Abstract: Objective　To describe the extraforaminal ligaments in the exit regions of the C2~7 intervertebral foramina and to discuss their possible clinical significance.　Methods　A total of 100 C2~7 intervertebral foramina from 10 adult cadavers were anatomically observed. All the ligaments that appeared were identified. The number, morphology, distribution, starting and ending position of the ligaments were observed and recorded. The length, width and thickness of each ligament were measured by vernier calipers. Results　There were 252 extraforaminal ligaments in the 100 intervertebral foramina. The extraforaminal ligaments could be divided into  radioactive ligaments (236pcs, accounting for 93.7%) and  transforaminal ligaments (16pcs, accounting for 6.3%). Radioactive ligaments, which connected the nerve root to the surrounding structures, could be divided into superior ligaments (accounting for 25.0%), inferior ligaments (accounting for 60.2%), anterior ligaments (accounting for 6.3%) and posterior ligaments (accounting for 8.5%). The transforaminal ligaments were perpendicular to the nerve root and straddled the nerve root. The transforaminal ligaments were the most common in C4~5 ligaments. The average length of the transforaminal ligaments at C4~5 intervertebral foramina was (8.12±1.38) mm (6.28~9.93 mm), and the thickest was 1.04 mm. There was one transforaminal ligament at most per cervical foramina.　Conclusions　The extraforaminal ligaments is a normal physiological structure of intervertebral foramen and may be related to the occurrence of C5 nerve palsy after cervical decompression surgery. After cervical decompression surgery, the transforaminal ligaments may be one of the potential causes of nerve root entrapment and nerve injury. The radioactive ligament could limit the displacement of spinal nerves and may cause nerve injury by traction.

Key words: Extraforaminal ligaments; ,  , Cervical intervertebral foramina; ,  , Anatomy; ,  , Nerve root compression