Lecture 17- Axilla and Brachial Plexus

Question 0

Axilla “armpit”
Apex: passageway for structures entering or leaving the shoulder and arm; bounded by ….. ….., ……. and superior portion of ………

Answer 0

1st rib
clavicle
scapula

Question 1

Axilla “Armpit”

• Floor: ……. ……. and ….. of armpit

Answer 1

axillary fascia

skin

Question 2

Axilla “armpit”
Anterior wall: pectoralis major & minor muscles, clavipectoral fascia
• Posterior wall: Subscapularis, teres major, latissimus dorsi, long head of triceps brachii muscle.

Answer 2

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Question 3

Axilla “armpit”
• Medial wall: superior rib cage, intercostal and serratus anterior muscles.
• Lateral wall: humerus.

Answer 3

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Question 4

Axilla 
Important structures in the axilla: 
 • Axillary artery 
• Axillary vein(s) 
• Axillary lymph nodes 
• Brachial plexus of nerves  
• Pectoralis minor muscle 
• Biceps brachii muscle 
• Coracobrachialis muscle 
• Axillary tail of female breast.

Answer 4

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Question 5

Arterial supply of axilla

Brachiocephalic trunk -> ……… artery ->
…….. artery -> …….. artery -> ……./……. arteries

Answer 5

subclavian
axillary
brachial
radial/ulnar

Question 6

Venous drainage of axilla 
Superficial: ....... & ...... veins 
Dive down to ......... vein 
Brachial veins surround brachial artery 
-> Axillary v. -> subclavian v

Answer 6

cephalic
basilic
axillary

Question 7

Axillary lymph nodes 
20-30 nodes divided into five groups: 
 • Central nodes 
 • Lateral (brachial, humeral) nodes 
 • Posterior (subscapular) nodes 
 • Anterior (pectoral) nodes 
 • Apical (subclavian) nodes

Answer 7

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Question 8

Brachial plexus
Neurovascular bundle in axilla=
•……. artery
•…….. vein
• Cords of brachial plexus => all bound in the …… …….
• Brachial plexus = …….. rami of spinal nerves …….

Answer 8

Axillary
Axillary
axillary sheath
ventral
C5-T1

Question 9

Functions of nerves in the upper limb
• Motor innervation to ………
• Sensory innervation to ….. & deep structures
• Vascular tone by sympathetic vasomotor nerve fibres
• Secretomotor fibres to supply …… ……

Answer 9

muscles
skin
sweat glands

Question 10

Brachial plexus
• 5 roots (ventral rami)
• 3 trunks
• 6 divisions (3 anterior, 3 posterior)
• 3 cords (named for their relationship to the axillary artery)
• 5 large terminal branches (M, A, R, M, U)
Randy travis drinks cold beers

Answer 10

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Question 11

Named nerves of the Brachial Plexus
Anterior rami of ……….
Supplies: Muscles of ……… (superficial back muscles, anterior thoracic wall muscles) All muscles of …….. …… And upper limb ….

Answer 11

C5-T1
shoulder
upper extremity
skin.

Question 12

“C5-C6-C7 lift your arms to heaven” corresponds with which muscle?

Answer 12

Serratus anterior

Question 13

Posterior cord nerves 
• Derived from posterior divisions of all 3 trunks. 
• (ULTRA) 
 • Upper subscapular nerve 
• Lower subscapular nerve 
• Thoracodorsal nerve 
• Radial nerve 
• Axillary nerve

Answer 13

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Question 14

Lateral cord nerves 
• Derived from the anterior divisions of the superior and middle trunks. 
• (LML) 
• Lateral pectoral nerve 
• Musculocutaneous nerve 
• Lateral root of median nerve

Answer 14

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Question 15

Medial cord nerves 
• Derived from the anterior division of the inferior trunk. 
• (M4U) 
• Medial pectoral nerve 
• Medial cutaneous nerve of arm 
• Medial cutaneous nerve of forearm 
• Medial root of the median nerve 
• Ulnar nerve

Answer 15

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Question 16

Brachial Plexus: Terminal Nerves
• Axillary —innervates the deltoid, teres minor, and skin and joint capsule of the shoulder
• Musculocutaneous —innervates the anterior arm muscles and skin of lateral forearm
• Median —innervates the skin, most flexors and pronators in the forearm, and thenar muscles
• Ulnar —supplies the flexor carpi ulnaris, medial half of flexor digitorum profundus, most intrinsic muscles of the hand, and skin of medial aspect of hand
• Radial —innervates essentially all extensor muscles, supinators, and posterior skin of limb

Answer 16

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Question 17

Axillary nerve
(C5-C6)
Deltoid muscle
Teres minor muscle
Derived from posterior cord and passes posterior to humerus
wrapping transversely across lateral aspect of humerus

Answer 17

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Question 18

Musculocutaneous nerve  
 (C5-C6-C7) 
 Coracobrachialis muscle 
 Brachialis muscle 
 Biceps brachii muscle 
 Derived from medial cord, pierces through coracobrachialis, travels deep to biceps brachii / superficial to brachialis then passes superficially to dermis to innervate lateral skin on forearm

Answer 18

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Question 19

Median nerve 
(C5-C6-C7-C8-T1) 
Pronator teres muscle  
Flexor carpi radialis  muscle 
Palmaris longus muscle 
Flexor digitorum superficialis muscle 
Flexor digitorum profundus muscles to thumb and index fingers 
Flexor pollicis longus muscle 
Pronator quadratus muscle 
Lumbricals to index and middle fingers 
Thenar muscles of thumb

Answer 19

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Question 20

Cutaneous innervation
• Posterior cutaneous nerves => Branches of radial nerve.
• Lateral cutaneous nerves => Each of these nerves arise from a separate source (axillary, radial, musculocutaneous
nerves)
• Medial cutaneous nerves => Branches of the medial cord of brachial plexus.

Answer 20

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Question 21

Arm  = C5, C6, T2 
Forearm = C5, C6, T1 
Hand = C6, C7, C8 

Thumb = C6
Middle finger = C7
Little finger = C8
Olecranon & medial epicondyle of humerus = T1

Answer 21

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