Lumbosacral Plexus

Question 1

Spinal nerves that from lumbosacral plexus

Answer 1

L1-L4

S1-S5

Question 2

L4 ramus + L5 ramus =

Answer 2

Lumbosacral trunk

Question 3

Posterior divisions of lumbar plexus nerves supply

Answer 3

Anterior thigh (embryo rotation)

Question 4

Ilioinguinal nerve

Answer 4

L1 root

Innervates skin of genitalia and upper medial thigh

Question 5

Genitofemoral nerve

Answer 5

L1 and L2 roots
Genital and femoral branches
Femoral - innervates skin on upper anterior thigh

Question 6

Lateral cutaneous nerve (lateral femoral cutaneous)

Answer 6

Posterior divisions of L2 and L3 roots
Purely sensory function
Innervates anterolateral thigh as far inferiorly as the knee.

Question 7

Obturator nerve

Answer 7

Anterior divisions of the L2, L3 and L4 roots.
Innervates skin over medial thigh
and the muscles of the medial compartment of the thigh

(Obturator externus, pectineus, adductor longus, adductor brevis, adductor magnus, gracilis muscle)

Question 8

Femoral nerve

Answer 8

Posterior divisions of the L2, L3 and L4 roots.
Femoral cutaneous branch = Skin of anterior thigh
Saphenous branch = skin of medial leg
Anterior compartment thigh

(Iliacus, pectineus, sartorius, rectus femoris, vastus latoralis, vastus medialis, vastus intermedius)

Question 9

Lumbar plexus branches and root

Answer 9

I get left overs on Fridays

Iiliogiunal (L1)
Genitofemoral (L1, L2)
Lateral femoral cutaneous (L2, L3)
Obturator (L2, L3, L4)
Femoral (L2, L3, L4)

Question 10

Which spinal nerve roots form the sacral plexus?

Answer 10

S1 - S4 (L4 and 5 via lumbosacral trunk)

Question 11

Superior gluteal nerve:
What are the roots?
Where does it enter and leave the pelvis?
Which structures does it innervate?
What doesn’t it have?
What is it accompanied by?

Answer 11

• L4, L5, S1 roots
• Leaves the pelvis via the greater sciatic foramen (described here) and enters the gluteal region above the piriformis muscle
• Innervates gluteus medius, gluteus minimus, tensor fascia lata
• NO SENSORY INNERVATION

(Accompanied by superior gluteal artery and vein)

Question 12

Inferior gluteal nerve

Answer 12

L5, S1, S2
Leaves the pelvis via the greater sciatic foramen but enters the gluteal region below the piriformis muscle
Innervates gluteus maximus
NO SENSORY BRANCHES

(Accompanied by inferior gluteal artery and vein)

Question 13

sciatic nerve

Answer 13

1. L4, L5, S1, S2, S3
2. 2 - Divides into tibial and common peroneal nerve (fibial)
3. Tibial - hamstring
   EXCEPT short head bicep femoris - common peroneal
4. No branches in the gluteal region

Question 14

Posterior cutaneous nerve

Answer 14

S1 - S3
It leaves the pelvis via the greater sciatic foramen below the piriformis muscle
Innervates skin of posterior thigh and leg
No motor function

Question 15

Sacral plexus and roots

Answer 15

Salmon is so perfectly pink

Superior gluteal (L4, L5, S1)
Inferior gluteal (L5, S1, S2)
Sciatic (L4,L5,S1,S2, S3)
Posterior femoral (S1, S2, S3)
Pudendal ( S2, S3, S4)

Question 16

How are the greater and lesser sciatic foramina formed?

Answer 16

Sacrospinous and sacrotuberous ligaments

Greater and lesser sciatic notch

Question 17

Where do the superior gluteal nerve and vessels exit the pelvis?

Answer 17

Greater sciatic foramen superior to piriformis muscle

Question 18

Which structures exit pelvis via greater sciatic foramen inferior to the piriformis muslce?

Answer 18

Sciatic nerve
Inferior gluteal nerve, artery and vein
Nerve to quadratus femoris
Nerve to obturator internus 
Pudendal nerve

Question 19

Which structures pass through the lesser sciatic foramen?

Answer 19

Tendon of obturator internus
Nerve to obturator internu
Pudendal nerve
Internal pudendal vessels

Question 20

Safe areas to inject gluteal intramuscular injection on child (3-7 years)

Answer 20

Dorsogluteal site
Upper outer quadrant
(Outer top Corners of top quadrants)

Question 21

Safe intramuscular injection adults (7+)

Answer 21

• Ventrogluteal (you form a v with your hand)
• Palm of hand over greater trochanter of femur
  Thumb towards inguinal region (top of thigh)
  Spread index and middle finger to make a V
  Carefully inject between the proximal interphalangeal joints of your fingers into the patient’s gluteus medius muscle.