• Nerve to piriformis 

• Pudendal nerve: 

• Posterior femoral cutaneous nerve: 

• Nerve to quadratus femoris: 

• Nerve to obturator internus:

• Sciatic nerve:

• Inferior gluteal nerve: 

• Superior gluteal nerve:

• Superior gluteal n.
• inferior gluteal n.
• sciatic n.
• nerve to obturator internus
• n. to quadratus femoris
• posterior femoral cutaneous n.
• pudendal n.
• n. to piriformis

• _____nerves- superior and medial clunial nerves are dorsal primary rami from the lumbar and sacral regions; inferior clunial nerves arise from the posterior cutaneous nerve of thigh.  They are seen superficially and supply skin in the buttock region.

• The _____ nerve of thigh- exits the greater sciatic foramen below piriformis and medial to the sciatic nerve; it supplies skin inferior to the gluteal fold

• The posterior cutaneous nerve of thigh- exits the greater sciatic foramen below piriformis and medial to the sciatic nerve; it supplies skin inferior to the gluteal fold

• The _____ nerve and _____ vessels- exit the greater sciatic foramen below piriformis and then enter the lesser sciatic foramen to supply structures of the perineum.

• The pudendal nerve and internal pudendal vessels- exit the greater sciatic foramen below piriformis and then enter the lesser sciatic foramen to supply structures of the perineum.

• The_____nerve- exits the greater sciatic foramen, typically below piriformis and descends into the posterior thigh.  

• The sciatic nerve- exits the greater sciatic foramen, typically below piriformis and descends into the posterior thigh.  

• The _____ nerve and vessels- exit the greater sciatic foramen and run deep to the gluteus maximus. They exit below piriformis.

• The inferior gluteal nerve and vessels- exit the greater sciatic foramen and run deep to the gluteus maximus. They exit below piriformis.

• The _____ nerve and vessels- exit the greater sciatic foramen and run in a plane between the gluteus medius and minimus.  They exit above piriformis.

• The superior gluteal nerve and vessels- exit the greater sciatic foramen and run in a plane between the gluteus medius and minimus.  They exit above piriformis.

1. Origin- Ischial tuberosity
2. Insertion- Intertrochanteric crest
3. Innervation- Nerve to quadratus femoris L5, S1
4. Function- Externally rotates thigh

1. Origin-
1. Superior- ischial spine
2. Inferior- ischial tuberosity
2. Insertion- trochanteric fossa (tendons blend with obturator internus tendon)
3. Innervation- 
1. Superior-  Nerve to obturator internus; L5, S1
2. Inferior- Nerve to quadratus femoris; L5, S1
4. Function- Externally rotates extended thigh; abducts flexed thigh

1. Origin- Pelvic surface of obturator foramen and membrane
2. Insertion- Trochanteric fossa  (medial aspect of greater trochanter)
3. Innervation- Nerve to obturator internus; L5, S1
4. Function- Externally rotates extended thigh; abducts flexed thigh

1. Origin- Anterior sacrum, sacrotuberous ligament
2. Insertion- Superior aspect of greater trochanter
3. Innervation- Direct branches of S1 and S2 or nerve to piriformis; S1, S2
4. Function- Externally rotates extended thigh; abducts flexed thigh

• piriformis
• obturator internus
• superior and inferior gemellli
• quadratus femoris

Deep Layer (the “Short Rotator” group)- 

Deep Layer (the “Short Rotator” group)- all are external rotators of the thigh and help to steady the femoral head in the acetabulum.  With the exception of quadratus femoris, all also abduct the flexed thigh.

• Ischial bursa

• Ischial bursa- separates gluteus maximus from ischial tuberosity, common site of friction bursitis

• Trochanteric bursa

• Trochanteric bursa- separates gluteus maximus/ITB from greater trochanter; common site of friction bursitis

• trochanteric bursa
• ischial bursa

Clinical Correlate- Trendelenburg Sign

Clinical Correlate- Trendelenburg Sign- In single leg stance, the gluteus medius/minimus complex on the stance side contracts to keep the pelvis from sagging to the opposite unsupported side.  If the pelvis sags to the opposite side during stance, this is a positive Trendelenburg sign and indicates weakness of the gluteus medius/minimus complex.

1. Origin- Lateral aspect of ilium, between anterior and inferior gluteal lines
2. Insertion- Greater trochanter, just anterior to gluteus medius attachment
3. Innervation- superior gluteal nerve; L4, L5, S1
4. Function- Abducts and internally rotates thigh, keeps pelvis level during ipsilateral stance (assists gluteus medius)

1. Origin- Lateral aspect of ilium, between anterior and posterior gluteal lines
2. Insertion- Lateral aspect of greater trochanter
3. Innervation- superior gluteal nerve; L4, L5, S1
4. Function- Abducts and internally rotates thigh, keeps pelvis level during ipsilateral stance

1. Origin- dorsal sacrum and coccyx, ilium posterior to posterior gluteal line, sacrotuberous ligament
2. Insertion- iliotibial band/tract (“ITB”)- via ITB to lateral condyle of tibia (“Gerdy’s tubercle”); gluteal tuberosity of femur
3. Innervation- inferior gluteal nerve; L5, S1, S2
4. Function- extends thigh (especially from flexion… standing up); external rotation thigh

• gluteus maximus
• gluteus medius
• gluteus minimus

• Sacrospinous ligament

• Sacrotuberous ligament

• Anterior sacroiliac ligament

• Interosseous sacroliliac ligament

• Posterior sacroiliac ligament

• posterior sacroiliag l.
• interosseous sacroiliac l.
• anterior sacroiliac l.
• sacrotuberous l.
• sacrospinous l.

• Iliac crest
• Anterior superior iliac spine (“ASIS”)
• Posterior superior iliac spine (“PSIS”)
• Ischial tuberosity
• Greater trochanter of femur