ABFAS ABFAS Surgical Anatomy and Biomechanics 1 — Questions and Answers
Question 1: Which tarsal bone serves as the keystone of the medial longitudinal arch?
- Navicular
- Talus (Correct answer)
- Calcaneus
- Cuboid
Correct answer: Talus
The talus is considered the keystone of the medial longitudinal arch because it transmits body weight from the tibia to the foot.
Question 2: The Achilles tendon inserts on which surface of the calcaneus?
- Anterior surface
- Superior surface
- Posterior surface (Correct answer)
- Medial surface
Correct answer: Posterior surface
The Achilles tendon inserts on the posterior surface of the calcaneal tuberosity, serving as the primary plantarflexor attachment.
Question 3: In normal gait, which phase involves the greatest load on the forefoot?
- Loading response
- Mid-stance
- Terminal stance and pre-swing (Correct answer)
- Initial contact
Correct answer: Terminal stance and pre-swing
Terminal stance and pre-swing involve the greatest forefoot loading as the heel rises and body weight transfers anteriorly through the metatarsal heads.
Question 4: Which nerve provides sensory innervation to the first web space of the foot?
- Sural nerve
- Deep peroneal nerve (Correct answer)
- Superficial peroneal nerve
- Medial plantar nerve
Correct answer: Deep peroneal nerve
The deep peroneal nerve provides sensory innervation to the first dorsal web space between the hallux and second toe.
Question 5: The spring ligament (plantar calcaneonavicular ligament) primarily supports which structure?
- Lateral column
- Head of the talus (Correct answer)
- Cuboid
- Base of the fifth metatarsal
Correct answer: Head of the talus
The spring ligament acts as a sling supporting the head of the talus and is critical to maintaining the medial longitudinal arch.
Question 6: Which muscle is the primary invertor of the subtalar joint?
- Peroneus longus
- Extensor hallucis longus
- Tibialis posterior (Correct answer)
- Flexor digitorum longus
Correct answer: Tibialis posterior
Tibialis posterior is the primary invertor of the subtalar joint and plays a central role in dynamic arch support during gait.
ABFAS ABFAS Surgical Anatomy and Biomechanics 1
Which tarsal bone serves as the keystone of the medial longitudinal arch?