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Variations within the musculature of the lateral compartment of the leg are uncommon. However, clinicians and radiologists should be aware of anatomical alterations in this region when involved in diagnosis or imaging interpretation. The present report describes a well-developed muscle of the lateral compartment of the leg that inserted distally onto the talus and calcaneus. This muscle could be considered a variation of the so-called peroneus quartus muscle. To the authors' knowledge this muscle variation has not been described as having an attachment onto the talus thus the term 'peroneotalocalcaneus muscle' is proposed.

Few reports are found in the extant medical literature regarding the vastoadductor membrane. This membrane effectively creates a subcompartment within the subsartorial canal. The lower limbs of 16 embalmed adult cadavers were dissected to identify the vastoadductor membrane and note its measurements. A vastoadductor membrane was identified in all specimens and was derived from the medial intermuscular septum. This membrane connected the medial edge of the vastus medialis muscle to the lateral edge of the adductor magnus muscle. Membranes were all wider proximally and narrowed distally. The mean length of this structure was 7.6 cm. The mean width of the vastoadductor membrane at its proximal, midportion, and distal parts was 2.2, 1.7, and 0.5 cm, respectively. The mean distance from the anterior superior iliac spine to the proximal border of the vastoadductor membrane was 28 cm. The mean distance from the distal border of the membrane to the adductor tubercle was 10 cm. Seventy-five percent of specimens exhibited a fenestrated vastoadductor membrane. Branches of the saphenous nerve to the skin of the medial thigh pierced the vastoadductor membrane in 31% of specimens. Two specimens demonstrated branches derived from the branch of the obturator nerve that pierced this membrane en route to the skin of the medial thigh. Perforating venous branches from the great saphenous vein were identified in 22% of specimens. As compression of the femoral artery at the adductor hiatus is a well-recognized entity, the clinician may also try to explore potential compression of this vessel more proximally by an overlying vastoadductor membrane. The authors would also hypothesize that due to the interconnection between the adductor magnus and vastus medialis by the vastoadductor membrane that a potential synergy exists between the functions of these two muscles.

Variations of the triceps brachii muscle are apparently rare. We report an additional attachment site of the medial head of the triceps brachii found on the left side of a male cadaver. This head originated from the posterior aspect of the surgical neck of the humerus. Clinicians diagnosing or treating patients with weakness or pain of the posterior arm should consider anomalous muscles in this region that may result in neurovascular compression., (Copyright 2006 Wiley-Liss, Inc.)

We report a case of the rare tensor fascia suralis muscle. This muscle was found during the routine dissection of the lower extremity in an adult male cadaver. No other anomalies were noted in this specimen. The innervation of this muscle was via the tibial component of the sciatic nerve. Although seemingly rare, the tensor fascia suralis muscle may be considered by the clinician in the differential diagnosis of masses over the posterior lower extremity.

The biceps femoris is the most lateral component of the so-called hamstring muscles. Classically, this muscle's insertion into the head of the fibula has been described but further details of its anatomy have not been universally appreciated. Additional insertions into the crural fascia and tibia have been described. We dissected 56 cadavers paying especially close attention to the insertion of the biceps femoris muscle. The tendon of this muscle was found to have both medial and lateral slips each with an anterior and posterior component. Further, we found an attachment not only into the lateral condyle of the femur but also the popliteus tendon and arcuate popliteal ligament. Our study has found that the tendon of insertion of the biceps femoris muscle is more complex than described previously and suggests that this tendon may be far more important in knee stability based on the multiple attachment sites found. We hypothesize that there may be a synergistic effect between the biceps femoris and the popliteus muscles based on our findings of an additional attachment of the biceps femoris tendon into the popliteus tendon. This study provides new detailed nomenclature for the description of the tendon of insertion of the biceps femoris muscle and indicates that the current description of the insertion of the tendon of the biceps femoris muscle should be revised. The clinician must have a thorough understanding of this anatomy before correct therapeutic maneuvers can be implemented.

Object: There is a paucity of information in the neurosurgical literature regarding the surgical anatomy surrounding the posterior interosseous nerve (PIN). The goal of the current study was to provide easily recognizable superficial bone landmarks for identification of the PIN., Methods: Thirty-four cadaveric upper extremities obtained from adults were subjected to dissection of the PINs, and measurements were made between this nerve and surrounding superficial bone landmarks. In all specimens the main radial trunk was found to branch into its superficial branch and PIN at the level of the lateral epicondyle of the humerus. Proximally, the PIN was best identified following dissection between the brachioradialis and extensor carpi radialis longus and brevis muscles. At its exit site from the supinator muscle, the PIN was best identified after retraction between the extensor carpi radialis longus and brevis and extensor digitorum communis muscles. This site was a mean distance of 6 cm distal to the lateral epicondyle of the humerus. No compression of the PIN by the tendon of origin of the extensor carpi radialis brevis muscle was seen. One specimen was found to have a proximally split PIN that provided a previously undefined articular branch to the elbow joint. The mean diameter of the PIN proximal to the supinator muscle was 4.5 mm. The leash of Henry crossed the PIN in all but one specimen and was found at a mean distance of 5 cm inferior to the lateral epicondyle. The PIN exited the distal edge of the supinator muscle at a mean distance of 12 cm distal to the lateral epicondyle of the humerus. Here the mean diameter of the PIN was 4 mm. The exit site from the distal edge of the supinator was found to be at a mean distance of 18 cm proximal to the styloid process of the ulna. This exit site for the PIN was best identified following dissection between the extensor carpi radialis longus and brevis and extensor digitorum communis muscles. The distal articular branch of the PIN was found to have a mean length of 13 cm and the proximal portion of this terminal segment was located at a mean distance of 7.5 cm proximal to the Lister tubercle., Conclusions: The addition of more anatomical landmarks can help the neurosurgeon to be more precise in identifying the PIN and in avoiding complications during surgery in this region.

Object: In neurotization procedures, donor nerves--either whole or in part-with relatively pure motor function can be carefully chosen to provide the optimal nearby motor input with as little donor site morbidity as possible. In this context, the ulnar nerve branches to the forearm muscles are relatively dispensable; however, quantitation of and landmarks for these branches are lacking in the literature., Methods: The ulnar branches to the flexor carpi ulnaris (FCU) and flexor digitorum profundus (FDP) muscles in 20 upper extremities obtained in adult cadaveric specimens were dissected and quantified. In the forearm, a mean of four nerve branches led to the FCU and FDP muscles. A mean of 3.4 branches led to the FCU muscle; of these, one to three were medial branches and zero to two were lateral. Medial branches to the FCU muscle originated a mean of 2.7 cm inferior to the medial epicondyle. Lateral branches to the FCU muscle originated at a mean of 3.3 cm inferior to the medial epicondyle. The mean length of the medial branches was 3.2 cm, whereas the mean length of the lateral branches was 3.3 cm. All nerves had a single trunk for the FDP muscle, and in all specimens this branch was located deep to the main ulnar nerve trunk, originating from the ulnar nerve a mean of 2.7 cm inferior to the medial epicondyle. These branches had a mean length of 5.6 cm. The mean diameter of all medial and lateral branches to the FCU muscle was 1 mm, and the mean diameter of the branch to the FDP muscle was 2.1 mm. All branches to both the FCU and FDP muscles arose from the ulnar nerve, over its first approximately 5 cm from the level of the medial epicondyle. Additionally, all branches could be easily lengthened by gentle proximal dissection from the main ulnar nerve., Conclusions: Ulnar branches to the forearm can be easily localized and used for neurotization procedures. The branch to the FDP muscle had the greatest diameter and longest length, easily reaching the median nerve and posterior interosseous nerve via a transinterosseous membrane tunneling procedure. Furthermore, this branch could be teased away from the main ulnar nerve trunk and made to reach the distal branches of the musculocutaneous nerve in the arm.

Object: There are scant data regarding the anterior interosseous nerve (AIN) in the neurosurgical literature. In the current study the authors attempt to provide easily identifiable superficial osseous landmarks for the identification of the AIN., Methods: The AIN in 20 upper extremities obtained in adult cadaveric specimens was dissected and quantified. Measurements were obtained between the nerve and surrounding superficial osseous landmarks. The AIN originated from the median nerve at mean distances of 5.4 cm distal to the medial epicondyle of the humerus and 21 cm proximal to the ulnar styloid process. The distance from the origin of the AIN to its branch leading to the flexor pollicis longus muscle and to the point it travels deep to the pronator quadratus (PQ) muscle measured a mean 4 and 14.4 cm, respectively. The mean distance from the AIN branch leading to the flexor pollicis longus muscle to the proximal PQ muscle was 12.1 cm, and the mean distance between this branch and the ulnar styloid process was 7.2 cm. The mean diameter of the AIN was 1.6 mm at the midforearm., Conclusions: Additional landmarks for identification of the AIN can aid the neurosurgeon in more precisely isolating this nerve and avoiding complications. Furthermore, after quantitation of this nerve, the AIN branches can be easily used for neurotization of the median and ulnar nerves, and with the aid of a transinterosseous membrane tunneling technique, passed to the posterior interosseous nerve.

During routine cadaveric dissection of the upper extremity an unusual muscle was discovered arising from the tendon of the flexor carpi ulnaris and inserting into the muscle belly of the flexor digiti minimi. The muscle's course was superficial to the ulnar nerve and artery in Guyon's canal. We review the literature regarding such muscle variations and discuss the potential for compression of the ulnar nerve by such muscles.

There is a paucity of information in the extant literature regarding the detailed anatomy of the subanconeus (articularis cubiti) muscle. Our current study seeks to elucidate further the presence, morphology, and potential function of this muscle. Eighteen cadaveric upper extremities underwent dissection of their posterior elbow joint capsule with special attention to any fibres attaching to it from the triceps brachii muscle. We found that all specimens had various amounts of muscular attachment of the medial head of the triceps into the posterior joint capsule. It was noted that the highest concentration of fibres was into the joint capsule near the groove for the ulnar nerve. No specimen was found to have a distinct muscle belly associated with these connections to the joint capsule. On all sides these fibres were simply deeper attachments of the medial head of the triceps brachii muscle. Following tension on these deeper fibres retraction of the joint capsule was not noted but rather compression of the capsule. We would speculate on the basis of our study that these fibres of the medial head of the triceps brachii muscle do not represent a separate muscle per se and do not retract the posterior elbow joint capsule with extension of the forearm as has been theorised. It is possible that compression of the posterior elbow joint capsule from these deeply placed fibres of the triceps brachii restricts the elbow fat pad from being displaced and allows it to cushion the contact made between the olecranon process and the olecranon fossa.

Variations of the adductor pollicis muscle of the hand are seemingly rare. We describe an unusual finding of this muscle made during the routine dissection of a cadaveric hand as part of our medical school's gross anatomy course. We believe this case report represents persistence of a portion of the contrahentes digitorum in a human hand. As muscle variations may compress the median nerve while in the carpal tunnel, the clinician should be aware of such a variation., (Copyright 2005 Wiley-Liss, Inc)

During the routine dissection of a 62-year-old male cadaver, bilateral atrophy of the supra and infraspinatus muscles was observed. The suprascapular nerves, cervical spinal cord and surrounding muscles were found to be normal. We propose that, in the face of normal histology and other normal shoulder girdle muscles and normal nerves, this case represents an instance of Parsonage-Turner syndrome. To our knowledge, this is the first report of bilateral spinati atrophy in a cadaver.

The authors report a presumably unusual bony attachment of the pectoralis minor muscle in an adult cadaver. The specimen's left pectoralis minor had no attachment to the coracoid process of the scapula but attached directly to the fibrous capsule of the glenohumeral joint. Some have theorized that the coracohumeral ligament represents fibers of the pectoralis minor that attach to this bone in some animals but that has degenerated in man. This case report seems to support this possibility., (Copyright 2005 Wiley-Liss, Inc.)