Musculoskeletal: Anatomy - Foot and ankle Flashcards
Proximal and distal attachment, innervation, and action of extensor digitorum brevis
Proximal: calcaneus, interosseous talocalcaneal ligament, stem of inferior extensor retinaculum
Distal: extensor tendons of 2nd-4th digits (not 5th!)
Innervation: deep fibular nerve (L5, S1)
Action: aids EDL in extending 2nd-4th digits at MTPJ and IPJ
What are the two muscles of the dorsum of the foot?
- Extensor hallucis brevis
- Extensor digitorum brevis
Proximal and distal attachment, innervation, and action of extensor hallucis brevis
Proximal: calcaneus, interosseous talocalcaneal ligament, stem of inferior extensor retinaculum
Distal: base of 1st proximal phalanx
Innervation: deep fibular nerve (L5, S1)
Action: aids EHL in extending great toe at MTPJ
Describe the arterial supply of the dorsum of the foot
By dorsalis pedis, with three named branches:
1. Lateral tarsal artery: supplies EDB and tarsal bones
2. Arcuate artery: supplies 2nd-4th toe clefts
3. First dorsal metatarsal artery: supplies 1st toe cleft and medial 1st toe, enters sole in 1st metatarsal space to become the deep plantar artery
Describe the venous drainage of the dorsum of the foot
By dorsal venous arch in subcutaneous tissue, which:
- Medially drains to great saphenous vein (pierces cribiform fascia and drains to femoral vein)
- Laterally drains to small saphenous vein (drains into popliteal which becomes femoral vein after passing through adductor hiatus)
Describe the motor and sensory supply of the dorsum of the foot
Motor by:
1. Deep fibular nerve: supplies EDB and EHB
Sensory by:
1. Deep fibular nerve: supplies 1st webspace
2. Superficial fibular nerve: supplies central dorsum (excluding 1st webspace)
3. Saphenous nerve: supplies medial foot (over 1st metatarsal)
4. Sural nerve: supplies lateral margin of foot
What is the deep fascia of the foot continuous with?
Proximally with the inferior extensor retinaculum
Distally with the plantar fascia
Describe the structure and anatomy of the plantar aponeurosis
Dense collagen fibres arranged mainly longitudinally
Arises from medial process of calcaneus and divides into five bands distally which are continuous with the fibrous tendon sheaths of the flexor tendons
Reinforced inferior to metatarsal heads by the superficial transverse metatarsal ligament
Describe the five components of the foot and their contents
In forefoot and midfoot:
1. Medial: abductor hallucis, flexor hallucis brevis and tendon of flexor hallucis longus, medial plantar nerve and vessels
2. Central: flexor digitorum brevis, tendons of flexor digitorum and hallucis longus, quadratus plantae, lumbricals, adductor hallucis, lateral plantar nerve and vessels
3. Lateral: abductor and flexor digiti minimi brevis
4. Dorsal: extensor hallucis and digitorum brevis, dorsal neurovascular structures
In forefoot only:
5. Interosseous: metatarsals, interossei, deep plantar and metatarsal vessels
Summarise the layers of the foot and their contents, from superficial to deep
- Abductor hallucis, flexor digitorum brevis, abductor digiti minimi
- Quadratus plantae, lumbricals, tendons of flexor hallucis and digitorum longus
- Flexor hallucis brevis, adductor hallucis, flexor digiti minimi
- Plantar and dorsal interossei, tendons of tibialis posterior and fibularis longus
Second and fourth layer have “uniquely” named foot muscles
Hallucis and digiti mini paired with same muscle types, with abductors superficial to flexors
Proximal and distal attachment, innervation, and action of abductor hallucis
Proximal: medial process of calcaneus, flexor retinaculum, plantar aponeurosis
Distal: medial base of 1st proximal phalanx
Innervation: medial plantar nerve (S2-3)
Action: great toe abduction and flexion
Which six intrinsic foot muscles are supplied by the lateral plantar nerve? Which of these are supplied by the superficial and deep branches?
1, 2. Flexor and abductor digiti minimi (flexor by superficial branch)
3. Adductor hallucis (deep branch)
4. Quadratus plantae
5. Lateral 3 lumbricals
6. Interossei (plantar and dorsal)
Which four intrinsic foot muscles are supplied by the medial plantar nerve?
1, 2. Flexor and abductor hallucis brevis
3. Flexor digitorum brevis
4. Medial lumbrical
Proximal and distal attachment, innervation, and action of flexor digitorum brevis
Proximal: medial process of calcaneus, plantar aponeurosis, intermuscular septa
Distal: both sides of 2nd-5th middle phalanges
Innervation: medial plantar nerve (S2-3)
Action: 2nd-5th digit flexion
Proximal and distal attachment, innervation, and action of abductor digiti minimi
Proximal: medial and lateral process of calcaneus, plantar aponeurosis, intermusfcular septa
Distal: base of 5th proximal phalanx
Innervation: lateral plantar nerve (S2-3)
Action: 5th digit abduction and flexion
Proximal and distal attachment, innervation, and action of quadratus plantae
Proximal: plantar surface of calcaneus
Distal: posterolateral margin of FDL tendon
Innervation: lateral plantar nerve (S2-3)
Action: assists FDL with 2nd-5th toe flexion
Proximal and distal attachment, innervation, and action of lumbricals
Proximal: tendons of FDL
Distal: extensor expansion
Innervation: lateral 3 by lateral plantar nerve (S2-3), medial 1 by medial plantar nerve (S2-3)
Action: flexion at MTPJ while assisting with maintaining extension at IPJ
Proximal and distal attachment, innervation, and action of flexor digiti minimi
Proximal: base of 5th metatarsal
Distal: base of 5th proximal phalanx
Innervation: lateral plantar nerve (S2-3)
Action: 5th digit flexion
Proximal and distal attachment, innervation, and action of adductor hallucis
Proximal: oblique head from base of 2nd-4th metatarsal, transverse head from plantar ligamants at MTPJ
Distal: lateral base of 1st proximal phalanx
Innervation: lateral plantar nerve (S2-3)
Action: great toe adduction, also assists in maintaining transverse arch
Proximal and distal attachment, innervation, and action of flexor hallucis brevis
Proximal: cuboid, lateral cuneiform
Distal: both sides of base of 1st proximal phalanx
Innervation: medial plantar nerve (S2-3)
Action: great toe flexion
Proximal and distal attachment, innervation, and action of plantar interossei
Proximal: medial shafts of 3rd-5th metatarsals
Distal: medial base of 3rd-5th proximal phalanges
Innervation: lateral plantar nerve (S2-3)
Action: toe adduction
Proximal and distal attachment, innervation, and action of dorsal interossei
Proximal: two heads from adjacent metatarsals
Distal: 1st: medial base of 2nd proximal phalanx, 2nd-4th: lateral base of 2nd-4th phalanges
Innervation: lateral plantar nerve (S2-3)
Action: toe abduction
How many plantar and dorsal interossei are there?
3 plantar
4 dorsal
What are the spinal nerve roots of the medial and lateral plantar nerves?
S2-3
Which intrinsic muscle of the foot inserts into the FDL tendon? Which arises from the tendon?
Quadratus plantae inserts into FDL
Lumbricals arise from FDL
Describe the vascular supply of the sole of the foot
Main arterial supply is via deep plantar arch, formed by lateral plantar artery from posterior tibial and deep plantar artery from dorsalis pedis
Posterior tibial divides into:
- Medial plantar artery -> supplies great toe
- Lateral plantar artery -> forms deep plantar arch with deep plantar artery of dorsalis pedis
Deep plantar arch gives off 4x plantar metatarsal arteries (which in turn give off plantar digital arteries), 3x perforating arteries, and many branches to skin, fascia and muscles in sole
In which layer of the sole do the medial and lateral plantar arteries pass?
Deep to abductor hallucis (deep to 1st layer)
Describe the lymphatic drainage of the foot
Medial superficial lymphatic vessels drain to great saphenous vein -> superficial inguinal lymph nodes -> deep inguinal lymph nodes
Lateral superficial lymphatic vessels drain to small saphenous vein -> popliteal lymph nodes
Which three tendons support the medial longitudinal arch?
Fibularis longus
Tibialis anterior
Tibialis posterior
What bones make up the medial arch? What is the keystone? Which tendons support this arch?
- Calcaneus
- Talus (keystone is talar head)
- Navicular
- Cuneiforms
- 3 medial metatarsals
Supporting tendons are fibularis longus, tibialis posterior and tibialis anterior
What is the keystone of the medial arch?
Talar head
Which bones make up the transverse arch? Which tendons maintain this arch?
- Cuboid
- Cuneiforms
- Base of metatarsals
Maintained by fibularis longus and tibialis posterior tendons
What are the two passive factors which help to maintain the arches of the foot?
- Shape of united bones (especially important for transverse)
- Fibrous tissue layers bowstringing the longitudinal arches:
- Plantar aponeurosis
- Long plantar ligament
- Plantar calcaneocuboid (short plantar) ligament
- Plantar calcaneonavicular (spring) ligament)
What bones make up the lateral arch?
- Calcaneus
- Cuboid
- 2 lateral metatarsals
What are the two dynamic factors which help to maintain the arches of the foot?
- Reflexive bracing of intrinsic foot muscles (important for longitudinal arch)
- Contraction of muscles with long tendons into foot:
- For longitudinal arches: flexor hallucis and digitorum longus
- For transverse arch: tibialis posterior, fibularis longus
What is the most important factor in maintaining the arches of the foot?
The fibrous tissue layers (plantar aponeurosis, short and long plantar ligaments, spring ligament)
Describe the course of the spring ligament
Calcaneonavicular:
- Fills gap between sustentaculum tali and posteroinferior navicular
Describe the course of the long plantar ligament
Plantar surface of calcaneus to groove on cuboid
Some fibres extend to metatarsal bases (forms tunnel for fibularis longus)
Describe the course of the short plantar ligament
Calcaneocuboid:
- Located on a plane between spring and long plantar ligaments
- Extends from anteroinferior calcaneus to inferior cuboid
What forms the malleolar mortise? What fits into it?
Structures forming the malleolar mortise:
- Distal tibia
- Distal fibula
- Inferior transverse part of posterior tibiofibular ligament
Trochlea of talus fits into mortise
In what position is the ankle most stable?
In dorsiflexion
Describe the joint capsule of the ankle joint. Where does it extend and what are the supporting structures?
Thin anteriorly and posteriorly
Attached to articular margins of all three bones EXCEPT anterior part of talus (attaches in front on neck of talus)
Supported on either side by lateral and medial collateral ligaments
Which three ligaments make up the lateral ligament of the ankle? Which of these is the weakest?
- Anterior talofibular*: lateral malleolus to neck of talus (anteromedial)
- Posterior talofibular: malleolar fossa -> lateral tubercle of talus (horizontal)
- Calcaneofibular: lateral malleolus -> lateral calcaneus (posteroinferior)
- weakest
Which four ligaments make up the medial (deltoid) ligament of the ankle?
- Tibionavicular part
- Tibiocalcaneal part
- Anterior tibiotalar part
- Posterior tibiotalar part
In what position does the medial malleolus stabilise the ankle?
Stabilises during eversion to prevent subluxation
What are the three ligaments making up the ankle joint?
Lateral
Medial
Posterior (posterior tibiofibular: includes inferior transverse ligament)
What vessels innervate the ankle joint?
Malleolar branches of fibular and anterior and posterior tibial arteries
What nerves innervate the ankle joint?
Saphenous
Tibial
Sural
Superficial fibular
Deep fibular
