Musculus obturator internus
The obturator internus originates from the internal surface of the obturator foramen and surrounding pelvic bone and inserts into the trochanteric fossa of the femur. Its actions are to laterally rotate the femur and stabilize the hip joint. It is innervated by a branch of the sciatic nerve (roughly L6-S1). As the tendon crosses the lesser sciatic notch it is surrounded by a tendon sheath. It is part of the deep hip rotator group and is assessed primarily during rectal examination.
Origin: Internal surface of the obturator foramen and surrounding pelvic bone
Insertion: Trochanteric fossa of the femur
Action: Laterally rotates the femur; stabilizes the hip joint
Innervation: Sciatic nerve branch (L6-S1)
Isolated injury is uncommon. The tendon sheath can be involved in rare cases of tenosynovitis. Relevant in pelvic trauma or neurologic evaluations involving the sciatic nerve.
## Overview Pelvic fracture involvement refers to fractures that affect the obturator foramen region or associated muscles and nerves. Severe hind-limb lameness, crepitus on rectal examination, pelvi
Persistent hind-limb lameness or abnormal hip posture after trauma should be evaluated. The veterinarian may assess this region during a rectal examination.
## Overview Pelvic fracture involvement refers to fractures that affect the obturator foramen region or associated muscles and nerves. Severe hind-limb lameness, crepitus on rectal examination, pelvic asymmetry, and swelling over the hip are typical. The obturator nerve may be damaged. ## Causes Trauma. ## Diagnosis Rectal palpation and ultrasound. ## Treatment Strict rest and pain management. Nerve damage is treated supportively. ## Recovery and Prognosis Variable and often guarded when the fracture is unstable or nerves are involved. ## Prevention Trauma avoidance. Signs include: severe hind-limb lameness; crepitus on rectal examination; asymmetric pelvis; swelling over the hip
Isolated injury is uncommon. The tendon sheath can be involved in rare cases of tenosynovitis. Relevant in pelvic trauma or neurologic evaluations involving the sciatic nerve.
Persistent hind-limb lameness or abnormal hip posture after trauma should be evaluated. The veterinarian may assess this region during a rectal examination.
See the Obturator Internus on our interactive 3D horse model. Open 3D Model