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

Question 1

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

Answer 1

Function – Extends 2nd – 4th toes
Origin – Dorsolateral aspect of calcaneus, inferior extensor retinaculum of foot, and talocalcaneal interosseous ligament
Insertion – Extensor expansions of 2nd- 4th toes
Innervation – Deep fibular nerve (L5-S1)

Question 2

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

Answer 2

Function – Extends great toe
Origin – Dorsolateral aspect of calcaneus, inferior extensor retinaculum of foot, and talocalcaneal interosseous ligament
Insertion – Dorsal aspect of base of proximal phalanx of great toe
Innervation – Deep fibular nerve (L5-S1)

Question 3

What is the function, origin, insertion and innervation of the dorsal interossei muscles?

Answer 3

o Dorsal interossei muscles are one of the two subgroups of the fourth layer of muscles of the plantar part of the foot (other being plantar interossei. Overall, these muscles mainly act to:
 Abduct 2nd – 4th toes at their metatarsophalangeal joints;
 Simultaneously flex the metatarsophalangeal joints and extends the interphalangeal joints of the 2nd – 4th toes
 These are the four dorsal interossei muscles in the foot and, from medial to lateral, they are numbered 1 - 4