Gluteus Medius: Origin, Insertion, Nerve, Action & Trendelenburg Sign

The Gluteus Medius is essentially the "Deltoid of the Hip." Located on the lateral aspect of the hip, it lies partly deep to the Gluteus Maximus and partly superficial. It is the primary hip abductor and plays a critical, often overlooked role in stabilizing the pelvis during walking.

[Image of Gluteus Medius muscle anatomy]

Quick Anatomy Snapshot

Origin (Proximal)	External surface of the Ilium (between the Anterior and Posterior Gluteal Lines).
Insertion (Distal)	Lateral surface of the Greater Trochanter of the Femur.
Nerve Supply	Superior Gluteal Nerve (L4, L5, S1).
Blood Supply	Superior Gluteal Artery.
Primary Actions	Abduction: Moves the thigh away from the midline. Medial Rotation: Anterior fibers turn the thigh inward. Pelvic Stabilization: Keeps the pelvis level when standing on one leg.

Deep Dive: The Pelvic Balancer

While the Gluteus Maximus is the powerhouse for extension, the Medius is the key to stability.

1. The Fan Shape

The muscle is fan-shaped, with fibers converging onto the Greater Trochanter.
• Anterior Fibers: Run vertically; act similarly to Gluteus Minimus (Abduction & Internal Rotation).
• Posterior Fibers: Run obliquely; assist in Extension and External Rotation.

2. The Gait Cycle Hero

When you lift your left leg to take a step, gravity wants to pull your left hip down. The Right Gluteus Medius contracts to hold the right hip stable, preventing the left side from dropping. This mechanism is vital for efficient walking.

Physio Corner: Clinical Relevance

💪 Functional Fact: Weakness in the Gluteus Medius is a leading cause of lower back pain, knee pain (runners knee), and IT Band Syndrome. If the hip drops, the knee collapses inward (valgus), stressing the ACL and patella.

Palpation

Have the patient lie on their side. Locate the Iliac Crest and the Greater Trochanter. The Gluteus Medius fills the space between these two landmarks. Ask the patient to lift their leg (abduct) to feel the muscle belly contract.

⚠️ Clinical Pathology: Trendelenburg Sign
If the Gluteus Medius is weak or paralyzed (Superior Gluteal Nerve injury), the pelvis will drop on the opposite side when standing on the affected leg.
Positive Sign: Stand on Right leg -> Left hip drops = Right Glute Medius weakness.

Manual Muscle Testing (MMT)

To test the Gluteus Medius, we must prevent substitution by the TFL or Gluteus Maximus.

Testing Tip: Ensure the hip stays in neutral rotation and slight extension. If the patient flexes the hip, they are cheating with the Tensor Fasciae Latae (TFL). If they roll backward, they are using Gluteus Maximus.

Step-by-Step Procedure (Oxford Scale)

Grade	Patient Action & Resistance
Grade 3, 4, 5 (Against Gravity)	Position: Side-lying. Bottom leg bent for stability. Top leg straight. Action: Patient lifts the top leg toward the ceiling (Abduction) without rotating or flexing. Resistance: Applied at the ankle (long lever) or knee (short lever), pushing down. Grade 3: Full range against gravity. Grade 4/5: Holds against moderate/max resistance.
Grade 2 (Gravity Eliminated)	Position: Supine (lying on back). Leg straight. Action: Patient slides the leg out to the side (abduction). Result: Full range of motion sliding on the table.
Grade 0, 1 (Palpation)	Action: Palpate just above the Greater Trochanter. Cue: "Try to push your leg out to the side." Grade 1: Contraction felt. Grade 0: No activity.

Frequently Asked Questions

What is Greater Trochanteric Pain Syndrome (GTPS)?

Formerly called "Trochanteric Bursitis," this is often actually a tendinopathy (degeneration) of the Gluteus Medius or Minimus tendons where they attach to the Greater Trochanter. It causes lateral hip pain, especially when lying on that side.

Does Glute Medius rotate the hip?

Yes. The anterior fibers are strong Internal (Medial) Rotators. The posterior fibers can assist in External Rotation.

How is it different from Gluteus Minimus?

The Gluteus Minimus lies deep to the Medius. They share the same actions and nerve supply, but the Minimus inserts on the anterior aspect of the trochanter and is a more potent internal rotator.

Test Your Knowledge: Gluteus Medius Quiz

1. Which nerve supplies the Gluteus Medius?

2. A positive Trendelenburg sign indicates weakness of the Gluteus Medius on which side?

3. Where does the Gluteus Medius insert?

4. What is the primary action of the anterior fibers?

5. During single-leg stance, what does the Glute Medius do?

6. Where does the Gluteus Medius originate?

7. Which muscle is the main compensator (cheater) during Glute Medius testing if the hip flexes?

8. GTPS (Greater Trochanteric Pain Syndrome) usually involves tendinopathy of:

9. Which muscle lies deep to the Gluteus Medius?

10. If the Gluteus Medius is weak, which structure often gets overloaded at the knee?

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.
• Kendall, F. P. (2005). Muscles: Testing and Function, with Posture and Pain. 5th ed. Lippincott Williams & Wilkins.