How many layers of muscles are in the sole of the foot, and what is their main function?

The sole contains four layers of intrinsic muscles, totaling 18 muscles. Their primary functions are to stabilize the foot, support the arches, and provide fine control of toe movements during activities like walking.

What are the muscles in the first layer of the sole, and what do they do?

The first layer includes three muscles: Flexor digitorum brevis flexes the lateral four toes, abductor hallucis abducts and flexes the big toe, and abductor digiti minimi abducts and flexes the little toe. They are innervated by medial and lateral plantar nerves.

Which nerves innervate the muscles of the sole of the foot?

Most muscles are innervated by the medial and lateral plantar nerves (S2, S3 spinal segments). For example, the medial plantar nerve supplies muscles like flexor digitorum brevis, while the lateral plantar nerve innervates others such as the adductor hallucis.

What is the role of the adductor hallucis muscle?

The adductor hallucis has two heads (oblique and transverse) and functions to adduct the big toe and help support the transverse arch of the foot. It is innervated by the deep branch of the lateral plantar nerve.

How do the interossei muscles in the fourth layer function?

In the fourth layer, dorsal interossei (4 muscles) abduct the toes and flex the metatarsophalangeal joints, while plantar interossei (3 muscles) adduct the toes and flex the metatarsophalangeal joints. Both are innervated by the lateral plantar nerve.

What are the neurovascular planes in the sole of the foot?

There are two main neurovascular planes: a superficial plane between the first and second layers, containing trunks of the medial and lateral plantar nerves and arteries, and a deep plane between the third and fourth layers, containing deep branches of the lateral plantar nerve and artery.

Which extrinsic tendons are found in the sole of the foot?

Extrinsic tendons pass through the sole, including flexor digitorum longus and flexor hallucis longus in the second layer, and tibialis posterior and peroneus longus tendons in the fourth layer. These aid in foot and toe movements.

Intrinsic Sole Muscles – Four Layers Explained

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