Gracilis muscle
Encyclopedia
The gracilis is the most superficial muscle on the medial side of the thigh
Thigh
In humans the thigh is the area between the pelvis and the knee. Anatomically, it is part of the lower limb.The single bone in the thigh is called the femur...

. It is thin and flattened, broad above, narrow and tapering below.

Origin and insertion

It arises by a thin 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...

 from the anterior margins of the lower half of the symphysis pubis
Pubic symphysis
The pubic symphysis or symphysis pubis is the midline cartilaginous joint uniting the superior rami of the left and right pubic bones. It is located anterior to the urinary bladder and superior to the external genitalia; for females it is above the vulva and for males it is above the penis...

 and the upper half of the pubic arch
Pubic arch
The eminences of the lower circumference of the true pelvis are separated by three notches: one in front, the pubic arch, formed by the convergence of the inferior rami of the ischium and pubis on either side. The angle at which they converge is known as the subpubic angle.-External links:* *...

.

The muscle's fibers run vertically downward, ending in a rounded tendon. This tendon passes behind the medial condyle of the femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...

, curves around the medial condyle of the tibia
Medial condyle of tibia
The medial condyle is the medial portion of the upper extremity of tibia.It is the site of insertion for the Semimembranosus muscle....

 where it becomes flattened, and inserts into the upper part of the medial surface of the body 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....

, below the condyle. For this reason, the muscle is a lower limb adductor. At its insertion the tendon is situated immediately above that of the semitendinosus
Semitendinosus muscle
The semitendinosus is a muscle in the back of the thigh; it is one of the hamstrings.-Structure:The semitendinosus, remarkable for the great length of its tendon of insertion, is situated at the posterior and medial aspect of the thigh ....

 muscle, and its upper edge is overlapped by the tendon of the sartorius muscle
Sartorius muscle
The Sartorius muscle – the longest muscle in the human body – is a long thin muscle that runs down the length of the thigh. Its upper portion forms the lateral border of the femoral triangle.-Origin and insertion:...

, which it joins to form the pes anserinus
Pes anserinus
Pes anserinus is the anatomic term used to describe two different structures:* Pes anserinus * Pes anserinus...

. The pes anserinus is separated from the medial collateral ligament
Medial collateral ligament
The medial collateral ligament of the knee is one of the four major ligaments of the knee. It is on the medial side of the knee joint in humans and other primates. It is also known as the tibial collateral ligament, or abbreviated as the MCL.- Structure :It is a broad, flat, membranous band,...

 of the knee-joint
Knee
The knee joint joins the thigh with the leg and consists of two articulations: one between the fibula and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a mobile trocho-ginglymus , which permits flexion and extension as...

 by a bursa
Bursa (anatomy)
A bursa is a small fluid-filled sac lined by synovial membrane with an inner capillary layer of slimy fluid . It provides a cushion between bones and tendons and/or muscles around a joint. This helps to reduce friction between the bones and allows free movement...

.

A few of the fibers of the lower part of the tendon are prolonged into the deep fascia of the leg.

Action

The muscle adducts and flexes
Hip flexors
In human anatomy, the hip flexors are a group of skeletal muscles that act to flex the femur onto the lumbo-pelvic complex, i.e., pull the knee upward....

 the hip as above, and also aids in flexion of the knee.

Relations

By its inner or superficial surface gracilis is in relation with the fascia lata
Fascia lata
-Thickness:It is an investment for the whole of the thigh, but varies in thickness in different parts.Thus, it is thicker in the upper and lateral part of the thigh, where it receives a fibrous expansion from the Glutæus maximus, and where the Tensor fasciæ latæ is inserted between its layers; it...

, and below with the sartorius
Sartorius muscle
The Sartorius muscle – the longest muscle in the human body – is a long thin muscle that runs down the length of the thigh. Its upper portion forms the lateral border of the femoral triangle.-Origin and insertion:...

 and internal saphenous nerve
Saphenous nerve
The saphenous nerve is the largest cutaneous branch of the femoral nerve.-Path:It approaches the femoral artery where this vessel passes beneath the sartorius, and lies in front of the artery, behind the aponeurotic covering of the adductor canal, as far as the opening in the lower part of the...

; the internal saphenous vein
Saphenous vein
Saphenous vein may refer to:*Great saphenous vein*Small saphenous vein...

 crosses it lying superficially to the fascia lata.

By its outer or deep surface with the adductor longus, brevis, and magnus, and the internal lateral ligament of the knee-joint, from which it is separated by a synovial bursa common to the tendons of the gracilis and semitendinosus.

Microsurgery

The gracilis muscle is commonly used as a flap in microsurgery
Microsurgery
Microsurgery is a general term for surgery requiring an operating microscope. The most obvious developments have been procedures developed to allow anastomosis of successively smaller blood vessels and nerves which have allowed transfer of tissue from one part of the body to another and...

. According to the classification of Mathes and Nahai, it presents a type II blood supply, allowing it to be transferred on its artery derived from the medial circumflex femoral artery. This artery enters the muscle about 10 cm from the pubic symphysis. At this point (or 1 cm proximal) the nerve also enters.

Gracilis muscle is widely used in reconstructive surgery, either as a pedicled flap or as a free microsurgical flap. Both pedicled and free flaps can be muscular or musculocutaneos (the so- called "composite flaps"). As a pedicled flap, gracilis muscle can be used in perineal and vaginal reconstruction, after oncological surgery, in the treatment of recurrent anovaginal and rectovaginal fistulas as well in the coverage of the neurovascular bundle after vascular surgery.

As a functioning pedicled flap, the gracilis muscle can be transferred for the treatment of anal incontinence. This technique called graciloplasty was described in the 1950s by Pickrell and was revolutionized in the late 1980s by the introduction of chronic muscle electro-stimulation. The gracilis microsurgical free flap is commonly used in the reconstruction of upper and lower limbs, in breast reconstruction and – as a free functioning flap – to restore forearm function or in dynamic reconstruction of facial paralysis.Gracilis Muscles Clinical Role

Transplantation sites

The muscle may be split to reduce bulk for facial reanimation, as well as to repair hand muscles. It can be used to fashion an external anal sphincter
Sphincter ani externus muscle
The Sphincter ani externus is a flat plane of muscular fibers, elliptical in shape and intimately adherent to the integument surrounding the margin of the anus.-Anatomy:...

.

External links

- "Muscles of the anterior (extensor) compartment of the thigh
Thigh
In humans the thigh is the area between the pelvis and the knee. Anatomically, it is part of the lower limb.The single bone in the thigh is called the femur...

." - "Muscles that form the superficial boundaries of the popliteal fossa
Popliteal fossa
The popliteal fossa is a shallow depression located at the back of the knee joint. The bones of the popliteal fossa are the femur and the tibia.-Boundaries:The boundaries of the fossa are:-Roof:...

."
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