OBJECTIVETo measure important parameters of anterior internal fixation for the cervicothoracic junction by us-ing imaging measurement, and provide reference for cervicothoracic junction surgery and design of steel plate screw internal fixation.

METHODSFrom June to November 2012, 120 health people's median sagittal plane MRI of cervical spine were ran-domly collected. Of the 120 cases, there were 58 males and 62 females with an average age of 48.3 +/- 13.7, ranging the age of 20 to 78 years old. The anterior,middle and posterior height of vertebral, anterior, upper, medium and lower sagittal diameter, an-terior height of different segments and Cobb angle were measured by measuring machine in the PACS system.

RESULTSThe an-terior, middle and posterior height of vertebral, medium and lower sagittal diameter gradually increased from cranial to caudal of cervicothoracic junction (P < 0.01). For single vertebral,posterior> anterior>middle height (P < 0.01), lower > upper>medium sagittal diameter (P < 0.01). The lower sagittal diameter of upper vertebral body was close to upper sagittal diameter of lower vertebral body. Cobb angle of male was (7.61 +/- 3.85) degrees, while female's was (5.58 +/- 2.59) degrees .

CONCLUSIONDuring the anterior in-ternal fixation of cervicothoracic junction, it is suggested that the entry points of upper vertebral body should locate on the lower and middle 1/3 of vertebral body, and screws could slightly incline towards cranial,the entry points of lower vertebral body should locate on the upper and middle 1/3 of vertebral body, while screws could slightly incline towards caudal, also can be prebent according to Cobb angle of health.