Fall_25_Brachial_Plexus

Question 1

The classic mnemonic for the sequence of the brachial plexus is?

Answer 1

Randy Taylor Drinks Cold Beers / Read That Da*n Cadaver Book

Mnemonic in the slides to recall Roots→Trunks→Divisions→Cords→Branches.

Question 2

How many roots form the brachial plexus?

Answer 2

5

Five ventral rami (C5–T1).

Question 3

Cervical nerve roots originate relative to their vertebrae:

Answer 3

Above the corresponding vertebra

Cervical roots arise above their vertebra; thoracic roots exit below.

Question 4

The T1 nerve root exits:

Answer 4

Below T1 vertebra

Thoracic roots, including T1, exit below the corresponding vertebra.

Question 5

Each brachial plexus root is associated with:

Answer 5

An ipsilateral sensory dermatome

Each root corresponds to a sensory dermatome.

Question 6

Which roots form the superior (upper) trunk?

Answer 6

C5–C6

Upper trunk is formed by C5 and C6.

Question 7

The middle trunk is formed by:

Answer 7

C7

Middle trunk derives from C7 alone.

Question 8

The inferior (lower) trunk is formed by:

Answer 8

C8–T1

Lower trunk is C8 and T1.

Question 9

Trunks are formed as the roots pass between which scalene muscles?

Answer 9

Anterior and posterior scalene muscles

As they cross the anterior and posterior scalene muscles.

Question 10

The interscalene block best targets:

Answer 10

Roots (transitioning to trunks)

US field captures roots transitioning to trunks; goal is roots.

Question 11

A frequent limitation of the interscalene block is sparing of:

Answer 11

C8–T1 (inferior trunk)

Inferior trunk is often spared, limiting hand coverage.

Question 12

Because of its distribution, the interscalene block is best for:

Answer 12

Shoulder surgery

Excellent coverage for the shoulder; less ideal distally.

Question 13

The subclavian artery is emphasized because it:

Answer 13

Helps identify plexus anatomy with ultrasound

Often the easiest landmark to find relevant anatomy on US.

Question 14

Each trunk divides into:

Answer 14

Anterior and posterior divisions

Trunks split into anterior and posterior divisions.

Question 15

Anterior divisions generally supply:

Answer 15

Flexors

Anterior divisions → flexor compartments.

Question 16

Posterior divisions generally supply:

Answer 16

Extensors

Posterior divisions → extensor compartments.

Question 17

The supraclavicular block primarily targets:

Answer 17

Trunks/divisions

Goal at this level is trunks/divisions around the artery.

Question 18

The infraclavicular block primarily targets:

Answer 18

Divisions/cords

Goal is divisions/cords in infraclavicular fossa.

Question 19

Supraclavicular and infraclavicular blocks are generally good for:

Answer 19

Most of the arm below the shoulder

Both provide anesthesia below the shoulder.

Question 20

The axillary artery runs from the outer border of the first rib to the outer border of the:

Answer 20

Teres major muscle

Defined from 1st rib to outer border of teres major.

Question 21

Cords are named based on their relationship to the:

Answer 21

Axillary artery

Cords are named by position around the axillary artery.

Question 22

The lateral cord is formed by the anterior divisions of:

Answer 22

Superior and middle trunks

Lateral cord = anterior divisions of superior + middle trunks.

Question 23

The posterior cord is formed by:

Answer 23

Posterior divisions of all three trunks

Posterior cord = three posterior divisions.

Question 24

The medial cord is formed by the anterior division of the:

Answer 24

Inferior trunk

Medial cord = anterior division of inferior trunk.

Question 25

The terminal branch mnemonic is:

Answer 25

MARMU MARMU = Musculocutaneous, Axillary, Radial, Median, Ulnar.

Question 26

Which terminal branch commonly breaks off early from the plexus?

Answer 26

Musculocutaneous Musculocutaneous typically leaves early.

Question 27

The axillary block targets structures located:

Answer 27

Around the axillary artery (four branches) Identify Axillary, Median, Radial, Ulnar around the artery.

Question 28

The axillary block is an excellent and safe choice for procedures from:

Answer 28

Elbow to hand Best coverage for elbow-to-hand procedures.

Question 29

During an axillary technique, a separate injection is often used for the:

Answer 29

Musculocutaneous nerve MCN often requires a separate injection.

Question 30

The musculocutaneous nerve provides motor to which muscles?

Answer 30

Biceps, brachialis, coracobrachialis Innervates anterior arm flexors; sensory to lateral forearm.

Question 31

The musculocutaneous nerve provides sensory to the:

Answer 31

Lateral forearm Sensory distribution to lateral forearm.

Question 32

The axillary nerve innervates which muscles?

Answer 32

Deltoid and teres minor Motor to deltoid (abduction) and teres minor (external rotation).

Question 33

The axillary nerve supplies cutaneous sensation to:

Answer 33

A small area of the shoulder region Small sensory patch over lateral shoulder.

Question 34

The ulnar nerve controls primarily:

Answer 34

Intrinsic hand and some forearm flexors Intrinsic hand + some forearm flexors; fine motor.

Question 35

Ulnar sensory distribution includes:

Answer 35

Palmar/dorsal little finger and half of the ring finger Little finger and ulnar half of ring finger.

Question 36

As block level moves distally, coverage becomes:

Answer 36

Lower and more focused distally Lower block → lower effective coverage area.

Question 37

Dermatome mapping is relevant because roots correspond to:

Answer 37

Sensory skin territories Roots map to dermatomes for sensory distribution.

Question 38

Distal to the elbow, you may block:

Answer 38

Individual branches or perform a wrist block Either block individual branches or do a wrist block.

Question 39

Exception to 'nerves follow arteries' distally:

Answer 39

Radial nerve is not next to the radial artery Median nerve lies by the radial artery; radial nerve does not.

Question 40

At the wrist, the median nerve is typically adjacent to the:

Answer 40

Radial artery Median nerve is next to radial artery distally.

Question 41

'Let's all get on the same plane' emphasizes:

Answer 41

Sonoanatomy alignment around main arteries Use arterial landmarks to align the ultrasound imaging plane.

Question 42

Goal structure for a supraclavicular approach:

Answer 42

Trunks/divisions compact around the artery Target trunks/divisions near the artery at the clavicle.

Question 43

Goal structure for an infraclavicular approach:

Answer 43

Divisions/cords Infraclavicular targets divisions/cords.

Question 44

In an axillary approach, the four nerves around the axillary artery are:

Answer 44

Axillary, Median, Radial, Ulnar MCN breaks off early; four around the artery are A/M/R/U.

Question 45

Block providing the broadest distal upper-extremity coverage:

Answer 45

Supraclavicular Dense coverage for most of the arm below the shoulder.

Question 46

Which block is not ideal for hand surgery due to lower trunk sparing?

Answer 46

Interscalene Interscalene often spares C8–T1 (ulnar distribution).

Question 47

The lateral cord contributes to which terminal branch?

Answer 47

Median (with medial cord) Median nerve receives fibers from lateral and medial cords.

Question 48

The posterior cord gives rise to which two terminal branches?

Answer 48

Axillary and radial Posterior cord → axillary & radial.

Question 49

The medial cord contributes prominently to which terminal branch?

Answer 49

Ulnar Medial cord → ulnar; also contributes to median.

Question 50

Primary motor role of axillary nerve:

Answer 50

Shoulder abduction Deltoid abduction is axillary nerve’s hallmark.

Question 51

Primary motor role linked with radial nerve divisions:

Answer 51

Extensors Posterior divisions supply extensors; radial is terminal branch.

Question 52

Primary motor role linked with median nerve proximally:

Answer 52

Forearm/wrist flexor-pronator mass Anterior divisions (flexors) contribute to median distribution.

Question 53

For wrist blocks, nerves generally track arteries; a key implication:

Answer 53

Median nerve is next to radial artery At the wrist, median nerve lies by the radial artery.

Question 54

Need ring and little finger anesthesia at the wrist. Target:

Answer 54

Ulnar nerve Ulnar supplies little finger and ulnar half of ring finger.

Question 55

For elbow-to-hand procedures, safest and effective single site:

Answer 55

Axillary Axillary block is excellent and safe for elbow-to-hand.

Question 56

Separate injection during axillary approach improves coverage of:

Answer 56

Musculocutaneous nerve MCN often needs separate deposition.

Question 57

Which block level most reliably covers the hand when done properly?

Answer 57

Supraclavicular Supraclavicular provides dense distal coverage.

Question 58

Axillary nerve sensory patch is located at the:

Answer 58

Small area over lateral shoulder Small cutaneous zone on shoulder region.

Question 59

Musculocutaneous nerve becomes which cutaneous nerve in the forearm?

Answer 59

Lateral antebrachial cutaneous Provides sensory to lateral forearm.

Question 60

Best single regional choice for shoulder arthroscopy:

Answer 60

Interscalene Shoulder procedures → interscalene block.

Question 61

For forearm fracture fixation, a high-density single injection option is:

Answer 61

Supraclavicular Covers most of the arm below the shoulder.

Question 62

Infraclavicular vs axillary: an infraclavicular advantage is:

Answer 62

More proximal plexus targeting (divisions/cords) Targets divisions/cords more proximally than axillary.

Question 63

Axillary block typical terminal branches visualized around the artery exclude:

Answer 63

Musculocutaneous MCN breaks off early; not typically in the perivascular ring.

Question 64

The subclavian artery landmark is most relevant to which block?

Answer 64

Supraclavicular Primary US landmark at supraclavicular level.

Question 65

Which statement about divisions is TRUE?

Answer 65

They lie tightly packed around the artery at the clavicle Divisions are compact near the artery as they cross the clavicle.

Question 66

The distal boundary of the axillary artery is the:

Answer 66

Outer border of teres major Axillary artery ends at the outer border of teres major.

Question 67

Which branch primarily powers elbow flexion?

Answer 67

Musculocutaneous Biceps/brachialis are innervated by musculocutaneous nerve.

Question 68

Which nerve is least likely to be reliably covered by an interscalene block?

Answer 68

Ulnar (C8–T1) Lower trunk (C8–T1) commonly spared by interscalene.

Question 69

For ulnar-sided hand surgery, a dependable distal option is:

Answer 69

Ulnar nerve block at wrist Targets ulnar distribution (little finger and half ring finger).

Question 70

A 'broad but distal' sensory-motor coverage ideal for forearm/hand is:

Answer 70

Supraclavicular Supraclavicular covers most of the arm below the shoulder.

Question 71

The lateral cord name reflects its position lateral to the:

Answer 71

Axillary artery Cords are named by location around the axillary artery.

Question 72

The posterior cord location is best described as:

Answer 72

Posterior to axillary artery By definition of cord naming around the axillary artery.

Question 73

For a wrist block targeting the median nerve, a helpful vascular landmark is:

Answer 73

Radial artery Median nerve lies next to radial artery distally.

Question 74

Key exception to 'nerves follow arteries' distally is that the:

Answer 74

Radial nerve does not accompany the radial artery Slide highlights: radial nerve is not next to the radial artery.