This study describes the anatomy of the musculocutaneous nerve (MCN) in the middle and lower thirds of the arm, with special reference to the motor branches to the biceps and brachialis muscles, given their importance in certain clinical, particularly surgical, procedures. In each dissection (46 upper limbs) we recorded the course of the MCN and its variations, and the number, type of distribution pattern and length of the motor branches to the biceps brachii and brachialis muscles. We also recorded the position at which those branches arose from the MCN trunk. We found three branching patterns for biceps brachii: 1) one branch (60.5%); 2) two branches, one for each biceps head (27.9%); and 3) two branches, one for the two biceps heads and one for the common belly (11.6%). The mean distance between the acromion and the motor branches to biceps brachii was 133.8 mm, 45.3% of the acromion-lateral epicondyle distance. The mean length of those branches was 31.2 mm. We found two branching patterns for brachialis: 1) one branch (72.1%); and 2) two branches (27.9%). These motor nerves to brachialis arose from the MCN at a mean distance of 185.3 mm, 61.5% of the acromion-lateral epicondyle distance, and their average length was 33.0 mm. The data were expressed as the percentage of the distance between the acromion and the lateral epicondyle of the humerus, to make their clinical use easy and to avoid errors caused by anthropometric differences.

The endoscopic endonasal technique is currently used by otolaryngologists for the management of different extradural lesions located below the ethmoidal planum. The cooperation between ENTs and neurosurgeons has recently pushed the use of such approach also in the removal of some intradural lesions, which has promoted the interest for an anatomic study to identify the anatomical landmarks and the dangerous points during the endoscopic approach to this area. In six fresh cadaver heads, unilateral and bilateral measurements between the main landmarks of the approach were performed by means of an endoscopic endonasal approach. A wide exposure of the midline anterior skull base was realized. The maximum of lateral extension was obtained between the two medial orbital walls, at the middle of the cribriform plate (mean distance 25,33 mm), while the mean distance between the anterior and posterior ethmoidal arteries at the level of the lamina papyracea was 16 mm. The endoscopic endonasal route can be considered a minimally invasive technique to approach the ethmoidal planum. It requires adequate anatomical knowledge and endoscopic skill for its realization. Due to the wide window realizable through this corridor, it could be considered in selected cases for the removal of intradural lesions such as meningiomas or estesioneuroblastomas.

PALABRAS CLAVE Anatomía; Tendón; FlexoresResumen El conocimiento de la anatomía de los tendones flexores es importante para el tratamiento de las lesiones de estas estructuras y su pronóstico. Es imprescindible tener un buen fundamento de las estructuras de los tendones y su relación con la patogénesis de las lesiones y su reparación. El aporte vascular es un punto crítico en la reparación de los tendones flexores. Los tendones flexores extrínsecos se mantienen aplicados sobre el esqueleto de los dedos por un sistema de poleas osteofibrosas que dirigen los tendones en el sistema poliarticular sobre el que actúan. Además, están rodeados de unas vainas sinoviales que permiten su deslizamiento y los nutren, junto con los mesotendones y vínculas. © 2015 SECMA. Publicado por Elsevier España, S.L.U. Este es un artículo Open Access bajo la licencia CC BY-NC-ND (http://creativecommons.org/licenses/by-nc-nd/4.0/). KEYWORDS Anatomy; Tendon; Flexors Anatomy applied to surgery of the flexor tendonsAbstract Anatomy of the flexor tendons is important for the treatment and prognosis of flexor tendon injuries. It is imperative to have a good knowledge of the structure of the tendons in relation to the pathogenesis of injuries and repair, and in particular their blood supply. The extrinsic flexor tendons of the fingers and the thumb have fibrous sheaths and a system of pulleys to apply and conduct the tendons to the polyarticular chain on which they work. Slipping of the tendons and their vascularisation is facilitated by the synovial sheaths, mesotendons and vincula tendinums.

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