Extensor digitorum longus muscle
Encyclopedia
The Extensor digitorum longus is a pennate
muscle, situated at the lateral part of the front of the leg.
of the tibia
; from the upper three-fourths of the anterior surface of the body of the fibula; from the upper part of the interosseous membrane
; from the deep surface of the fascia; and from the intermuscular septa between it and the Tibialis anterior on the medial, and the Peronæi on the lateral side. Between it and the Tibialis anterior are the upper portions of the anterior tibial vessels and deep peroneal nerve.
The muscle passes under the transverse and cruciate crural ligament
s in company with the Peronæus tertius, and divides into four slips, which run forward on the dorsum of the foot, and are inserted into the second and third phalanges of the four lesser toes.
The tendons to the second, third, and fourth toes are each joined, opposite the metatarsophalangeal articulation, on the lateral side by a tendon of the Extensor digitorum brevis. The tendons are inserted in the following manner: each receives a fibrous expansion from the Interossei
and Lumbricalis
, and then spreads out into a broad aponeurosis, which covers the dorsal surface of the first phalanx: this aponeurosis
, at the articulation of the first with the second phalanx, divides into three slips—an intermediate, which is inserted into the base of the second phalanx; and two collateral slips, which, after uniting on the dorsal surface of the second phalanx, are continued onward, to be inserted into the base of the third phalanx.
The tendons to the second and fifth toes may be found doubled, or extra slips are given off from one or more tendons to their corresponding metatarsal bones, or to the short extensor, or to one of the interosseous muscles.
A slip to the great toe from the innermost tendon has been found.
Pennate
Pennate is used to mean "winged", "feathered" or simply "shaped like a wing". The latter definition is sometimes used to describe plant leaf morphology .Pennate diatoms are bilaterally symmetrical, and belong to the order Pennales....
muscle, situated at the lateral part of the front of the leg.
Origin and insertion
It arises from the lateral condyleLateral condyle of tibia
The lateral condyle is the lateral portion of the upper extremity of tibia.It serves as the insertion for the Biceps femoris muscle....
of the tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
; from the upper three-fourths of the anterior surface of the body of the fibula; from the upper part of the interosseous membrane
Interosseous membrane
An interosseous membrane is a broad and thin plane of fibrous tissue that separates many of the bones of the body. It is an important component of many joints.Interosseous membranes in the human body:* Interosseous membrane of the forearm...
; from the deep surface of the fascia; and from the intermuscular septa between it and the Tibialis anterior on the medial, and the Peronæi on the lateral side. Between it and the Tibialis anterior are the upper portions of the anterior tibial vessels and deep peroneal nerve.
The muscle passes under the transverse and cruciate crural ligament
Cruciate crural ligament
The inferior extensor retinaculum of the foot is a Y-shaped band placed in front of the ankle-joint, the stem of the Y being attached laterally to the upper surface of the calcaneus, in front of the depression for the interosseous talocalcanean ligament; it is directed medialward as a double...
s in company with the Peronæus tertius, and divides into four slips, which run forward on the dorsum of the foot, and are inserted into the second and third phalanges of the four lesser toes.
The tendons to the second, third, and fourth toes are each joined, opposite the metatarsophalangeal articulation, on the lateral side by a tendon of the Extensor digitorum brevis. The tendons are inserted in the following manner: each receives a fibrous expansion from the Interossei
Interossei
Interossei refer to muscles between certain bones. There are many interossei in a human body. Specific interossei include:-On the hands:* Dorsal interossei muscles of the hand* Palmar interossei muscles-On the feet:...
and Lumbricalis
Lumbricalis
-Species Latin names:* Amphisbaena lumbricalis, Vanzolini, 1996, a worm lizard species in the genus Amphisbaena* Asteriacites lumbricalis, a five-rayed fossil found in rocks : see Asteriacites...
, and then spreads out into a broad aponeurosis, which covers the dorsal surface of the first phalanx: this aponeurosis
Aponeurosis
Aponeuroses are layers of flat broad tendons. They have a shiny, whitish-silvery color, are histologically similar to tendons, and are very sparingly supplied with blood vessels and nerves. When dissected, aponeuroses are papery, and peel off by sections...
, at the articulation of the first with the second phalanx, divides into three slips—an intermediate, which is inserted into the base of the second phalanx; and two collateral slips, which, after uniting on the dorsal surface of the second phalanx, are continued onward, to be inserted into the base of the third phalanx.
Variations
This muscle varies considerably in the modes of origin and the arrangement of its various tendons.The tendons to the second and fifth toes may be found doubled, or extra slips are given off from one or more tendons to their corresponding metatarsal bones, or to the short extensor, or to one of the interosseous muscles.
A slip to the great toe from the innermost tendon has been found.