Sartorius muscle

Origin and insertion

The sartorius muscle originates by a round tendon from the anterior superior iliac spine and the upper half of the notch between the anterior superior iliac spine and the anterior inferior iliac spine. The fibers form a thin, flat muscle, which extends inferomedially across the anterior surface of the thigh.

The muscle descends in an almost vertical fashion through the medial aspect of the thigh. It crosses the medial side of the knee joint and then inserts onto the medial aspect of the proximal tibia, anterior to the gracilis and semitendinosus muscles.

The inserting tendons of these three muscles form a wide aponeurotic sheath called the pes anserinus. Some fibers from the inferior part of the tendon blend with the medial collateral ligament of the knee joint, and the deep fascia over the medial aspect of the leg, while some superior fibers blend with the knee joint capsule. These connections contribute to the medial stability of the knee joint.

Are you feeling a bit overwhelmed? Learn the attachments, innervations and functions of the muscles of the lower limb, faster and easier with our muscle charts!

Relations

The sartorius muscle lies superficially in the thigh, with only fascia and skin over its surface. Deep to the sartorius is the quadriceps femoris muscle.

As it crosses from the lateral to the medial side of the thigh, the sartorius muscle crosses the surfaces of the iliopsoas, pectineus and adductor longus muscles. The tensor fasciae latae muscle originates just lateral to the proximal attachment of the sartorius muscle.

The medial edge of the sartorius forms the lateral border of an important anatomical space known as the femoral triangle. The triangle is completed superiorly by the inguinal ligament and medially by the medial margin of the adductor longus muscle. The structures found within the triangle, the femoral artery, vein and nerve, therefore, lie medial to the sartorius. The femoral artery continues inferiorly, deep to the sartorius.

In order to easily remember the borders of the femoral triangle, you can use the mnemonic SAIL which stands for:

• Sartorius
• Adductor longus
• Inguinal Ligament

Innervation

Sartorius receives its innervation from the femoral nerve L2 and L3.

Blood supply

As sartorius is such a long muscle, it comes as no surprise that it requires extensive vascular supply from several sources:

• The proximal third may receive its vascular supply from the branches of the femoral, deep femoral, lateral circumflex femoral arteries and/or artery of quadriceps (branch of either the femoral, deep femoral, or lateral circumflex femoral artery).

• The middle third is supplied by branches of the femoral artery.

• The distal third receives blood supply from the femoral artery and descending genicular artery.

Learn everything with about the muscles of the lower limb and the muscles of the hip and thigh with the following study units. 

Function

The sartorius muscle crosses both the hip and knee joints, producing movements on both of them. At the hip joint it is capable of flexion, external rotation and abduction of the leg. The contraction of sartorius can also cause flexion of the knee joint and inward, or medial, rotation of the tibia against the femur.

The combination of all these movements allows an individual to sit in a cross-legged position. However, movements created by the contraction of sartorius are not limited to that single function. It is also suggested that sartorius may play an important role in climbing.

Test your knowledge about the sartorius and other muscles of the hip and thigh with the following quiz!