Gluteal And Posterior Thigh

Question 1

3 nerves that come off the sacral plexus laterally

Answer 1

Superior gluteal nerve L4-S1
Inferior gluteal nerve L5-S2
Nerve to the piriformis S1-S2

Question 2

4 nerves that come off sacral plexus medially

Answer 2

Nerve to quadratus femoris (which also innervates inferior gemellus)
Nerve to obturator internus (which also innervates superior gemellus)
Posterior femoral cutaneous nerve
Sciatic nerve (main)

Question 3

Sciatic nerve 2 components

Answer 3

Medial component called the tibial nerve
Lateral component called the common fibular nerve

Can be compressed in piriformis, from disc herniation, or running lateral to long head of biceps femoris

Question 4

Pudendal nerve S2-S4

Answer 4

Innervates all pelvic floor muscles

In hip surgery during long periods of traction this nerve may be stretched causing temporary conduction block

Question 5

Skin of buttocks innervated by

Answer 5

Superior, middle, and inferior cluneal nerves

Question 6

Posterior thigh innervated by

Answer 6

Posterior femoral cutaneous nerve

Question 7

Gluteus maximus

Answer 7

Origin: posterior aspect of ilium, sacrum, coccyx
Insertion: posterior aspect of ITB
Innervated by inferior gluteal nerve L5-S1
Does hip extension and external rotation (better extensor)

Even level surface walking doesn’t contract this muscle, going up stairs and going sit to stand does

Question 8

Gluteus medius

Answer 8

Origin: posterior aspect of ilium
Insertion: lateral aspect of greater trochanter
Innervated by superior gluteal nerve L4-S1
Does hip abduction and internal rotation

Question 9

Trembelenburg sign or gait

Answer 9

When the pelvis collapses.
Right gluteus medius prevents left pelvis from collapsing during the right stance phase of gait.
If your right leg is in the ground and your left pelvis collapses it’s called a right trembelenburg

Question 10

Gluteus minimis

Answer 10

Origin: posterior aspect of ilium
Insertion: anterior aspect of greater trochanter
Innervated by superior gluteal line L4-S1
Does hip abduction and internal rotation

If gluteus medius is weak, minimis cannot prevent trembelenburg by itself

Question 11

Piriformis

Answer 11

Origin: anterior sacrum
Insertion: superior aspect of greater trochanter
Innervated by ventral rami
Did hip external rotation

Question 12

Sciatic nerve exits

Answer 12

Underneath piriformis 85% of time, and right through it in 10% of individuals

Question 13

Superior gemellus

Answer 13

Origin: ischial spine
Insertion: medial aspect of greater trochanter
Innervated by nerve to obturator internus L5-S1
Does hip external rotation

Question 14

Obturator internus

Answer 14

Origin: obturator foramen
Insertion: medial aspect of greater trochanter
Innervated by nerve to obturator internus L5-S1
Does hip external rotation

Question 15

Inferior gemellus

Answer 15

Origin: ischial tuberosity
Insertion: medial aspect of greater trochanter
Innervated by nerve to quadratus femoris
Does hip external rotation

Question 16

Quadratus femoris

Answer 16

Origin: ischial tuberosity
Insertion: medial aspect of greater trochanter
Innervated by nerve to quadratus femoris
Does hip external rotation

Question 17

Superior gluteal nerve

Answer 17

Exits pelvis through greater sciatic notch and innervates TFL, gluteus medius/minimis

Question 18

Inferior gluteal nerve

Answer 18

exits greater sciatic notch inferior to piriformis and innervates gluteus Maximus

Question 19

Sciatic nerve

Answer 19

Exits greater sciatic notch and innervates no muscles in gluteal region

Question 20

Hamstrings

Answer 20

All originate on ischial tuberosity (except short head of biceps which is posterior aspect of proximal femur)
Semitendinosis insertion: superior medial aspect of tibia (pes anserine)
Semimembranosis insertion: posterior medial tibia
Biceps femoris insertion: fibular head
All innervated by sciatic nerve L4-S3
All do hip extension and knee flexion, except for short head of biceps which can’t extend hip

Question 21

Popliteal fossa

Answer 21

Superior medial: semitendinosis, semimembranosis
Inferior lateral: lateral gastrocnemius
Inferior medial: medial gastrocnemius
Contents: popliteal artery, vein, tibial nerve, common fibular nerve, posterior femoral cutaneous nerve