BACKGROUND: Accessory head of Flexor pollicis longus in the forearm is one of the factors for causing anterior interosseous nerve syndrome. The objectives were to study the incidence, morphology of accessory head of flexor pollicis longus and its relation with median nerve and anterior interosseous nerve. METHODS: The present study was observational and descriptive type. A total of 60 upper limbs from 30 cadavers were dissected in the Department of Anatomy. The accessory head of flexor pollicis longus muscle was identified and its relation with median and anterior interosseous nerve was observed. The shape, origin and insertion of accessory head of flexor pollicis longus were noted. The length and width of the muscle belly and tendon were measured with digital vernier caliper. The findings were compared with that of previous studies. RESULTS: The accessory head of flexor pollicis longus was present in 13(43.3%) cadavers. The shape of muscle was fusiform in 84.61% and slender in 19.38%.Commonest site of origin was coronoid process of ulna (53.33%)., from the medial epicondyle 33.33% and 6.66% each form tendon of brachialis and deep head of pronator teres respectively. The average length and width of muscle belly were 93.48 ± 1.76mm and 7.03 ± 1.43 respectively. The tendon length and width were 20 ± 8.09mm and 0.55 ± 0.23mm. The median nerve was running anteriorly and the anterior interosseous nerve laterally to the muscle belly in all the cases. CONCLUSION: The presence of accessory head of flexor pollicis longus can be an important factor in anterior interosseous nerve syndrome, pronator teres syndrome. The results obtained in the present study would be useful for both physicians and surgeons to know the cause and therefore an appropriate management of the clinical syndromes. KEY WORD: accessory head of flexor pollicis longus, morphology, anterior interosseous nerve, Flexor digitorum superficialis.
During a routine dissection of the posterior triangle of the neck (right side) on a male cadaver, a variation related to the dorsal scapular nerve and long thoracic nerve was encountered. After firm identification of the variation, the region was dissected to reveal the full details of the course of dorsal scapular and long thoracic nerve, and the variation was photographed using an 8 megapixel digital camera. An atypical formation of dorsal scapular nerve [Table/ Fig-1] was seen, in the posterior triangle of the neck. The dorsal scapular nerve (DSN) which usually comes from the C5 root, had contributions from C5 and the C6 roots. The C5 component of the DSN pierced the scalenus medius muscle and divided into two branches within the muscle. The bigger branch ended by supplying the levator scapula muscle, while a smaller branch continued downwards and joined with a branch arising from the C6 root. On further dissection, it was found out that the two branches from the C5 and C6 roots united and coursed down as main trunk of dorsal scapular nerve. On the contrary, it was observed that the long thoracic nerve was formed by two components C6, C7 [Table/ Fig-1] mainly instead of three ventral rami of C5, C6, C7 cervical nerves. The C5 component of the long thoracic nerve was not apparently seen, but a communicating branch was given from C6 which seemed to carry fibres from C5. The C7 component was seen to arise from the middle trunk, which is a continuation of the ventral rami of the C7 spinal nerve. The C6 nerve root pierced the scalenus medius muscle and divided within the muscle into two smaller branches. The larger branch coursed down to join the C7 component of the long thoracic nerve (LTN), while the smaller branch coursed down to join a branch from the C5.Further, the brachial plexus as a whole was prefixed with contribution from the ventral rami of the 4 th cervical nerve [Table/ Fig-1], thus the upper trunk formed by the union of the C5 and C6 was thick and long. The Erbs point was identified and the nerve to subclavius and suprascapular nerves were also seen.A band of muscle fibers was further observed to connect the middle portion of the scalenus medius with the scalenus anterior muscle Pre and post-fixed variations at roots of the brachial plexus have been well documented, however little is known about the variations that exist in the branches which arise from the brachial plexus. In this paper, we describe about one such rare variation related to the dorsal scapular and the long thoracic nerve, which are the branches arising from the roots of the brachial plexus. The variation was found during routine dissection. The dorsal scapular nerve, which routinely arises from the fifth cervical nerve root (C5), was seen to receive contributions from C5 as well as sixth cervical nerve (C6), while the long thoracic nerve arose from C6 and seventh cervical nerves (C7) only. Furthermore along with variations in origin of the dorsal scapular and long thoracic nerves, the brachial plexus was seen to exist as a prefixed ...
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