Middle cluneal nerve entrapment sites in the surgical field.

INTRODUCTION: Middle cluneal nerve (MCN) entrapment around the sacroiliac joint elicits low back pain (LBP). For surgical decompression to be successful, the course of the MCN must be known. We retrospectively studied the MCN course in 15 patients who had undergone MCN neurolysis. METHODS: Enrolled in this retrospective study were 15 patients (18 sides). We inspected their surgical records and videos to determine the course of the entrapped MCN. The area between the posterior superior- and the posterior inferior iliac spine was divided into areas A-D from the rostral side. The MCN transit points were identified at the midline and the lateral edge connecting the posterior superior- and posterior inferior iliac spine. Before and 6 months after surgery, the patients recorded the degree of LBP on the numerical rating scale and the Roland-Morris Disability Questionnaire. RESULTS: We decompressed 24 MCNs. The mean number was 1.3 nerves per patient (range 1-2). The MCN course was oblique in the cranio-caudal direction; the nerve tended to be observed in areas C and D. In six patients (40%), we detected two MCN branches, they were in the same area and adjacent. Postoperatively, LBP was improved significantly in all patients. CONCLUSION: Between the posterior superior- and the posterior inferior iliac spine, the MCN ran obliquely in the cranio-caudal direction; it was prominent in areas on the caudal side. In six (40%) patients, we decompressed two adjacent MCNs. Our findings are useful for MCN decompression surgery.

Intramuscular innervation of the tensor fasciae latae: Application to total hip arthroplasty.

The aims of this study were to clarify the extra- and intramuscular branching patterns of the tensor fasciae latae (TFL) with reference to surface landmarks on the thigh and to thus suggest a safe approach for total hip arthroplasty. Sixteen fixed and four fresh cadavers were dissected and subjected to the modified Sihler's staining method to reveal the extra- and intramuscular innervation patterns, and the findings were matched with surface landmarks. The landmarks were measured from the anterior superior iliac spine (ASIS) to the patella and divided into 20 parts along the total length. The average vertical length of the TFL was 15.92 ± 1.61 cm, which was 38.79 ± 2.73% when converted to a percentage. The entry point of the superior gluteal nerve (SGN) was an average of 6.87 ± 1.26 cm (16.71 ± 2.55%) from the ASIS. In all cases, the SGN entered parts 3-5 (10.1%-25%). As the intramuscular nerve branches traveled distally, they had a tendency to innervate more deeply and inferiorly. In all cases, the main SGN branches were intramuscularly distributed in parts 4 and 5 (15.1%-25%). Most tiny SGN branches were found inferiorly in parts 6 and 7 (25.1%-35%). In three of 10 cases, very tiny SGN branches were observed in part 8 (35.1%-38.79%). We did not observe SGN branches in parts 1-3 (0%-15%). When information on the extra- and intramuscular nerve distributions was combined, we found that the nerves were concentrated in parts 3-5 (10.1%-25%). We propose that damage to the SGN can be prevented if parts 3-5 (10.1%-25%) are avoided during surgical treatment, particularly during the approach and incision.

Cluneal neuropathy: Background, diagnosis, and treatment.

BACKGROUND AND AIMS: Cluneal neuropathy is encompassed by three distinct clinical entities. Superior, middle, and inferior cluneal neuralgia make up the constellation of symptoms associated with cluneal neuropathy. Each has its own variable anatomy. MATERIALS AND METHODS: We compiled a narrative review including a review of available literature. We conducted searches on PubMed/MEDLINE, Embase and Google Scholar on the topics of cluneal neuropathy and treatment therein. RESULTS: We collected source articles regarding original descriptions of the disease entities in addition to articles focused on treatment. DISCUSSION: Adjusted incidence rates of superior cluneal neuropathy are 1.6%-11.7%. Accurate diagnosis remains challenging due to the lack of standardized criteria and the aforementioned variability. Treatment may include therapeutic nerve blocks, ablative techniques, neuromodulation, and surgical decompression. Gaps including those related to true incidence and work up exist. Outcomes from interventional studies are limited and mixed due to significant population heterogeneity and non-standardized treatment approaches coupled with very small sample sizes.

Cluneal nerve release: a systematic review.

BACKGROUND: Despite the heterogeneity of chronic lower back pain aetiologies, cluneal nerve entrapment remains underdiagnosed and poorly understood with few studies discussing the efficacy of its surgical release. OBJECTIVE: The current study opts to conduct a systematic review reporting on the efficacy of cluneal nerve surgical decompression in patients with an established diagnosis who fail conservative treatment. We aimed to systematically evaluate the literature regarding the clinical outcomes, recurrence of symptoms and revision rates of surgical intervention. METHODS: A systematic review of the English language literature dating up until May 2022 was undertaken according to the PRISMA guidelines. Isolated case reports were excluded. RESULTS: Of a total of 54 articles, 4 studies met the inclusion criteria (three were level IV evidence and one level III evidence) and were analyzed. Overall, 98 patients of mean age 61 years, (range 17-86) underwent cluneal nerve release with a mean follow-up of 25.5 months (6-58 months). There was significant improvement in symptoms post operatively in the 4 studies. No systemic or local complications were encountered during the surgeries. Four articles reported on revision surgery for recurrent symptoms in 8 patients out of 98 with a rate of 8.2%. Of the reoperated patients, 7/8 had new branches released that were not addressed initially and 1 had neurectomy for an adhered pre-released branch. CONCLUSION: This systematic review demonstrated that cluneal nerve decompression has been performed in a total of 98 patients with significant clinical improvement, zero systemic and local complications and revision rates of 8.2% of the cases.

Simultaneous Posterior Femoral Cutaneous Nerve and Sciatic Nerve Variations: A Case Report.

During the routine dissection of a formalin fixed Caucasian cadaver, a previously unreported variation of the sacral plexus was found in the right gluteal region. The posterior femoral cutaneous nerve was found to pierce the piriformis muscle as opposed to running along its more common course below the muscle. At the same level of the posterior femoral cutaneous nerve, the common fibular nerve also pierced the piriformis muscle, while the tibial nerve passed inferior to the piriformis muscle. No other anatomical variations were found.

Review of Interventional Treatments for Cluneal Neuropathy.

BACKGROUND: The most common presentation of cluneal neuropathy is ipsilateral low back and gluteal pain. Cluneal neuralgia has been described historically in surgical contexts, with much of the description and treatment related to entrapment and decompression, respectively. Treatment options for addressing axial low back pain have evolved with advancements in the field of interventional pain medicine, though clinical results remain inconsistent. Recent attention has turned toward peripheral nerve stimulation. Nonsurgical interventions targeting the superior and medial cluneal nerve branches have been performed in cases of low back and buttock pain, but there is no known review of the resulting evidence to support these practices. OBJECTIVES: In this manuscript we provide a robust exploration and analysis of the available literature regarding treatment options for cluneal neuropathy. We provide clinical manifestations and recommendations for future study direction. STUDY DESIGN: Narrative review. METHODS: This was a systematic, evidence-based narrative, performed after extensive review of the literature to identify all manuscripts associated with interventional treatment of the superior and medial cluneal nerves. RESULTS: Eleven manuscripts fulfilled inclusion criteria. Interventional treatment of the superior and middle cluneal nerves includes blockade with corticosteroid, alcohol neurolysis, peripheral nerve stimulation, radiofrequency neurotomy, and surgical decompression. LIMITATIONS: The supportive evidence for interventions in cluneal neuropathy is largely lacking due to small, uncontrolled, observational studies with multiple confounding factors. There is no standardized definition of cluneal neuropathy. CONCLUSION: Limited studies promote beneficial effects from interventions intended to target cluneal neuropathy. Despite increased emphasis and treatment options for this condition, there is little consensus on the diagnostic criteria, endpoints, and measures of therapeutics, or procedural techniques for blocks, radiofrequency, and neuromodulation. It is imperative to delineate pathology associated with the cluneal nerves and perform rigorous analysis of associated treatment options.

Superior and Middle Cluneal Nerve Entrapment: A Cause of Low Back and Radicular Pain.

BACKGROUND: The superior and middle cluneal nerves are sources of low back, buttock, and leg pain. These nerves are cutaneous branches of the lateral branches of the dorsal rami of T11- S4. Pain arising from entrapment or dysfunction of one or more of these nerves is called "cluneal nerve syndrome." A clear understanding of the anatomy underlying cluneal nerve syndrome and its treatment has been hampered by the very small size of the cluneal nerves and their complex, varying anatomy. Because of differing methods and foci of investigation, the literature regarding cluneal nerves has been confusing and even contradictory. OBJECTIVES: This paper provides a thorough critical literature review of cluneal nerve anatomy and implications for therapy. STUDY DESIGN: A modified scoping review. METHODS: The bibliographic trail of English language papers on the anatomy and treatment of cluneal nerve syndrome was used to resolve the contradictions that have appeared in some of the anatomic descriptions and, where applicable, to examine their implications for therapy. RESULTS: Recent anatomic and surgical investigations confirm a wider than previously realized range of central nervous system origins of these peripheral nerves, explaining why cluneal nerve dysfunction can cause a wide array of symptoms, including low back, buttock, and/or leg pain or "pseudosciatica." CONCLUSIONS: Cluneal nerve syndrome is characterized by a triad of pain, tender points, and relief with local anesthetic injections. The pain is a deep, aching, poorly localized low back pain with variable involvement of the buttocks and/or legs. Tender points are localized at the iliac crest or caudal to the posterior superior iliac spine. Muscle weakness and dermatomal sensory changes are absent in cluneal nerve syndrome. If the pain returns after injections, neuroablation, nerve stimulation, or surgical release may be needed.

Morphometric study of sciatic nerve and its topographic anatomical variations in relation to landmark structures around pelvis: a Nigerian population study.

BACKGROUND: Sciatic nerve (SN) presents significant variations that pertain to its topography and divisions. The topographic variation shows sex effect due to differences in the dimension of pelvis that makes for the adaptability of female pelvis for pregnancy and childbirth. The objective therefore was to evaluate the SN morphology and its topographical variations in relation to landmark structures in the pelvis of both sexes. MATERIALS AND METHODS: Ninety-eight lower limb adult cadavers, 66 males and 32 females devoid of any gross pathology from Nigerians were used for the study. The cadavers were dissected to expose the SNs and the variations recorded. Anthropological measurements were taken and analysed using a Spearman's rank-order correlation model. RESULTS: The relationships between SN and the piriformis muscle shows five varied types with the typical type comprising 83.0%. The largest thickness of SN in males and females were 18.5 cm and 17.3 cm, respectively while the smallest thickness were 8.6 cm and 11.9 cm, respectively. The dimensions between posterior superior iliac spine and greater trochanter (PSIS-GT) and between lateral edges of SN intersection with piriformis to the tip of greater trochanter (LESN-GT) shows inverse correlation relationship between the two sexes. In males, there was a weak positive correlation (rs = 0.165) between LESN-GT (4.75 ± 1.52) and PSIS-GT (15.3 ± 2.90) which was not statistically significant at 0.01 level (p = 0.989). In females, the relationship between LESN-GT (6.39 ± 0.59) and PSIS-GT (12.2 ± 3.70) shows moderate negative correlation (rs = -0.476) which was not statistically significant at 0.01 level (p = 0.195). CONCLUSIONS: The dimension of LESN-GT which was observed to be longer in females was deemed to account for the deviation of sciatic nerve of females from the males' topographic anatomical relations.

An overlooked nerve in neuropathies associated with intragluteal injections: the posterior femoral cutaneous nerve.

OBJECTIVE: The aim of this study was to investigate the frequency of posterior femoral cutaneous nerve (PFCN) lesions in patients referred to the electrophysiology laboratory with an initial diagnosis of sciatic nerve lesion following injection, and to create awareness that PFCN lesions can occur following intramuscular injections administered to the gluteal region. METHODS: Fifty-seven patients who were referred to the electrophysiology laboratory because of injection neuropathy were identified from the hospital records. In addition to the routine electrophysiological examination, PFCN sensory conduction study was performed according to the technique of Dumitru and Nelson. The scores of the Hospital Anxiety and Depression Scale (HADS) and the Leeds Assessment of Neuropathic Symptoms and Signs Pain Scale were recorded for all participants. RESULTS: Of the 21 participants who agreed to participate in the study, 2 patients were diagnosed with PFCN lesions, one of them had isolated complete PFCN lesion, and another had it accompanied by sciatic nerve lesion. Patients with PFCN lesions had a lower body mass index and a higher HADS score than patients with sciatic nerve lesions (p = 0.01, p = 0.04, respectively). CONCLUSIONS: As correct diagnosis is the priority starting point for successful treatment, clinicians should plan examinations taking into consideration the fact that PFCN lesions can occur following gluteal region injection.

Imaging of peripheral nerve causes of chronic buttock pain and sciatica.

Chronic buttock pain is a common and debilitating symptom, which severely impacts daily activities, sleep, and may affect athletic performance. Lumbar spine, posterior hip, or hamstring pathology are usually considered as the primary diagnoses; however, pelvic neural pathology may be a significant cause of chronic buttock pain, particularly if there are prolonged (>6 months) buttock and/or radicular symptoms. The subgluteal space is the site of most pelvic causes of neural-mediated buttock pain, primarily relating to entrapment neuropathy of the sciatic nerve (deep gluteal syndrome), although other nerves within the subgluteal space including the gluteal nerves, pudendal nerve, and posterior cutaneous nerve of thigh may also be involved. Additionally, cluneal nerve entrapment at the iliac crest may result in "pseudo-sciatica". Anatomical variants of the pelvic girdle muscles and functional factors, including muscle spasm and pelvic instability, may contribute to development of deep gluteal syndrome, along with neural senescence. Imaging findings primarily relate to the presence of sciatic neuritis and peri-sciatic pathology, including neural compression and peri-neural adhesions or fibrosis. This imaging review describes the causes, magnetic resonance imaging and ultrasound imaging findings and imaging-guided treatment of pelvic neural causes of chronic buttock pain and sciatica.

Anatomic landmarks for a safe arthroscopic approach to the deep gluteal space: a cadaveric study / Hitos anatómicos para un abordaje artroscópico seguro del espacio glúteo profundo: un estudio cadavérico

SUMMARY: To determine the morphometric landmarks and anatomical variants relevant to the arthroscopic approach to the deep gluteal space. Twenty deep gluteal spaces from cadaveric specimens were dissected. The anatomical variants of the sciatic nerve (SN) were determined according to the Beaton and Anson classification. A morphometric study of the distances in the subgluteal space was carried out to define the anatomical references to achieve a safe arthroscopic approach for piriformis syndrome [GT-SN=Distance from greater trochanter (GT) to SN emergence; GT-IT=Distance from GT to ischial tuberosity (IT); GT-IGA=distance from GT to inferior gluteal artery (IGA) emergence; IT-SN=distance from IT to SN emergence; IT-IGA=distance from IT to IGA]. The SN showed the most frequent anatomical pattern with an undivided nerve coming out of the pelvis below the piriformis muscle (Beaton type A) in 16 specimens (80 %). The common peroneal nerve emergence in the subgluteal space through the piriformis muscle (PM) with the tibial nerve being located at the lower margin of the piriformis muscle (Beaton type B) was observed in 4 specimens (20 %). The morphometric measurements of the surgical area of study were: GT-SN=7.23 cm (±8.3); GT-IT=8.56 cm (±0.1); GT-IGA=8.46 cm (±0.97); IT-SN=5.28 cm (±0.73), IT- IGA=5.47 cm (±0.74). When planning surgery for the deep gluteal syndrome in adult patients, the fact that the emergence of the SN in the subgluteal space is approximately 7 cm from the greater trochanter and 5 cm from the ischial tuberosity must be considered.

RESUMEN: El objetivo del estudio fue determinar referentes morfométricos y variantes anatómicas relevantes en el abordaje artroscópico del espació subglúteo. Se disecaron veinte regiones glúteas procedentes de cadáver. Las variaciones anatómicas del nervio ciático (SN) se determinaron de acuerdo con la clasificación de Beaton y Anson. Se llevó a cabo un estudio morfométrico de distancias en el espacio subglúteo, con objeto de determinar referencias que permitan un abordaje artroscópico seguro del sindrome piriforme [GT-SN= distancia trocánter mayor (GT) a la emergencia del nervio ciático (SN); GT-IT= distancia GT a la tuberosidad isquiática (IT); GT-IGA= distancia GT a la emergen- cia de la arteria glútea inferior (IGA); IT-SN= distancia IT a la emergencia del SN; IT-IGA= distancia IT a la IGA]. El patrón más frecuente del SN fue su emergencia no dividida por el margen inferior del músculo piriforme (tipo A Beaton) en 16 especímenes (80 %). La salida del nervio fibular común a través del músculo piriforme (PM) con el nervio tibial localizado en el margen inferior del PM (tipo B Beaton) se observó en 4 especímenes (20 %). Las medidas en el área quirúrgica de estudio fueron: GT-SN= 7,23 cm ± 8,3; GT-IT= 8,56 cm ± 0,1; GT-IGA= 8,46 cm ± 0,97; IT-SN= 5,28 cm ± 0,73 IT-IGA= 5,47 cm ± 0,74. En la cirugía del síndrome glúteo profundo en adultos, debe considerarse que la sa- lida del SN hacia el espacio subglúteo tiene lugar aproximadamente a 7 cm del GT y a 5 cm de la IT.

Neuromuscular variations in the gluteal region - Embryological basis and clinical significance.

ABSTRACT: Piriformis, is a key muscle in the gluteal region. Under its lower border sciatic nerve and inferior gluteal nerves exit. During routine educational dissection of the lower limb, bilateral gluteal regions in fifteen cadavers (30 gluteal regions) focusing on the variations of inferior gluteal nerve and sciatic nerve with respect to piriformis muscle were observed in the department of anatomy, All India Institute of Medical Sciences, New Delhi, India. In one of the left sided specimens, inferior gluteal nerve had an abnormal course, piercing superior belly of piriformis muscle instead of emerging through the lower border of it along with variation of the sciatic nerve. The common peroneal component of the sciatic nerve was coming out between the two anomalous tendinous slips of the piriformis muscle, whereas the tibial component, emerged along lower border of the piriformis muscle bilaterally in the same cadaver. In the remaining cadavers, there were no variations of the inferior gluteal nerve with respect to the piriformis muscle. But in another cadaver, there was a similar variation of the sciatic nerve bilaterally. Inferior gluteal and sciatic nerves, when compressed by muscle belly or tendinous slips of the piriformis muscle, may cause lurching gait and sciatica respectively. Knowledge of the different variations of these peripheral nerves with respect to the piriformis muscle is important to clinicians and surgeons for the accurate diagnosis and intervention.

Clinical features of middle cluneal nerve entrapment neuropathy.

BACKGROUND: Entrapment of the middle cluneal nerve (MCN), a peripheral nerve in the buttock, can elicit low back pain (LBP). We examined the epidemiology, clinical course, and treatment of MCN entrapment (MCN-EN). METHODS: Among 383 LBP patients who visited our institute, 105 were admitted for intractable LBP. They were 42 men and 63 women; their average age was 64 years. Based on clinical symptoms, palpation, and the effects of MCN block, we suspected MCN-EN in these 105 patients, 50 of whom are our study subjects. Their treatment outcomes were assessed at the time of discharge and at follow-up visits. RESULTS: MCN-EN was diagnosed in 50 of the 383 patients (13.1%) and they were hospitalized. In 43 (11.2%), MCN-EN was associated with other diseases (superior cluneal nerve entrapment, n = 21, sacroiliac joint pain, n = 9, other, n = 13). At the time of discharge, the symptoms of patients with LBP due to MCN-EN were significantly improved by repeat MCN blocks. In 7 of the 383 patients (1.8%), LBP was improved by only MCN blocks; 5 of them had reported leg symptoms in the dorsal part of the thigh. After discharge, 22 of the 50 hospitalized patients required no additional treatments after 2-5 blocks; 19 required only conservative treatment, and 9 underwent microsurgical release of the MCN. CONCLUSIONS: We confirmed MCN-EN in 50 of 105 patients admitted for intractable LBP. Repeat MCN blocks were effective in 22 patients; 19 required additional conservative treatment, and 9 underwent surgery. Buttock pain radiating to the posterior thigh was an MCN-EN symptom that has been diagnosed as pseudo-sciatica. Before subjecting patients with intractable LBP to surgery, the presence of MCN-EN must be ruled out.

A novel method for predicting superior gluteal nerve safe zones in the lateral approach to the hip.

INTRODUCTION: The superior gluteal nerve (SGN) is at risk for laceration during lateral approach total hip arthroplasty (THA). The purpose of this study is to assess the accuracy of the trochanter-to-iliac crest distance (TCD) and the nerve-to-trochanter distance (NTD) ratio in determining a reproducible safe zone around the SGN independent of height. MATERIALS AND METHODS: Eighteen hemipelvises were dissected and the SGNs were exposed. The distance (NTD) from greater trochanter (GT) to the most inferior branch of the SGN encountered in each of the three approaches (Bauer et al., 1979) was measured. A reference distance (TCD) was measured from the GT to the highest point on the iliac crest. The NTD was divided by the TCD to generate standardized ratios. Coefficient of variation CV = (SD/mean) × 100 was calculated for each distance and ratio to measure relative variability. RESULTS: The standardized ratios (and CV) were determined for the nerve branches in three different surgical approaches: Hardinge 0.464 (0.9%), Bauer 0.406 (1.7%), and Frndak 0.338 (4.1%). There was a strong correlation of the individual NTDs with the TCD: NTD for Hardinge (r = 0.996, p < .001), NTD for Bauer (r = 0.984, p < .001), and NTD for Frndak (r = 0.932, p < .001). CONCLUSION: By measuring the TCD preoperatively and using the respective standardized ratios, surgeons can accurately predict the NTD and how proximal to the GT each SGN branch can be expected to be encountered during lateral approach to the hip. This will allow surgeons to work with a more precise safe zone around the SGN and minimize the possibility for a nerve injury.

High-frequency thermal coagulation to treat middle cluneal nerve entrapment neuropathy.

OBJECTIVE: Middle cluneal nerve entrapment (MCN-E) around the sacroiliac joint can elicit low back pain (LBP). Pain control can be obtained with anesthetic nerve blocks; however, when their effectiveness is transient, surgical release may be necessary. We investigated the efficacy of radiofrequency thermocoagulation (RFTC) in patients with MCN-E. METHODS: Between December 2018 and August 2019, 11 consecutive patients (4 men, 7 women; mean age 76.4 years) with intractable medial buttock pain due to MCN-E underwent MCN RFTC. The mean symptom duration was 49.5 months; pre-RFTC local MCN blocks provided pain relief for a mean of 7.7 days. The severity of pain in the medial buttock due to MCN-E was recorded before and 2, 6, 12, and 24 weeks after RFTC on the numerical rating scale (NRS) and the Roland-Morris Disability Questionnaire (RDQ). RESULTS: All patients reported pain alleviation; there were no complications. While there was a significant difference in the pre- and post-RFTC treatment NRS (p < 0.05), the RDQ scores were significantly lower only after 12 weeks. The duration of pain relief was significantly prolonged by RFTC (p < 0.05). Two patients suffered pain relapse 10 weeks post-RFTC; pain alleviation was obtained by re-RFTC performed 2 weeks after pain recurrence. Two other patients relapsed 20 and 21 weeks post-RFTC; their symptoms also disappeared by MCN block administered 24 weeks after they had undergone RFTC. CONCLUSION: RFTC may safely control intractable LBP due to MCN-E.

Pain Syndromes Secondary to Cluneal Nerve Entrapment.

PURPOSE OF REVIEW: The purpose of this review is to provide an overview of the cluneal nerves, present a summary of pain syndromes secondary to clunealgia, and evaluate current literature for diagnostic and treatment modalities. RECENT FINDINGS: Multiple trials and studies have reported success with numerous modalities ranging from nerve blocks, neuroablation, and even peripheral neuromodulation with varying degrees of clinical benefit. Cluneal nerve entrapment or chronic impingement can cause buttock pain or referred pain to nearby areas including the lower back, pelvic area, or even the lower extremities. Clunealgias and associated pain syndromes can often be challenging to diagnose and differentiate. An appreciation of the pathophysiology of clunealgias can assist with patient selection for interventional pain strategies targeted towards the cluneal nerves, including nerve blocks, neuroablation, and peripheral neuromodulation. More research is needed to better delineate the efficacy of these procedures for clunealgias.

Recommendation of the best site based on the distribution pattern of extramuscular and intramusular nerves for gluteal muscle injection / Recomendación del mejor sitio para la inyección del músculo glúteo basado en el patrón de distribución de los nervios extramusculares e intramusculares

To reveal the extra- and intramuscular nerve distribution patterns of the gluteus maximus, medius, and minimus, and to provide guidance for gluteal muscle injection in order to avoid nerve injury. Ten adult and 10 child cadavers were used. The superior and inferior gluteal nerves innervating the gluteus maximus, medius, and minimus were dissected, exposed, and sutured in-situ on the muscle. The three gluteal muscles were removed, and the distribution patterns of the intramuscular nerves were revealed by modified Sihler's nerve staining. The nerve distribution pattern was returned to the corresponding position in the body, and the patterns in the four quadrants of the buttock were analyzed. There were 3-12 extramuscular nerve branches of the gluteus maximus, medius, and minimus. After entering the muscle, these nerve branches arborized and anastomosed to form an arc-shaped, nerve-dense zone. The nerve distribution was most dense in the inferomedial region of the superolateral quadrant and the inferolateral region of the superomedial quadrant of the buttocks. The nerve distribution was relatively dense in the inferolateral region of the superolateral quadrant, and the medial region of the inferomedial quadrant. An arc-shaped, nerve-sparse zone in the superolateral and superomedial quadrants near the lower iliac crest accounted for about two-fifths of the two quadrants' limits. The arc-shaped, nerve-sparse zone in the superolateral quadrant is the preferred injection site, and the superomedial quadrant near the lower iliac crest is also recommended as a gluteal intramuscular injection region, free from nerve injury.

El objetivo de este trabajo fue revelar los patrones de distribución nerviosa extramusculat e intramuscular de los músculos glúteo máximo, medio y mínimo y proporcionar orientación para la inyección en la región glútea con el propósito de evitar lesiones nerviosas. Se utilizaron diez cadáveres adultos y diez niños. Los nervios glúteos superior e inferior que inervan a los músculos glúteo máximo, medio y mínimo fueron disecados, expuestos y suturados in situ en el músculo. Se extirparon los tres músculos glúteos y se revelaron los patrones de distribución de los nervios intramusculares mediante la tinción nerviosa de Sihler modificada. El patrón de distribución nerviosa se devolvió a la posición correspondiente en el cuerpo y se analizaron los patrones en los cuatro cuadrantes de la región glútea. Se encontraron 3 a 12 ramos nerviosos extramusculares de los músculos glúteo máximo, medio y mínimo. Después de ingresar al músculo, estas ramas nerviosas se arborizaron y anastomizaron para formar una zona densamente nerviosa en forma de arco. La distribución nerviosa fue de mayor densidad en la región inferomedial del cuadrante superolateral y en la región inferolateral del cuadrante superomedial de la región glútea. La distribución nerviosa era relativamente densa en la región inferolateral del cuadrante superolateral y en la región medial del cuadrante inferomedial. Una zona en forma de arco en los cuadrantes superolateral y superomedial y con escasa inervación, cerca de la cresta ilíaca representaba una parte de los límites de los dos cuadrantes. La zona de poca inervación en forma de arco en el cuadrante superolateral es el sitio de inyección preferido, y el cuadrante superomedial próximo a la cresta ilíaca también se recomienda como una región de inyección intramuscular glútea, libre de lesión nerviosa.