Brachial Plexus:Odds and Sods

Emily Matthews (e.k.matthews@warwick.ac.uk)Alex Clarke (alexander.clarke@warwick.ac.uk)

Content

• Mnemonic for nerve roots of main nerves

• Activity: Root values associated with key movements

• Question: Axillary nerve

Nerve roots of main nervesTHREE musketeers assassinate 5 rats, 5 mice, 2 unicorns

LABEL YOUR FINGERS

http://www.stritch.luc.edu/lumen/meded/grossanatomy/2013_2014/revisedbp14/revisedbp14_print.html

Nerve roots of main nervesTHREE musketeers assassinated 5 rats, 5 mice, 2 unicorns

Nerve roots of main nervesTHREE musketeers assassinated 5 rats, 5 mice, 2 unicorns

Nerve roots of main nervesTHREE musketeers assassinated 5 rats, 5 mice, 2 unicorns

FIVE RATS- FIVE MICE - Median

Nerve roots of main nervesTHREE musketeers assassinated 5 rats, 5 mice, 2 unicorns

Root values associated with key movementsQuestion 1

Joint Movement Root value

Shoulder

Elbow

Forearm

Digit

Hip

Knee

Root values associated with key movementsQuestion 2

Side Joint Movement Root value

Right Shoulder

Elbow

Hip

Knee

Left Shoulder

Elbow

Hip

Knee

Foot

Root values associated with key movementsAnswer 1

Joint Movement Root value

Shoulder Abduction C5

Elbow Extension C6, 7

Forearm Pronation C6

Digit Flexion C7-8

Hip Abduction L4, L5

Knee Extension L3, L4

Root values associated with key movementsAnswer 2

Side Joint Movement Root value

Right Shoulder Flexion C5

Elbow Flexion C5, 6

Hip Flexion L1, 2, 3

Knee Flexion L5, S1

Left Shoulder Extension C6, 7, 8

Elbow Flexion C5, 6

Hip Extension L5, S1

Knee Extension L3, 4

Foot Plantarflexion S1, S2

Root values associated with key movements

MAIN POINT:

Note how NOT all nerve roots of a named nerve are involved in movement

e.g. Biceps brachii and brachialis muscles are involved in elbow flexion.These muscles are in anterior compartment of the arm and innervated by musculocutaneous nerve. Nerve roots of musculocutaneous nerve: C5, C6, C7

Brachioradialis also involved in elbow flexion. Innervated by radial nerve. Radial nerve has nerve roots C5, 6, 7, 8 & T1

However, only neurons from C5, C6 innervate muscles involved in elbow flexion, so the nerve root value of elbow flexion is C5, C6

Root values associated with key movementsUPPER LIMB: From this year’s lectures slides:

LOWER LIMB: From last year’s lectures slides

QuestionBertha Jugs is diagnosed with breast cancer. Her surgeon performs a wide local excision and sentinel node biopsy.

(a) What is a sentinel node and what is the purpose of biopsying it?

A sentinel node is the first lymph node a carcinoma drains to

Sentinal node bx: radioactive (technetium 99) substance blue dye is injected into the nipple. Drains through the lymphatic system of the breast

All blue/radioactive lymph nodes are excised (radioactive nodes detected with Gieger counter)

If sentinel node clear of cancer then no need for further axillary node clearance.

Useful as only affected lymph nodes are removed, thus reducing need for axillary node clearance in most women which is associated with pain and lymphoedema http://health.kernan.org/patiented/articles/sentin

el_node_biopsy_000378.htm

QuestionAn axillary node clearance is required for Bertha.

(b) Name 5 main groups of axillary lymph nodes

CentralHumeralApicalPectoralSubscapular

CHAPS like breasts

QuestionThe surgeon’s credentials are questionable. He blunders about in the axilla and damages the axillary nerve.

(b) Describe the likely consequences of damaging the axillary nerve

Deltoid and teres minor affected:• Loss of shoulder contour id wasting)• Weakness of shoulder movement except adduction• Limb hang limp at side

loss of sensation over regimental badge region

n/a

MOTOR

SENSORY

REFLEX