[Anatomicosurgical comments on the importance of the spinal accessory nerve].
The preserved integrity of the spinal accessory nerve plays an extremely important role in cervico-facial surgery since the majority of surgical approaches involve this nervous structure. Following a short historical outline of the surgical method, the Authors illustrate the anatomo-topographical aspects and anatomo-surgical problems. A number of points emerge from a review of the literature which are vital to isolate the spinal accessory nerve: 1) the transversal apophysis of the atlas is particularly prominent in the retrostyloid space and lies half-way across an imaginary horizontal segment connecting the mastoid process with the angle of the mandible; 2) the posterior edge of the sternocleidomastoid muscle at approximately six centimetres from the mastoid process; 3) the nervous point of Erb located at the point where the superficial branches of the cervical plexus emerge from the posterior edge of the sternocleidomastoid muscle (the nerve generally emerges from the posterior edge of the sternocleidomastoid muscle two centimetres above this point and two centimetres below it the nerve meets the anterior edge of the trapezius). This is followed by an analysis of the possible complications deriving from lesions to this vital nervous structure. The resection of the spinal accessory nerve leads to the so-called "shoulder syndrome" mainly due to the denervation of the trapezius. This syndrome is characterised by the onset of regional pain, the typical deformation of the shoulder joint and functional deficit. The deformation is provoked by the decreased muscular strength of the superior and middle portion of the trapezius manifested as the rocking of the shoulder and a higher superointernal angle.(ABSTRACT TRUNCATED AT 250 WORDS)