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Introduction The coracobrachialis muscle (CRM) originates from the apex of the coracoid process, in common with the short head of the biceps brachii muscle, and from the intermuscular septum. It inserts to the medial part of the humerus between the attachment of the medial head of the triceps brachii and the brachial muscle. Both the proximal and distal attachments of the CRM, as well as its relationship with the musculocutaneus nerve, demonstrate morphological variability. Material and methods One hundred and one upper limbs (52 left, and 49 right) fixed in 10% formalin solution were examined. Results Three main types, with subtypes, were identified. The most common was Type I (49.5), characterized by a single muscle belly with a classical origin from the coracoid process, medially and posteriorly to the tendon of the biceps brachii. Type II (42.6%), characterized by two heads, was divided into two subtypes (A-B) depending on its origin: Type IIA, where one head originated from the coracoid process posteriorly to the tendon of the biceps brachii and the second head from the short head of the biceps brachii, and Type IIB, in which both heads originated from the coracoid process; however, the superficial head fused with the insertion of a short head of the biceps brachii, while the deep head was directly originating. Finally, Type III (7.9%) was characterized by three heads: two originated from the coracoid process (superficial and deep), and the third from a short head of the biceps brachii. Two types of insertion and two types of musculocutaneous nerve (MCN) relative to CRM could be distinguished. Conclusion An adapted classification is needed for all clinicians working in this area, as well as for anatomists. The CRM demonstrates morphological variability in both its proximal and distal attachments, as well as the variable course of the MCN relative to the CRM. What is known about this subject "and" What this study adds to existing knowledge Not much is known about the variability of coracobrachialis muscle. The present paper introduces a completely new classification, both clinical and anatomical.

Background:The abductor pollicis longus (APL) originates from the lateral part of the dorsal surface of the body of the ulna below the insertion of the anconeus muscle, from the interosseous membrane, and from the middle third of the dorsal surface of the body of the radius. However, the number of its accessory bands and their insertion vary considerably.Material and methods: Fifty upper limbs (2 paired, 31 male, 19 female) were obtained from adult Caucasian cadavers, and fixed in 10 % formalin solution before examination Results: The APL muscle was present in all specimens. The muscles were divided into three main categories, with Type II and III being dived into subtypes. Type I was characterized by a single distal attachment, with the tendon inserting to the base of the I metacarpal bone. Type II was characterized by a bifurcated distal attachment, with the main tendon inserting to the base of the first metacarpal bone; this type was divided into three subtypes (A-C). Type III was characterized by the main tendons inserting to the base of the first metacarpal bone, while the accessory band was characterized by mergers (fusion) with other tendons. This type was divided into two subtypes (A-B). Conclusions:The abductor pollicis longus is characterized by high morphological variability.

The tibialis anterior muscle originates on the lateral condyle of the tibia, on the upper two-thirds of the lateral surface of this bone, on the anterior surface of the interosseous membrane and on the deep surface of the fascia cruris. The distal attachment is typically at the medial cuneiform and first metatarsal. However, the tibialis anterior tendon can vary morphologically in both adults and fetuses. Different authors have created new classification systems for it. The main aim of this review is to present condensed information about the tibialis anterior tendon based on the available literature. Another aim is to compare classification systems and the results of previous studies.

The flexor pollicis longus (FPL) is located in the anterior compartment of the forearm. It is morphologically variable in both point of origin and insertion. An additional head of the FPL can lead to anterior interosseous syndrome. This report presents a morphological variation of the FPL (additional head in proximal attachment and bifurcated tendinous insertion in distal attachment) and an unrecognized structure that has not so far been described in the literature. This structure originates in six heads (attached to the FPL or interosseous membrane) that merge together, and inserts on to the FPL. All the variations noted have clinical significance, ranging from potential nerve compression to prevention of tendon rupture.