Overview
This lecture covers systematic identification of bones, ligaments, tendons, and key soft tissue structures of the ankle joint on MRI, crucial for anatomy exams.
Bony Anatomy of the Ankle
- The tibia sits superiorly and articulates with the Talus.
- Talus consists of dome, body, neck, and head; the head articulates with the navicular bone.
- Subtalar joint between talus and calcaneus has posterior, middle, and anterior articulations.
- Calcaneus articulates with cuboid; cuboid with 4th and 5th metatarsals.
- Navicular articulates with three cuneiforms (medial, intermediate, lateral), which join the 1st, 2nd, and 3rd metatarsals.
Major Ligaments of the Ankle
- Syndesmosis: Includes anterior and posterior inferior tibiofibular ligaments, connecting tibia and fibula.
- Lateral Ligaments:
- Anterior talofibular ligament (ATFL) – commonly torn in inversion injuries.
- Calcaneofibular ligament (CFL).
- Posterior talofibular ligament (PTFL).
- Medial Ligaments (Deltoid):
- Deep layer: tibio-talar (continuous anterior and posterior bands).
- Superficial layer: tibio-calcaneal and tibio-navicular bands.
- Spring Ligament Complex (Plantar Calcaneonavicular):
- Superior medial, medial plantar oblique, and inferoplantar longitudinal bands support the talar head.
Tendon Groups of the Ankle
- Posterior: Achilles tendon (gastrocnemius and soleus), plantaris tendon, retrocalcaneal bursa.
- Medial: “Tom, Dick, and Harry” – tibialis posterior, flexor digitorum longus, flexor hallucis longus; pass through tarsal tunnel along with neurovascular bundle.
- Lateral: Peroneus brevis (inserts base of 5th metatarsal), peroneus longus (wraps under foot to medial cuneiform).
- Anterior: Tibialis anterior, extensor hallucis longus, extensor digitorum longus.
Miscellaneous Structures
- Plantar fascia: Originates from calcaneal tuberosity; has lateral, central, and medial bands.
- Sinus tarsi: Fat-filled space between talus and calcaneus, important to assess for pathology.
Key Terms & Definitions
- Subtalar joint — Articulation between talus and calcaneus with three facets.
- Syndesmosis — Fibrous joint holding tibia and fibula together.
- Deltoid ligament — Strong, triangular ligament on medial ankle.
- Spring ligament — Plantar calcaneonavicular ligament supporting the talar head.
- Tarsal tunnel — Passageway for medial tendons and neurovascular bundle behind the medial malleolus.
Action Items / Next Steps
- Review previous ankle and foot radiograph tutorial for bony anatomy.
- Study labeled ankle MRI images to reinforce ligament and tendon identification.
- Prepare for a future lecture on the four layers of foot muscles.