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
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
References
[1] Murray CJ, Atkinson C, Bhalla K, et al. The state of US health, 1990-2010: burden of diseases, injuries, and risk factors[J]. JAMA, 2013, 310(6):591-608. DOI:10.1001/jama.2013.13805.
[2] Wang T, Wang H, Liu S, et al. Incidence of C5 nerve root palsy after cervical surgery: A meta-analysis for last decade[J]. Medicine (Baltimore), 2017, 6(45):e8560. DOI:10.1097/MD.0000000000008560.
[3] Yoshihara H, Margalit A, Yoneoka D. Incidence of C5 palsy: meta-analysis and potential etiology[J]. World Neurosurg, 2019, 122:e828-e837. DOI:10.1016/j.wneu.2018.10.159.
[4] Zhao Q, Zhong E, Shi B, et al. The morphology and clinical significance of the intraforaminal ligaments at the L5-S1 levels[J]. Spine J, 2016, 16(8):1001-1006. DOI:10.1016/j.spinee.2016.03.048.
[5] Zhong E, Zhao Q, Shi B, et al. Morphology and possible clinical significance of the radiating extraforaminal ligaments at the L1-L5 levels[J]. Spine (Phila Pa 1976), 2017, 42(18):1355-1361. DOI:10.1097/BRS.0000000000002120.
[6] Zhong E, Zhao Q, Shi B, et al. The morphology and possible clinical significance of the intraforaminal ligaments in the entrance zones of the L1-L5 levels[J]. Pain physician, 2018, 21(2):E157-E165.
[7] Arslan M, Acar HI, Comert A. Cervical extraforaminal ligaments: an anatomical study[J]. Surg Radiol Anat, 2017, 39(12):1377-1783. DOI:10.1007/s00276-017-1896-x.
[8] Lohman CM, Gilbert KK, Sobczak S, et al. 2015 Young investigator award winner: cervical nerve root displacement and strain during upper limb neural tension testing: Part 2: role of foraminal ligaments in the cervical spine[J]. Spine (Phila Pa 1976), 2015, 40(11):801-808. DOI:10.1097/BRS.0000000000000687.
[9] Jack AS, Osburn BR, Tymchak ZA, et al. Foraminal ligaments tether upper cervical nerve roots: a potential cause of postoperative C5 palsy[J]. J Brachial Plex Peripher Nerve Inj, 2020, 15(1):e9-e15. DOI:10.1055/s-0040-1712982.
[10] Qian Y, Qin A, Zheng MH. Transforaminal ligament may play a role in lumbar nerve root compression of foraminal stenosis[J]. Med Hypotheses, 2011, 77(6):1148-1149. DOI:10.1016/j.mehy.2011.09.025.
[11] Sioutas G, Kapetanakis S. Clinical anatomy and clinical significance of the cervical intervertebral foramen: a review[J]. Folia Morphol (Warsz), 2016, 75(2):143-148. DOI:10.5603/FM.a2015.0096.
[12]Zhao Q, Zhang W, Su Z, et al. The morphology and clinical significance of the extraforaminal ligaments at the T1-T12 levels[J]. Spine (Phila Pa 1976), 2018, 43(21):E1241-e1248. DOI:10.1097/brs.0000000000002675.
PDF(546 KB)
