Brachial Plexus

Front 1

The brachial plexus nerve fibers pass through which triangle of the neck?

Back 1

Posterior cervical triangle

Front 2

The brachial plexus nerve fibers pass in between which two muscles?

Back 2

Anterior and middle scalene muscles

Front 3

What type of nerve fibers are found in the brachial plexus?

Back 3

Somatic Afferent
Somatic Efferent
Visceral Afferent
Visceral Efferent

Front 4

How is the brachial plexus divided?

Back 4

(from proximal to distal:)
Roots
Trunks
Division
Cords
Branches

Front 5

In general, the shoulder and proximal limb is innervated from the _______ (upper/lower) roots of the brachial pluxus.

Back 5

Upper

Front 6

Lesions involving the C5 or C6 spinal cord or nerve roots will be seen as problems in which regions of the upper limb?

Back 6

Scapula and shoulder

Front 7

Lesions involving C8 or T1 will be expressed as weakness or problems in which region of the upper limb?

Back 7

Hand

Front 8

What are the roots of the brachial plexus composed of?

Back 8

Ventral primary rami of spinal nerves C5, C6, C7, C8, T1

Front 9

List 2 nerves that branch from the roots of the brachial plexus.

Back 9

1. Dorsal scapular N (C5) --> levator scapulae, rhomboid major/minor
2. Long thoracic N (C5-C7)--> serratus anterior

Front 10

Name the 3 trunks of the brachial plexus.

Back 10

1. Upper
2. Middle
3. Lower

Front 11

Which nerve roots form the upper trunk?

Back 11

C5 and C6 nerve roots

Front 12

Which nerve root forms the middle trunk?

Back 12

Direct continuation of the C7 nerve root

Front 13

Which nerve roots form the lower trunk?

Back 13

C8 and T1

Front 14

T or F.

The upper trunk is the only trunk to give off nerves.

Back 14

TRUE.

Front 15

Name the 2 branches of the upper trunk.

Back 15

1. Suprascapular N (C5-C6) --> Supraspinatus and infraspinatus
2. Nerve to subclavius (C5-C6)

Front 16

Which nerve runs laterally across the posterior cervical triangle to pass through the scapular notch under the suprascapular ligament?

Back 16

Suprascapular N (C5-6)

Front 17

T or F.

Several nerves originate from the middle and lower trunks of the brachial plexus.

Back 17

FALSE

Only the upper trunk gives off nerve branches

Front 18

T or F.

No nerves originate from the divisions of the brachial plexus.

Back 18

TRUE.

Front 19

How many divisions are there?

Back 19

3 anterior and 3 posterior divisions

Front 20

The anterior divisions of the upper trunk and the middle trunk join to form the _____ cord.

Back 20

Lateral cord

Front 21

The anterior division of the lower trunk continues as the _______ cord.

Back 21

Medial cord

Front 22

The 3 posterior divisions come together to produce the ______ cord.

Back 22

Posterior cord

*Lead to the formation of the postaxial nerves of the limb

Front 23

T or F.

The lower trunk has a small and variable contribution to the posterior cord.

Back 23

TRUE.

Front 24

The Lateral pectoral N (C5-C7) is a branch off of which cord?

What muscle does it innervate?

Back 24

Lateral cord

Innervates the Pectoralis major M.

Front 25

Name the 2 terminal branches of the lateral cord.

Back 25

1. Musculocutaneous N
2. Median N (contribution)

Front 26

Which nerve passes through the fibers of the coracobrachialis and terminates as the lateral cutaneous nerve of the forearm?

Back 26

Musculocutaneous N (C5-6)

Front 27

Which specific nerve fibers does the lateral cord contribute to the formation of the Median N?

Back 27

C6 and C7 fibers

Front 28

Name 3 non-terminal branches of the Medial cord.

Back 28

1. Medial Pectoral N (C8-T1) --> Pectoralis major and minor
2. Medial brachial cutaneous N (C8-T1) --> innervates skin on medial side of arm
3. Medial Antebrachial cutaneous N (C8-T1) --> innervates skin on medial side of forearm down toward wrist

Front 29

Which nerve innervates the skin o nthe medial side of the arm?

Back 29

Medial brachial cutaneous N

Front 30

Which nerve innervates the skin on the medial side of the forearm down toward the wrist?

Back 30

Medial antebrachial cutaneous N

Front 31

Name the terminal branches of the Medial cord?

Back 31

1. Ulnar N (C8-T1)
2. Median head of the Median N (C8-T1)

Front 32

Which cord gives off several branches that innervate the muscles of the posterior axillary fold?

Back 32

Posterior cord

Front 33

Name 3 non-terminal branches of the posterior cord.

Back 33

1. Upper subscapular N (C5-C6) --> upper portion of Subscapularis
2. Lower subscapular N (C5-6C6) --> lower portion of Subscapularis and teres major
3. Thoracodorsal N (C7-C8) --> Latissimus dorsi

Front 34

Name the terminal branches of the posterior cord.

Back 34

1. Axillary N
2. Radial N

Front 35

Which artery accompanies the Axillary N as it passes through the quadrangular space?

Back 35

Posterior humeral circumflex A

Front 36

Which muscles does the Axillary N innervate?

Back 36

1. Deltoid
2. Teres minor

Front 37

Which nerve innervates the Coracobrachialis, biceps brachii, and brachialis muscles?

Back 37

Musculocutaneous N

Front 38

Which nerve supplies the skin on the lateral side of the forearm?

Back 38

Lateral antebrachial cutaneous N

(continuation of the musculocutaneous N)

Front 39

T or F.

The Median N innervates some muscles in the arm.

Back 39

FALSE

It supplies most of the flexors of the forearm.

Front 40

The Median N supplies all of the flexors of the forearm and wrist EXCEPT for 2 1/2. List these exceptions.

Back 40

1. Flexor carpi ulnaris
2. Ulnar half of the flexor digitorum profundus
3. Brachioradialis

Front 41

Describe the course of the Median N as it passes through the Median tunnel.

Back 41

It passes the biceps tendon, then passes through the two heads of the pronator teres and the two heads of the flexor digitorum superficialis muscle.

Front 42

Which nerve passes through the carpal tunnel between the flexor retinaculum and the flexor digitorum superficialis muscle?

Back 42

Median N

Front 43

List the structures that the Median N innervates.

Back 43

1. 3 muscles of the thenar eminence
2. Lateral two lumbrical muscles
3. Skin of the palm
4. Skin of the lateral 3 1/2 digits (as well as the dorsal aspect of these fingers past the distal interphalangeal joint)

Front 44

Which cervical spinal nerves make up the musculocutaneous N?

Back 44

C5-C7

Front 45

Which cervical spinal nerves make up the Median N?

Back 45

C5-T1

Front 46

Which cervical spinal nerves make up the radial N?

Back 46

C5-T1
(but mostly C6, C7, and a little from C8)

Front 47

Which nerve is the largest terminal branch of the brachial plexus?

Back 47

Radial N

Front 48

Which nerve travels posteriorly throug hthe triceps muscle separating the lateral head from the medial head and travels in the spiral groove of the humerus?

Back 48

Radial N

Front 49

Name the 2 branches of the Radial N.

Back 49

Deep branch
Superficial branch

Front 50

The deep branch of the Radial N enters the _________ (anterior/posterior) compartment of the forearm as the _________ nerve.

What does this nerve innervate?

Back 50

Posterior compartment

Posterior interosseous N

Innervates extensors of the forearm and wrist

Front 51

What does the superficial branch of the Radial N innervate and which compartment of the forearm is it found in?

Back 51

Innervates the skin of the radial side of the hand and 1/2 digits over the proximal to middle phalanx.

Front 52

Which nerve passes through the scapular notch under the suprascapular (transverse scapular) ligament?

Back 52

Suprascapular N

Front 53

What tunnel is formed by the two heads of the flexor carpi ulnaris muscle, and which nerve passes through this tunnel?

Back 53

Ulnar tunnel
Ulnar N

Front 54

Which muscles does the Ulnar N innervate in the forearm?

Back 54

1. Flexor carpi ulnaris M
2. Ulnar half of the flexor digitorum profundus

Front 55

Which muscles does the deep branch of the Ulnar N innervate?

Back 55

1. Hypothenar muscles
2. Medial two lumbricals
3. All of the interosseous muscles
4. Adductor pollicis M
5. Deep head of flexor pollicis brevis M (usually)

*Ulnar N innervates all the muscles in the hand except for the thenar muscles and the lateral two lumbricals, which are innervated by the Median N.

Front 56

Which nerve innervates the palmaris brevis and the skin over the palmar and dorsal surfaces of the medial 1/3 of the hand?

Back 56

Superficial branch of Ulnar N

Front 57

Which portion of the brachial plexus may be severely injured as a result of a sudden, forcible widening of the angle between the shoulder and the head?

Back 57

Upper trunk
(avulsion of the C5-C6 roots)

*Often seen in individuals thrown from a moving vehicle or horseback.

Front 58

Which portion of the brachial plexus is most likely to be injured during delivery, where the infant's should becomes lodged against the mother's pelvis (shoulder dystocia)?

Back 58

Upper trunk
(avulsion of the C5-C6 roots)

*Shoulder dystocia is considered an obstetrical emergency

Front 59

Which portion of the brachial plexus is most likely to be injured by an excessively increased angle between the body trunk and upper limb?

(Ex: person using an outstretched arm to grasp a tree branch in breaking a fall)

Back 59

Lower brachial plexus

Front 60

Nerve injury that results from tearing away the nerve root at the spinal nerve.

Back 60

Avulsion
(most severe nerve injury)

Front 61

Nerve injury that results from a tearing away the nerve at a site other than the root/spinal nerve attachment.

Back 61

Rupture

Front 62

Nerve injury that results from the formation of scar tissue, preventing appropriate nerve conduction.

Back 62

Neuroma

Front 63

Nerve injury that results from a stretched or damaged nerve that is not torn.

Back 63

Neuroapraxia
(least severe nerve injury)

Front 64

What type of brachial plexus injury results in Erb-Duchenne palsy?

What are the clinical characteristics of this injury?

Back 64

Upper plexus injury
Caused by excessive separation of the head and shoulder, and affects the C5-C6 nerves and brachial plexus roots.
(Paralysis--> supraspinatus, infraspinatus, rhomboids, deltoid, biceps, brachialis, and supinator muscles)

*Results in characteristic "waiter's tip" position, with the arm adducted in internal rotation.

Front 65

This injury results in weakness and atrophy affecting the intrinsic muscles of the hand, producing a characteristic claw-hand deformity.

What type of injury typically causes this?

Back 65

Lower plexus injury-- "Klumpke's paralysis"

*Caused by excessive traction on the upper limb--> damages Ulnar N

(Avulsion of the T1 cervical nerve can also produce a concomitant Horner syndrome)

Front 66

What type of injury results in a characteristic "winged scapula" and an inability to elevate the arm above the head?

Back 66

Damage to long thoracic N
Can be caused by penetrating chest wounds, damage during chest wall or thoracic surgery, and contact sports injuries.

Front 67

Damage to which nerve is characterized by:
1. Atrophy of the supraspinatus and infraspinatus muscles
2. Difficulty initiating arm abduction
3. External rotation of the arm

Back 67

Suprascapular nerve damage

Front 68

Deficits in the lateral rotation and arm abduction may indicate damage to which nerve?

Back 68

Axillary nerve
(weakness in Deltoid and Teres minor muscles)

Front 69

Which nerve is most likely damaged if the following signs are presented:
1. Weakened flexion of the supinated forearm
2. Weakness or paralysis and/or atrophy of anterior arm muscles
3. Sensory deficits in the lateral portion of the forearm.

Back 69

Musculocutaneous N

Front 70

The supinator muscle is innervated by which nerve?

Back 70

Radial N

Front 71

The abductor pollicis longus muscle is innervated by which nerve?

Back 71

Radial N

Front 72

Injury to which nerve produces a characteristic "wrist drop" due to wrist extensor weakness?

Back 72

Radial N

Front 73

Injury to which nerve will result in an inability to pronate the forearm and flex the interphalangeal joints, and weakness of thumb opposition and abduction?

Back 73

Median N

Front 74

A "hand of benediction" is a clinical sign which indicates damage to which nerve?

Back 74

Median N
(when patient makes a fist, 2nd and 3rd fingers are partially extended)

Front 75

What syndrome is caused by entrapment of the median N between the heads of the pronator teres muscle?

Back 75

Pronator syndrome

Front 76

What syndrome results in pain and tenderness along the proximal aspect of the naterior forearm and sensory loss over the palm and thenar eminence?

Back 76

Pronator syndrome
(Median N entrapped b/w heads of pronator teres)

Front 77

Damage to which nerve can result in claw-hand deformity and paralysis/atrophy of intrinsic hand muscles?

Back 77

Ulnar N

Front 78

A patient presents with upper limb neurologic deficits, Horner's syndrome, and subscapular paint. This patient has a history of smoking.

What is the probable diagnosis?

Back 78

Pancoast's tumor
(cancer in the apex of the lung)

Front 79

Syndrome caused by trauma to the cervical/shoulder region that can produce a transient brachial brachial plexus injury--also known as a "stinger."

Back 79

Burner's syndrome
(often seen in young athletes playing contact sports)

*Caused by overstretching or micro-tears of brachial plexus roots