Brachial Plexus

Question 1

The brachial plexus provides somatomotor and somatosensory innervation to
the

Answer 1

upper extremity

Question 2

The brachial plexus arises from the

Answer 2

cervical enlargement of the spinal cord

Question 3

It is formed by the anterior rami of cervical spinal nerve roots

Answer 3

C5-T1

Question 4

These spinal nerve roots emerge from the — — of cervical
vertebrae and pass between the — of the neck

Answer 4

intervertebral foramina
anterior and middle scalene muscles
(interscalene space)

Question 5

The brachial plexus is made up of the

Answer 5

ANTERIOR (VENTRAL) RAMI

of cervical and thoracic spinal nerves (C5 – T1)

Question 6

Topographically, portions of the brachial plexus (trunks) emerge

Answer 6

posterolateral to the sternocleidomastoid muscle in the
lateral neck region, in an area called the posterior triangle, through the interscalene space (between the middle and anterior
scalene muscles) at approximately the level of the cricoid cartilage of the larynx.

Question 7

The brachial plexus maintains an anatomical relationship with vascular structures emerging from the root of the neck
(subclavian a. and v.) as it travels

Answer 7

posterior to the omohyoid muscle and the clavicle

on its way into the axilla

Question 8

For some surgeries involving the upper extremity, an — — is one example of a
procedure that can be performed as an alternative to general anesthesia

Answer 8

interscalene block

Question 9

Typically guided by ultrasound, local anesthetic agents are injected close to the brachial plexus,
temporarily blocking

Answer 9

sensation and motor function to the the upper limb

Question 10

Knowledge of the anatomical relationships within the — — of the neck is essential to
the safety success of this procedure

Answer 10

posterior triangle

Question 11

Common complication:

Answer 11

Accidental partial anesthesia of the diaphragm and temporary respiratory
depression due to proximity of phrenic nerve (C3-C5; cervical plexus) to the anterior scalene m. and
compartmentalization of fascia within the neck

Question 12

As the brachial plexus travels posterior to the clavicle, it enters the axillary region and travels posterior to the

Answer 12

pectoralis minor m.

Question 13

Here it forms an intimate relationship with the axillary a. such that the artery itself runs

Answer 13

in

the middle of the plexus, surrounded by the cords and terminal branches.

Question 14

The — — and it’s tributaries also seem to “entangle” themselves with
the various branches of the brachial plexus

Answer 14

axillary vein

Question 15

As the brachial plexus runs into the axilla, along with the axillary a. and v., it is surrounded in this
neurovascular bundle by the

Answer 15

axillary sheath

Question 16

Dermatome

Answer 16

area of cutaneous sensory innervation supplied by a single spinal nerve

Question 17

For upper extremity this means brachial plexus (C5-T1), but some areas in the axilla are supplied by

Answer 17

lower thoracic spinal nerves (T2-T5)

Question 18

C4 dermatome

Answer 18

Supraclavicular and upper shoulder region

Question 19

C5 dermatome

Answer 19

Upper lateral arm and shoulder

Question 20

C6 dermatome

Answer 20

Posteriolateral arm and lateral forearm

Question 21

C7 dermatome

Answer 21

Middle of forearm and hand

Question 22

C8 dermatome

Answer 22

Posteriomedial forearm and medial hand

Question 23

T1 dermatome

Answer 23

Medial arm

Question 24

T2-T5 dermatome

Answer 24

Axillary region

Question 25

SKIP This is a MAP of cutaneousspinal nerve distribution in the upper limb, with the corresponding dermatome map • It includes spinal nerves

Answer 25

C4 – T5

Question 26

Note that there is not a --- correspondence between named cutaneous nerves and dermatomes. Named nerves may be comprised of --- spinal nerve and thus will span more than one dermatome.

Answer 26

1:1 | >1

Question 27

As a general rule, an individual named muscle in the limbs is supplied by

Answer 27

more than one spinal nerve

Question 28

Anatomically, the term myotome refers to a group of muscles that receive

Answer 28

motor innervation from a single spinal nerve

Question 29

Myotomes may ---

Answer 29

overlap

Question 30

C4 myotomes (motor)

Answer 30

Shoulder elevation

Question 31

C5 myotomes (motor)

Answer 31

shoulder abduction; elbow flexion

Question 32

C6 myotomes (motor)

Answer 32

Elbow flexion; wrist extension

Question 33

C7 myotomes (motor)

Answer 33

Elbow extension; wrist flexion

Question 34

C8 myotomes (motor)

Answer 34

Thumb and finger extension

Question 35

T1 myotomes (motor)

Answer 35

Intrinsic hand muscles

Question 36

T2 myotomes (motor)

Answer 36

Intercostal muscles

Question 37

Each of the trunks of the brachial plexus has | (2) division

Answer 37

an anterior and a posterior

Question 38

These divisions will contribute to branches | that correspond to

Answer 38

anterior parts of the limb | or posterior parts of the limb

Question 39

Innervation of the Upper Limb Follows a --- Pattern

Answer 39

Compartmentalized

Question 40

ARM (BRACHIUM): Anterior Compartment =

Answer 40

``` Musculocutaneous Nerve (flexors of elbow joint) ```

Question 41

ARM (BRACHIUM): Posterior Compartment =

Answer 41

``` Radial Nerve (extensors of elbow joint) ```

Question 42

anterior compartment has only

Answer 42

anterior division contributions from spinal | nerves

Question 43

posterior compartment has only

Answer 43

posterior division contributions from spinal | nerves

Question 44

FOREARM (ANTEBRACHIUM) and HAND: Anterior Compartment =

Answer 44

Ulnar & Median Nerves

Question 45

FOREARM (ANTEBRACHIUM) and HAND: Posterior Compartment =

Answer 45

Radial Nerve

Question 46

``` The shoulder (pectoral girdle) region is innervated by ```

Answer 46

nerves that come directly from the roots, trunks, or cords of the brachial plexus (mostly)

Question 47

The arm (brachial) region is innervated by

Answer 47

the nerves from the medial cord (cutaneous), the musculocutaneous n. (anterior) and the radial n. (posterior)

Question 48

``` The forearm (antebrachial) region is innervated by ```

Answer 48

a branch from the medial cord | cutaneous) , the median and ulnar nerves (anterior) and the radial n. (posterior

Question 49

The hand receives all motor innervation from (2), and sensation from (3)

Answer 49

the median and ulnar nerves median, ulnar and radial nerves

Question 50

Upper/Superior Trunk Lesion =

Answer 50

Erb’s Palsey

Question 51

Erb's Halsey results from

Answer 51

excessive, forceful increase in angle between neck | and shoulder

Question 52

Erb's Palsey is most common

Answer 52

obstetric brachial plexopathy

Question 53

Erb's Halsey can also occur in adults from a

Answer 53

fall onto the shoulder

Question 54

Erbs Palsey

Answer 54

Injuries to Superior Trunk (C5 & C6)Upper/Superior Trunk Lesion = Erb’s Palsey Clinical Presentation: At the shoulder and elbow: •Arm will be adducted •Arm will be internally (medially) rotated at the elbow •There will be pronation •There will be extension This describes the “waiter’s tip”position of the affected upper limb.

Question 55

Nerve Deficits & Affected Muscles • C5 Spinal Nerve Root (3) • C6 Spinal Nerve Root (1)

Answer 55

• Axillary nerve (weakness in deltoid and teres minor) • Suprascapular nerve (from Superior Trunk- weakness in supraspinatus and infraspinatus) • Musculocutaneous nerve (weakness in biceps) • Radial nerve (weakness in brachioradialis and supinator, and wrist extensors)

Question 56

``` Injuries to the Radial Nerve (C5-T1) Axillary Region (nerve is injured before it supplies triceps): Clinical Presentation ```

Answer 56

•Improper use of crutches can compress and injure the nerve in the axilla Clinical Presentation (posterior compartment affected) •Weakness when trying to push something away with arm •Difficulty extending the wrist •Difficulty extending the fingers and opening the hand •“wrist drop” posture

Question 57

Injuries to the Radial Nerve (C5-T1) | Injury at Spiral Groove of Humerus: Clinical presentation

Answer 57

•Compression of the radial nerve along the midshaft of the humerus in certain positions (“Sleep Palsy”, “Saturday Night Palsy”) •Humeral fracture at midshaft (spiral groove fracture) Clinical Presentation •Difficulty extending the wrist •Difficulty extending or straightening the fingers and opening the hand •Triceps retains strength because nerve fibers entering this muscle branch off proximal to the mid shaft of the humerus •Also causes “wrist drop” posture

Question 58

Injuries to the Axillary Nerve (C5, C6) Causes: (3) Clinical Presentation: (4)

Answer 58

* Fracture to surgical neck of humerus * Anterior dislocation of glenohumeral joint * Rotator cuff repair surgery * Numbness in posterior deltoid region * Difficulty abducting arm * Diminished lateral rotation of arm * Deltoid muscle wasting (prolonged injury)

Question 59

Injuries to the Long Thoracic Nerve (C5, C6, C7)(innervation to the serratus anterior muscles) Causes: (2) Clinical Presentation: (2)

Answer 59

* Penetrating wound to the axillary region * Surgical removal of axillary lymph nodes * cannot raise arms above 90O * “winged scapula”