Flexor digitorum brevis muscle: Origin, Insertion, Action, Exercise

Flexor digitorum brevis (FDB) is a large muscle located deep in the sole of the foot, just above the central part of the plantar fascia, with which it is firmly united and inferior to the tendon of Flexor Digitorum Longus.

It is the central muscle of the superficial layer of the plantar foot muscles.

Origin:

Flexor digitorum brevis (FDB) originates from the medial process of calcaneal tuberosity and the central part of the plantar aponeurosis, from the central part of the plantar fascia, and make the intermuscular septa between it and other the adjoining muscles.

It travels forward and is split into 4 tendons, each for lesser toes.

Insertion:

Opposite the bases of the first phalanges, each tendon divides into two slips, to allow of the passage of the adjoining tendon of the flexor digitorum longus; the two parts of the tendon then unite and form a grooved channel for the reception of the related long Flexor tendon.

Ultimately, it split a second time and is inserted into the sides of the second phalanx in the middle. The mode of division of the tendons of the flexor digitorum brevis, and of their insertion into the phalanges, is in a similar manner to the flexor digitorum superficialis in the hand.

Middle phalanges of toe 2-5 through the tendon of each toe.

Nerve:

The medial plantar nerve (S1, 2), is a terminal branch of the tibial nerve.

Blood supply:

• the branches of the posterior tibial artery
• medial plantar
• lateral plantar arteries.

The optional blood supply is:

• the branches of the anastomotic network of anterior tibial
• posterior tibial arteries
• plantar metatarsal arteries
• common plantar digital arteries.

Actions:

Flexion of the lateral four digits at the proximal IP(interphalangeal) Joints.

Variation:

Little toe tendon may be absent sometimes, in this condition, there may be a small fusiform muscle that originates from the long flexor tendon or from the quadratus plantae.

Relations:

Flexor digitorum brevis is located lateral to abductor digiti minimi and medial to abductor hallucis muscles. This muscle travels deep to the thick layer of the plantar fascia. Its tendons travel medially to the common plantar digital nerves and vessels.

Underneath the muscles, you will see quadratus plantae, lumbrical muscles, and the tendons of flexor digitorum longus muscle.

Clinical importance:

It is important an intrinsic muscle of the foot, this muscle also helps in stabilizing the longitudinal arch of the foot.

Flexor digitorum brevis muscle exercise:

Mainly 2 types of exercise: Stretching exercise and strengthening exercise

How do you strengthen the Flexor digitorum brevis muscle?

To strengthen the muscles, you should do this exercise in a standing or sitting position, flex all four toes fully, Hold for 10 to 20 seconds, and then extend, doing 8 to 10 repetitions daily.

You can also perform towel-grasping exercises.

To strengthen the muscles, you can resist toe bending exercises with the help of a therapist or others.