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

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...

that runs down the length of the

thigh In human 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 ...

in the anterior compartment.

Structure

The sartorius muscle originates from the

anterior superior iliac spine The anterior superior iliac spine (abbreviated: 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 ing ...

, and part of the notch between the anterior superior iliac spine and

anterior inferior iliac spine Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

. It runs obliquely across the upper and anterior part of the

in an inferomedial direction. It passes behind the

medial condyle of the femur The medial condyle is one of the two projections on the lower extremity of femur, the other being the lateral condyle. The medial condyle is larger than the lateral (outer) condyle due to more weight bearing caused by the centre of mass being med ...

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 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, r ...

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

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

. 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 rot ...

, 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 adduct the thigh and it is innervated by the obturator nerve. It forms the medial wall of the fem ...

marks the apex of the triangle. Deep to sartorius and its fascia is the

adductor canal The adductor canal, also known as the subsartorial canal or Hunter’s canal, is an aponeurotic tunnel in the middle third of the thigh. It extends from the apex of the femoral triangle to the adductor hiatus. Structure The adductor canal extends ...

, through which the

saphenous nerve The saphenous nerve (long or internal saphenous nerve) is the largest cutaneous branch Cutaneous innervation refers to the area of the skin which is supplied by a specific cutaneous nerve. Dermatome (Anatomy), Dermatomes are similar; however, a ...

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 or profunda femoris artery and descends along the anteromedial part of the thigh in the fem ...

and

vein Veins are blood vessels in 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 the pulmonary and umbilical veins, both of which carry oxygenated b ...

, 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 present i ...

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. Structure The femoral nerve is the major nerve supplying the anterior compartment of the thigh. It is the largest ...

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 dev ...

, the notch of the ilium, the

ilio-pectineal line Medial to the anterior inferior iliac spine is a broad, shallow groove, over which the iliacus and psoas major muscles pass. This groove is bounded medially by an eminence, the iliopubic eminence (or iliopectineal eminence), which marks the point ...

or the pubis. The muscle may be split into two parts, and one part may be inserted into the

fascia lata The fascia lata is the deep fascia of the thigh. It encloses the thigh muscles and forms the outer limit of the fascial compartments of thigh, which are internally separated by the medial intermuscular septum and the lateral intermuscular septu ...

, the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

, the ligament of the

patella The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in many tetrapods, such as m ...

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, r ...

. 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 Anatomical terminology is used to uniquely describe aspects of skeletal muscle, cardiac muscle, and smooth muscle such as their actions, structure, size, and location. Types There are three types of muscle tissue in the body: skeletal, smooth, a ...

. 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 semiten ...

, 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 branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word ''sartor'', meaning tailor, and it is sometimes called the tailor's muscle. This name was chosen in reference to the cross-legged position in which tailors once sat. In French, a muscle name itself "couturier" comes from this specific position which is referred to as "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