Retinacula

Question 1

Describe the flexor retinaculum of the ankle

Answer 1

• Strap-like layer of connective tissue
• Spans bony depression formed by the M mallelous,medial and posterior talus, medial calcaneus and inferior sustentaculum tali
• Attaches
○ Superiorly to M mallelous
○ Infero-posteriorly to inferomedial margin of calcaneus

• Continuous above with deep fascia (leg) and below with deep fascia (plantar aponeurosis) of foot
•Septa of flexor retinaculum - convert grooves on the bones into tubular connective tissue channels for the tendons of the flexor muscles
• Tarsal tunnel - formed on the medial side of the foot in the groove between the medial malleolus and the heel (calcaneal tuberosity) and by the overlying flexor retinaculum.
○ Structures of the tarsal tunnel lat-med:
§ Tibialis posterior (TOM), FDL (DICK), posterior tibial artery (BLOODY), tibial nerve (NERVOUS), FHL (HARRY)

Question 2

Describe the Extensor retinaculum of the ankle

Answer 2

• Two extensor retinacula - strap the tendons of the extensor muscles to the ankle region and prevent tendon bowing during extension of the foot and toes

• Superior extensor retinaculum
○ Thickening of deep fascia in the distal leg just superior to the ankle joint
○ Attached to the anterior borders of the fibula and tibia

• Inferior extensor retinaculum - Y-shaped
○ Base - supero-lateral surface of the calcaneus
○ Superior band(arm) - crosses medially over the foot to the medial malleolus
○ Inferior band (arm) - wraps medially around the foot to the medial side of the plantar aponeurosis

Question 3

Describe the plantar aponeurosis

Answer 3

• Thickening of deep fascia in the sole of the foot
• Attachments
○ Base - medial process of the calcaneal tuberosity
○ Extends anteriorly on plantar surface as a thick band of longitudinally arranged connective tissue fibres, Fibres diverge as they pass anteriorly and form digital bands, which enter the toes and connect with bones, ligaments, and dermis of the skin

• Distal to the MTP joints, the digital bands are interconnected by transverse fibres, which form superficial transverse metatarsal ligaments
• Supports the longitudinal arch of the foot and protects deeper structures in the sole

Question 4

Describe fibrous sheaths (tunnels) of the ankle

Answer 4

• Tendons of FDL, FDB, FHL enter fibrous digital sheaths (tunnels) on the plantar aspect of the digits
• Attachments:
○ From - anterior to MTP joints
○ Extend - to distal phalanges
• Hold the tendons to the bony plane and prevent tendon bowing when the toes are flexed
• Within each tunnel, the tendons are surrounded by a synovial sheath
• Formed by fibrous arches and cruciate (cross-shaped) ligaments attached posteriorly to the margins of the phalanges and to the plantar ligaments associated with the MTP and IP joints

Question 5

Describe the extensor hoods of the digits

Answer 5

• Tendons of EDL, EDB, EHL pass into the dorsal aspect of the digits and expand over the proximal phalanges to form complex dorsal digital expansions (extensor hoods)
• Extensor hood is triangular in shape
• Attachments
○ Base - wrapped around the sides of the MTP joints, Corners of the hoods attach mainly to the deep transverse metatarsal ligaments
○ Apex - distal phalanx
○ Central region - middle (toes II to V) or proximal (toe I) phalanx