Nerve Plexi

Question 1

What two nerves are part of the Cervical Plexus?

Answer 1

Supraclavicular nerve
Phrenic Nerve

Question 2

What does the Supraclavicular nerve block?

Answer 2

It blocks the shoulder via the interscalene groove

Question 3

What does the Phrenic nerve control?

Answer 3

Breathing via the diaphragm

Question 4

Where is the Cervical Plexus located in the neck?

Answer 4

Posterior triangle of the neck, halfway up the sternocleidomastoid muscle and within the prevertebral layer of the cervical fascia

Question 5

The Cervical plexus is formed by the _____ ______ (divisions) of cervical spinal nerves _____-_____.

Answer 5

The Cervical plexus is formed by the anterior rami (divisions) of cervical spinal nerves C1-C4.

Question 6

What is a complication if you are off on your block of the supraclavicular nerve?

Answer 6

You can hit the phrenic nerve and cause hemi-diaphragmatic paralysis.

Not good for patients with COPD or breathing issues

Question 7

Where is the Stellate Ganglion located?

Answer 7

C-7 and comes off the front side of the neck, above the FIRST rib.

Question 8

What does the Stellate Ganglion have to do with the Cervical Plexus?

Answer 8

It is not part of the Cervical Plexus, however it comes off of and is adjacent to a cervical vertebrae.

Question 9

What does the Stellate Ganglion do to the body? What are its branches?

Answer 9

It is a collection of sympathetic nerves and increases SNS transmission via multiple branches in the body.

Somatic branches - gray rami communicantes to C7, C8 and T1

Visceral branches - via the inferior cardiac nerve and contributes to cardiac plexus in the thorax

SNS branches to the brachial plexus, subclavian, vertebral arteries and brachiocephalic trunk

Question 10

If you block the Stellate Ganglion what can you end up treating? (5 things he mentioned in class, but there is a long list.)

Answer 10

1. Chest pain
2. Scleroderma
3. Long Covid symptoms (return smell/taste)
4. Chronic pain
5. Craniofacial hyperhidrosis (excessive sweating)

• Refractory angina
• Atypical angina
• Postherpetic neuralgia
• Phantom limb pain
• Chronic post-surgicalpain
• Post-traumatic stress disorder
• Neuropathic pain syndromes in cancer pain
• Vascular headaches including cluster headache and migraine headache
• Raynaud syndrome
• Upper extremity embolism
• Meniere syndrome
• Refractory cardiac arrhythmias including Roman/Ward syndrome and Jervell/Lang/Nielson syndrome
• To diagnosesympathetically mediated pain
• Quinine poisoning
• Sudden loss of hearing accompanied by tinnitus
• Accidental intraarterial injection of intravenous medications

Question 11

What type of syndrome and symptoms do you see when you block the stellate ganglion?

Answer 11

Horners syndrome

Partial ptosis ( eyelid drooping)
Miosis ( constricted pupil)
Facial anhidrosis (absence of sweating)

Question 12

Does blocking the phrenic nerve cause Horner’s syndrome?

Answer 12

No. It is the blockade of the stellate ganglion that causes Horner’s syndrome

*Phrenic nerve blockade can be associated because of how close it is to the stellate ganglion. - this causes respiratory problems

Question 13

Interscalene blocks are associated with which spinal vertebrae nerve roots?

Answer 13

C5-C7

Question 14

Which nerve plexus is the interscalene block associated with and what structures does it block?

Answer 14

Brachial Plexus - shoulder structures

Question 15

When blocking the Interscalene what other structures could you block around it accidentally?

Answer 15

Stellate Ganglion, Phrenic nerve

Question 16

What plexus innervates the upper extremities and what spinal root vertebrae does it come off of it?

Answer 16

The brachial plexus - C5-T1

It exits the cervical spine and traces between the anterior and middle scalene muscles and around the axillary artery.

Question 17

What are the five parts that the Brachial Plexus is divided into?

Answer 17

Roots
Trunks
Divisions
Cords
Branches

There are no functional difference between these divisions, they are simply used to aid explanation of the brachial plexus

Mnemonic - Read That Damn Cadaver Book.

Question 18

What four types of blocks can you do in the brachial plexus area?

Answer 18

Interscalene
Supraclavicular
Infraclavicular
Axillary

Question 19

What area do you block when you put local anesthetic in the Axillary Nerve? What spinal root vertebrae is this associated with?

Answer 19

Primarily blocks the sensory functions of the upper lateral cutaneous nerve aka the skin over the lower deltoid (“regimental badge area”)

Blocks the motor functions of the teres minor and deltoid muscles

Spinal roots from C5-C6

Question 20

Why would you block the Axillary Nerve?

Answer 20

Posterior shoulder pain
Tourniquet pain

Question 21

Where are the spinal nerve roots located for the Musculocutaneous Nerve? What areas does this block?

Answer 21

C5-C7

Blocks the motor functions high in the biceps of the anterior compartment of the arm (coracobrachialis, biceps brachii and the brachialis)

Blocks the sensory down low to the lateral cutaneous nerve of the FOREARM.

Question 22

Median nerve is innervated by which spinal nerve roots? What areas does it block?

Answer 22

C6 - T1 (also contains fibers from C5 in some individuals)

Blocks motor functions of the flexor and pronator muscles in the anterior compartment of the forearm. Thenar muscles and lateral two lumbricals in the hand

Blocks sensory functions in the palmar cutaneous branch, lateral aspect of the palm, and the digital cutaneous branch, which innervates the lateral three and a half fingers on the anterior palmar surface of the hand

Question 23

What spinal nerve root innervates the Radial nerve? What areas does this block?

Answer 23

C5-T1

Blocks sensory to most of the skin of the posterior forearm, lateral aspect of the dorsum of the hand, and the dorsal surface of the lateral three and half digits

Blocks motor functions of the triceps brachii and the extensor muscles in the forearm.

Question 24

Where is the Radial Nerve easiest to find?

Answer 24

You can find it easily next to the radial artery. It can also be found in the axilla.

The radial nerve is a spiral Nerve that wraps around the bone several times, not easy to find.

Question 25

What spinal nerve root is associated with the Ulnar nerve? What does it block?

Answer 25

C8 - T1

Block of motor function to the two muscles of the anterior forearm - flexor carpi ulnaris and medial half of flexor digitorum profundus. Intrinsic muscles of the hand.

Blocks sensory functions - Medial one and half fingers and the associate palm area

Question 26

Where do you expect to see the motor response if you stimulated the Ulnar nerve?

Answer 26

Pinky finger!!

Question 27

What spinal nerve roots make up the Lumbar Plexus? What are the six major peripheral nerves of this plexus?

Answer 27

L1-L4

These nerves descend down the posterior abdominal wall to reach the lower limbs

Iliohypogastric - abdomen

Ilioinguinal
Genitofemoral
Lateral cutaneousnerve of the thigh
Obturator
Femoral

Mneumonic
I, I GetLeftoversOnFridays.

Question 28

Which spinal nerve roots innervate the Iliohypogastric nerve? What does blocking this nerve do?

Answer 28

L1 (some T12)

Blocks motor function of the internal oblique and transverse abdominis muscle

Blocks sensory - posterolateral gluteal skin in the pubic region.

Question 29

What surgery did Cornelius mention for blocking the Iliohypogastric nerve?

Answer 29

Inguinal hernia repair

Question 30

What spinal nerve root innervates the Ilioinguinal nerve? What does blocking it do?

Answer 30

L1

After innervating the muscles of the anterior abdominal wall, it passes through the superficial inguinal ring to innervate the skin of the genitalia and middle thigh.

Blocks motorfunctions of the internal oblique and transversus abdominis.

Blocks sensoryfunctions of the skin on the superior antero-medial thigh.

Question 31

Why do you need to warn males and females about when blocking the Ilioinguinal nerve?

Answer 31

In males, it also supplies the skin over the root of the penis and anterior scrotum.

In females, it supplies the skin over mons pubis and labia majora.

Question 32

Which spinal nerve roots innervate the Lateral Femoral Cutaneous nerve? What happens when you block this nerve?

Answer 32

L2, L3
Lateral thigh

This nerve has a purely sensory function. It enters the thigh at the lateral aspect of the inguinal ligament, where it provides cutaneous innervation to the skin there.

Blocks sensory Functions in the anterior and lateral thigh down to the level of the knee.

Question 33

What patients would you do a Lateral Femoral Cutaneous nerve block on?

Answer 33

Femoral fractures

Question 34

Which spinal nerve roots innervate the Obturator nerve? What happens when you block this nerve?

Answer 34

L2, L3, L4
Medial Thigh

Blocks motor functions in the obturator externus, adductor longus, adductor brevis, adductor magnus and gracilis.

Blocks sensory functions of the skin over the medial thigh.

Question 35

Which spinal nerve roots innervate the femoral nerve? What happens when you block this nerve?

Answer 35

L2, L3, L4
Anterior thigh
“Catch-all for the thigh”
Large nerve

Blocks motor functions in the muscles of the anterior thigh – the illiacus, pectineus, sartorius and quadriceps femoris (can’t walk d/t weakness).

Blocks sensory functions in the skin on the anterior thigh and the medial leg.

Question 36

What spinal nerve roots innervate the Sacral plexus? What happens when you block this nerve?

Answer 36

L4-S4

Thesacral plexusis a network of nerve fibers that supplies the skin and muscles of the pelvis and lower limb.
Deep in the pelvis there is the internal pudendal nerve

It is located on the surface of the posterior pelvic wall, anterior to the piriformis muscle.

Question 37

What spinal nerve roots innervate the Sciatic nerve? What happens when you block this nerve?

Answer 37

L4-S3

Thesciatic nerveis a major nerve of the lower limb. It is a thick flat band, approximately 2cm wide – the largest nerve in the body.

Higher up is mostly motor functions - Directly the posterior thigh (biceps femoris, semimembranosus and semitendinosus) and the hamstring portion of the adductor magnus (remaining portion of which is supplied by the obturator nerve).
Indirectly all the muscles of the leg and foot.

Distal down the leg is more sensory - Indirectly innervates (via its terminal branches) the skin of the lateral leg, heel, and both the dorsal and plantar surfaces of the foot.