Flexor hallucis brevis muscle is a

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

of the

foot The foot (: feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is an organ at the terminal part of the leg made up o ...

that flexes the

big toe Toes are the Digit (anatomy), digits of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being ''digitigrade''. Humans, and other animals that walk on the soles of their feet, are described as being ' ...

Structure

Flexor hallucis brevis muscle arises, by a pointed tendinous process, from the medial part of the under surface of the

cuboid bone In the human body, the cuboid bone is one of the seven tarsal bones of the foot. Structure The cuboid bone is the most lateral of the bones in the distal row of the tarsus. It is roughly cubical in shape, and presents a prominence in its infer ...

, from the contiguous portion of the third

cuneiform Cuneiform is a Logogram, logo-Syllabary, syllabic writing system that was used to write several languages of the Ancient Near East. The script was in active use from the early Bronze Age until the beginning of the Common Era. Cuneiform script ...

, and from the prolongation of the tendon of the tibialis posterior muscle which is attached to that bone. It divides in front into two portions, which are inserted into the medial and lateral sides of the base of the first phalanx of the great toe, a sesamoid bone being present in each tendon at its insertion. The medial portion is blended with the

abductor hallucis muscle The abductor hallucis muscle is an intrinsic muscle of the foot. It participates in the Anatomical terms of motion#Abduction and adduction, abduction and Anatomical terms of motion#Flexion and extension, flexion of the Toe#Hallux, great toe. Stru ...

previous to its insertion; the lateral portion (sometimes described as the first plantar interosseus) with the

adductor hallucis muscle The Adductor hallucis (adductor obliquus hallucis) arises by two heads—oblique and transverse and is responsible for adducting the big toe. It has two heads, both are innervated by the lateral plantar nerve. Structure Oblique head The ''obliqu ...

. The tendon of the

flexor hallucis longus muscle The flexor hallucis longus muscle (FHL) attaches to the plantar surface of phalanx of the great toe and is responsible for flexing that toe. The FHL is one of the three deep muscles of the posterior compartment of the leg, the others being the ...

lies in a groove between the two. Its tendon usually contains two

sesamoid bones In anatomy, a sesamoid bone () is a bone embedded within a tendon or a muscle. Its name is derived from the Greek word for 'sesame seed', indicating the small size of most sesamoids. Often, these bones form in response to strain, or can be presen ...

at the point under the first

metatarsophalangeal joint The metatarsophalangeal joints (MTP joints) are the joints between the metatarsal bones of the foot and the proximal bones (proximal phalanges) of the toes. They are analogous to the knuckles of the hand, and are consequently known as toe knuckles ...

Innervation

The medial and lateral head of the flexor hallucis brevis is innervated by the

medial plantar nerve The medial plantar nerve (internal plantar nerve) is the larger of the two terminal divisions of the tibial nerve (medial and lateral plantar nerve), which accompanies the medial plantar artery. From its origin under the laciniate ligament it pa ...

. Both heads are represented by spinal segments S1, S2.

Variation

Origin subject to considerable variation; it often receives fibers from the

calcaneus In humans and many other primates, the calcaneus (; from the Latin ''calcaneus'' or ''calcaneum'', meaning heel; : calcanei or calcanea) or heel bone is a bone of the Tarsus (skeleton), tarsus of the foot which constitutes the heel. In some other ...

or long plantar ligament. Attachment to the

sometimes wanting. Slip to first phalanx of the second toe.

Function

Flexor hallucis brevis flexes the first

metatarsophalangeal The metatarsophalangeal joints (MTP joints) are the joints between the metatarsal bones of the foot and the proximal bones (proximal phalanges) of the toes. They are analogous to the knuckles of the hand, and are consequently known as toe knuck ...

joint, or the

. It helps to maintain the medial longitudinal arch. It assists with the toe-off phase of gait providing increased push-off.

Clinical significance

Sesamoid bones In anatomy, a sesamoid bone () is a bone embedded within a tendon or a muscle. Its name is derived from the Greek word for 'sesame seed', indicating the small size of most sesamoids. Often, these bones form in response to strain, or can be presen ...

contained within the tendon of flexor hallucis brevis muscle may become damaged during

exercise Exercise or workout is physical activity that enhances or maintains fitness and overall health. It is performed for various reasons, including weight loss or maintenance, to aid growth and improve strength, develop muscles and the cardio ...

Additional images

Image:Gray269.png, Bones of the right foot. Plantar surface. File:Slide1ABA.JPG, Flexor hallucis brevis muscle File:Slide8ABA.JPG, Flexor hallucis brevis muscle

References

External links

PTCentral
{{Authority control Foot muscles Muscles of the lower limb