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The sartorius muscle is the longest muscle in the human body. It is a long, thin, superficial muscle that runs down the length of the thigh, crossing the hip and knee joints. The muscle is named after tailors, who would often sit cross-legged while working, a position that demonstrates all four actions of the sartorius. The muscle has long parallel fibres that extend for the whole length of the muscle, running obliquely from lateral to medial down the thigh.
| Characteristics | Values |
|---|---|
| Muscle Name | Sartorius |
| Muscle Type | Longest muscle in the human body |
| Muscle Appearance | Thin, long, superficial |
| Muscle Origin | Anterior superior iliac spine |
| Muscle Insertion | Tendon of the semitendinosus |
| Muscle Action | Flexes, abducts, and rotates the hip and thigh laterally |
| Muscle Innervation | Femoral nerve |
| Muscle Blood Supply | Muscular branches of the femoral artery |
| Muscle Function | Hip and knee flexor |
| Muscle Conditions | Pes anserine bursitis |
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What You'll Learn
The sartorius muscle is the longest muscle in the human body
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, the sartorius medially rotates the leg. Sitting cross-legged demonstrates all four actions of the sartorius. The sartorius muscle has long parallel fibres that extend for the whole length of the muscle, running obliquely from lateral to medial down the thigh anterior to the quadriceps. It spirals obliquely down across the thigh, passes downwards on the fascial roof of the adductor canal, and lies near the posterior aspect of the medial condyle of the femur. Its tendon inserts onto the anteromedial aspect of the tibia as part of the pes anserinus tendon.
The sartorius muscle is also associated with the pes anserinus, which involves the tendons of the gracilis, semitendinosus, and sartorius muscles. These tendons attach to the anteromedial proximal tibia. When inflammation of the bursae underlying the tendons occurs, they separate from the head of the tibia, resulting in a condition called pes anserine bursitis. This condition is characterised by pain, swelling, and tenderness, and usually occurs in athletes due to overuse. The name "sartorius" comes from the Latin word "sartor," meaning tailor, and it is sometimes referred to as the "tailor's muscle." This name likely refers to the cross-legged position in which tailors once sat while working. Antique sewing machines, which required continuous crossbody pedalling, also contributed to the development of particularly strong sartorius muscles in tailors.
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It is a hip and knee flexor
The sartorius muscle is the longest muscle in the human body. It is a long, thin, superficial muscle that runs down the length of the thigh in the anterior compartment. The sartorius muscle originates from the anterior superior iliac spine and crosses the thigh towards the medial aspect of the knee. It is named the tailor's muscle because it allowed tailors to sit cross-legged while working.
The sartorius muscle is a hip and knee flexor. At the hip, it can flex, weakly abduct, and laterally rotate the femur. This means that it can bend, lift, and rotate the femur outwards. At the knee, it can flex the leg and medially rotate the leg, which means that it can bend the leg and rotate it inwards.
The ability to sit cross-legged demonstrates the sartorius muscle's function as a hip and knee flexor. This is achieved through the combination of flexion, abduction, and lateral rotation of the hip, as well as flexion of the knee. These movements are not strong in isolation, and the sartorius muscle is considered a synergist muscle, meaning that it works together with other muscles to produce these movements.
The sartorius muscle plays an important role in stabilising the pelvis, especially in women. This is due to the constrictive effect that the muscles on both sides of the body have on the pubic symphysis. The sartorius muscle also helps with balance, as it connects the hip bone to the leg and balances the hip bone on the femur.
One condition that can affect the sartorius muscle is pes anserine bursitis, an inflammatory condition of the medial portion of the knee. This condition usually occurs in athletes from overuse and is characterised by pain, swelling, and tenderness. It is caused by inflammation of the bursa underlying the tendons of the sartorius, gracilis, and semitendinosus muscles.
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It is innervated by the femoral nerve
The sartorius muscle is the longest muscle in the human body. It is a long, thin, superficial muscle that runs down the length of the thigh in the anterior compartment. The sartorius muscle is innervated by the femoral nerve, which receives its nerve supply from L2, L3, and L4 nerve roots. The femoral nerve innervates both the hip flexor and quadriceps muscle groups. The femoral nerve (motor divisions and branches) innervates the following muscles.
The sartorius muscle originates from the anterior superior iliac spine and runs obliquely across the upper and anterior part of the thigh 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 muscles in the pes anserinus, where it inserts into the superomedial surface of the tibia. Its upper portion forms the lateral border of the femoral triangle, and the point where it crosses the adductor longus marks the apex of the triangle.
Deep to the sartorius and its fascia is the adductor canal, through which the saphenous nerve, femoral artery and vein, and nerve to vastus medialis pass. 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, the sartorius medially rotates the leg.
The blood supply to the sartorius is mainly from the muscular branches of the femoral artery. Over half of the blood supply comes from these muscular branches of the femoral artery, but collateral flow also arises from the superficial circumflex iliac artery, lateral circumflex femoral artery, superficial femoral artery, descending genicular artery, and superior medial genicular artery. The innervation to the sartorius is derived explicitly from the anterior division of the femoral nerve. The posterior division supplies innervation to the muscles of the quadriceps.
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It is also called the 'tailor's muscle'
The sartorius muscle is the longest muscle in the human body. It is a long, thin, superficial muscle that runs down the length of the thigh in the anterior compartment. The sartorius muscle originates from the anterior superior iliac spine and passes behind the medial condyle of the femur to end in a tendon. This tendon joins the tendons of the gracilis and semitendinosus muscles in the pes anserinus, where it inserts into the superomedial surface of the tibia. The sartorius muscle is also involved in flexion, abduction, and lateral rotation of the hip, and flexion of the knee. These movements are involved in drawing the lower limb into a cross-legged sitting position, which was commonly adopted by tailors.
The name 'sartorius' comes from the Latin word 'sartor', meaning tailor, and it is sometimes called the 'tailor's muscle'. This name likely refers to the cross-legged position in which tailors once sat while working. Antique sewing machines required continuous cross-body pedalling, which would have given tailors particularly developed sartorius muscles due to the combination of lateral rotation and flexion of the hip and flexion of the knee. In French, an older name for this muscle is "couturier" (seamstress or dressmaker), with a similar reference to "sitting as a tailor" ("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. The sartorius muscle can be difficult to identify due to its small size near the anterosuperior iliac spine, but it is easier to visualise in the proximal thigh.
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It is involved in stabilising the pelvis
The sartorius muscle is the longest muscle in the human body. It is a thin, long, superficial muscle that runs down the length of the thigh in the anterior compartment. The sartorius muscle originates from the anterior superior iliac spine, 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 thigh 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 muscles in the pes anserinus, where it inserts into the superomedial surface of the tibia.
The sartorius muscle plays an important role in stabilising the pelvis, especially in women. This is due to the constrictive effect that the muscles on both sides of the body have on the pubic symphysis. The sartorius muscle is involved in the flexion, abduction, and external rotation of the hip, and flexion of the knee. These movements are important for maintaining balance and stability in the pelvic region.
The sartorius muscle is unique in that it can serve as both a hip and knee flexor. At the hip, it acts to flex, abduct, and externally rotate the femur. At the knee, it can flex the leg and, when the knee is flexed, the sartorius muscle medially rotates the leg. This muscle is often associated with the cross-legged sitting position, as seen in tailors, which gives it its name. The word "sartorius" is derived from the Latin word "sartor," which means "patcher" or "tailor."
The sartorius muscle is highly susceptible to overuse injuries, especially in athletes. One common condition associated with the sartorius muscle is pes anserine bursitis, an inflammatory condition of the medial portion of the knee. This condition is characterised by pain, swelling, and tenderness, and it typically occurs due to chronic overuse of the sartorius, gracilis, and semitendinosus muscles. It is important to manage and treat these injuries properly to ensure the continued stability and functionality of the pelvis and lower limbs.
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Frequently asked questions
The sartorius muscle is the longest muscle in the human body. It is a thin, long, superficial muscle that runs down the length of the thigh, from the hip to the knee.
The word "sartorius" comes from the Latin word "sartor", meaning "patcher" or "tailor". This is likely due to the cross-legged position in which tailors once sat, demonstrating all four actions of the sartorius muscle.
The sartorius muscle acts as both a hip and knee flexor. It can flex, weakly abduct, and laterally rotate the femur at the hip. At the knee, it can flex the leg and medially rotate it when the knee is flexed.
The blood supply to the sartorius muscle comes primarily from the muscular branches of the femoral artery. However, collateral flow also comes from other sources, such as the superficial circumflex iliac artery and the lateral circumflex femoral artery.
Young athletes are susceptible to ASIS avulsion injuries, which can occur during activities like sprinting or swinging a bat. Additionally, a condition called pes anserine bursitis can cause inflammation of the medial portion of the knee, resulting in pain, swelling, and tenderness.
