Gracilis Muscle: Origin, Insertion, Nerve, Action & Pes Anserinus

The Gracilis is the most superficial muscle on the medial side of the thigh. Its name comes from the Latin word for "slender," describing its long, strap-like appearance. It is unique among the hip adductors because it is the only one that crosses both the hip and the knee joints.

[Image of Gracilis muscle anatomy]

Quick Anatomy Snapshot

Origin (Proximal)	Body and Inferior Ramus of the Pubis and the Ramus of the Ischium.
Insertion (Distal)	Medial surface of the upper part of the Tibia (as part of the Pes Anserinus).
Nerve Supply	Obturator Nerve (Anterior division) - L2, L3.
Blood Supply	Medial Circumflex Femoral Artery and Obturator Artery.
Primary Actions	Hip: Adduction and Flexion. Knee: Flexion and Internal (Medial) Rotation of the leg.

Deep Dive: The Two-Joint Adductor

While categorized as an adductor, the Gracilis functions heavily at the knee due to its distal attachment.

1. The Pes Anserinus ("Goose's Foot")

The Gracilis tendon joins with the tendons of the Sartorius and Semitendinosus to insert onto the medial tibia. Together, these three tendons resemble a goose's foot.
Mnemonic: Say Grace before Tea (Sartorius, Gracilis, Semitendinosus).

2. Muscle Transplantation

Because the Gracilis is a relatively weak adductor and its function can be compensated by the larger adductors (Longus/Magnus), surgeons often harvest the Gracilis muscle or tendon for reconstruction surgeries, such as repairing the ACL or restoring facial expressions in Bell's Palsy.

Physio Corner: Clinical Relevance

💪 Functional Fact: The Gracilis is most active during the swing phase of walking, helping to flex the knee and adduct the thigh. It acts as a dynamic stabilizer of the medial knee against valgus stress.

Palpation

Have the patient lie supine with the knee slightly flexed. Abduct the leg slightly. Ask the patient to adduct against resistance. The Gracilis tendon stands out prominently on the medial side of the groin (pubic bone). It is the most medial cord you can feel. Follow it down to the medial knee.

⚠️ Clinical Pathology: Pes Anserine Bursitis
Inflammation of the bursa lying underneath the insertion of the Gracilis, Sartorius, and Semitendinosus tendons. It causes pain on the medial side of the knee, often mistaken for medial meniscus pathology or knee osteoarthritis.

Manual Muscle Testing (MMT)

It is difficult to isolate the Gracilis from the other Adductors, but we can bias it by manipulating the knee.

Testing Tip: Since the Gracilis crosses the knee, extending the knee stretches the muscle, making it more effective. To test general adductors without Gracilis bias, flex the knee slightly. To test Gracilis specifically, keep the knee straight and palpate the medial tendon.

Step-by-Step Procedure (Oxford Scale)

Grade	Patient Action & Resistance
Grade 3, 4, 5 (Against Gravity)	Position: Side-lying on the affected side (test leg on bottom). Top leg is held up in abduction by the therapist. Action: Patient lifts the bottom leg toward the top leg (Adduction). Resistance: Applied at the distal medial thigh (above knee) pushing down. Grade 3: Full range against gravity. Grade 4/5: Holds against resistance.
Grade 2 (Gravity Eliminated)	Position: Supine. Leg abducted. Action: Patient slides the leg medially to bring legs together. Result: Full range of motion.
Grade 0, 1 (Palpation)	Action: Palpate the tendon at the pubic origin or medial knee. Cue: "Squeeze your legs together." Grade 1: Tendon tension felt. Grade 0: No activity.

Frequently Asked Questions

Can you live without your Gracilis?

Yes. It is often harvested for reconstructive surgery (e.g., ACL repair using hamstring/gracilis grafts). The remaining adductors (Longus, Brevis, Magnus) are powerful enough to compensate for the loss of adduction strength.

What is "Groin Strain"?

A groin strain is a tear in one of the adductor muscles. While the Adductor Longus is most commonly injured, the Gracilis can also be strained, especially during activities involving sudden changes of direction or kicking.

Does Gracilis rotate the hip?

Yes, weakly. It assists in internal (medial) rotation of the leg, especially when the knee is flexed.

Test Your Knowledge: Gracilis Quiz

1. Which nerve supplies the Gracilis muscle?

2. The Gracilis inserts into the Tibia as part of which structure?

3. Which other muscles make up the Pes Anserinus?

4. What is the primary action of the Gracilis on the hip?

5. What action does the Gracilis perform at the knee?

6. The Gracilis is the only adductor muscle that:

7. Where is the origin of the Gracilis?

8. Pes Anserine Bursitis causes pain on which aspect of the knee?

9. The Gracilis assists in which rotation of the leg when the knee is flexed?

10. In muscle flap surgery (Gracilis Flap), the muscle is often used to repair:

References

• Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2018). Clinically Oriented Anatomy. 8th ed. Philadelphia: Wolters Kluwer.
• Standring, S. (2016). Gray's Anatomy: The Anatomical Basis of Clinical Practice. 41st ed. Elsevier.
• Magee, D. J. (2014). Orthopedic Physical Assessment. 6th ed. Elsevier.