Alar ligaments
Original Editor - Rachael Lowe
Top Contributors - Rachael Lowe, Kim Jackson, Evan Thomas, WikiSysop, Alistair James, George Prudden, Wendy Snyders, Aminat Abolade and Ahmed M Diab
Description
The alar ligaments are two strong rounded cords that attach the dens of C2 (Axis) to the occipital condyles[1]. They are accessory ligaments of the Atlanto Axial joint. [2]Their orientation is superolateral (running upwards and outwards) [3] they tend to be more horizontal[1][4]. The alar and transverse ligaments are the strongest ligaments that stabilise the craniocervical junction [5] with the alar ligament only failing at a mean force of 394 ± 52 N[1][1]
Attachments
Origin: Arise from either side of the dens/odontoid process (varying attachment points)[4]
Insertion: Usually the medial aspect of the occipital condyles but some studies have found it to insert on the lateral walls of the foramen magnum[4]
Function
- Limits C0-C2 extension[1]
- Limits axial rotation[1][5][4]
- Limits lateral bending[1][5]
- Limits flexion secondarily[5]
- Play a role in stabilizing C1 and C2, especially in rotation[6].
Pathology
Isolated alar ligament ruptures are rare[7] but are hypothesised to occur when the head is subjected to sudden rotation and hyperflexion[1]. Usually, alar ligament ruptures occur together with fractures and other ligament injuries after trauma to the craniovertebral junction[7].
Examination
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Ishak B, Glinski AV, Dupont G, Lachkar S, Yilmaz E, Iwanaga J, Unterberg A, Oskouian R, Tubbs RS, Chapman JR. Update on the biomechanics of the craniocervical junction, part II: alar ligament. Global Spine Journal. 2021 Sep;11(7):1064-9.
- ↑ Fung YC. Biomechanics: mechanical properties of living tissues. Springer Science & Business Media; 2013 Mar 14. [1]
- ↑ Nidecker AE, Shen PY. Magnetic resonance imaging of the craniovertebral junction ligaments: normal anatomy and traumatic injury. Journal of Neurological Surgery Part B: Skull Base. 2016 Oct;77(05):388-95. [2]
- ↑ 4.0 4.1 4.2 4.3 Osmotherly PG, Rivett DA, Mercer SR. Revisiting the clinical anatomy of the alar ligaments. European Spine Journal. 2013 Jan;22(1):60-4.
- ↑ 5.0 5.1 5.2 5.3 Rizvi A, Iwanaga J, Oskouian RJ, Loukas M, Tubbs RS. Duplication of the Alar Ligaments: A Case Report. Cureus. 2018 Jun 29;10(6).
- ↑ Magee DJ (2007). Orthopedic Physical Assessment (5th ed). St Louis, MO: Saunders Elsevier.
- ↑ 7.0 7.1 Unal TC, Dolas I, Unal OF. Unilateral alar ligament injury: diagnostic, clinical, and biomechanical features. World Neurosurgery. 2019 Dec 1;132:e878-84.