Coincidence between the distribution of myofascial trigger points and the presence of blood vessels in the gastrocnemius muscle: Implications for invasive procedures.

PURPOSE: The gastrocnemius venous system presents different anatomical variants. There have been described four locations of myofascial trigger points (MTrPs) in this muscle. However, no studies have analyzed the coincidence between vessels and MTrPs present in the gastrocnemius. Therefore, the main objective was to study the anatomical variability of the venous system by ultrasound and its coincidence with the location of the MTrPs. METHODS: A total of 100 lower limbs were studied. The gastrocnemius vessels were analyzed one by one by sector (medial, central, and lateral), quantifying the number of vessels, their distribution, and the coincidence with MTrPs. RESULTS: All muscle heads showed at least one vessel per section. A large variability was observed, from one to eight vessels per muscle head, with the most frequent number being three in the gastrocnemius medialis and two in the gastrocnemius lateralis. In all cases, the location of the vessels coincided with the MTrPs. CONCLUSIONS: The proximal gastrocnemius venous pattern is very variable between subjects in number of vessels and distribution, which has made it impossible to define a "safe" approach window for invasive procedures without ultrasound guidance. The coincidence between the clinical location of MTrPs of the gastrocnemius and the presence of vessels is total.

Retrospective evaluation and descriptive analysis of the prevalence of anatomical structures and variations in CBCT images before dental implant planning in a group Turkish population, part I.

PURPOSE: The aim of this study is to emphasize the importance of using cone-beam computed-tomography in order to determine the anatomical structures and their variations before the treatment in patients who apply to the dentist clinic for implant treatment. METHODS: In the study, CBCT images of 500 adult patients (240 female and 260 male), aged between 21 and 82 years, who applied for implant treatment due to missing teeth, were retrospectively analyzed. Anatomical structures and variations such as nasopalatine canal(NPC), canalis sinuosus(CS), antral alveolar artery(AAA), were evaluated in multiplanar reformation(MPR) sections which are axial, sagittal and coronal can be viewed in consistence with each other. RESULTS: The incidence of anatomical variation of CS in the right region was similar according to gender. The "Funnel" appearance of the NPC shape was found most common shape in both female and male patients (n = 89; 37.1% for females and n = 71; 27.3% for males). CONCLUSION: CBCT has become the most popular 3D imaging method in dental practice especially for planning dental implants. Understanding the relationship with important anatomical structures before implant applications is crucial in dealing with potential complications that may arise afterward. Assessing significant anatomical structures by CBCT and taking precautions against possible risks facilitate the work of dentists during and after procedures.

Reappraisal of the anatomical diversities of the pyramidalis muscle with their potential clinical applicability: cadaveric analysis.

INTRODUCTION: The present study examined the morphology and morphometric parameters of the pyramidalis muscle (PM) in detail with their potential applicability in making midline infra-umbilical incisions and biomechanics of the linea alba. METHODS: PM was examined in 51 formalin-fixed cadavers (36 males and 15 females), and based on the mode of insertion or the level of apex, the formation or shape of the muscle was classified into nine types (Mori's classification). RESULTS: Bilateral PM was more prevalent (39.21%) than unilateral (1.96%) (p = 0.001). All the cases showed side symmetry except one. Mori's type 7 (right PM is higher apex and the left PM with elongated origin) was the most common form. The mean length of PM in males and females was 4.51 ± 0.14 and 3.33 ± 0.12 cm on the right and 4.51 ± 0.11 and 3.26 ± 0.16 cm on the left side. The mean width of right-sided PMs in males and females was 1.90 ± 0.17 and 1.58 ± 0.13 cm and left-sided 1.88 ± 0.14 and 1.55 ± 0.38 cm. The mean of pyramidalis-pubo-umbilical index (PPI) in males and females was 32.82 ± 1.65 and 27.50 ± 1.08, respectively. The mean insertion angle was 24.56 ± 3.07 on right side and 23 ± 2.03 on the left side (p = 0.03). Male predominance existed on right- and left-sided PM length (p < 0.001 and p < 0.001), width (p = 0.001) and PPI (p = 0.001). The strong positive correlation (r = 0.83) between length and width indicates a symmetrical muscle augmentation in the two dimensions. CONCLUSION: PM is an inconsistent anatomical structure with persistent morphology. The level and angle of insertion into the linea are crucial in the biomechanics of linea alba. PPI, determining the termination level would be useful to surgeons making midline infra-umbilical incisions.

Exploring celiac trunk parameters in median arcuate ligament syndrome: A CT study.

PURPOSE: To assess anatomical variations in the celiac trunk (Ct) in patients with Median Arcuate Ligament Syndrome (MALS) using computed tomography (CT). The primary objectives were to investigate the celiac trunk angle (CtA), origin level, length (CtL), and their relationships with the superior mesenteric artery (SMA) in MALS patients. Additionally, the study intended to evaluate gender differences in these parameters and explore correlations between variables. METHODS: Retrospectively, reports of abdominal CT scans taken between January 2018, and Sepmtember 2021, in the hospital image archive were screened vey two observers independently for MALS diagnosis. Parameters such as CtA, CtL, Ct-SMA distance, SMA angle (SMAA), and median arcuate ligament thickness (MALT) were measured. Statistical analyses were conducted using SPSS software. RESULTS: Among the 81 patients (25 females, 56 males), significant differences were observed in MALT between genders (p = 0.001). CtA showed a negative correlation with CtL and Ct-SMA (p < 0.001), and a positive correlation was found between CtL and Ct-SMA (p = 0.002). CtL was measured as 25 mm for the all group. Origin levels of Ct and SMA were evaluated in comparison to vertebral levels. Ct-SMA distance was relatively shorter (9.19 mm) compared to the literature. SMAA findings were consistent with normal population values. CONCLUSION: This study provided valuable insights into the anatomical parameters of the Ct ans SMA in MALS patients. Despite some differences compared to normal population parameters, no evidence supported the hypothesis of a superiorly placed Ct contributing to MALS.

Feasibility and outcomes of living-donor liver transplantation utilizing the right hemi-liver graft with portal vein anatomical variations.

PURPOSE: Portal vein (PV) reconstruction is a key factor for successful living-donor liver transplantation (LDLT). Anatomical variations of right PV (RPV) are encountered among potential donors. METHODS: To evaluate a single center experience of reconstruction techniques for the right hemi-liver grafts with PV variations during the period between May 2004 and 2022. RESULTS: A total of 915 recipients underwent LDLT, among them 52 (5.8%) had RPV anatomical variations. Type II PV was found in 7 cases (13.5%), which were reconstructed by direct venoplasty. Type III PV was found in 27 cases (51.9%). They were reconstructed by direct venoplasty in 2 cases (3.8%), Y graft interposition in 2 cases (3.8%), and in situ double PV anastomoses in 23 cases (44.2%). Type IV PV was found in 18 cases (34.6%) and was reconstructed by Y graft interposition in 9 cases (17.3%), and in situ double PV anastomoses in 9 cases (17.3%). Early right posterior PV stenosis occurred in 2 recipients (3.8%). Early PV thrombosis occurred in 3 recipients (5.8%). The median follow-up duration was 54.5 months (4 - 185). The 1-, 3-, and 5-years survival rates were 91.9%, 86%, and 81.2%, respectively. Late PV stenosis occurred in 2 recipients (3.8%) and was managed conservatively. CONCLUSION: Utilization of potential living donors with RPV anatomic variations may help to expand the donor pool. We found that direct venoplasty and in situ dual PV anastomoses techniques were safe, feasible, and associated with successful outcomes.

Anatomical variations, treatment and outcomes of Herlyn-Werner-Wunderlich syndrome: a literature review of 1673 cases.

PURPOSE: This study aimed to perform a systematic review of patients with Herlyn-Werner-Wunderlich syndrome (HWWS) and present the prevalence of symptoms, anatomical variants, endometriosis, surgical interventions, and short- and long-term outcomes. METHODS: A structured search was performed in PubMed, Scopus, Embase, and China National Knowledge Infrastructure, and studies published between 1 January, 2000 and 19 April, 2022 were included. The following data on HWWS were recorded: symptoms, anatomical variations, surgical interventions and short- and long-term outcomes. RESULTS: A total of 1673 patients were included in our analysis. The main symptoms were dysmenorrhea (53.8%), abnormal uterine bleeding (28.9%), and vaginal discharge (26.6%). The principal anomalies were right-obstructed hemivagina (57.3%), haematocolpos (81.7%), uterus didelphys (88.8%), and ipsilateral renal agenesis (93.1%). A majority of patients belonged to classification 1.1 (46.7%), with a blind hemivagina, and classification 2.1 (39.2%), with a small communication between two vaginas. The mainstay of treatment was vaginal septum excision (91.8%). Minimally invasive surgery (48.5%) was performed only after vaginal surgery (61.9%), and only a few patients required a second surgery (2.2%). Endometriosis was found in 9.6% of the patients. Fifty-two percent of them had ipsilateral ovarian endometriosis cysts. Pregnancy rate of these patients was 72.1%. The rate of adverse pregnancy outcomes was 22.4%. The caesarean section rate was 61.2%. CONCLUSIONS: Patients with HWWS presented with nonspecific symptoms and demonstrated various combinations of anomalies. The most common anatomical variants are classifications 1.1 and 2.1. Vaginal septum excision is effective in relieving symptoms and preventing complications, with hysteroscopic surgery as an option where there is concern about protecting the hymen from minor injury. The pregnancy rate for these patients after surgery was satisfactory, and the rate of adverse pregnancy outcomes after surgery was acceptable. We advise females with urological anomalies to be screened for Müllerian anomalies because of the close association between these two types of anomalies. Thus, HWWS contributes to the occurrence of endometriosis; however, more research is required to investigate the relationship between pelvic endometriosis and HWWS.

Ultrasonographic visualization of anatomical variations of the supraclavicular nerves.

Typical anatomy of the supraclavicular nerve (SCN) is described as originating from the cervical plexus and dividing into medial, intermediate, and lateral branches. The SCN is vulnerable to injury during clavicular surgery, leading to altered sensation post-operatively. There is also increasing interest in anesthetizing the SCN in shoulder or clavicular surgery. Utilizing a high-frequency (20 MHz) ultrasound probe, 20 healthy volunteers were scanned, giving data for 40 SCNs. For each nerve, anatomical course and branches were graphically plotted using a custom Python 3.8.12 program and Microsoft Excel. Of 40 nerves, only 19 (47.5%) demonstrated a typical course, with the rest showing considerable variability of branching patterns. Crossing branches (CBs) were found in 24 (60%) with a total of 54. Just over half (29, 54.7%) of these crossed the clavicle lateral to its midpoint, with 32 (59.6%) CBs having a diameter of ≥25% compared to that of the SCN main trunk. The distance from the mid-clavicular point at which the branches crossed the clavicle was recorded. This study demonstrated that over half the SCNs had atypical branching patterns with intra-volunteer variability. Preoperative mapping may be useful in preventing injury and subsequent numbness.

Topographical study of scapular foramina and scapular nutrient foramina in dried skeletons.

PURPOSE: The aim of our study is to study the prevalence and anatomy of scapular foramina (SF) and scapular nutrient foramina (SNF) in dried skeletons from the Northeastern Thai population. METHODS: A total of 150 dried scapulae were investigated. Both SF and SNF were identified using a metal wire with a diameter of 0.36 mm. The number, locations, lengths, and diameters of SF were recorded. Subsequently, SNF were identified using the same metal wire. Their number and locations were recorded. Two observers performed the evaluations and measurements. RESULTS: SF were present in 78.0% of scapulae. They could have up to five openings. Eighteen types were found. On average they were longer in males (21.7 ± 5.0 mm) than females (19.45 ± 4.6 mm). The mean diameters of both the superior and inferior openings were significantly greater in females (p < 0.01). SNF, in contrast, were present in 100% of scapulae. They were located in the supraspinous fossa (36.7%), subscapular fossa (31.3%), infraspinous fossa (22.8%), and peri-glenoid area (10.0%). CONCLUSION: Unlike previous studies, the present study suggests that SF are normal anatomical findings, present in 78.0% of the scapulae investigated. Surgeons should be aware of both SNF and SF when operating or interpreting radiological findings.

Association between flow patterns of the posterior cerebral arterial circle and basilar-tip aneurysms.

PURPOSE: The Cerebral arterial circle presents multiple individual anatomical configurations which are of the highest importance regarding the pathological processes for intracranial aneurysms development. Previous studies highlighted the importance of geometry and especially arterial bifurcations leading to aneurysms development. The primary objective of this study was to determine whether a flow pattern asymmetry of the P1 segments of the posterior cerebral arteries was associated with a higher risk of basilar tip aneurysm. MATERIAL AND METHODS: Two different populations were retrospectively reviewed. The first population, without aneurysm, for which TOF MRI sequences were reviewed. The second population with patients harboring basilar tip aneurysms for whom cerebral angiograms were reviewed. We retrospectively analyzed the flow contribution and symmetry of the two right and left P1 segments of the posterior cerebral arteries and the two posterior communicating arteries (Pcomm). We analyzed the association and risk factors for basilar tip aneurysm. RESULTS: The anatomical and flow configurations of P1 and Pcomm have been reviewed in 467 patients without aneurysms and 35 patients with aneurysms. We identified a significant association between the flow pattern asymmetry of the P1 segments and the presence of a basilar tip aneurysm (OR = 2.12; IC95% = [1.01-4.36]; p = 0.04). We also confirmed that the male gender was protective against aneurysm (OR = 0.45; IC95% = [0.194-0.961]; p = 0.04). CONCLUSION: Non-modal basilar tip bifurcation and flow asymmetry of P1 segments are associated with an increased risk of basilar tip aneurysm. These findings highlight the importance of analyzing MRI-TOF of the posterior configuration of the Cerebral arterial circle to potentially refine the aneurysms risk prediction.

Anatomical Variants Identified on Computed Tomography of Oropharyngeal Carcinoma Patients.

Background and Objectives: Anatomical variations in the head, neck and chest are common, and are observed as occasional findings on computed tomography (CT). Although anatomical variations are mostly asymptomatic and do not cause any negative influence on the body function, they may jeopardize diagnosis and may be confused with pathological conditions. The presence of variations may also limit surgical access during tumor removal. The aim of this study was to investigate the prevalence of six anatomical variations-os acromiale, episternal ossicles, cervical rib, Stafne bone cavity, azygos lobe and tracheal bronchus-in an open-access computed tomography dataset obtained from oropharyngeal cancer patients. Materials and Methods: A total of 606 upper-chest and neck computed-tomography scans (79.4% male and 20.6% female) were retrospectively investigated. Sex difference was evaluated using the z-test for two proportions. Results: Os acromiale, episternal ossicles, cervical rib, Stafne bone cavity, azygos lobe, and tracheal bronchus were present in 3.1%, 2.2%, 0.2%, 0%, 0.3% and 0.5%, respectively, of all patients. Os acromiale was identified as meso-acromion in 86.6%, and as pre-acromion in 17.4%, of all acromia. Episternal ossicles were present unilaterally in 58.3%, and bilaterally in 41.7%, of all sterna. Only the cervical rib showed a sex difference in prevalence. Conclusions: awareness of these variations is important for radiologists interpreting head, neck and chest CTs; for example, those of oropharyngeal cancer patients. This study also illustrates the applicability of publicly available datasets in prevalence-based anatomical research. While most of the variations investigated in the present study are well-known, the episternal ossicles are not well explored, and need further investigation.

New Insights into the Communications of the Facial Vein with the Dural Venous Sinuses.

Background and Objectives: Anastomoses of the extracranial and intracranial venous system have been described in the literature. The presence of such anastomoses may facilitate a possible spread of infection into the dural venous sinuses. However, the frequency and relevance of such anastomoses is highly debated. The aim of this study was to quantify frequencies of anastomoses between the facial vein and the dural venous sinuses. Materials and Methods: In 32 sides of 16 specimens, latex was injected into the facial vein. Dissection was carried out to follow and described these anastomoses, yielding the presence of latex in the intracranial venous system. Results: In 97% of cases, a dispersal of latex into the cavernous sinus as well as anastomoses was observed. A further dispersal of latex into other dural venous sinuses was found at rates ranging between 34% (transverse sinus)-88% (superior petrosal sinus), respectively. Conclusions: The presence of anastomoses between the extracranial and intracranial venous system in a majority of cases needs to be considered when dealing with pathologies as well as procedures in the facial region.

Degenerated extensor hallucis brevis accessorius: A case report.

The extensor hallucis brevis accessorius has rarely been mentioned in the extant medical literature. Here, we present the case of a cadaver found to have such a muscle and discuss the findings. Specifically, the muscle was observed to be degenerated both grossly and histologically. Therefore, both the gross and histological findings are presented. Such unusual cases are of archival value for future authors to compare their findings.

Anatomical variations of the superior thyroid artery: A systematic review.

BACKGROUND: The superior thyroid artery (STA) is one of the main arteries that provide blood supply to the thyroid gland. It has a plethora of anatomical variations, and knowledge of its anatomy is necessary in procedures in this area. The aim of this review is to summarize and describe human studies (cadaveric and angiographic) that investigate the anatomical variations related to the STA. MATERIAL AND METHODS: A systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed. A literature search in PubMed, and Embase databases was carried out. Original studies that investigated the origin of the STA and reported data on the variant arterial anatomy were considered, including only cadaveric and angiographic studies. RESULTS: A total of 34 studies (4048 heminecks in total; heminecks in each study: min: 25-max: 1280) were finally included. All studies provide details about sex [men/women ratio median (IQR): 2(1-5)] but none about age and 10 (29%) about nationality. STA morphological characteristics described in the included studies are origin, length, number of branches, distance from the carotid bifurcation and the vessel's diameter. CONCLUSIONS: The STA's anatomical features are subject to a non-negligible degree of variability. Our results should improve the awareness of anatomical variations of the STA, and eventually have an impact on the interventions regarding the visceral compartment of the neck in clinical practice.

Radiographic assessment of sacral hiatus anatomy with backache.

Objectives: To determine hiatal variations in cases of backache and controls on radiographs and association of age groups with hiatal parameters in patients with backache versus normal individuals. Methods: This case control study on 178 patients (89 cases and 89 controls), aged from 18-65 years, selected by non-probability convenience sampling was conducted at Radiology Department of PNS Shifa Hospital, Karachi over six months.The sacral hiatus was identified on lumbosacral spine radiographs. Both metric and non-metric parameters of hiatus with respect to sacral vertebra were noted and compared between the groups. Results: Inverted "U" was the most common type observed in cases with base of hiatus at S5 level. Comparison of hiatal shape among different age groups showed inverted "U" and inverted "V" types among all age groups. Hiatal anteroposterior diameter and width were greatest in 36-45-year age group, and it was longest in 46-55-year age group. Determination of relationship between sacral hiatal parameters and incidence of low back pain showed positive association of inverted "U" and "M" shapes with back pain. Increased risk of back pain was observed with high apex (first sacral vertebra (S1)). Conclusion: Strong positive correlation was determined with inverted "U" and "M" shapes, and level of apex at S1 with low backache.

Classification of the popliteofibular ligament.

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

Classification of the superior mesenteric artery.

The aim of this study was to characterize the branching pattern and morphology of the superior mesenteric artery (SMA), and also to create a new SMA classification, which seems necessary for clinicians performing surgery in this anatomical area. The anatomical variations in the branching patterns of the SMA were examined in 30 cadavers fixed in 10% formalin. Morphometric measurements were then obtained twice by two researchers. In the proposed classification system, Type I, characterized by all normal branches-inferior pancreatoduodenal artery, ileocolic artery, right colic artery, middle colic artery and intestinal arteries-occurred in 53.33% of the specimens. Type II, characterized by absence of the inferior pancreatoduodenal artery, was present in 26.67%. Type III, characterized by absence of the right colic artery, was present in 3.33%. Type IV, characterized by a common trunk for the inferior pancreatoduodenal artery and middle colic arteries, was observed in 3.33%. Type V, characterized by an aberrant hepatic artery and absence of the inferior pancreatoduodenal artery, was observed in 13.33%. The origin of the SMA was at the Th12/L1 level in 10% of cases, at L1 in 43.33%, at L1/L2 in 36.67%, and at L2 in 10%. The SMA is characterized by high morphological variability, the variants being associated with distinct clinical aspects. The introduction of a new, structured, anatomical classification seems necessary for all clinicians.

Common trunk of the internal thoracic artery, inferior thyroid artery and thyrocervical trunk from the subclavian artery: a rare arterial variant.

PURPOSE: In this article, we describe a complex and rare variant of the common trunk arising as a branch of the subclavian artery. This description highlights the clinical relevance of such a variation for medical practice. METHODS: A routine dissection was carried out on an adult 74-year-old female cadaver. After identification and preparation of the common trunk, measurements and photographs were taken. RESULTS: The dissection revealed a common trunk arising from the first part of the left subclavian artery. It divided into the left internal thoracic artery, the inferior thyroid artery, and the thyrocervical trunk. Further on, the branches of the thyrocervical trunk supplied blood to the trapezius muscle, the longus colli muscle and the supraspinatus muscle. CONCLUSION: For the first time, we report the specific appearance of a common trunk from the left subclavian artery that includes the origin of the left internal thoracic artery, inferior thyroid artery, and thyrocervical trunk. Knowledge of the different variations of subclavian branches is essential because of the high frequency with which this region is involved in diagnostic and surgical procedures. LEVEL OF EVIDENCE: II Basic Science Research.

Case report of unusual insertion of the fibularis brevis muscle.

The fibularis brevis and fibularis longus muscles belong to the lateral compartment of the leg. The fibularis brevis is morphologically variable, especially in the number of tendons and place of insertion. Its type of insertion is correlated with the presence of a fibularis digiti quinti, which is also anatomically variable. We present a case study based on dissection of a seventy-three-year-old female cadaver with an unusual insertion of the fibularis brevis muscle. The tendon had three bands inserting into the fifth metatarsal bone. There was a coexisting fibularis digiti quinti, which was fused with the fibularis tertius muscle. Awareness of such anatomical variation could be useful during reconstructive surgery and planning rehabilitation protocols.

Hand size affects branching of the deep ulnar nerve and deep palmar arch.

PURPOSE: Understanding the anatomy of the deep neurovascular structures of the hand is essential in surgical planning. There is a lack of literature regarding hand size and its influence in branching variation and the distances between branches of various neurovascular structures. Our study quantifies the variation in branching distances of the deep ulnar nerve and deep palmar arch branches. METHODS: Twenty-five fresh-frozen cadaveric hands were dissected. Each branch of the deep ulnar nerve and deep palmar arch was identified. The distance from the most distal portion of the pisiform to the proximal aspect of the branch was measured. The relationship between the length of the third metacarpal and the distance of each branch from the pisiform was examined. RESULTS: There was no relationship between branching differences in the deep ulnar nerve and the length of the third metacarpal. There was a significant association between the length of the third metacarpal and the second, third, and fourth branches of the deep palmar arch (p < 0.05). CONCLUSIONS: Our study found a significant association between the branching distances of the second, third, and fourth branches of the deep palmar arch and hand size as measured by the length of the third metacarpal.

An unreported infraspinatus muscle variation-two-headed infraspinatus minor muscle and three-headed fusion with the teres minor muscle.

The infraspinatus muscle is situated under the scapular spine in the infraspinous fossa and inserts into the greater tuberosity of the humerus. It is a component of a crucial shoulder muscle group, the rotator cuff. There are a few interesting additional muscles in the infraspinal region. In the literature they are called the infraspinatus superficialis, infraspinatus minor and infraspinatus accessory muscles. The infraspinatus minor muscle is described as a superficial muscle bundle running under the scapular spine. During routine anatomical dissection, an unreported variation of the infraspinatus minor muscle was found. It derived from the inferior surface of the scapular spine and the infraspinous fossa. It had two heads. The superior head inserted on the greater tuberosity of the humerus. The inferior head inserted on the tendinous part of the infraspinatus muscle. There was also an unusual fusion of the infraspinatus muscle with the teres minor muscle. In this paper we will discuss the anatomical and physiological relationships of this morphological variation.