Nerves of the Lower Extremity and Back

Question 1

Superior Clunial

Answer 1

Spinal Roots: Dorsal Rami L1 - L3

Course: located around where the love handles are above the iliac crest

Supply: Sensory to the superior and central buttock

Question 2

Middle Clunial

Answer 2

Spinal Roots: Dorsal Rami S1 - S3

Course: over the central buttock

Supply: Sensory to the central buttock

Question 3

Inferior Clunial

Answer 3

Spinal Roots: Comes off Posterior Femoral Cutaneous (S1 - S3)

Course: Originates from the posterior femoral cutaneous nerve, come out superficially and run upward at the inferior border of gluteus maximus

Supply: Sensory to the inferior buttock

Question 4

Posterior Femoral Cutaneous Nerve

Answer 4

Spinal Roots: Sacral Plexus S1 -S3

Course: Exits the Greater Sciatic Foramen inferior to the piriformis and runs into the thigh.

It gives off the Inferior Clunial Nerves (S2-S3) which branch off deep to gluteus maximus and emerge superficially around the inferior border of gluteus maximus. These nerves are sensory to the inferior buttocks

Posterior Femoral Nerve then descends along the posterior midline of the thigh, running medial to the sciatic nerve and deep to the fascia lata.

It runs down to the popliteal fossa

Supply: Sensory to the posterior thigh and popliteal fossa

Question 5

Superior Gluteal

Answer 5

Spinal Roots: L4 - S1

Course: enters the gluteal region through the greater sciatic foramen superior to the piriformis and runs between gluteus medius and minimus; runs with the superior gluteal artery and vein

**only structures that come out superior to piriformis

Supply: Motor to Gluteus Medius, Gluteus Minimus, and Tensor Fascia Lata

Question 6

Inferior Gluteal

Answer 6

Spinal Roots: Ventral Rami L5 - S2

Course: exits the greater sciatic foramen and emerges inferior to piriformis; runs between gluteus medius and gluteus minimus; runs with the superior gluteal artery and vein

Supply: Motor to gluteus maximus

Question 7

Nerve to Obturator Internus

Answer 7

Spinal Roots: Ventral Rami L5-S2

Course: Exits the Greater sciatic Foramen and emerges inferior to piriformis; runs around the ischial spine, and tuns back around to enter the lesser sciatic foramen with the internal pudendal artery and the pudendal nerve

Supply: Motor to obturator Internus and Superior Gemellus

Question 8

Nerve to Quadratus Femoris

Answer 8

Spinal Roots: Ventral Rami L4 - S1

Course: Exits the greater sciatic foramen inferior to the piriformis and runs deep to the gluteal muscles; it can be seen between the inferior gemellus and quadratus femoris just before it pierces quadratus femoris

Supply: Motor to Inferior Gemellus and Quadratus Femoris; Sensory to the Hip Joint

Question 9

Pudendal Nerve

Answer 9

Spinal Roots: S2 - S4 ventral rami from the sacral plexus

Course: Exits the greater sciatic foramen, then hooks around the sacrospinous ligament and enters the lesser sciatic foramen along with the internal pudendal artery and the nerve to obturator internus

Supply: Sensory to the Perinium and External Genitalia

Question 10

Sciatic Nerve

Answer 10

Spinal Roots: Ventral Rami L4 - S3
Spinal Roots of Tibial Division: L4-S3
Spinal Roots of Common Fibular Division: L4-S2

Course:
Enters the gluteal region through the greater sciatic foramen inferior to the piriformis and descends through the gluteal region into the posterior thigh.

It descends along th posterior surface of Adductor Magnus and the Short Head of Biceps femoris, running deep to the long head of biceps femoris

Just proximal to the knee/popliteal fossa, it divides into TIBIAL and COMMON FIBULAR branches

Question 11

Tibial Nerve

Answer 11

Origin: Sciatic Nerve (L4-S3)

Course:
Branches from the sciatic nerve just proximal to the popliteal fossa

Stays in the middle

Descends though the popliteal fossa where it passes over the popliteus muscle.

It runs inferiorly on Tibialis posterior between
Flexor Hallucis Longus and Flexor Digitorum Longus WITH the posterior tibial artery and vein

Supply: It is motor to all of the muscles of the posterior leg and on the plantar surface of the foot.

Question 12

Common Fibular Nerve

Answer 12

Origin: Sciatic Nerve (L4-S2)

Course:
Branches from the sciatic nerve just proximal to the popliteal fossa

Diverges laterally from the sciatic nerve at the lower edge of biceps femoris.

Passes over the medial aspect of the head of the fibula and then winds around the neck of the fibula

It goes deep to Fibularis Longus where it divides into SUPERFICIAL and DEEP FIBULAR NERVES

Supply: It is motor to the short head of biceps femoris and sensory to the knee joint

Question 13

Superficial Fibular Nerve

Answer 13

Origin: Common Fibular Nerve

Course:
Branches off of the Common Fibular Nerve deep to Fibularis Longus

Found between Fibularis Longus and Fibularis Brevis

It comes out into the subcutaneous tissue (just deep to the crural fascia) between the tendons of fibularis longus and fibularis brevis in the distal third of the lateral leg

It then runs anterior to the lateral malleolus and superficial tot he extensor retinaculum to the dorsum of the foot where it arborizes over the dorsum of the foot, giving off DORSAL DIGITAL NERVES

Supply: It is motor to the muscles of the lateral compartment of the leg (fibularis longus and brevis)

Sensory to the anterolateral aspect of the middle and distal leg, and the dorsum of the foot and digits with the exception of the first web space

Question 14

Deep Fibular Nerve

Answer 14

Origin: Common Fibular Nerve

Course:
Branches from the Common Fibular Nerve deep to Fibularis Longus

It then runs down the anterior surface of the interosseous membrane with the anterior tibial artery

It is located between tibialis anterior and extensor digitorum longus, before it crosses medially to run between tibialis anterior and extensor hallucis longus at the distal end of the tibia

It continues onto the dorsum of the foot where it runs with the dorsalis pedis artery

Supply:
Motor to the muscles of the anterior compartment of the leg and the dorsum of the foot

Sensory to the first web space (between digits 1 and 2)

Question 15

Sural Nerve

Answer 15

Origin: Contributions from Tibial and Common Fibular Nerves

Course:
The Tibal Nerve gives off a branch called the medial Sural Nerve, and the common fibular nerve gives of a branch called the lateral sural nerve.

Those branches join to form the sural Nerve

The sural nerve then runs inferiorly with the small saphenous vein.

It accompanies the small saphenous vein posterior to the lateral malleolus of the fibula

Ends on the lateral side of the foot

Supply:
Sensory to the posterior and lateral aspects of the leg and the lateral aspect of the foot as far as the head of the 5th metatarsal

Question 16

Medial Calcaneal Nerves

Answer 16

Origin: Tibial Nerve

Course: Branch off of the tibial nerve in the distal posterior leg and run to the skin over the heel

Supply: Sensory to the skin over the heel

Question 17

Lateral Calcaneal Nerves

Answer 17

Origin: Sural Nerve

Course: Branch off of the sural nerve in the distal ] leg and run to the skin over the heel

Supply: Sensory to the skin over the heel

Question 18

Medial Plantar Nerve

Answer 18

Origin: Tibial Nerve

Course:
Passes anteriorly into the foot and branches off ot the tibial Nerve deep to abductor hallucis

Runs between abductor hallucis and flexor digitorum brevis and stays more superficial than the lateral plantar nerve

Supply:
Motor to abductor Hallucis, Flexor Hallucis Brevis, Flexor Digitorum Brevis, and the 1st lumbrical

Sensory to the sole of the foot medial to the line bisecting the 4th digit

Question 19

Lateral Plantar Nerve

Answer 19

Origin: Tibial Nerve

Course: Passes anteriorly into the foot and branches from the tibial nerve deep to abductor hallucis

Running deeper than the medial plantar nerve, it corsses over laterally passing deep to abductor hallucis and flexor digitorum brevis

It runs between flexor digitorum brevis and quadratus plantae in between layers 1 and 2 of intrinsic foot muscles

Supply:
Motor to all intrinsic muscles of the foot not supplied by the medial plantar nerve

Sensory to the sole of the foot lateral to the line bisecting the 4th digit

Question 20

Femoral Nerve

Answer 20

Origin: Ventral Rami L2 - L4

Course:
Emerges in the femoral triangle deep to the inguinal ligament at the middle of the inguinal ligament lateral to the femoral artery and vein

Gives off several muscular branches in the anterior thigh

Gives off 2 cutaneous branches: ANTERIOR FEMORAL CUTANEOUS NERVE and SAPHENOUS NERVE

Gives off 1 motor branch called NERVE TO VASTUS MEDIALIS

Supply:
Motor to all the muscles of the anterior thight except Psoas Major (L1-l3) and Psoas Minor ( L1-L2)

Sensory to the distribution of anterior femoral cutaneous and saphenous nerves

Question 21

Anterior Femoral Cutaneous Nerve

Answer 21

Origin: Femoral Nerve

Course:
Branches off of the femoral nerve in the direction of the sartorius muscle

Either passes over or pierces Sartorius

Comes through the fascia lata towards the skin of the anterior thight

Supply:
Sensory to the anterior and medial aspects of the thigh

Question 22

Saphenous Nerve

Answer 22

Origin: Femoral Nerve

Course:
Branches off of the femoral nerve in the femoral triangle

Runs inferiorly with the femoral artery and vein it runs between sartorius and gracilis in the adductor (aka subsartorial) canal

It emerges between the tendons of sartorius and gracilis, and continues distally running in the subcutaneous with the great saphenous vein on the medial side of the leg

It continues all the way down to the foot

Accompanies the great saphenous vein anterior to the medial malleolus of the tibia

Gives off a sensory INFRAPATELLAR branch

Supply:
Sensory to the anterior and medial aspects of the leg, the medial aspect of the foot as far forward as the head of the first metatarsal, hip joint, and knee joint

Question 23

Lateral Femoral Cutaneous

Answer 23

Origin: Lumbar plexus L2 - L3

Course: emerges under the inguinal ligament about 2 cm away from the ASIS

Supply: Sensory to the lateral thigh

Question 24

Obturator Nerve

Answer 24

Origin: Ventral Rami L2 - L4 of Lumbar Plexus

Course:
Traverses through the obturator membrane and divides into ANTERIOR DIVISION OBTURATOR NERVE and POSTERIOR DIVISION OBTURATOR NERVE

The anterior division of the obturator nerve runs anterior to adductor brevis between adductor brevis and adductor longus

The posterior division of the obturator nerve runs posterior to adductor brevis between adductor brevis and adductor magnus

Supply:
Motor to all muscles of the medial thigh except the hamstrings part of adductor magnus

Sensory to the superior medial thigh

Question 25

Lumbar Plexus

Answer 25

Made up of Ventral Rami L1 - L4

Question 26

Sacral Plexus

Answer 26

Made up of Ventral Rami L4 - S2

Question 27

Suboccipital Nerve

Answer 27

Segmental Level: Dorsal Ramus C1

Emerges inferior to the vertebral Artery in the Suboccipital Triangle

Motor to The 4 suboccipital muscles

Question 28

Greater Occipital Nerve

Answer 28

Dorsal Ramus C2 Spinal Nerve

Comes out below the suboccipital triangle

Sensory to the Back of the head and the neck