Foot Musculature (3rd and 4th Layer; Dorsal Intrinsics)

Question 1

Plantar interossei (3)

Answer 1

Origin
- Medial aspect of 3rd -5th metatarsals
Insertion
- Medial aspect of base of proximal phalanx of the same ray (3rd -5th)
Action
- Adducts toes 3-5
- Flexes toes 3-5
Nerve
- Lateral plantar

Question 2

Dorsal interossei (4)

Answer 2

Origin
- From both metatarsals between which they lie
Insertion
- Medial side of proximal phalanx of 2nd toe
- Lateral side of proximal phalanx of 2nd toe
- Lateral side of proximal phalanx of 3rd toe
- Lateral side of proximal phalanx of 4th toe
Action
- Abducts toes 2-4
- Flexes toes 2-4
Nerve
- Lateral plantar

Question 3

Extensor hallucis brevis

Answer 3

Origin
- Dorsal surface of calcaneus
Insertion
- Base of proximal phalanx of hallux on dorsum
Action
- Extends big toe
Nerve
- Deep peroneal

Question 4

Extensor digitorum brevis

Answer 4

Origin
- Dorsal surface of anterolateral calcaneus
Insertion
- Lateral side of tendons of extensor digitorum longus for 2nd – 4th toes
Action
- Extends 2nd-4th toes
Nerve
- Deep peroneal

Question 5

Flexor hallucis brevis

Answer 5

Origin:
- Medial aspect of cuboid
Insertion:
- Base of proximal phalanx of hallux 
Action
- Flexes big toe
Nerve
- Medial plantar

Question 6

Adductor hallucis

Answer 6

Origin:
- Oblique head: base of 2nd-4th metatarsals and long plantar ligament
- Transverse head: transverse metatarsal ligament and plantar ligaments at MTP joint
Insertion:
- Lateral aspect of the base of proximal phalanx of the hallux
Action:
- Adducts big toe
- Flexes big toe
Nerve:
- Lateral plantar

Question 7

Flexor digiti minimi brevis

Answer 7

Origin:
- Base of 5th metatarsal 
Insertion:
- Lateral aspect of the base of the proximal phalanx of the 5th ray
Action:
- Flexes 5th toe
Nerve:
- Lateral plantar