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Purpose The aim of the study was to assess the quadriceps femoris system for the presence of additional layers. Methods One hundred and twenty-eight lower limbs fixed in 10% formalin were examined. Results Five types of quadriceps tendon layering were found based on the accessory heads of the quadriceps muscle. Type I (55%)—represented by four heads and four layers, and it was something new because standard orthopaedic textbooks described quadriceps tendon as a structure composed of only three layers. Type II (27.4%)—the first four layers were the same as in Type 1, but the accessory tendon of the fifth head of the quadriceps femoris muscle had the deepest attachments. Type III (10.9%)—this type included 6 heads of quadriceps femoris. It consisted of five layers. Type IV (3.1%)—this type included 7 quadriceps femoris heads. This type consisted of only four layers. Type V (3.1%)—this type included 8 heads of the quadriceps femoris heads. This type consist of 5 layers. Conclusion The findings of this study provide a detailed anatomy of the quadriceps tendon including the accessory tendons of the accessory heads of the quadriceps tendon. The accessory heads of the quadriceps femoris muscle contribute to the layering of the quadriceps tendon. The second conclusion of this study is the development of safe distances depending on the types. Not all types are perfect for harvesting—Type IV seems to be the safest type, in turn Type V the most dangerous.

Background: The quadriceps femoris (QF) muscle is traditionally described as a four-headed structure (QF4), yet recent anatomical studies have identified significant morphological variations, including accessory heads and complex quadriceps femoris tendon (QFT) layering. These anatomical differences are especially relevant when harvesting the QFT for anterior cruciate ligament (ACL) reconstruction, where graft quality and structure are critical to surgical success. This study aimed to systematically review and quantitatively synthesize available data on QF variants, with a focus on accessory heads and tendon architecture. Methods: This systematic review and meta-analysis followed PRISMA 2020 and Evidence-Based Anatomy Workgroup guidelines. Cadaveric studies reporting QF variants were identified through searches of multiple databases and anatomical journals. Pooled prevalence estimates and mean QFT lengths were calculated using random-effects models. Heterogeneity and publication bias were also assessed. Results: Eighteen studies encompassing 1066 lower limbs met inclusion criteria. The five-headed QF (QF5) was the most common variant (54.11%), followed by the classical four-headed form (QF4) (40.74%). Rare morphologies with six to eight heads (QF6–QF8) were also documented. Among accessory heads, the vastus lateralis (VL) type was most prevalent (21.35%), while an independent tensor vastus intermedius (TVI) occurred in 13.54% of limbs. The QFT most frequently displayed a trilaminar structure (47.73%), with quadrilaminar architecture observed in 42.49%. The mean QFT length was 78.63 mm. Conclusions: This meta-analysis confirms that the QF often deviates from classical anatomical descriptions, frequently exhibiting supernumerary heads and multilayered tendon architecture. These findings highlight the importance of detailed preoperative imaging and personalized surgical planning to minimize complications and optimize graft selection in ACL reconstruction.

BACKGROUND: The sartorius muscle (SM) belongs to the thigh anterior compartment musculature. It is the longest muscle of the human body, while its variations are described rarely. The current case report aims to describe a distal bifurcation of the SM, forming the bicaudatus SM variant. MATERIALS AND METHODS: An 84-year-old male cadaver was dissected for educational and research purposes at the Department of Anatomy, National and Kapodistrian University of Athens. RESULTS: On the left lower limb, the SM originated, typically, from the anterior superior iliac spine. After 351.22 mm of length, it was bifurcated into an anterior and posterior part. Both muscular parts contributed to the pes anserinus morphology. Femoral nerve branches provided innervation to the variant muscle, while the saphenous nerve and vein coursed posteriorly to the variant muscle. CONCLUSIONS: SM morphological variability is described quite rarely. The current case report corresponds to the bicaudatus SM variant. Accessory parts of the SM could lead to compression symptoms to the femoral nerve anterior branches, as well as to the saphenous nerve.

The sartorius muscle belongs to the anterior compartment of the thigh. Morphological variations of this muscle are very rare, few cases being described in the literature. An 88-year-old female cadaver was dissected routinely for research and teaching purposes. However, an interesting variation was found during anatomical dissection. The proximal part of the sartorius muscle had the normal course, but the distal part bifurcated into two muscle bellies. The additional head passed mediallyto the standard head; thereafter, there was a muscular connection between them. This connection then passed into the tendinous distal attachment. It created a pes anserinus superficialis, which was located superficially to the distal attachments of the semitendinosus and gracilis muscles. This superficial layer was very wide and attached to the medial part of the tibial tuberosity and to the crural fascia. Importantly, two cutaneous branches of the saphenous nerve passed between the two heads. The two heads were innervated by separate muscular branches of the femoral nerve. Such morphological variability could be clinically important.

BACKGROUND: While many structures within the human body demonstrate anatomical variations, this is not typically the case for the iliopsoas muscle complex. However, the present paper describes a case of an anomalous psoas major composed of 4 different muscular heads in a 78-year-old male cadaver. MATERIALS AND METHODS: During a routine dissection of the right posterior abdominal wall, an unusual psoas major was observed, measured, and photographed. RESULTS: The psoas major was found to possess 4 muscular heads, otherwise the anatomy of the wall was normal. CONCLUSIONS: The presence of so many heads could interfere with the functions of the psoas major muscle. Therefore, this anatomical variation merits further study.

Several branching patterns of the axillary artery (AA) have been described. Unusually, the brachial artery (BA) follows a course in front of the median nerve (MN), the so-called superficial brachial artery (SBA). The SBA may result in MN entrapment. The current cadaveric report highlights a high AA bifurcation, its continuation as SBA and the coexistence of muscular, neural, and vascular asymmetric aberrations. At the right side, the coracobrachialis muscle (CB) had a single head, and the ipsilateral musculocutaneous nerve (MCN) followed a medial course. The AA was highly divided into superficial and deep stems (SAS and DAS), at the 2nd rib lower border. Between two stems, the brachial plexus (BP) lateral and medial cords were identified. The MN originated from the BP lateral cord. The SAS, continued as SBA with a tortuous course. The DAS coursed posterior to the BP medial and lateral cords and gave off the subscapular artery. A bilateral 3rd head of the biceps brachii was identified. The MN atypically originated from the BP lateral cord. At the left side, the two-headed CB was typically penetrated by the MCN. A common trunk of the circumflex humeral arteries was identified in coexistence with an interconnection of the BP lateral cord with the MN medial root. The rare coexistence of muscular, neural, and arterial variants in axillary and brachial region is emphasized, taking into consideration the AA high division and related branching pattern. Documentation of such rare vascular variants is important in aneurysm and trauma surgery, and angiography, where all therapeutic manipulations must be accurately performed due to the possibility of complications.

PurposeThe study report describes a rare bilateral variant of a six- and five-headed coracobrachialis muscle (CB). The musculocutaneous nerve (MCN) (bilaterally) and the median nerve (MN) lateral root (unilaterally) pierced CB heads, separating superficial from deep heads.MethodsThe variant bilateral CB was identified in a 78-year-old formalin-embalmed male cadaver, derived from a body donation program after a signed informed consent.ResultsAt the right side: The 6-headed CB was pierced by the MCN, while the MN lateral root pierced the one superficial and deep head. CB was supplied by the lateral cord and the MCN. At the left side: A 5-headed CB was identified with three superficial distinct origins that fused into a common superficial head coursing anterior to MCN. The variant CB bilaterally (with 11 heads in total) coexisted with a MN variant formation, an atypical course of the MN lateral root through CB (right side), a connection of the MN lateral root with the MCN (left side) and a variant axillary artery branching pattern (bilaterally).ConclusionsCourse and direction of the accessory CB heads may occasionally entrap the MCN and/or adjacent structures (brachial artery and MN). The MCN compression results in problems in the glenohumeral joint flexion and adduction, and tingling or numbness of the elbow joint, the forearm lateral parts and the hand.

PurposeThe Gantzer’s muscle is considered to be the accessory head of the flexor pollicis longus. The prevalence of the Gantzer’s muscle and its anatomical relations vary in the literature. So, we aimed to study its prevalence and anatomical relations on a broad population on magnetic resonance (MRI) and ultrasound (US) images.Materials and methodsWe investigated a total of 473 upper extremities of 378 people (171 women, 207 men), aged between 18 and 73 years, by MRI and US. We investigated the prevalence and length of the Gantzer’s muscle and its anatomical relationship with the median (MN) and anterior interosseous nerves (AIN).ResultsOf the 473 extremities, 96 had Gantzer’s muscle (20.3%). Overall prevalence of the Gantzer’s muscle was 21.9% (51 in 232) in women and 18.7% (45 in 241) in men. In the population we performed US, Gantzer’s muscle was located 40.0% in only the right limb, 37.1% in only the left limb and 22.9% bilaterally. All the Gantzer’s muscles originated from the coronoid process. Of the 43 Gantzer’s muscles seen in US, thirty-four (79.1%) were attached to flexor pollicis longus and nine (20.9%) were attached to flexor digitorum superficialis. The mean length of the Gantzer’s muscle was 29.7 (range 17.2–44.5) mm. MN was anterior to the Gantzer’s muscle in all extremities except ten. In all extremities, AIN was located posterior to the Gantzer’s muscle.ConclusionAlthough it is seen at a rare rate of 20.3%, Gantzer’s muscle should be considered in MN and AIN compressions due to its close proximity to these nerves.

PurposeThe aim of the present case is to describe an interesting variation of the additional head of the rectus femoris.MethodsA male body donor, 81 years old at death, was subjected to routine anatomical dissection for research and teaching purposes at the Department of Anatomical Dissection and Donation, Medical University of Lodz, Poland.ResultsWe have found an example of an accessory head of the quadriceps femoris, a double-headed rectus femoris in which the proximal attachment is connected to the rectus femoris muscle originating from the anterior inferior iliac spine. The muscle belly of this additional structure is separate but fused distally with the vastus lateralis muscle. It then passes into the patellar ligament inserted into the tibial tuberosity.ConclusionsKnowledge of the possible occurrence of an additional head is nevertheless important for clinicians, especially for orthopedists performing reconstructive surgeries. It could also be significant for physiotherapists arranging rehabilitation plans after such surgeries because it could potentially help to achieve faster recovery.

PurposeAnterior compartment muscles of the arm present high morphological variability, with possible clinical significance. The current cadaveric report aims to describe a bilateral four-headed brachialis muscle (BM) with aberrant innervation. Emphasis on the embryological background and possible clinical significance are also provided.MethodsClassical upper limb dissection was performed on an 84-year-old donated male cadaver. The cadaver was donated to the Anatomy Department of the National and Kapodistrian University of Athens.ResultsOn the left upper limb, the four-headed BM was supplied by the musculocutaneous and the median nerves after their interconnection.On the right upper limb, the four-headed BM received its innervation from the median nerve due to the musculocutaneous nerve absence.A bilateral muscular tunnel for the radial nerve passage was identified, between the BM accessory heads and the brachioradialis muscle.ConclusionBM has clinical significance, due to its proximity to important neurovascular structures and frequent surgeries at the humerus. Hence, knowledge of these variants should keep orthopedic surgeons alert when intervening in this area. Further dissection studies with a standardized protocol are needed to elucidate the prevalence of BM aberrations and concomitant variants.