Deep layer of collateral medial ligament
Pars profunda ligamenti collateralis medialis
- Latin synonym: Pars profunda ligamenti deltodei articulationis talocruralis
- Synonym: Deep layer of deltoid ligament of ankle
Definition
The deep layer of the collateral medial ligament (deltoid ligament) of the ankle is the deeper, intraarticular portion of the deltoid ligament complex that primarily consists of the anterior and posterior tibiotalar fascicles, connecting the medial malleolus of the tibia to the talus. It is the principal stabilizer against valgus talar tilt and external rotation of the talus within the ankle mortise.
The posterior tibiotalar ligament (Deep posterior tibiotalar ligament; Posterior tibiotalar fascicle) is the largest and thickest band of the entire deltoid complex. It originates from the intercollicular groove and posterior colliculus of the medial malleolus and inserts onto the medial surface of the talus.
The anterior tibiotalar ligament (Deep anterior tibiotalar ligament; anterior tibiotalar fascicle) is a smaller, more variable component that also courses from the medial malleolus to the talus. Its prevalence ranges from approximately 63% to 92% across cadaveric studies.
Some authors consider the deep layer as a single tibiotalar fascicle with anterior and posterior portions rather than two distinct ligaments.
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