What does the Alar Ligament Instability Test assess?

• A. Paraspinal muscle function
• B. Nerve root impingement
• C. Transverse ligament attachment
• D. Alar ligament stability

Answer: (D)

The Alar Ligament Instability Test specifically evaluates the stability of the alar ligaments at the craniocervical junction. The alar ligaments connect the dens of the axis to the occipital bones and act to limit rotation and side-bending of the head on the upper cervical spine. By stressing this ligamentous complex, the test checks whether these ligaments can properly restrain movement between the skull and C2. A finding suggesting instability points to compromised alar ligaments, which can occur with trauma, inflammatory conditions, or odontoid injuries. This test is not about paraspinal muscle function, nerve root impingement, or the transverse ligament, making alar ligament stability the best fit for what this test assesses.