Adductor Longus: Origin, Insertion, Nerve, Action & Groin Strain

The Adductor Longus is the most anterior and superficial muscle of the adductor group. It fans out from the pelvis to the thigh, forming a distinct ridge that is easily felt in the groin. It is a key player in hip stability and is anatomically famous for defining the medial border of the Femoral Triangle.

[Image of Adductor Longus muscle anatomy]

Quick Anatomy Snapshot

Origin (Proximal)	Body of the Pubis (specifically inferior to the pubic crest and lateral to the pubic symphysis).
Insertion (Distal)	Middle third of the Linea Aspera (medial lip) on the posterior Femur.
Nerve Supply	Obturator Nerve (Anterior Division) - L2, L3, L4.
Blood Supply	Deep Femoral Artery (Profunda Femoris) and Obturator Artery.
Primary Actions	Adduction: Powerful adductor of the thigh. Flexion: Flexes the hip (up to ~70 degrees). Stabilization: Balances the pelvis during walking.

Deep Dive: The Triangle Maker

The Adductor Longus is not just a mover; it is a major anatomical landmark.

1. The Femoral Triangle

The medial border of the Adductor Longus forms the medial boundary of the Femoral Triangle. This triangle is critical because it contains the femoral nerve, artery, and vein. If you can find the Adductor Longus tendon, you know the major vessels are just lateral to it.

2. The "Fan" Shape

It starts as a strong, round tendon at the pubis (often confused with bone due to its hardness) and expands into a broad, fan-like aponeurosis as it attaches to the Linea Aspera on the back of the femur.

Physio Corner: Clinical Relevance

💪 Functional Fact: The Adductor Longus acts as a synergist for hip flexion in the early swing phase of gait. However, once the hip is flexed past 70 degrees, it can actually assist in extension. This dual role makes it susceptible to strain during rapid direction changes.

Palpation

Abduct the patient's hip slightly. Palpate the groin region just below the pubic bone. Ask the patient to adduct against resistance. The Adductor Longus tendon is the most prominent, cord-like structure felt at the proximal medial thigh.

⚠️ Clinical Pathology: Groin Strain / Rider's Strain
The Adductor Longus is the most commonly injured muscle in a "groin pull." This is frequent in soccer players (kicking across the body) and hockey players (skating stride). Tenderness at the pubic origin may indicate Adductor Tendinopathy or Osteitis Pubis.

Manual Muscle Testing (MMT)

While the adductors work as a group, the Longus is the primary force generator in the superficial layer.

Testing Tip: Ensure the patient does not internally rotate the hip, which would recruit the TFL/Gluteus Minimus, or extend the hip, which recruits the Adductor Magnus (Hamstring part).

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 is on the bottom). Top leg is held up in abduction by the therapist. Action: Patient lifts the bottom leg straight up towards the top leg. Resistance: Applied at the distal medial thigh (above the knee), pushing down. Grade 3: Lifts leg off the table. Grade 4/5: Holds against pressure.
Grade 2 (Gravity Eliminated)	Position: Supine. Leg abducted to start. Action: Patient slides the leg medially towards the other leg. Result: Full range of motion sliding on the table.
Grade 0, 1 (Palpation)	Action: Palpate the prominent tendon at the groin. Cue: "Squeeze your legs together." Grade 1: Tendon pops out/tension felt. Grade 0: No activity.

Frequently Asked Questions

Is Adductor Longus a rotator of the hip?

This is controversial. Anatomically, its position suggests it can assist in Lateral (External) Rotation, but EMG studies show its rotation function is weak and dependent on limb position.

What forms the Femoral Triangle?

Superior: Inguinal Ligament.
Lateral: Sartorius muscle.
Medial: Medial border of Adductor Longus.

Does it cross the knee joint?

No. The Adductor Longus inserts on the femur. Only the Gracilis (part of the adductor group) crosses the knee joint to insert on the tibia.

Test Your Knowledge: Adductor Longus Quiz

1. Which nerve supplies the Adductor Longus?

2. The Adductor Longus forms the medial border of which anatomical space?

3. What is the origin of the Adductor Longus?

4. Where does the Adductor Longus insert?

5. Which muscle is most superficial in the adductor group?

6. Besides adduction, what is a secondary action of the Adductor Longus?

7. Tenderness at the Adductor Longus origin is characteristic of:

8. Which muscle lies directly deep to the Adductor Longus?

9. The Adductor Longus tendon is easily palpated at the:

10. To bias the Adductor Longus during testing, the knee should be:

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.
• Brukner, P., & Khan, K. (2017). Clinical Sports Medicine. 5th ed. McGraw-Hill Education.