Muscles of the Sole of the Foot

Question 1

Abductor hallucis

Layer 1

Answer 1

O: Medial tubercle of tuberosity of
calcaneus, flexor retinaculum, and plantar aponeurosis

I: Medial side of base of proximal
phalanx of 1st digit

I: Medial plantar nerve

B: Medial plantar and 1st plantar metatarsal
arteries

A: Abducts and flexes 1st digit

Question 2

Flexor digitorum brevis

Layer 1

Answer 2

O: Medial tubercle of tuberosity of
calcaneus, plantar aponeurosis, and intermuscular septum

I: Both sides of middle phalanges of
lateral four digits

I: Medial plantar nerve

B: Medial and lateral plantar arteries
and plantar arch, plantar metatarsal and plantar digital arteries

A: Flexes 2nd through 5th digits

Question 3

Abductor digiti minimi

Layer 1

Answer 3

O: Medial and lateral tubercles of
tuberosity of calcaneus, plantar aponeurosis, and intermuscular septum

I: Lateral side of base of proximal
phalanx of 5th digit

I: Lateral plantar nerve

B: Medial-lateral plantar artery, plantar
metatarsal and plantar digital arteries to 5th digit

A: Abducts and flexes 5th digit

Question 4

Quadratus plantae

Layer 2

Answer 4

O: Medial and lateral sides of plantar surface of calcaneus

I: Posterolateral edge of flexor
digitorum longus tendon

I: Lateral plantar nerve

B: Medial and lateral plantar arteries
and deep plantar arterial arch

A: Corrects for oblique pull of flexor
digitorum longus tendon, thus assists in flexion of toes

Question 5

Lumbricals

Layer 2

Answer 5

O: Tendons of flexor digitorum longus

I: Medial side of dorsal digital
expansions of lateral 4 digits

I: Medial one: medial plantar nerve
Lateral three: lateral plantar nerve

B: Lateral plantar artery and plantar metatarsal
arteries

A: Flexes proximal phalanges at MTP joint, extends phalanges at PIP and DIP joints

Question 6

Flexor hallucis brevis

Layer 3

Answer 6

O: Plantar surfaces of cuboid and lateral cuneiform

I: Both sides of base of proximal
phalanx of 1st digit

I: Medial plantar nerve

B: Medial plantar artery, first
plantar metatarsal artery

A: Flexes proximal phalanx of 1st
digit

Question 7

Adductor hallucis

Layer 3

Answer 7

O: Oblique head: bases of 2nd through 4th
metatarsals
Transverse head:
ligaments of metatarsophalangeal joints of digits 3-5

I: Tendons of both heads lateral
to side of base of proximal phalanx of 1st digit

I: Deep branch of lateral plantar
nerve

B: Medial and lateral plantar arteries
and plantar arch, plantar metatarsal arteries

A: Adducts 1st digit, maintains transverse arch of foot

Question 8

Flexor digiti minimi brevis

Layer 3

Answer 8

O: Base of 5th metatarsal

I: Lateral base of proximal
phalanx of 5th digit

I: Superficial branch of lateral plantar
nerve

B: Lateral plantar artery, plantar
digital artery to 5th digit, arcuate artery

A: Flexes proximal phalanx of 5th
digit

Question 9

Plantar interossei (three muscles)
(Layer 4)

Answer 9

O: Bases and medial sides of 3rd through 5th metatarsals

I: Medial sides of bases of
proximal phalanges of 3rd through 5th digits

I: Lateral plantar nerve

B: Lateral plantar artery and plantar arch, plantar
metatarsal and plantar digital arteries

A: Adduct digits (2–4) and flex
metatarsophalangeal joint and extend phalanges

Question 10

Dorsal interossei (four muscles)
(Layer 4)

Answer 10

O: Adjacent sides of 1st through 5th metatarsals

I: 1st: medial side of proximal
phalanx of 2nd digit
2nd through 4th: lateral sides of
digits 2–4

I: Lateral plantar nerve

B: Arcuate artery, dorsal and
plantar metatarsal arteries

A: Abduct 2nd through 4th toes, flex
metatarsophalangeal joints, and extend phalanges