Anatomy (Axilla and Brachial Plexus - 11/3)

Question 1

Axillary Sheath

Answer 1

Continuation of fascia associated with anterior/middle scalene muscles – continues laterally as tubular sheath surrounding nerves of brachial plexus/axillary artery (not axillary vein)

Question 2

Anterior Wall of Axilla

Answer 2

Pec major, minor, clavipectoral fascia

Question 3

Posterior Wall of Axilla

Answer 3

Subscapularis, teres major, Lat dorsi

Question 4

Medial Wall of Axilla

Answer 4

First 4 ribs, intercostal muscles, upper part of serratus anterior

Question 5

Lateral Wall of Axilla

Answer 5

Humerus, coracobrachialis, biceps brachii

Question 6

Cervicoaxillary canal

Answer 6

Bound by clavicle, scapula, 1st rib. Contains axillary a/v, brachial plexus

Question 7

Intercostobrachial nerve

Answer 7

Lateral branch of second intercostal nerve (T2), supplies lateral chest wall –> medial arm

Question 8

Branches of Axillary Artery

Answer 8

1 - Superior Thoracic
2 - Thoracoacromial Trunk
Lateral Thoracic 
3 - Subscapular artery (-- circumflex scapular artery, thoracodorsal artery)
Posterior Circumflex humeral artery
Anterior circumflex artery

Question 9

Lateral thoracic artery –>

Answer 9

Lateral portion of breast

Question 10

Circumflex scapular artery pathway

Answer 10

From subscapular artery –> enter infraspinous fossa, form anastomosis w/ suprascapular artery

Question 11

Thoracodorsal artery pathway

Answer 11

From subscapular artery –> join with thoracodorsal nerve –> latissimus dorsi

Question 12

Posterior circumflex humeral artery pathway

Answer 12

Accompanies axillary nerve through quadrilateral space, encircles humerus to anastomose w/ anterior circumflex humeral artery

Question 13

Posterior Triangle

Answer 13

Trapezius, sternocleidomastoid, clavicle (brachial plexus here + axilla)

Question 14

5 Major branches of brachial plexus (from top to bottom)

Answer 14

Musculocutaneous
Axillary
Radial
Median
Ulnar

Question 15

Branches from lateral cord

Answer 15

Lateral pectoral nerve

musculocutaneous nerve
lateral root –> median nerve (with medial root of medial cord)

Question 16

Branches from posterior cord

Answer 16

upper/lower subscapular nerves
thoracodorsal nerve

axillary nerve
radial nerve

Question 17

Branches from Medial cord

Answer 17

Medial pectoral nerve
medial brachial cutaneous nerve
medial antebrachial cut. nerve

ulnar
Medial root –> median nerve (with lateral root of lateral cord)

Question 18

Thoracodorsal nerve innervates _______

Answer 18

Latissimus dorsi

Question 19

Medial Pectoral nerve innervates

Answer 19

Pectoralis major and minor

Question 20

Upper/Lower subscapular nerves innervates ____

Answer 20

subscapularis + Teres major

Question 21

Lateral pectoral nerve innervates ________

Answer 21

pectoralis major

Question 22

Lateral cord spinal nerve derivatives

Answer 22

C5,6,7

Question 23

Posterior Cord spinal nerve derivatives

Answer 23

C5,6,7,8,T1 –> extensors! (except brachioradialis = forearm flexor)

Question 24

Medial cord spinal nerve deri.

Answer 24

C8, T1

Question 25

Musculocutaneous Nerve SCD

Answer 25

C5,6,7 (from lateral cord)

Question 26

Median Nerve SCD

Answer 26

C5,6,7 (From Lateral cord) AND C8,T1 (from medial cord)

Question 27

Ulnar nerve SCD

Answer 27

C8/T1

Question 28

Axillary / Radial Nerves SCD

Answer 28

C5,6,7,8,T1 –> Extensors

Question 29

Upper Brachial Plexus Injury

Answer 29

Erb-Duchenne Palsy
Injury to C5,C6 –> Supply lateral rotators (infraspinatus, teres minor)/Abductors of arm (supraspinatus, deltoid)
Increase in angle between neck and shoulder
Fall, delivery of baby
Adducted arm, medial roation or arm (hand faces backward), extended elbow
“Waiter’s Tip” Hand

Question 30

Lower Brachial Plexus Injury

Answer 30

Klumpke Paralysis
Less common
Upper limb pulled up (falling and try to catch self, or delivery of baby)
Injury to C8-T1 –> Ulnar nerve - major influence of hand –> weakness/atrophy of hand muscles
Median nerve (also hand muscles)
“Claw” Hand

Question 31

Medial brachial/antebrachial cutaneous nerves

Answer 31

Sensory nerves from medial cord of plexus - provide sensory innervation to medial areas of UE

Question 32

Subscapularis

Answer 32

Inner surface of Scapula (subscapular fossa)
Medial aspect of scap –> Lesser tubercle of humerus
Rotator cuff - medial rotate the arm
Upper/lower subscapular nerves (from posterior cord of BP)

Question 33

Latissimus Dorsi

Answer 33

Adduct arm, laterally rotate & extend arm
Spinous processes T7-L5, iliac crest of spine, Inferior angle of scapula, thoracolumbar fascia --> intertubercular groove of humerus (lateral to teres major)
Thoracodorsal nerve (middle subscapular nerve) from posterior cord of BP

Question 34

Teres major

Answer 34

Adduct arm, medially rotate, extend arm
Attaches to humerus at intertubercular groove of humerus (medial to LD insertion) –> inferior aspect (posterior) of scapula
Lower subscapular nerve

Question 35

Serratus anterior

Answer 35

Stabilizes scapula (protracts)
Scapular to anterior ribs
Long thoracic nerve

Question 36

Where does axillary artery come from/go (as continuation)

Answer 36

Subclavian artery –> first rib = axillary artery –> 6 branches/3 parts d/t pec minor –> at inferior border teres minor = brachial artery

Question 37

Where does axillary vein come from/go (as continuation)

Answer 37

Brachial + Basilic veins –> axillary vein –> first rib = subclavian vein

Question 38

Axillary lymph nodes

Answer 38

Pectoral, subscapular, humeral –> central –> apical

Question 39

What groups of muscles are supplied by the anterior and posterior divisions of the plexus?

Answer 39

Anterior division –> anterior compartment = flexors

Posterior division –> posterior compartment = extensors

Question 40

What nerves associated with wrist drop? Crutches too long?

Answer 40

Radial nerve (off of posterior cord) - runs posteriorly through radial groove
Wrist extensors don't work - wrist flexed (dropped)

Question 41

Where is brachial plexus block performed?

Answer 41

Around axillary sheath