Sartorius
Musculus sartorius
Also known as: tailor's muscle
The longest muscle in the body, a narrow strap running obliquely across the thigh from the ASIS to the medial tibia. It flexes, abducts and laterally rotates the hip and flexes the knee (the cross-legged "tailor's" position).
Overview
Sartorius arises from the anterior superior iliac spine and crosses the front of the thigh obliquely from lateral to medial. It runs down the medial side of the knee to insert on the upper medial surface of the tibia as the most anterior part of the pes anserinus. Its parallel fibres are the longest of any muscle (up to ≈30 cm, nearly the full length of the muscle), which suits it to producing a large range of movement rather than great force.
Acting across two joints, it flexes, abducts and laterally rotates the hip and flexes the knee, then medially rotates the flexed leg. Together these actions put the limb into the cross-legged sitting position of a tailor (sartor). Sartorius is a key landmark. It forms the lateral border of the femoral triangle and the roof of the adductor (subsartorial) canal. It is supplied by the femoral nerve (L2–L3).
- Location
Anterior thigh, running obliquely from the ASIS to the medial knee.
Anatomy
- Origin
Anterior superior iliac spine.
- Insertion
Superior part of the medial surface of the tibia (pes anserinus).
- Action
Flexion, abduction and lateral rotation of the thigh; flexion of the leg at the knee.
- Innervation
Femoral nerve.
- Nerve roots
L2–L3
- Arterial supply
Muscular branches of the femoral artery (segmental); descending genicular artery.
- Relations
Lateral border of the femoral triangle (with the inguinal ligament and adductor longus). Roof of the adductor canal, covering the femoral vessels and the saphenous nerve. The great saphenous vein lies superficial and posterior to it at the knee.
Function
- Flexes, abducts and laterally rotates the hip
- Flexes the knee and medially rotates the flexed leg
Clinical significance
ASIS avulsion
In adolescent sprinters and footballers, forceful contraction of sartorius can avulse the unfused ASIS apophysis.
Pes anserinus bursitis
Medial knee pain below the joint line, over the conjoined insertion of sartorius, gracilis and semitendinosus. Common in runners and in knee osteoarthritis.
Mnemonics
Femoral triangle contents (lateral → medial)
NAVeL: femoral Nerve, Artery, Vein, Lymphatics (deep inguinal nodes in the femoral canal). Borders: inguinal ligament, sartorius, adductor longus.
Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.