Anatomical study of neck back muscle and spinal nerve dorsal rami

Abstract

Objective To provide the microanatomy for surgical operation for spastic torticollis.Methods Through the anatomy research of adult embalmed cadaver (8 cases,16 sides) to description the layer、course、beginning and ending points of muscle and the ramification course、distribution and diameter of spinal nerve dorsal rami nerve.Results Neck back muscles can be divided into four layers.The first layer are trapezius muscle and sternocleidomastoid; The second are splenius capitis muscle、splenius cervicis and levator scapulae muscle; The third layer are semispinalis capitis muscle、semispinalis cervicis muscle and longissimus capitis muscle; The last layer are obliquus capitis superior、obliquus capitis inferior、rectus capitis posterior major and rectus capitis posterior minor.Except C1 、C2 the others dorsal branch of spinal nerve are traveling backward.The diameter of the dorsal branch(mm):Left C1:0.87-1.62 mm(1.28 ±0.33) mm;C2:2.64-3.92 mm(3.12 ±0.49) mm;C3:1.56-2.11 mm(1.79 ±0.20) mm;C4:0.91-1.98 mm(1.41 ±0.46)mm;C5:0.92-1.39 mm(1.16 ±0.19)mm;C6:0.93-1.36 mm (1.14 ±0.24)mm.Right C1:0.92-1.49 mm(1.23 ±0.23) mm;C2:2.81-3.93 mm(3.19 ±0.43) mm; C3:1.52-1.92 mm (1.72 ± 0.17) mm ; C4:1.02-2.01 mm (1.42 ± 0.39) mm ; C5:0.89-1.63 mm (1.17 ± 0.31) mm; C6:0.81-1.39 mm (1.17 ± 0.23) mm.The C2-6 spinal nerve dorsal rami can be observed in the gap between semispinalis capitis and semispinalis cervicis muscle.Accessory nerve at a distance about 2 cm where great auricular nerve pierce the back edge of stemocleidomastoid muscle,the accessory nerve appear in the posterior cervical triangle.The diameter of accessory nerve which pierce the back edge of stemocleidomastoid muscle is 1.93-2.37 mm(2.10 0.18)mm (Left) ; 1.89-2.23 mm (2.09 0.14)mm (Right).Conclusions The above-mentioned anatomic relations of neck back muscles and spinal nerves can be provided foundation for post-cranial and neck surgery.Especially for the spinal nerve dorsal branch cut to treatment spastic torticollis provide an important reference. Key words: Neck back muscles; Dorsal branch of spinal nerve; Accessory nerve