Objective    To study the course of different cervical nerve segments and their related intervertebral foramen’s size so as to increase safety and decrease complications in microinvasive surgery for cervical syndrome.     Methods    Fifteen human cervical specimens (30 sides) were anatomically observed for the course

branches and distribution of cervical nerves.     Results    The diameter of intervertebral foramen ranges from 0.54 to 0.65 cm

and increases gradually from top to bottom. The vertical diameter and anteroposterior diameter

between C

4

C

5

and C

6

vertebrae are smaller

and those between C

3

and C

7

are larger

but the diameter line of nerve root in intervertebral foramen from up to down gradually increases. The anteversion angle between nerve root and spine cord on horizontal plane is from 15°  to 19°

within a small variation

while the declination angle on coronal plane gradually decreases from C

3

to C

7

. There exist plenty of anastomosis branches among the cervical dorsal rami.     Conclusion    In the range of 0.6 cm around articular process at the entrance of intervertebral foramen

it is the narrowest part

the removal of which may alleviate the pressure on nerve root and benefit spinal stability. Because of the general existence of anastomosis branches of cervical nerve

the symptoms of cervical syndrome are not completely consistent to innervation. The intervertebral foramen between C

4

C

5

C

6

is relatively small and the diameter line of nerve root is comparatively large

so the nerve root at C

4

C

5

C

6

is most likely to be pressed.