Structural diversity of the vastus intermedius origin revealed by analysis of isolated muscle specimens

Is there a relationship between knee crepitus with quadriceps muscle thickness and strength in individuals with patellofemoral pain? A cross-sectional study

OBJECTIVE

To explore the relationship between knee crepitus, quadriceps muscle thickness and isometric strength in individuals with patellofemoral pain (PFP).

DESIGN

Cross-sectional.

PARTICIPANTS

Individuals with PFP.

MAIN OUTCOME MEASURES

Participants with PFP underwent assessments for presence, frequency and severity of knee crepitus. Real-time ultrasound images of the quadriceps muscles (rectus femoris, vastus medialis and lateralis) at rest and during contraction were obtained, muscle thickness was measured in both conditions. Maximal voluntary isometric contraction tests were performed to measure knee extensor strength. The relationship between knee crepitus and quadriceps muscle thickness and knee extensor strength was explored using logistic and linear regressions.

RESULTS

Sixty individuals with PFP were included (age: 24; 60% women; 38% with crepitus). Knee crepitus severity was related to rectus femoris and vastus medialis thickness during rest (R2 = 0.19 and 0.09, respectively) and contraction (R2 = 0.16 and 0.07, respectively) and with vastus lateralis during contraction (R2 = 0.08). Isometric knee extensor strength was not related to knee crepitus presence, frequency, or severity.

CONCLUSION

Higher severity of knee crepitus is related to lower quadriceps muscle thickness in individuals with PFP. There is no relationship between the presence and frequency of knee crepitus with quadriceps muscle thickness or knee extensor strength.

Anatomy, Morphology and Function of the Tensor of Vastus Intermedius: A Systematic Review

The tensor of vastus intermedius is a newly discovered muscle that is located at the anterior compartment of the thigh. The aim of the present study is to report, assess and synthetize the existing evidence on the anatomy, variation and morphological characteristics of the TVI as well as to examine its clinical importance. A systematic review was performed evaluating both anatomical and medical imaging studies which provided information about TVI anatomy, prevalence, variations and morphological characteristics. The search strategy was conducted in major electronic databases. Two reviewers worked independently to screen all possible references via a title/abstract examination. Methodological quality was examined with the Anatomical Quality Assurance checklist. A total of 295 cadaveric knees were included in the nine studies where in 244 (82.7%) cases the TVI was identified. Based on this evidence, it appears that the TVI is located between the vastus lateralis and vastus intermedius. The muscle belly is located proximally, and it is combined with a broad and flat aponeurosis before forming a tendinous structure that is attached at the medial aspect of the patella. The TVI presented some morphological variations and complex muscle architecture that varied along its length. There is insufficient good quality evidence as more than half of the included studies were ranked as having a "High" risk of bias with various methodological issues. Higher quality studies are recommended to evaluate the TVI morphology to better understand its functional and clinical importance.

Epimuscular myofascial force transmission from biarticular rectus femoris elongation increases shear modulus of monoarticular quadriceps muscles

This study aimed to examine the effect of rectus femoris (RF) elongation with passive hip angle change on the shear moduli of the vastus lateralis (VL) and medialis (VM) to verify whether Epimuscular myofascial force transmission (EMFT) occurs in the human quadriceps. Fourteen healthy men participated in this study. The shear moduli of the RF, VL, and VM were measured in four hip positions: flexion (Flex), extension and abduction (Ext-Abd), extension (Ext), and extension and adduction (Ext-Add). As the behavior of shear moduli may differ depending on the parts of the vasti muscles, we measured the medial and lateral parts of the VL (Medial-VL and Lateral-VL) and VM (Medial-VM and Lateral-VM). The shear moduli at the Ext and Ext-Add positions were higher than at the Flex position in the RF, VL, and VM. The shear moduli during Ext and Ext-Add were higher than at the Ext-Abd in the RF, VL, and Lateral-VM. Moreover, the shear modulus of the Lateral-VM was higher than of the Medial-VM (Flex: 8.5% higher; Ext-Abd: 15.6%; Ext: 30.2%; Ext-Add: 32.6%). The shear moduli of the VL and VM, which are monoarticular muscles of the knee, increased with passive hip extension or adduction with extension, even when the knee angle was kept constant. The results suggest that EMFT occurs in the quadriceps, and EMFT had a great impact in the Lateral-VM, which is anatomically adjacent to the RF, but it had little effect in the Medial-VM, which is further away from the RF.

Three-dimensional modelling of human quadriceps femoris forces

Quadriceps intramuscular anatomy is typically described in two dimensions. However, anatomical descriptions indicate fascicles in the quadriceps may have a three-dimensional orientation. The purpose of this investigation was to quantify the maximum force generating capacity of the individual quadriceps' muscles in three dimensions. Muscle architectural parameters were obtained from three cadaver specimens (two female) and input into a geometry-based multiple fascicle muscle force model. Vastus lateralis, vastus medialis, and rectus femoris had partitions which could be defined based on differences in the sense and direction of fascicles between partitions. Vastus lateralis and rectus femoris were bipennate due to partitions sharing an aponeurosis. Vastus lateralis deep and superficial partitions exerted posterior- (maximum: -29 ± 5 N) and anterior-directed (maximum: 58 ± 15 N) forces on their shared distal aponeurosis. Rectus femoris medial and lateral partitions exerted medial- (maximum: -38 ± 17 N) and lateral-directed (maximum: 19 ± 12 N) forces on their shared proximal aponeurosis. All vastus medialis fascicles ran along the proximal-distal axis. However, fascicles arising near the lesser trochanter also ran along the superficial-deep axis, while fascicles arising from the linea aspera ran along the medial-lateral axis. Thus, vastus medialis could be divided into longus and oblique partitions. Due to the large pennation angle, vastus medialis oblique could exert maximum medial-directed (-219 ± 93 N) and proximal-directed (279 ± 168 N) forces at approximately -40° and -70° knee flexion, respectively, indicating dual roles for vastus medialis oblique dependent on knee flexion angle.

Gross anatomical investigation of the muscular head between the vastus lateralis and intermedius in the Japanese population: a cadaver study

Unlike the general understanding of the quadriceps femoris, the existence of a new muscular head between the vastus lateralis and the vastus intermedius was reported, and named the tensor of the vastus intermedius in the Swedish population. The purpose of this study was to investigate the presence and form of the muscular head in the Japanese population and to clarify its structure by gross anatomical approaches. A total of 35 thighs of 20 Japanese cadavers were investigated. We searched for the muscular head and classified it into four types. In addition, nerve fiber analysis was performed for each classification type. Regarding classification, 11% were the independent type, 29% were the common type, 37% were the vastus lateralis type, and 23% were the vastus intermedius type. Based on nerve fiber analysis, in the common type, the muscular head was under dual nerve supply from the vastus lateralis and intermedius. The other three types were innervated only by nerves from the vastus lateralis. The target muscular head may always be present in Japanese. The nerves from the vastus lateralis were always distributed in the target muscular head based on nerve fiber analysis; therefore, this muscular head may be most closely related to the vastus lateralis. The name of this muscular head should be "the accessory head of the vastus lateralis" rather than "the tensor of the vastus intermedius."

Triceps, quadriceps or pentaceps femoris? Need for proper muscle definition

INTRODUCTION

Over the last years, the definition of quadriceps femoris (QF) has evolved somewhat and some authors now define a fifth head: the tensor of vastus intermedius (TVI). Descriptions of the different components of QF in textbooks and recent findings remain confusing. Therefore, the aim of this study is to obtain more information on this possible fifth head.

MATERIALS AND METHODS

Twenty lower limbs of 10 embalmed cadavers, six females and four males, were investigated by macro-dissection. The dissection and separation of the different heads were performed with the fingers and a distinction between the different parts of the quadriceps was noted only if it was possible to separate the heads without scalpel to avoid artificial separation of muscle parts.

RESULTS

In 9 lower limbs we found a QF as classically described in textbook. TVI was found in only 7 limbs and in 4 cases we were not able to differentiate VI and VM or VI and VL (triceps femoris as described by Testut). These results, and the diversity of descriptions found in the literature have led us to review the definition of an isolated muscle.

CONCLUSION

In this study, the presence of TVI was not demonstrated in all limbs unlike previously published studies on the subject. Harmonisation of dissection techniques, but also a clear definition of a muscle is required in order to be able to compare studies and draw clear conclusions.