Osteology (Part 2): Talus Flashcards
Talus (Astraglus)
- Links leg and foot
- Transmit forces between foot and leg
- 2nd largest foot/ankle bone
- No muscular insertions
- Multiple ligament attachments
Trabeculae of talus orientated
- Anteriorly toward navicular
- Posteriorly toward calcaneus
3 parts of talus
- Head
- Body
- Neck
Head of talus
- Angled anteriorly and medially
Body of talus
- Square shaped portion
- Articulates with the tibia/fibula
- Convex anterior to posterior
- Concave medial to lateral
Neck of talus
- Narrowed portion between the head and body
Talus forms synovial joints with the
- Tibial plafond, medial malleolus and lateral malleolus of fibula (talocrural joint)
- Calcaneus (subtalar joint)
- Navicular (midtarsal joint)
Structures of body of talus
- Trochlea (trochlea tail)
- Lateral malleolar facet
- Lateral process
- Medial malleolar facet
- Posterior process
- Posterior facet (posterior calcaneal facet)
5 surfaces of body of talus
- Posterior
- Lateral
- Inferior
- Medial
- Superior
Trochlea (trochlea tali)
- Large cartilage covered superior articular surface
- Wider anteriorly than posteriorly (wedged-shaped)
- Articular facet for inferior transverse tibofibular ligament (posterior lateral surface of trochlea)
Trochlea (trochlea tali) articulates with
- Tibial plafond
- Only about 2/3 of trochlea covered by plafond in any position
Lateral malleolar facet
- Concave triangular articular face (apex inferior)
- Continuous with trochlea
- Extends onto lateral process
- Articulates with lateral malleolus
Lateral process of talus body
- Lateral malleolar facet extends onto lateral process (articulates with fibula)
- Load-bearing structure
- Contributes to the ankle mortise and lateral part of subtalar joint
- Lateral talocalcaneal ligament attaches
- Fracture in “Snowboarders fracture”
- Dorsiflexion injury
Medial malleolar facet
- Slightly concave, comma-shaped facet (tear-drop shaped) on medial talus
- Continuous with trochlea
- Extends more anteriorly than lateral malleolar facet, slightly concave
- Articulates with medial malleous
Posterior process
- Formed by 2 smaller projections
- Medial tubercle
- Lateral tubercle
- Sulcus (groove) for flexor hallucis longus tendon is between tubercles
Medial tubercle (posterior process)
- Attachment of posterior tibiotalar ligament
Lateral tubercle (posterior process)
- Attachment of posterior talofibular ligament
- Larger than medial (significant enlargement is called Steida’s process)
- Fracture of lateral tubercle is called “Shepard’s Fracture”
- Os trigonum (accessory ossicle, failure of fusion of lateral tubercle)
Posterior facet of talus (posterior calcaneal facet)
- Located on the inferior surface of the body
- Large concave facet
- Articulates with the posterior facet of calcaneus (posterior talar facet)
- Subtalar joint (anatomic subtalar joint)
Neck (collum tail)
- Begins at the anterior border of trochlea
- Not in line with or in the same horizontal plane as body
- Foramina for nutrient vessels (fracture can cause AVN of the talus)
Neck (collum tail) angles
- In the horizontal plane, shifted medially compared to the body
- In the sagittal plane, angled inferiorly
- Angled 10-20⁰ (larger in children) medially from longitudinal axis (neck and head)
Neck (collum tail) is an attachment point for
- Cervical ligament
- Part of the inferior extensor retinaculum
Sulcus tali
- Groove on inferior surface that runs anterolaterally
- Wider laterally
- Multiple ligament attachments
Sulcus tali runs between
- Anterior/middle facets of talus
- Posterior facets of talus
Sulcus tali combines with calcaneal sulcus to form
- Tarsal Canal
- Sinus tarsi
Head of talus is palpable between
- Sustentaculum tali
- Navicular tuberosity
Structures of head of talus
- Navicular articular surface
- Anterior/middle facet of talus
- Articular facet for spring ligament
- Angle of talar torsion
Navicular articular surface
- Located at the anterior end of the head
- Articulates with navicular
- Continuous with anterior facet of talus
Anterior/middle facet of talus (anterior/middle calcanean facet)
- Located on inferior surface of the head of talus
- Articulates with anterior/middle facet of calcaneus (anterior/middle talar facet)
Anterior/middle facet of talus (anterior/middle calcanean facet) can either be
- Confluent with each other
- Separated by a small ridge
- Sometimes all 3 anterior, middle, and posterior facets are all confluent
Articular facet for spring ligament (plantar calcaneonavicular ligament)
- Medially located on inferior aspect of talar head
- Articulates with cartilage of spring ligament
Angle of talar torsion
- Angle between longitudinal axis of head and transverse plane
- Head is rotated around talar body
- Clockwise on the right, counterclockwise on the left
- ~40-60 degrees
- Lateral side is more superior
Talus blood supply
- Branches from dorsalis pedis, posterior tibial, fibular arteries
Neck/head of talus blood supply
- Branches from dorsalis pedis (medial/lateral tarsal) and anterior tibial)
- Artery of tarsal canal and Artery of sinus tarsi
Body of talus blood supply
- Deltoid artery
- Artery of sinus tarsi and artery of tarsal canal directly
- Other branches from posterior tibial
Deltoid artery arises from
- Artery of tarsal canal
- OR directly off posterior tibial
