Introducing the craniocervical Y-ligament.

Area of Science:

• Anatomy
• Biomechanics
• Orthopedics

Background:

• The upper cervical spine's complex anatomy necessitates a thorough understanding of its stabilizing structures.
• Accessory atlantoaxial ligaments have been recognized, but their full integration into a functional unit was unclear.

Purpose of the Study:

• To investigate the accessory atlantoaxial ligaments and define their anatomical structure.
• To name and characterize a newly identified ligamentous complex in the craniocervical region.

Main Methods:

• Dissection of upper cervical spine ligaments in Thiel embalmed human cadavers.
• Detailed photographic and video documentation of the Y-ligament in various head positions (neutral, flexion, extension, rotation).
• Description of the Y-ligament's origin, attachment, and behavior during dynamic movements.

Main Results:

• The craniocervical Y-ligament was consistently found to be paired and symmetrical.
• The ligament's 'Y' shape features lateral arms connecting atlas to axis and a medial arm connecting occiput to axis, merging with alar and transverse ligaments.
• The Y-ligament tensed during flexion and rotation, and relaxed during extension, indicating a role in controlling atlantooccipital and atlantoaxial motion.

Conclusions:

• The craniocervical Y-ligament is a constant anatomical structure with a significant role in limiting upper cervical spine movements.
• Understanding this ligament is vital for comprehending upper cervical stability.
• This study provides a foundation for future biomechanical and radiological investigations into the craniocervical Y-ligament.