Gluteal deep muscles

Question 1

What are the attachments, actions and innervation of the piriformis ?

Answer 1

• Most superior of the deep muscles ( inferior to the gluteus minimus )
• Origin - Anterior surface of the sacrum
• Insertion - greater trochanter ( travels inferior and laterally through the greater sciatic foramen )
• Actions - lateral rotation / abduction
• Innervation - nerve to piriformis

Question 2

What are the attachments, actions and innervation of the obturator internus ?

Answer 2

• Forms the lateral walls of the pelvis
• Origin - Pubis and ischium at the obturator foramen
• Insertion - greater trochanter ( travels through the lesser sciatic Foramen ).
• lateral rotation and abduction
• Innervation - nerve to obturator internus.

Question 3

What are the attachments, actions and innervation of the the gemelli superior and inferior ?

Answer 3

• Two narrow and triangular muscles separated by obturator internus tendon.
• Origin of superior - ischial spine / origin of inferior - ischial tuberosity.
• Insert - greater trochanter
• Actions - lateral rotation and abduction
• Innervation - superior - nerve to obturator internus / inferior - nerve to Quadratus femoris

Question 4

What are the attachments, actions and innervation of the quadratus femoris ?

Answer 4

• Square shaped. Most inferior of the deep muscles.
• Origin - lateral ischial tuberosity
• insertion - quadrate tuberosity of the intertrochanteric crest.
• Actions - Lateral rotation
• innervation - Nerve to the quadratus femoris.