The sartorius muscle () is the longest muscle in the human body. It is a long, thin, superficial

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 ...

that runs down the length of the

thigh In anatomy, the thigh is the area between the hip (pelvis) and the knee. Anatomically, it is part of the lower limb. The single bone in the thigh is called the femur. This bone is very thick and strong (due to the high proportion of bone tissu ...

in the anterior compartment.

Structure

The sartorius muscle originates from the

anterior superior iliac spine The anterior superior iliac spine (ASIS) is a bony projection of the iliac bone, and an important landmark of surface anatomy. It refers to the anterior extremity of the iliac crest of the pelvis. It provides attachment for the inguinal ligament, ...

, and part of the notch between the anterior superior iliac spine and anterior inferior iliac spine. It runs obliquely across the upper and anterior part of the

in an inferomedial direction. It passes behind the medial condyle of the femur to end in a tendon. This tendon curves anteriorly to join the tendons of the gracilis and

semitendinosus muscle The semitendinosus () is a long superficial muscle in the Posterior compartment of thigh, back of the thigh. It is so named because it has a very long tendon of insertion. It lies posteromedially in the thigh, superficial to the semimembranosus. ...

s in the pes anserinus, where it inserts into the superomedial surface of the

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

. Its upper portion forms the lateral border of the

femoral triangle The femoral triangle (or Scarpa's triangle) is an anatomical region of the upper third of the thigh. It is a subfascial space which appears as a triangular depression below the inguinal ligament when the thigh is flexed, abducted and laterally r ...

, and the point where it crosses

adductor longus In the human body, the adductor longus is a skeletal muscle located in the thigh. One of the adductor muscles of the hip, its main function is to Adduction, adduct the thigh and it is innervated by the obturator nerve. It forms the medial wall ...

marks the apex of the triangle. Deep to sartorius and its fascia is the adductor canal, through which the saphenous nerve,

femoral artery The femoral artery is a large artery in the thigh and the main arterial supply to the thigh and leg. The femoral artery gives off the deep femoral artery and descends along the anteromedial part of the thigh in the femoral triangle. It enters ...

and

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

, and nerve to

vastus medialis The vastus medialis (vastus internus or teardrop muscle) is an extensor muscle located medially in the thigh that extends the knee. The vastus medialis is part of the quadriceps muscle group. Structure The vastus medialis is a muscle presen ...

pass.

Innervation

Like the other muscles in the anterior compartment of the thigh, the sartorius is innervated by the

femoral nerve The femoral nerve is a nerve in the thigh that supplies skin on the upper thigh and inner leg, and the muscles that extend the knee. It is the largest branch of the lumbar plexus. Structure The femoral nerve is the major nerve supplying the ant ...

Variation

It may originate from the outer end of the

inguinal ligament The inguinal ligament (), also known as Poupart's ligament or groin ligament, is a band running from the pubic tubercle to the anterior superior iliac spine. It forms the base of the inguinal canal through which an indirect inguinal hernia may ...

, the notch of the ilium, the ilio-pectineal line or the pubis. The muscle may be split into two parts, and one part may be inserted into the fascia lata, the

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

, the ligament of the patella or the tendon of the

semitendinosus The semitendinosus () is a long superficial muscle in the back of the thigh. It is so named because it has a very long tendon of insertion. It lies posteromedially in the thigh, superficial to the semimembranosus. Structure The semitendinosus, ...

. The tendon of insertion may end in the fascia lata, the capsule of the

knee-joint In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the hu ...

, or the fascia of the leg. The muscle may be absent in some people.

Function

The sartorius muscle can move the hip joint and the knee joint, but all of its actions are weak, making it a synergist muscle. At the hip, it can flex, weakly abduct, and laterally rotate the femur. At the knee, it can flex the leg; when the knee is flexed, sartorius medially rotates the leg. Sitting cross-legged demonstrates all four actions of the sartorius.

Clinical significance

One of the many conditions that can disrupt the use of the sartorius is

pes anserine bursitis Pes anserine bursitis is an inflammatory condition of the medial (inner) knee at the anserine bursa, a sub muscular bursa, just below the pes anserinus. Pathology The pes anserinus is where the tendons of the sartorius, gracilis, and semite ...

, an inflammatory condition of the medial portion of the knee. This condition usually occurs in athletes from overuse and is characterized by pain, swelling and tenderness. The pes anserinus involves the tendons of the gracilis, semitendinosus, and sartorius muscles; these tendons attach onto the anteromedial proximal tibia. When inflammation of the bursae underlying the tendons occurs, they separate from the head of the tibia.

History

The name sartorius comes from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word ''sartor'', meaning tailor, and it is sometimes called the tailor's muscle. This name is likely in reference to the cross-legged position in which tailors once sat. Similarly in French, an older name for this muscle is "couturier" (seamstress or dressmaker), with similar reference to "sitting as a tailor" (in French: "s'asseoir en tailleur"). There are other hypotheses as to the origin of the name. One is that it refers to the location of the inferior portion of the muscle being the "inseam" or area of the inner thigh that tailors commonly measure when fitting trousers. Another is that the muscle closely resembles a tailor's ribbon. Additionally, antique sewing machines required continuous crossbody pedaling. This combination of lateral rotation and flexion of the hip and flexion of the knee gave tailors particularly developed sartorius muscles.

Additional images

File:Gray430.png, Muscles of the iliac and anterior femoral regions. File:Thigh cross section.svg, Cross-section through the middle of the thigh. File:Gray549.png, The left femoral triangle. File:Gray1238.png, Front and medial aspect of right thigh. File:Anatomical dissection4.JPG File:Slide1rrr.JPG, Sartorius muscle File:Slide1www.JPG, Sartorius muscle File:Slide2A.JPG, Sartorius muscle File:Slide2CCCC.JPG, Sartorius muscle File:Slide7GGGGG.JPG, Sartorius muscle File:Slide8NNNNN.JPG, Sartorius muscle File:Slide2EA.JPG, Muscles of thigh. Cross section.

References

External links

* * * {{Authority control Hip abductors Hip flexors Hip lateral rotators Knee flexors Thigh muscles Anterior compartment of thigh Muscles of the lower limb