CorpusHuman Anatomy
MuscularMuscle group

Deep lateral rotators of the hip

Musculi rotatores laterales coxae

Also known as: short external rotators, obturator internus, obturator externus, superior gemellus, inferior gemellus, quadratus femoris, gemelli

A group of short muscles behind the hip joint (piriformis, superior and inferior gemelli, obturator internus, quadratus femoris and obturator externus). They laterally rotate the thigh and act like a rotator cuff of the hip.

Show on body map Muscles — Posterior View

Overview

Below piriformis, from superior to inferior, lie the following muscles.
- Superior gemellus: ischial spine → obturator internus tendon. Nerve to obturator internus (L5–S2).
- Obturator internus: the internal surface of the obturator membrane and its bony margins. Its tendon turns at right angles around the lesser sciatic notch, over a bursa, to the medial surface of the greater trochanter. Nerve to obturator internus.
- Inferior gemellus: ischial tuberosity → obturator internus tendon. Nerve to quadratus femoris (L4–S1).
- Quadratus femoris: lateral ischial tuberosity → quadrate tubercle on the intertrochanteric crest. Nerve to quadratus femoris.
- Obturator externus: the external surface of the obturator membrane → trochanteric fossa. It belongs to the medial compartment and is supplied by the obturator nerve (L3–L4).

Together they laterally rotate the extended thigh, abduct the flexed thigh (upper members) and, most importantly, press the femoral head into the acetabulum, giving dynamic stability. In posterior approaches to the hip they are divided and then repaired to reduce the risk of dislocation. The medial circumflex femoral artery, which supplies the femoral head, runs close to quadratus femoris and obturator externus.

Parts & subdivisions

  1. Piriformis
    The uppermost lateral rotator.
  2. Superior and inferior gemelli
    Small muscles flanking the obturator internus tendon.
  3. Obturator internus
    Exits through the lesser sciatic foramen. Its fascia gives origin to levator ani.
  4. Quadratus femoris
    A thick quadrilateral muscle to the quadrate tubercle. A strong lateral rotator.
  5. Obturator externus
    Obturator nerve. Passes below the femoral neck to the trochanteric fossa.

Anatomy

Origin

Sacrum (piriformis), ischial spine and tuberosity (gemelli, quadratus femoris), obturator membrane and its margins (obturators).

Insertion

Greater trochanter, trochanteric fossa and the intertrochanteric crest of the femur.

Action

Lateral rotation of the hip; stabilisation of the hip joint.

Innervation

Nerve to piriformis (S1–S2), nerve to obturator internus (L5–S2), nerve to quadratus femoris (L4–S1), obturator nerve (L3–L4) for obturator externus.

Nerve roots

L3–S2

Arterial supply

Inferior and superior gluteal, internal pudendal, obturator and medial circumflex femoral arteries.

Relations

The sciatic nerve passes over the gemelli, the obturator internus and quadratus femoris, deep to gluteus maximus.

Function

  • Laterally rotate the thigh
  • Stabilise the femoral head in the acetabulum
  • Abduct the flexed thigh

Clinical significance

Posterior hip approach

Detaching and then repairing the short external rotators (and capsule) during hip replacement reduces the risk of posterior dislocation. The sciatic nerve must be protected during this step.

Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.