The Anatomy of the Sartorius Muscle

Anatomy of the Tailor's Muscle

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The sartorius muscle is a long muscle located in the front of your thigh. It courses from your hip and crosses the front of your thigh, inserting near the inner part of your knee. The sartorius serves to flex and rotate your hip and bend your knee. It is the longest muscle in the human body. There are two sartorius muscles, one on either side of your body.

The sartorius is also known as the tailor's muscle. This is because it helps to flex and rotate your hip and flex your knee; if you were to sit with one leg crossed over the other, then the sartorius muscle would be working. This position was often adopted by tailors who were working on sewing seams by hand. Hence, the sartorius is called the tailor's muscle.

Anatomy

The sartorius muscle arises from the front part of your pelvis called the anterior superior iliac spine (ASIS). From there, the muscle courses down in a spiral fashion across the front of your thigh. It then crosses your inner knee, inserting in the front of your shin bone at a place called the pes anserine. (The pes anserine is called the goose foot and is the insertion point for the sartorius, gracilis muscle, and the semi-tendinosis muscle of the hamstring.)

The muscle is very long, and it can be palpated or touched in the front part of your hip near your pelvic bone. Simply place your hand on the bony part of your pelvis in the front of your hip. Then, flex your thigh up and rotate it outward; the muscle that protrudes is the sartorius. It is difficult to palpate the sartorius as it crosses your knee joint or at the pes anserine insertion.

Function

Since the sartorius muscle is very long and crosses two joints (the hip and the knee) it serves many functions for your body and lower extremities. The movements that the sartorius does is:

  • Flexion of your hip. This means that it bends your hip up as if you were marching. Other muscles, such as your psoas muscle, also flex your hip up.
  • External rotation of your hip. The sartorius has a line of pull across the front of your thigh, and this line of pull helps to rotate your hip outwards. If you are standing and lift your foot up and in to look at the bottom of your shoe, your sartorius would be active lifting and externally rotating your hip.
  • Flexion of your knee. You may be surprised to learn that the sartorius actually flexes your knee. This occurs because the muscle courses behind your knee joint on the inner side of your knee and attaches to the front of your shin bone. When the muscle contracts, it bends your knee. (Your hamstrings also bend your knee, so the sartorius is most active with knee bending while your hip is flexed and rotated.)

These different actions of the sartorius make it a unique muscle that moves your hips and knees in various directions. It also means that the sartorius may be implicated in a few different problems and conditions.

The sartorius muscle is innervated by the femoral nerve. This nerve arises from your low back at lumbar level two, three, and four. The sartorius muscle receives blood supply from various arteries the penetrate the muscle at irregular intervals. These blood vessels include the superficial circumflex iliac, the lateral femoral, and the deep femoral arteries of your thigh.

Associated Conditions

Your sartorius muscles may be implicated in several different conditions that may limit your functional mobility. These may include:

  • Sartorius muscle strain
  • Tear of the sartorius muscle
  • Pes anserine tendonitis
  • Sartorius paresis or paralysis due to a pinched nerve injury in your lumbar spine

If you suspect you have any of these problems, visit your doctor right away to get an accurate diagnosis and to start the proper treatment for your condition.

Rehabilitation

If you have an injury to your sartorius, you may benefit from working with a physical therapist (PT) during rehabilitation. The treatments you receive from your PT may vary based upon your specific injury.

  • Sartorius Tendonitis: This condition typically results in pain and limited mobility of the muscle. Many people feel pain in the front of their hip while flexing and rotating it during walking. Your PT may help decrease the inflammation of the muscle and help improve its ability to contract properly to help you regain normal walking and movement.
  • Sartorius Tear: A tear to the sartorius may involve a significant period of immobility and rest to allow for the muscle to heal. Once healing has taken place, your PT may work with you to improve scar tissue mobility, improve sartorius muscle flexibility, and improve strength of the muscle.
  • Pes Anserine Tendonitis: The hallmark of this condition is pain in the medial and front aspect of your upper shin bone just below your knee. Your PT can help you decrease pain and inflammation, improve sartorius flexibility, and improve strength.
  • Weakness in the sartorius due to nerve injury: If you have a condition with your low back like a herniated disc or spinal foraminal stenosis, nerve compression may occur. This pinched nerve may cause pain and weakness in the front of your thigh, and your sartorius may be affected. Treatment for this may include performing exercises to relieve nerve compression and to correct your posture to keep pressure off the nerve.

    An injury to the sartorius muscle usually occurs in conjunction with injury to another thigh muscle like the psoas and the quadriceps. These muscles all work together to move your thigh and knee, and therefore an injury to one muscle may also affect the others.

    Most problems with the sartorius and associated muscles heal within four to six weeks. Of course, your specific course of treatment may be shorter or longer depending on the severity of your injury and any other co-morbidities you may have.

    Your doctor and physical therapist can help you understand your specific prognosis when it comes to an injury to your sartorius.

    A Word From Verywell

    The sartorius, or tailor's muscle, is the longest muscle in your body and helps you flex and rotate your hip and flex your knee. Having a basic comprehension of the function and location of this important muscle can help you understand your rehab should you suffer an injury to it.

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    Article Sources

    • Lee B, Stubbs E. Sartorius muscle tear presenting as acute meralgia paresthetica. Clin Imaging. 2018;51:209-212. DOI: 10.1016/j.clinimag.2018.05.011

    • Wysocki J, Krasuski P, Czubalski A. Vascularization of the sartorius muscle. Folia Morphol (Warsz). 1996;55(2):115-20.