The flexor retinaculum of the foot (laciniate ligament, internal annular ligament) is a strong fibrous band in 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 ...

Structure

The flexor retinaculum of the foot extends from the

medial malleolus A malleolus is the bony prominence on each side of the human ankle. Each leg is supported by two bones, the tibia on the inner side (medial) of the leg and the fibula on the outer side (lateral) of the leg. The medial malleolus is the promin ...

above, to 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 ...

below. This converts a series of bony grooves into canals for the passage of the tendons of the flexor muscles and the posterior tibial vessels and

tibial nerve The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus. Structure Popliteal fossa The tibial nerve is the larger terminal branch of the sciatic nerve with root val ...

into the sole of the

, known as the

tarsal tunnel The tarsal tunnel is a passage found along the inner leg underneath the Malleolus, medial malleolus of the ankle. Structure The roof of the tarsal tunnel is formed by the Flexor retinaculum of foot, flexor retinaculum of the foot. The floor of th ...

. It is continuous by its upper border with the

deep fascia Deep fascia (or investing fascia) is a fascia, a layer of dense connective tissue that can surround individual muscles and groups of muscles to separate into fascial compartments. This fibrous connective tissue interpenetrates and surrounds the m ...

of the leg, and by its lower border with the plantar

aponeurosis An aponeurosis (; : aponeuroses) is a flattened tendon by which muscle attaches to bone or fascia. Aponeuroses exhibit an ordered arrangement of collagen fibres, thus attaining high tensile strength in a particular direction while being vulnerable ...

and the fibers of origin of 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 ...

. Enumerated from the medial side, the four canals which it forms transmit the tendons of the

tibialis posterior The tibialis posterior muscle is the most central of all the leg muscles, and is located in the deep posterior compartment of the leg. It is the key stabilizing muscle of the lower leg. Posterior tibial tendonitis Posterior tibial tendonitis i ...

and

flexor digitorum longus The flexor digitorum longus muscle or flexor digitorum communis longus is situated on the tibial side of the leg. At its origin it is thin and pointed, but it gradually increases in size as it descends. It serves to flex the second, third, fourth ...

muscles; the posterior tibial artery and

, which run through a broad space beneath the ligament; and lastly, in a canal formed partly by the talus, the tendon of the

flexor hallucis longus 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 ...

Clinical significance

Tarsal tunnel syndrome can be caused by entrapment of the

beneath the flexor retinaculum of the foot. This is characterized by

pain Pain is a distressing feeling often caused by intense or damaging Stimulus (physiology), stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sense, sensory and emotional experience associated with, or res ...

numbness Hypoesthesia or numbness is a common side effect of various medical conditions that manifests as a reduced sense of touch or sensation, or a partial loss of sensitivity to Sensory receptor, sensory stimuli. In everyday speech this is generally r ...

, and tingling of the medial plantar surface of the

. This is made worse by

standing Standing, also referred to as orthostasis, is a position in which the body is held in an upright (orthostatic) position and supported only by the feet. Although seemingly static, the body rocks slightly back and forth from the ankle in the ...

and

walking Walking (also known as ambulation) is one of the main gaits of terrestrial locomotion among legged animals. Walking is typically slower than running and other gaits. Walking is defined as an " inverted pendulum" gait in which the body vaults o ...

, and often worse at

night Night, or nighttime, is the period of darkness when the Sun is below the horizon. Sunlight illuminates one side of the Earth, leaving the other in darkness. The opposite of nighttime is daytime. Earth's rotation causes the appearance of ...

Tinel's sign Tinel's sign (also Hoffmann-Tinel sign) is a way to detect irritated nerves. It is performed by lightly tapping ( percussing) over the nerve to elicit a sensation of tingling or "pins and needles" in the distribution of the nerve. Percussion is us ...

can be elicited by tapping the part of the flexor retinaculum of the foot over the tibial nerve.

References

External links

* {{Authority control Foot