Lower leg and foot: Intrinsic muscles (Plantar intrinsic foot muscles)

Question 1

What 3 muscles make up the 1st layer of the plantar intrinsic foot muscles?

Answer 1

Flexor digitorum brevis muscle
Abductor Hallucis Muscle
Abductor digiti minimi muscle

Question 2

What is the function, origin, insertion and innervation of the flexor digitorum brevis muscle?

Answer 2

Function – Flexes 2nd, 3rd, 4th and little toes
Origin – Medial process of calcaneal tuberosity and plantar aponeurosis.
Insertion – Plantar aspects of bodies of middle phalanges of the 2nd, 3rd, 4th and little toes
Innervation – Medial plantar nerve (S1-S3)

Question 3

What is the function, origin, insertion and innervation of the abductor hallucis muscle?

Answer 3

Function – Abducts great toe at its metatarsophalangeal joint
Origin – Medial process of calcaneal tuberosity, flexor retinaculum of foot and plantar aponeurosis.
Insertion – Medial aspect of base of proximal phalanx of great toe
Innervation – Medial plantar nerve (S1-S3)

Question 4

What is the function, origin, insertion and innervation of the abductor digiti minimi muscle?

Answer 4

Function – Abducts and flexes little toe at its metatarsophalangeal joint
Origin – Medial and lateral processes of calcaneal tuberosity and plantar aponeurosis
Insertion – Lateral aspect of base of proximal phalanx of little toe
Innervation – Lateral plantar nerve (S2-S3)

Question 4

What 2 muscles make up the 2nd layer of the plantar intrinsic foot muscles?

Answer 4

Quadratus Plantae Muscle
Lumbricals Muscle(s)

Question 5

What is the function, origin, insertion and innervation of the quadratus plantae muscle?

Answer 5

Function – Assists in flexion of 2nd, 3rd, 4th and little toes
Origin – Medial and lateral aspects of plantar surface of calcaneus
Insertion – Tendon of flexor digitorum longus muscle
Innervation – Lateral plantar nerve (S1-S3)

Question 6

What is the origin and insertion of the lumbricals muscle(s)?

Answer 6

Origin – Tendons of flexor digitorum longus that travel to the 2nd and 3rd toes
Insertion – Medial aspect of extensor expansion of 3rd toe

Question 7

What 3 muscles make up the 3rd layer of the plantar intrinsic foot muscles?

Answer 7

Flexor Hallucis Brevis Muscle
Flexor Digiti Minimi Muscle
Adductor Hallucis Muscle (Transverse head and Oblique head)

Question 8

What is the function, origin, insertion and innervation of the flexor hallucis brevis muscle?

Answer 8

Function –
Origin – Plantar surfaces of cuboid and lateral cuneiform bones; tendon of tibialis posterior
Insertion – Medial and lateral aspects of base of proximal phalanx of great toe
Innervation – Medial plantar nerve (S1-S3)

Question 9

What is the function, origin, insertion and innervation of the flexor digiti minimi muscle?

Answer 9

Function – Assists in flexion of little toe
Origin – Plantar aspects of base of 5th metatarsal bone
Insertion – Plantar aspect of base of proximal phalanx of little toe
Innervation – Superficial branch of lateral plantar nerve (S2-S3)

Question 10

What is the function, origin, insertion and innervation of the adductor hallucis muscle (transverse head)?

Answer 10

Function – Adducts great toe at its metatarsophalangeal joint
Origin – Plantar ligaments of metatarsophalangeal joints and deep transverse metatarsal ligament
Insertion – Lateral aspect of base of proximal phalanx of great toe
Innervation – Deep branch of lateral plantar nerve (S2-S3)

Question 11

What is the function, origin, insertion and innervation of the adductor hallucis muscle (oblique head)?

Answer 11

Function – Adducts great toe at its metatarsophalangeal joint
Origin – Plantar aspects of bases of 2nd – 4th metatarsal bones and tendon of fibularis longus muscle
Insertion – Lateral aspect of base of proximal phalanx of great toe
Innervation – Deep branch of lateral plantar nerve (S2-S3)

Question 12

What muscle make up the 4th layer of the plantar intrinsic foot muscles?

Answer 12

Plantar Interrosei Muscle (Adducts)

Question 13

What is the function, origin, insertion and innervation of the plantar interossei muscle?

Answer 13

o The plantar interossei muscles are one of the two subgroups of the fourth layer of muscles of the plantar part of the foot, the other being the dorsal interossei. Overall, these muscles act to:
 Adduct the 3rd, 4th and little toes at their metatarsophalangeal joints;
 Simultaneously flex the metatarsophalangeal joints and extend the interphalangeal joints of the 3rd, 4th and little toes
 There are three plantar interossei muscles in the foot and, from medial to lateral, they are numbered 1-3

Question 14

What is the Plantar Aponeurosis and what does it do?

Answer 14

Plantar Aponeurosis - an extremely strong layer of fascia which is superficial to all foot muscles and helps to provide some arch support for underside of foot.