is located at the superficial compartment of the posterior leg. The purpose of the current cadaveric report is to describe a rare variant of the plantaris muscle. During a routine dissection, a three-headed plantaris with two accessory heads was identified with a variant insertion of the two accessory heads. All heads originated from the femur popliteal surface, independently the one from the other. The first head contributed to the long and thin calcaneal tendon, and the two accessory heads were mainly inserted via their musculoaponeurotic expansion into the medial femoral condyle. The plantaris muscle morphological variability has been extensively studied lately. The incidence of the two-headed muscle has been estimated at 1.6%, while the three-headed muscle corresponds to an even rarer variation. This is the third case reported in the English literature, while the insertion of the two accessory heads has never been described before.

Morphological variability of the fibularis brevis tendon in human fetuses

INTRODUCTION

The morphological variability of the fibularis brevis tendon in adults is well known. However, studies on its classification in the human fetus do not exist. The aim of this study was to provide the first comprehensive classification of the fibularis brevis tendon based on its insertion in human fetuses. The second aim of the study is to evaluate the prevalence of fibularis digiti quinti.

MATERIAL AND METHODS

Forty-three spontaneously aborted human fetuses were studied (21 male, 22 female, 86 lower limbs). All were from a Central European population), aged 18-38 weeks of gestation at the time of death.

RESULTS

Three main types of fibularis brevis tendon were distinguished. The most common was Type I (77%), characterized by a single distal attachment. The tendon was attached to the tuberosity at the base of the fifth metatarsal, on the lateral side. The second most common was Type II (19%) - a bifurcated distal attachment. The main tendon was attached to the tuberosity at the base of the fifth metatarsal on the lateral side. Based on the attachment site of the accessory tendon, four subtypes were determined: Type IIA - the accessory tendon attached to the dorsal surface of the base of the fifth metatarsal. At the side of attachment, the fibularis brevis tendon was connected with a portion of the fibularis tertius tendon. Type IIB - the accessory tendon attached to the proximal part of the shaft of the fifth metatarsal. Type IIC - the accessory tendon was attached to the fascia covering the fourth interosseous space. Type IID - the accessory tendon was fused with fibularis longus tendon. Type III is the rarest (4%) - triple branched distal attachment. The main tendon was attached to the tuberosity at the base of the fifth metatarsal. The first accessory tendon was attached to the proximal part of the shaft of the fifth metatarsal, and the second accessory tendon was attached to the fascia covering the fourth interosseous space. The fibularis digiti quinti was present in 24 feet (28%) of the 86 lower limbs dissected.

CONCLUSION

The fibularis brevis is characterized by high morphological variability. The proposed classification consists of three main Types (I-III), with Type II divided into subtypes (A-D). The fibularis digiti quinti is not closely related to the type of fibularis brevis tendon.

Accessory plantaris muscle can result in symptomatic hardware impingement following ACL reconstruction

Anatomic variants of lower extremity musculature, such as the gastrocnemius, popliteus, and the plantaris have been well described in the literature. The impact of these anatomical variations on clinical outcomes depends on their proximity to and effects on adjacent anatomical structures, particularly in the context of planned surgical procedures in the region. While the presence of the accessory plantaris is rare, no previous cases have described it negatively affecting surgical outcomes to our knowledge. We present a case of a 42-year-old patient who underwent an anterior cruciate ligament (ACL) reconstruction using a femoral Endobutton for graft fixation positioned just beneath an accessory plantaris, leading to impingement and persistent knee pain. This case highlights the importance of understanding anatomical variations when planning and performing surgical procedures and suggests the need for further research in this area.

An assessment of the variation of the intramuscular innervation of the gracilis muscle, with the aim of determining its neuromuscular compartments

Some muscles present neuromuscular compartments, one of which is the gracilis muscle. The aim of the present study is to determine the number of compartments present within the gracilis muscle based on its intramuscular innervation patterns; such knowledge could be of value in free functional muscle transfer. The study comprised 72 gracilis muscles (38 women, 34 men), fixed in 10% formalin solution. The muscles were removed and then stained using Sihler's method. When sufficient transparency was achieved, some measurements were made. Three different types of intramuscular innervation were distinguished. Type I (70.8%) was featured by at least one direct proximal nerve branch. Type II (23.6%) presented at least one indirect proximal nerve branch. Type III (5.6%) did not possess any proximal nerve branch. The median of descended nerve branches was five. Considerable anatomical variation is possible within the intramuscular innervation of the gracilis muscle. The muscle presents neuromuscular compartments, but the exact number depends on the type of its intramuscular innervation and the number of the main descendent nerve branches. All three types seem to be appropriate for free functional muscle transfer. Our findings may be of great value for surgeons carrying out complex reconstructions with the use of the gracilis muscle.

A new look at quadriceps tendon - Is it really composed of three layers?

BACKGROUND

The aim of this study was to qualitatively and quantitatively describe the anatomy of the QT including its size, its layers and relationship between layers.

METHODS

Sixty lower limbs (15 females and 15 males fixed in 10% formalin were examined. A retrospective analysis of 20 thigh MRI examinations was performed (10 males, and 10 females).

RESULTS

In all dissected specimens, the quadriceps femoris was composed of 4 layers: superficial (first layer), middle (second layer), middle-deep (third layer) and deep (fourth layer). The first layer (superficial) was formed by the rectus femoris tendon and fascia. The second layer was composed of tendons of the vastus medialis and superficial part of the vastus lateralis. The third layer was formed by the intermediate part of the vastus lateralis. The fourth layer was composed of the tendon of the vastus intermedius. This type of anatomy was visualized in 4 males and 2 female on MRI scans.

CONCLUSION

The findings of this study provide a detailed anatomy of the quadriceps tendon. There were 4 different layers of the QT consistently found in all specimens. The first layer was independent and composed by the rectus femoris tendon, the second was formed by the superficial part of the vastus lateralis and vastus medialis. The third layer was formed by the intermediate part of the vastus lateralis, and the deepest fourth layer was composed of the vastus intermedius. This detailed structural anatomy was also able to be visualized on MRI scans.

The subpopliteal fat body

INTRODUCTION

The knee is likely to get hurt due to its excessive weight-bearing, for which it is surrounded by strongly tensioned ligaments, connectives and muscles. These highly active structures are imbedded in fatty tissue. The Fatty and loose connective tissue of the knee recently gained a renaissance in research. While the Hoffa fat body in the ventral knee attracted attention over the last years, we have investigated a smaller, dorsal fat body, ventral to the popliteus muscle. This fat body has not been described before.

MATERIALS AND METHODS

11 knees of 11 fresh specimens were investigated. All muscles but the popliteus muscle were removed. The popliteus was released from its tibial origin and dissected towards its tendinous insertion. Thereby, a subpopliteal fat body (SFB) was shown. The related vessels and nerves were evaluated. The size of the body was measured. Examples of histological slices were stained with HE and immunostained against neurofilament.

RESULTS

The SFB lies ventral of the popliteus muscle at the concave posterior tibia and attaches to the periosteum and the popliteus muscle. It is not attached to the posterior cruciate ligament. It is separated from the subpopliteal recess by a lamella deriving from the fibular head. Arterial and venous vessels are seen entering the SFB, deriving from the popliteal artery or the anterior tibial artery. A subbranch of the tibial nerve was seen to reach the SFB. The SFB could be identified in MRI scans and in plastinations.

DISCUSSION

Primarily, the SFB provides a gliding space for the mobile part of the popliteus muscle over the tibia. The SFB lies within the tibial concavity, ventral to the popliteus muscle. This is exactly where embryologically, the popliteal artery passes through, before its involution in later stages. Therefore, the SFB may show the former perivascular autonomic nerves which encompass the embryologically created arteries, from which we have seen the arterial remnants. The nerves seen here form neurovascular bundles which could be a source of pain, when compressed. This anatomy may explain the autonomic component of pain in the deep lateral region of the knee. The SFB is functional fat, comparable to the Hoffa's fat pad in the ventral knee.

A Proposal for a New Classification of the Supernumerary Heads of the Biceps Brachii Muscle

Introduction

The anterior compartment of the arm consists of three muscles: the biceps brachii (BB), brachialis, and coracobrachialis muscle. The aim of the present study was to characterize possible variations in the supernumerary heads of the biceps brachii and use these to prepare an accurate classification of the area that could be used for planning surgical procedures in the region. Material and Methods. One hundred (51 left and 49 right, 52 females and 48 males) upper limbs fixed in 10% formalin solution were examined.

Results

Four types of supernumerary BB heads were identified, with subtypes. Type I was the most common type, characterized by the two heads (64%); this was subdivided into Type IA, with a single muscle belly, and Type IB with two muscle bellies. The second most common type was Type II, which was characterized by the three BB heads (26%). This type was divided into four subtypes (A-D): Type IIa characterized by attachment to the middle part of the shaft of the humerus; Type IIb characterized by the origin to the coracoid process together with the short head of the BB; Type IIc characterized by origin to the tendon of the pectoralis major muscle; and Type IId characterized by the attachment to the capsule of the humeral joint. The third most common type was Type III, which was characterized by four heads (6%); this was divided into Type IIIa, where two heads originated from the humerus bone, and Type IIIb, where one head originated from the short heads and the second from the long head of the BB. The rarest type was Type IV (4%) which was characterized by five heads: the short head originated from the coracoid process and the long head originated from the supraglenoid tubercle, the third and fourth head originated from the shaft of the humerus, while the fifth head originated from the pectoralis major muscle.

Conclusion

The biceps brachii is characterized by very high morphological variability. The new classification proposes four types of supernumerary head arrangement (I-IV), divided into subtypes. This classification has both clinical and anatomical significance.

The relationship between additional heads of the quadriceps femoris, the vasti muscles, and the patellar ligament

INTRODUCTION

The quadriceps femoris consists of four muscles: the rectus femoris, vastus medialis, vastus intermedius, and vastus lateralis. However, the effect of additional quadriceps femoris heads on the vasti muscles and patellar ligaments is unknown. The aims of the present study are to determine the relationship between additional quadriceps femoris heads and the vasti muscles and patellar ligaments and to review the morphology of the vastus lateralis, vastus medialis, and vastus intermedius.

MATERIALS AND METHODS

One hundred and six lower limbs (34 male and 19 female cadavers) fixed in 10% formalin were examined.

RESULTS

On all lower extremities, the vastus lateralis consisted of superficial, intermediate, and deep layers. The vastus medialis, on the other hand, consisted of only the longus and obliquus layers. The quadriceps head had one or more supplementary heads in 106 dissected limbs from 68 cadavers (64.1%). The distal portion of the patella was wider in lower limbs without supplementary heads than in type IA but narrower than in type IIIA. In general, the distal portion of the patella was narrower in specimens with a supplementary head than in those without (19.03 SD 3.18 mm vs. 20.58 SD 2.95 mm, p = 0.03817). Other patellar ligament dimensions did not differ significantly.

CONCLUSION

The quadriceps femoris muscle is characterized by high morphological variability. Occurrence of extra heads is at the level of 64.1%. The vastus lateralis consists of three parts (superficial, intermediate, and deep), and vastus medialis consists of two (longus and oblique).

Sensitivity of musculoskeletal models to variation in muscle architecture parameters

Musculoskeletal models, like all theoretical models of physical processes, depend on the assumptions needed to construct the model. For musculoskeletal models, these assumptions include, among other things, the kinematic data, the kinetic data and the muscle parameters. The former (dynamic) data can be acquired relatively easily from living subjects, but the latter are usually based on limited information, frequently determined from cadaver studies performed on elderly individuals. Previously, we determined the sensitivity of forces to dynamic differences among 10 humans walking on a straight path. Here, we assess the sensitivity of the muscle and joint reaction forces developed in human walking to variable muscle parameters obtained from 10 living adults, whose data were recently reported, and compared the results with the values from a standard model that depends on cadaveric data. We found that, while the force patterns across the stance cycle were similar among muscle parameter models, differences of as much as 15% in the force magnitude were produced. Whether or not the variation between the standard model and other muscle parameters is important depends on why the forces are required.

Classification of the popliteofibular ligament

PURPOSE

The purpose of this study was to characterize the morphological variations in the distal attachment of the popliteofibular ligament (PFL) and create an accurate classification for use in planning surgical procedures in this area and in evaluating radiological imaging.

METHODS

One hundred and thirty-seven lower limbs of body donors fixed in 10% formalin solution were examined for the presence and course of the popliteofibular ligament.

RESULTS

The PFL was present in 88.3% of cases. We propose the following three-fold classification: type I (72.3%), the most common type, characterized by the attachment onto the apex of the head of the fibula, type II (8.7%), characterized by a bifurcation, with the dominant band inserting on the anterior slope of the styloid process of the fibula and the smaller band onto the posterior surface of the styloid process of the fibula and type III (7.3%), characterized by a double PFL: the first PFL (main) originated from the popliteus tendon and inserted onto the anterior slope of the styloid process of the fibula, while the second originated from the musculotendinous junction of the popliteus muscle and inserted on the posterior surface of the styloid process of the fibula.

CONCLUSION

The PFL was characterized by high morphological variation, as reflected in our proposed classification. This variation may present clinical and biomechanical issues for both medical personnel and researchers. Our proposed classification may be valuable for clinicians who evaluate and perform surgical procedures within the knee joint area.

Morphological variability of the plantaris tendon in the human fetus

Muscular anatomy often differs between species and individuals. In particular, the plantaris muscle (PM) demonstrates great morphological variability in its course and its proximal and distal attachments. The aim of this study was to investigate the morphological variation of the PM tendon in human fetuses. Forty-six spontaneously aborted human fetuses (23 male, 23 female) aged 18-38 weeks of gestation were studied. Morphology of the attachment of the PM was assessed in both lower extremities (n = 92). The PM was present in 72 lower limbs (78.26%) and absent in 20 (21.74%). Eight types of PM distal attachment were identified. We propose an eight-fold classification of PM insertion in fetuses. Leg length, length of tendon, extension point (ExP) from the calcaneus, and ExP thickness differed significantly among types of PM insertion.

A proposal for a new morphological classification of the popliteus muscle tendon with potential clinical and biomechanical significance

The purpose of this study was to characterize the morphological variations in the proximal attachments and create an accurate classification of the PPM for use in planning surgical procedures in this area, for evaluating radiological imaging and rehabilitation. One hundred and thirty-four lower limbs of body donors (52 woman and 82 man) fixed in 10% formalin solution were examined. The popliteus muscle was present in all 134 limbs. Four main types were identified with subtypes. The most common type was Type I (34.3%), characterized by a single tendon in the popliteus sulcus. Type II (30.6%) characterized by a main tendon in the popliteus sulcus and accessory bands. This type was divided into five subtypes (A-E) based on presence of specific accessory bands. Type III (15.3%) was characterized by two tendons in the popliteal sulcus. Type IV (19.4%) was characterized by two tendons in the popliteus sulcus and additional bands. This type was also divided into five subtypes (A-E) based on presence of specific accessory bands. The popliteofibular ligament was present in 90.3% of cases. A new classification based on a proximal attachment is proposed. The popliteus tendon is characterized by a very high morphological variability, which can affect posterolateral knee stability and the natural rotation of the tibia. Such a classification system may be useful for clinicians performing medical procedures within the knee joint, including orthopedic surgeons.

Morphological variability of the plantaris muscle origin in human fetuses

INTRODUCTION

The plantaris muscle (PM) is a small, fusiform muscle located between the gastrocnemius muscle (GM) and soleus muscle (SM). PM supports movements of the knee and ankle. This muscle presents a great variability, and also has a high clinical significance. Nevertheless, data concerns morphology and morphometry of the origin of PM in human fetuses are scarce.

MATERIAL AND METHODS

Forty-seven spontaneously-aborted human fetuses (23 male, 24 female) aged 18-38 weeks of gestation were examined. The morphology and morphometry of the origin of PM were evaluated.

RESULTS

PM was present in 74 lower limbs (78.7%), and absent on 20 limbs (21.3%). We distinguished VI types of the proximal attachment of PM. Belly width and thickness, as well as thickness of the tendon and MT junction differed significantly between types of PM origin.

CONCLUSIONS

We distinguished six (I-VI) types of origin of PM in human fetuses. The most common type was type Ia, characterized by an attachment to the lateral head of GM, lateral femoral condyle and to the knee joint capsule. Our results of PM anatomical variation in fetuses will pave the way for detailed comparisons with studies carried out on adult cadavers.

Bicipital origin and the course of the plantaris muscle

The plantaris muscle (PM) has a small fusiform muscle belly and a long slender tendon sandwiched between the soleus (SM) and gastrocnemius muscle (GM). During routine dissection for research, an additional PM in the popliteal region of a 75-year-old Korean female was discovered. Two distinct PMs were present, the superior PM (sPM) and inferior PM (iPM). While the sPM originates from the lower lateral supracondylar ridge and the knee capsule, the iPM originates from the femoral condyle and sPM tendon splitting into two parts at the distal belly. The lateral side of the iPM tendon travels between GM and SM and ends at the calcaneal tendon. sPM and the medial side of the iPM tendon run along with the sPM tendon and inserts at the fascia at the inner surface of proximal 1/3 of the medial head of GM. This case report introduces a new variation of the PM that should be taken into consideration.

A proposal for a new classification of coracobrachialis muscle morphology

INTRODUCTION

The coracobrachialis muscle (CRM) originates from the apex of the coracoid process, in common with the short head of the biceps brachii muscle, and from the intermuscular septum. It inserts to the medial part of the humerus between the attachment of the medial head of the triceps brachii and the brachial muscle. Both the proximal and distal attachments of the CRM, as well as its relationship with the musculocutaneus nerve, demonstrate morphological variability.

MATERIAL AND METHODS

One hundred and one upper limbs (52 left, and 49 right) fixed in 10% formalin solution were examined.

RESULTS

Three main types, with subtypes, were identified. The most common was Type I (49.5), characterized by a single muscle belly with a classical origin from the coracoid process, medially and posteriorly to the tendon of the biceps brachii. Type II (42.6%), characterized by two heads, was divided into two subtypes (A-B) depending on its origin: Type IIA, where one head originated from the coracoid process posteriorly to the tendon of the biceps brachii and the second head from the short head of the biceps brachii, and Type IIB, in which both heads originated from the coracoid process; however, the superficial head fused with the insertion of a short head of the biceps brachii, while the deep head was directly originating. Finally, Type III (7.9%) was characterized by three heads: two originated from the coracoid process (superficial and deep), and the third from a short head of the biceps brachii. Two types of insertion and two types of musculocutaneous nerve (MCN) relative to CRM could be distinguished.

CONCLUSION

An adapted classification is needed for all clinicians working in this area, as well as for anatomists. The CRM demonstrates morphological variability in both its proximal and distal attachments, as well as the variable course of the MCN relative to the CRM. WHAT IS KNOWN ABOUT THIS SUBJECT "AND" WHAT THIS STUDY ADDS TO EXISTING KNOWLEDGE: Not much is known about the variability of coracobrachialis muscle. The present paper introduces a completely new classification, both clinical and anatomical.

Coexistence of two accessory flexor pollicis longus heads or coexistence of two-headed flexor pollicis longus with an unrecognized anatomical structure?

The flexor pollicis longus (FPL) is located in the anterior compartment of the forearm. It is morphologically variable in both point of origin and insertion. An additional head of the FPL can lead to anterior interosseous syndrome. This report presents a morphological variation of the FPL (additional head in proximal attachment and bifurcated tendinous insertion in distal attachment) and an unrecognized structure that has not so far been described in the literature. This structure originates in six heads (attached to the FPL or interosseous membrane) that merge together, and inserts on to the FPL. All the variations noted have clinical significance, ranging from potential nerve compression to prevention of tendon rupture.

Impact of plantaris ligamentous tendon

There are countless morphological variations among the muscles, tendons, ligaments, arteries, veins and nerves of the human body, many of which remain undescribed. Anatomical structures are also subject to evolution, many disappearing and others continually emerging. The main goal of this pilot study was to describe a previously undetected anatomical structure, the plantaris ligamentous tendon, and to determine its frequency and histology. Twenty-two lower limbs from 11 adult cadavers (11 left, and 11 right) fixed in 10% formalin were examined. The mean age of the cadavers at death was 60.1 years (range 38–85). The group comprised six women and five men from a Central European population. All anatomical dissections of the leg and foot area accorded with the pre-established protocol. Among the 22 lower limbs, the PLT was present in 16 (72.7%) and absent in six (27.3%). It originated as a strong fan-shaped ligamentous tendon from the superior part of the plantaris muscle, the posterior surface of the femur and the lateral aspect of the knee joint capsule. It inserted to the ilio-tibial band. Histologically, a tendon and ligament were observed extending parallel to each other. A new anatomical structure has been found, for which the name plantaris ligamentous tendon is proposed. It occurs around the popliteal region between the plantaris muscle, the posterior surface of the femur, and the ilio-tibial band.

The plantaris muscle - Anatomical curiosity or a structure with important clinical value? - A comprehensive review of the current literature

PURPOSE

Although the plantaris muscle is vestigial in humans, it is far too important to remain omitted. The aim of this study is to provide a comprehensive review of the existing literature focused on plantaris muscle clinical value, grafting usefulness and its morphological variations. Hopefully this study will be of great use for every medical practitioner due to its clarity and conciseness despite such broaden scope of this article.

MATERIAL AND METHODS

The article is written based on 100 studies published since 1868 until 2020. During careful selection process 12 papers were dismissed due to their insufficient sample size, wrong methods used or results that were previously discovered.

RESULTS

Many aspects concerning the plantaris muscle are already well examined, summarized and described. However this study has shown how much we still do not know and which fields require further investigations.

CONCLUSION

The anatomical variations of plantaris muscle morphology may cause mid-portion Achilles tendinopathy, tennis leg syndrome or increase the risk of failure while harvesting the tendons.

The double fascicular variations of the anterior talofibular ligament and the calcaneofibular ligament correlate with interconnections between lateral ankle structures revealed on magnetic resonance imaging

The anterior talofibular ligament and the calcaneofibular ligament are the most commonly injured ankle ligaments. This study aimed to investigate if the double fascicular anterior talofibular ligament and the calcaneofibular ligament are associated with the presence of interconnections between those two ligaments and connections with non-ligamentous structures. A retrospective re-evaluation of 198 magnetic resonance imaging examinations of the ankle joint was conducted. The correlation between the double fascicular anterior talofibular ligament and calcaneofibular ligament and connections with the superior peroneal retinaculum, the peroneal tendon sheath, the tibiofibular ligaments, and the inferior extensor retinaculum was studied. The relationships between the anterior talofibular ligament's and the calcaneofibular ligament's diameters with the presence of connections were investigated. Most of the connections were visible in a group of double fascicular ligaments. Most often, one was between the anterior talofibular ligament and calcaneofibular ligament (74.7%). Statistically significant differences between groups of single and double fascicular ligaments were visible in groups of connections between the anterior talofibular ligament and the peroneal tendon sheath (p < 0.001) as well as the calcaneofibular ligament and the posterior tibiofibular ligament (p < 0.05), superior peroneal retinaculum (p < 0.001), and peroneal tendon sheath (p < 0.001). Differences between the thickness of the anterior talofibular ligament and the calcaneofibular ligament (p < 0.001), the diameter of the fibular insertion of the anterior talofibular ligament (p < 0.001), the diameter of calcaneal attachment of the calcaneofibular ligament (p < 0.05), and tibiocalcaneal angle (p < 0.01) were statistically significant. The presence of the double fascicular anterior talofibular ligament and the calcaneofibular ligament fascicles correlate with connections to adjacent structures.

Is the plantaris muscle the most undefined human skeletal muscle?

The plantaris muscle is located in the posterior aspect of the superficial compartment of the lower leg, running from the lateral condyle of the femur to the calcaneal tuberosity. Classically, it is characterized by a small and fusiform muscle belly, which then changes into a long slender tendon. From the evolutionary point of view, the muscle is considered vestigial. However, it has recently been suspected of being a highly specialized sensory muscle because of its high density of muscle spindles. It has a noticeable tendency to vary in respect of both origin and insertion. Researchers have published many reports on the potential clinical significance of the muscle belly and tendon, including mid-portion Achilles tendinopathy, ‘tennis leg syndrome’, and popliteal artery entrapment syndrome. The right knee joint area was subjected to classical anatomical dissection, during which an atypical plantaris muscle was found and examined in detail. Accurate morphometric measurements were made. The muscle belly was assessed as bifurcated. Morphologically, superior and inferior parts were presented. There was a tendinous connection (named band A) with the iliotibial tract and an additional insertion (named band B) to the semimembranosus tendon. Both bands A and B presented very broad fan-shaped attachments. The human plantaris muscle is of considerable interest and has frequent morphological variations in its proximal part. Its specific characteristics can cause clinical problems and lead to confusion in diagnosis. More studies are needed to define its actual features and functions.

The subscapularis tendon: A proposed classification system

BACKGROUND

The subscapularis muscle originates from the medial two-thirds and from the lower two-thirds of the groove on the subscapular fossa of the scapula and inserts into the lesser tubercle of the humerus. Our initial hypothesis is that it shows little morphological variation. The aim of this study is to demonstrate and classify the morphological variability of the subscapularis muscle.

METHODS

Classical anatomical dissection was performed on 64 upper limbs (44 females, 20 males, 30 left and 34 right, fixed in 10% formalin). The mean age "at death" of the cadavers was 75.6 years (range 48-95), and the group comprised equal numbers of female and male adults (Central European population). Upon dissection, the following morphological features were assessed: the number of tendons of the SM, the type of insertion of each tendon of the SM, morphometric measurements of the SM.

RESULTS

Four types of morphology (based on number of tendons) were observed in the cadavers. Type I was characterized by a single band. This was the most common type, occurring in 43.7% of all cases. Type II was characterized by a double tendon (superior and inferior); it occurred in 9.4%. Type III had three tendons (superior, middle, and inferior). It was the rarest type (7.8% of cases). Type IV, called "multiband", was the second most common (39.1%) and was divided into five subtypes.

CONCLUSIONS

The subscapularis muscle is highly morphologically variable. Knowledge of particular types of insertion is essential for both clinicians (for example orthopedists, physiotherapists) and anatomists.

Quadriceps or multiceps femoris?-Cadaveric study

PURPOSE

The quadriceps femoris (QF) consists of four muscles: the rectus femoris; vastus medialis; vastus lateralis, and vastus intermediate. The tendons of all of these parts join together into a single tendon that attaches to the patella. The QF is a powerful extensor of the knee joint that is needed for walking. A growing number of publications have examined the fifth head of the QF muscle. There is no information about the possibility of other heads, and there is no correct classification of their proximal attachments. Further, the frequency of occurrence of additional heads/components of the QF remains unclear.

METHODS

One hundred and six lower limbs (34 male and 18 female) fixed in 10% formalin solution were examined.

RESULTS

Additional heads of the QF were present in 64.1% of the limbs. Three main types were identified and included subtypes. The most common was Type I (44.1%), which had an independent fifth head. This type was divided into two subtypes (A-B) depending on its location relative to the vastus intermediate. The second most common type was Type II (30.8%), which originated from other muscles: IIA from the vastus lateralis; IIB from the vastus intermediate, and IIC from the gluteus minimus. In addition, Type III (25%) was characterized by multiple heads: IIIA-two heads with a single common tendon; IIIB-two heads with two separate tendons; IIIC-three heads (lateral, intermediate, medial), and IIID-four heads (bifurcated lateral and bifurcated medial).

CONCLUSION

The introduction of a new classification based on a proximal attachment is necessary. The presence of the fifth, sixth, seventh, or eighth head varies.

A very rare case of an accessory subscapularis muscle and its potential clinical significance

The subscapularis muscle is the largest muscle of the rotator cuff and its main function is internal rotation. It is morphologically variable in both point of origin and insertion. The presence of an accessory subscapularis muscle can lead to brachial plexus neuropathy. This report presents a very rare accessory subscapularis muscle originating from two distinct bands on the subscapularis and teres major muscles. The insertion was divided among four tendons. The fourth tendon is bifurcated. One of these was connected to the tendon of the subscapularis muscle and the other three inserted into the base of the coracoid process of the scapula. This anomalous muscle has the potential to entrap the nerves of the posterior cord such as the axillary, lower subscapular, and thoracodorsal nerves.

A three-headed plantaris muscle: evidence that the plantaris is not a vestigial muscle?

The plantaris is a small muscle that typically originates at the lateral supracondylar line of the femur and the knee joint capsule, from where it continues distally, forming a long and slender tendon. However, considerable controversy surrounds the status of this seemingly inconspicuous muscle: is it a residual muscle, or one that it is just developing? In addition, both the proximal and distal attachments are highly morphologically variable. These variations can lead to many diseases. Interestingly, the course of the PM tendon is also variable. The present case study presents a new description of a complex origin type and a rare course of the PM tendon. Understanding of the PM and its tendon has clear clinical value and is a significant indicator of the development of interest in this overlooked muscle.