Posterior Intermuscular Septum Research Articles

Evaluation of a New Method of Sciatic Nerve Block: A Prospective Pilot Study.

The location of the sciatic nerve deep within the thigh tissue makes it challenging to locate while the patient is in a supine position. The posterior intermuscular septum of the thigh, which encircles the posterior surface of the adductor magnus muscle (AMM), is where the sciatic nerve is located. Our hypothesis was that administering local anesthetic injections into this area could block the sciatic nerve. Therefore, our aim was to evaluate the effectiveness of sciatic nerve block achieved by injecting local anesthetic into the posterior intermuscular septum of the thigh, named the AMM approach. Twenty-six patients undergoing total knee arthroplasty were included in the study. We performed an ultrasound-guided sciatic nerve block by injecting 20 mL of 0.25% ropivacaine into the posterior surface of the adductor magnus muscle, using the AMM approach. Additionally, we administered a femoral nerve block with 20 mL of 0.4% ropivacaine. We assessed the sensory and motor effects of the blockade in the operated lower limb and recorded postoperative pain scores at 0, 4, 8, 12, 24, and 48 hours after the operation. The AMM approach successfully block the sciatic nerve in all 26 patients. The onset of the sensory and motor blockades was achieved within 5.4 ± 1.9 min and 8.7 ± 3.5 min, respectively. We achieved a satisfactory position with the first puncture in 19 of 26 patients (73.1%). The muscle strength of the tibialis anterior immediately after surgery was 4 (ranging from 2 to 5). Additional rescue analgesics were required in 5 of the 26 patients (19.2%) during the first 24 hours postoperatively. The AMM approach is an innovative and effective method for sciatic nerve block. When combined with simultaneous femoral nerve block in patients undergoing total knee arthroplasty, it provides a useful analgesic treatment option.

Discovery of a Bilateral Fibulocalcaneus Externum Invertus Muscle: A Novel Fibularis Quartus Variant

The fibularis (peroneus) quartus is a variant muscle found within the lateral leg compartment in ~11.5% of cadaveric specimens, though recent studies have shown a higher prevalence of ~20.9 – 21.9%. The proximal muscular attachments can originate from the fibula, fibularis brevis, fibularis longus, and/or the intermuscular septi that form the boundaries of the lateral leg compartment, but it then descends to reside posterior to the lateral malleolus of the fibula. The distal attachment of the fibularis quartus varies greatly, and fibularis quartus muscular variants are often named according to location of its distal attachment. The most common distal insertion site of a fibularis quartus muscle is the lateral surface of the calcaneus into either the fibular trochlea or the retrotrochlear eminence. Therefore, this variant of the fibularis quartus inserting into the lateral surface of the calcaneus is called the fibulocalcaneus externum. During routine cadaveric dissection of a 79‐year‐old Caucasian male, a rare and novel variation of the fibularis quartus muscle was discovered. Although this variant is seen arising from the fibula, fibularis brevis, and the posterior intermuscular septum, descending posterior to the lateral malleolus, and attaching distally to the lateral surface of the calcaneus, it is unique in that the muscle is inverted, with the tendonous part being more proximal and the muscular portion arising distally. This novel muscle was found unilaterally in the left leg via dissection initially with its distal head inserting on the fibular trochlea of the calcaneus, but ultrasonographic imaging verified its bilateral presence. The subsequent dissection of the right leg revealed a similar inverted muscle, but this variation split into two distal muscle bellies inserting into the retrotrochlear eminence posteriorly and the fibular trochlear anteriorly. Given its anatomy, we have named this rare fibularis quartus variant the fibulocalcaneus externum invertus muscle. Like most fibularis quartus variants, the fibulocalcaneus externum invertus muscle can cause ankle instability, ankle locking, chronic lateral ankle pain, and peroneal compartment syndrome, especially due to acting as a space‐occupying lesion within the superior peroneal tunnel due to its distal muscle belly/bellies. While it is unknown if this person had any clinical signs and/or symptoms, clinicians, surgeons, and/or radiologists should be aware of the fibulocalcaneus externum invertus when assessing radiological imaging or preparing for ankle surgeries in and around the lateral leg compartment.

Discovery of a Flexor Digitorum Accessorius Longus (FDAL) Muscle – Implications for Tarsal Tunnel Syndrome

The flexor digitorum accessorius longus (FDAL) is a variant posterior leg muscle with a reported incidence of 2-8% of lower limbs. The FDAL can originate from many structures in the lower limb, including the tibia fibula, posterior intermuscular septum, or any muscle within the deep posterior leg compartment.1 The FDAL typically travels through the tarsal tunnel before inserting in the flexor digitorum longus (FDL) or the quadratus plantae. In this case, we present a FDAL variant that originates from the flexor hallucis longus (FHL) and the neurovascular bundle containing the tibial nerve and posterior tibial artery and vein and inserts distally into the FDL. We observed this variant travel superficial to the neurovascular bundle within the tarsal tunnel, closely associated with the tibial nerve. After it traversed the tarsal tunnel, the FDAL variant dove deep to the neurovascular bundle before inserting into the FDL. Because of the size and proximity of the FDAL to the tibial nerve, a person with this accessory muscle may be predisposed to symptoms of tarsal tunnel syndrome.

Correction of exotropia and improved adduction by fixation of the anterior encircling fascia to the medial rectus insertion site following myectomy of the four horizontal rectus muscles for infantile nystagmus

Myectomy of the four horizontal rectus muscles for infantile nystagmus syndrome without a null point may improve visual acuity and quality of life. Exotropia and adduction loss are complications of this procedure, although abduction is typically preserved. We investigated whether adduction loss may be rescued by reestablishing the attachment of the anterior intermuscular septum (AIMS) to the globe at the medial rectus insertion. We present 2 cases of exotropia and adduction loss following myectomy and transposition surgery, where the nasal AIMS and the medial rectus insertion site were joined with nonabsorbable polyester suture. Both patients experienced improvements in eye alignment and adduction. Based on radiologic observations of the posterior displacement of the pulley, or posterior intermuscular septum (PIMS), with medial rectus contraction, we hypothesize that adduction and alignment were improved by providing an anterior site of action for the posterior movement of the PIMS.

New aspect of morphometric study of the superior peroneal retinaculum: pertinent data for surgical repair and reconstruction.

This study was conducted to investigate characteristics, attachments and morphometric parameters of the superior peroneal retinaculum (SPR). Morphology and morphometric details including width, length, thickness and angle of alignment of SPR in 109 embalmed cadaveric legs were investigated. The occurrence of peroneal tendon tear was also noted. Most of SPR originated from the fibrocartilaginous ridge of the lateral malleolus. The SPR might be a single band or split into proximal and distal bands inserted on the posterior intermuscular septum and lateral wall of calcaneus, respectively. Based on the characteristics and insertion patterns, the SPR could be divided into 3 types: type I (double band with subtype Ia and Ib), type II (single band) and type III (single band) with the prevalence of 56.88% (12.84%, 44.04%), 1.83%, and 41.28%, respectively. The average coordinate (X, Y axis) of the midpoint of width at origin measured from the tip of fibula in all types was 7.26±3.15 and 10.45±4.52 mm. The average coordinate of the midpoint at insertion on the posterior intermuscular septum was 24.06±4.94 and 13.35±5.18, and those inserted on the lateral wall of calcaneus was 21.45±7.88 and 13.59±6.73 mm. Prevalence of peroneus brevis (PB) tendon tear was 12.84% (14 cases) and was associated with SPR type Ib with statistical significance. Precise information of the characteristics, morphometric data and coordinates of attachment sites of SPR are essential for surgical procedures and reconstruction.

Safe zones and a technical guide for cerclage wiring of the femur: a computed topographic angiogram (CTA) study.

Cerclage wiring for reduction of complex femoral shaft fractures can create iatrogenic vascular injury. To describe the anatomical relation of blood vessels to the femur and develop a technical guide for safe passage of cerclage wire. CT lower-limb angiographs (CTA) of 80 patients were reviewed and analysed to identify the superficial femoral artery (SFA) and the deep femoral artery (DFA) as well as the relation of those arteries to the femoral cortex. The total length of the femur was measured and divided into eight equal segments (seven levels). At each level, the medial half of the femur was divided into eight sectors labelled A through H and the position of the SFA and DFA was recorded. The shortest distance between the femoral cortex and the SFA and DFA at each level was measured. The data was analysed using STATA version 10.0. The average total femoral length from the tip of greater trochanter to lateral joint line was 402.98±26.16cm. The average distances from the SFA to the femur (d1) for levels 1 through 7 were 37.20±5.0, 32.09±4.74, 27.13±4.19, 27.71±5.46, 23.71±4.40, 13.63±3.59 and 10.08±3.09mm, respectively. The average distances between the DFA and the femur (d2) for levels 1 through 3 were 26.70±4.13, 14.76±3.27 and 9.58±3.79mm, respectively. The position of the SFA is located in sectors B through E at levels 1-3 and in sectors E through H at levels 4-7 and the position of the DFA located in sectors B through F at levels 1-3. Cerclage wiring should be started from the posterior intermuscular septum at the linea aspera. The safe area is the proximal half (midshaft) of the femur where the SFA and DFA lie at a safe distance from the femur. Between the midshaft and the distal 1/4, insertion of the passer must be done meticulously with the tip kept close to posteromedial cortex. Below the distal 1/4, the tip of the passer should be kept close to the posterior cortex to avoid injury to the SFA and the sciatic nerve.

Supernumerary muscle of tarsal tunnel: a case report

AbstractSupernumerary muscles are an infrequent fmding during dissections around the ankle. This report focusses on the finding of one such muscle which was found in the tarsal tunnel of the left lower limb unilaterally during routine dissection of a 70 year old male cadaver in Bankura Sammilani Medical College, West Bengal.This supernumerary muscle had a single head of origin from the flexor hallucis longus and posterior intermuscular septum and was traced to its insertion into the flexor digitorum accessorius in the sole and hence was named flexor digitorum accessorius longus, and its relations with the neurovascular bundle were noted. Flexor digitorum accessorius longus may be a cause of tarsal tunnel syndrome so it should be kept in mind during its management. It may also produce symptoms mimicking soft tissue tumors. Thus knowledge of this muscle will be of utmost importance to anatomists, clinicians, radiologists and athletes.

Ultrasound analyses, anatomical considerations, and clinical experience with the peroneus brevis muscle flap

This ultrasound study investigated the frequency, location, and diameter of segmental blood supply of 34 lower legs in relation to muscle size. Furthermore, we investigated the possibilities and constraints of distally pedicled peroneus brevis muscle flaps, which allow defect coverage down to the medial as well as the lateral ankle. In the proximal part of the peroneus brevis muscle, blood is supplied by branches from the anterior tibial artery that perforate the anterior intermuscular septum; in the distal part of the muscle, blood is supplied by branches from the peroneal artery that perforate the posterior intermuscular septum. All lower legs showed at least one perforating vessel penetrating the posterior intermuscular septum. In all, 32.4% of the legs showed two perforators and 17.6% three perforators. The average position of the most distal perforator was 4.8cm proximal to the tip of the malleolus lateralis. Based on this blood supply, muscle tissue measuring up to 15-20cm can be harvested and rotated by 180° to cover defects of the lower ankle. Our ultrasound study is supplemented by an anatomical dissection and two clinical cases of successful defect coverage with the distally pedicled peroneus muscle flap.

The peroneus quartus muscle: clinical correlation with evolutionary importance

The peroneus quartus (PQ) is an accessory muscle of the peroneal/lateral compartment of the leg. The muscle has often been implicated as a cause of pain in the lateral ankle region, and subluxation or attrition of the peroneal tendons. The present study was aimed at observing the prevalence and morphology of this muscle in human cadavers. Ninety-two embalmed lower limbs were dissected for this study. The PQ muscle was found in 21% of the limbs. In all these limbs it originated from the lower part of the lateral surface of the fibula, the undersurface of peroneus brevis and the posterior intermuscular septum. In the majority of limbs, insertion was on the retrotrochlear eminence of the calcaneus. Taking into account the possibility of this muscle being a cause of lateral ankle pathology, the present study attempts to correlate the findings with the anatomy of the surrounding region. The frequent occurrence of this muscle in humans is suggestive of a progressive evolutionary change to evert the foot in order to assume a bipedal gait.

The fibulocalcaneus (peroneocalcaneus) internus muscle of MacAlister: Clinical and surgical implications

A fibulocalcaneus (peroneocalcaneus) internus (PCI) muscle (of MacAlister) was identified and photographed in the left leg of a 78-year-old Caucasian female cadaver. This case study provides the first gross anatomical photo of this anomalous leg muscle and represents the first gross anatomical dissection of this muscle since 1914. The PCI muscle arose from the distal third of the fibula, posterior intermuscular septum of the leg, and flexor hallucis longus muscle. The PCI muscle inserted into the inferior surface of the medial calcaneus distal to the coronoid fossa, a small depression between the anterior tuberosity and the anterior apex of the sustentaculum tali. This insertion point differs from the historical literature, which commonly refers to the muscle inserting into the inferior surface of the sustentaculum tali of the calcaneus or simply distal to the sustentaculum tali into the medial aspect of the calcaneus. The PCI muscle is one of the least common muscular variants associated with the ankle joint, and it has been implicated in posterior ankle pain and impingement, as well as involvement in tarsal tunnel syndrome. This muscle is often confused with the flexor digitorum accessorius longus (FDAL) muscle. Additionally, this study describes ways to differentiate between the PCI and FDAL muscles in the lower leg. Radiologists and clinicians should be aware of this anomalous muscle when considering various diagnoses, interpreting radiographs, and pursuing surgical intervention to relieve posterior ankle symptoms.

Raising the Osteocutaneous Fibular Flap for Oral Reconstruction With Reduced Tissue Alteration

Raising the osteocutaneous fibular flap offers excellent possibilities for oral reconstructive surgery but is associated with specific donor-site risks. Moreover, with inadequate surgical technique, flap-specific complications can occur, such as loss of the skin paddle or inadequate pedicle length. A flap-raising technique has been used to decrease surgical damage but provide maximal pedicle length. Sixty-six osteocutaneous fibular flaps were raised by the lateral approach with the following modifications: 1) flap-raising was carried out without a tourniquet, 2) only the amount of bone needed was removed, leaving the rest of the fibula intact, 3) only a minimal muscle cuff was included, and 4) the complete pedicle was dissected along the posterior intermuscular septum without opening the interosseous membrane and without touching the deep flexor muscles proximal to the osteotomized fibular segment. The skin paddle was placed distally in the leg, perfused by only 1 perforator in most cases. Medical records were analyzed and patients were examined postoperatively for up to 32 months to evaluate the above-mentioned complications. Of the 66 reconstructions, 44 were performed in a previously operated or irradiated neck. Three flaps and 1 skin paddle were lost. The most common donor-site complications were temporary wound-healing disturbances of the skin graft (n = 17) and transient pain or sensory alterations (n = 12). No compartment syndrome, ankle instability, or need for walking aids was recorded. A hammertoe deformity developed in 1 patient. On average, pedicle length was 9 cm and flap-raising took 130 minutes. In conclusion, maximal pedicle length and minimal bone and muscle resections can be achieved with a small number of donor-site complications. The skin paddle is highly reliable based on only 1 perforator. Perforators can be precisely controlled when raising the flap in the perfused leg.

Anatomy of the Superior Peroneal Tunnel

Standard texts of anatomy provide cursory and varied descriptions of the superior peroneal retinaculum and the contents of the tunnel formed by it. The available clinical literature suggests that the boundaries and contents of the superior peroneal tunnel have a direct bearing on the causation of peroneal tendinopathies. Knowledge of the anatomy of this region is essential for successful diagnosis and treatment. Fifty-eight embalmed lower limbs were dissected and the boundaries and contents of the superior peroneal tunnel were ascertained. Sixty dry fibulas were also studied to observe the contour of the retromalleolar groove. The tunnel was spacious, with the superior peroneal retinaculum forming its roof. The floor of the tunnel has an osseous and a nonosseous component. The osseous component is formed by the retromalleolar groove of the fibula, and the nonosseous component is formed by the lower part of the posterior intermuscular septum of the leg. Muscle fibers of the peroneus brevis muscle were the most frequent additional contents followed by an aberrant muscle, termed the peroneus quartus. A split peroneus brevis tendon, a double peroneus longus tendon, and an accessory peroneal nerve were some of the variants observed. In the study of the dry fibulas, it was observed that the contour of the retromalleolar groove was constantly concave. The study suggests that frequent additional structures can normally exist within the spacious superior peroneal tunnel. The retromalleolar groove has a concave contour and forms only a part of the floor of the tunnel and so is an unlikely cause of tendinopathies. The findings may facilitate radiographic evaluation of the tunnel and lead to improvements in the treatment of peroneal tendinopathies.

Bilateral accessory flexor digitorum longus muscle in man

An accessory muscle (flexor digitorum longus accessorius) was encountered in the deep posterior compartment of both legs of a 57-year-old male cadaver. The muscle originated with two heads from the medial margin of the tibia, lateral margin of the fibula, posterior intermuscular septum and the deep fascia at the distal part of the leg. Both heads came together just posterior and superficial to the tibial nerve, and converged into a slender tendon which traversed the tarsal tunnel in the vicinity of the neurovascular bundle to reach the sole of the foot. It terminated by merging into the tendon of the quadratus plantae muscle. The potential of such an anomalous muscle to lead to misinterpretations of the radiodiagnostic examinations and the fact that it can be one of the causes of tarsal tunnel syndrome should be borne in mind.

Sensate osteocutaneous fibula flap: anatomic study of the innervation pattern of the skin flap.

For oromandibular reconstructions, an osteocutaneous fibula flap provides sufficient bone and pliable skin. Sensory reinnervation could possibly prevent problems in mastication and deglutition. In this anatomic study, 33 cadaver limbs were microsurgical dissected. We investigated the lateral sural cutaneous nerve (LSCN), which supplies sensation to the skin of the lateral lower leg, in relation to the fibula skin flap. The fibula is vascularized by the peroneal vessels via the posterior intermuscular septum. Therefore, the posterior septum determines the center line of the flap design. The LSCN runs in 74% of the dissections posterior to the posterior septum, whereas an anterior branch was seen in 26%. In 54% of the dissections, the distance to the posterior septum was within 3 cm from the septum, whereas in 86%, the distance was found to be within 4 cm. The skin flap should be designed more posteriorly to achieve maximal reinnervation.

Microsurgical anatomy of the lateral skin flap of the leg.

The blood supply, venous drainage, and innervation of the lateral skin flap of the leg were studied in 52 fresh specimens by dissection, angiography, and selected injection of cutaneous arteries with india ink. This flap has a long vascular pedicle that contains the peroneal artery and vein and their branches. The diameter of the peroneal artery is about 3.7 mm. There are 4 to 7 cutaneous branches that penetrate the posterior intermuscular septum and widely anastomose with each other in the subcutaneous tissue. The skin area supplied by the peroneal artery measures approximately 32 X 15 cm. There are 2 sets of veins in the flap: (1) 2 deep veins, the peroneal veins, are about 4 mm in diameter, and (2) a superficial vein, the small saphenous vein, is about 3.3 mm in diameter. The cutaneous nerve is the lateral sural cutaneous nerve. This new lateral skin flap of the leg may be used either as a free flap or as a cutaneous flap and has been proven successful clinically.