413-414 - Brachial plexus

Question 1

Put the following in order from proximal to distal: cords, divisions, roots, branches, trunks

Answer 1

Roots, trunks, divisions, cords, branches

Randy Travis Drinks Cold Beer

Question 2

What nerve injury causes Erb palsy?

Answer 2

Traction or tear of upper trunk: C5-C6 roots

“Erb-er” trunk

Question 3

What can cause Erb’s palsy in infants? In adults?

Answer 3

lateral traction on neck during delivery; trauma

Question 4

What muscles and related deficits are involved in Erb’s palsy?

Answer 4

1. Deltoid, supraspinatus → can’t abduct (arm hangs by side)
2. Infraspinatus → can’t laterally rotate (arm hangs medially rotated)
3. Biceps brachii → can’t flex or supinate (arm extended and pronated)

Question 5

What nerve injury causes Klumpke palsy?

Answer 5

traction or tear of lower trunk: C8-T1 root

Question 6

How can infants get Klumpke palsy? Adults?

Answer 6

upward force on arm during delivery; trauma (eg. grabbing a tree branch to break a fall)

Question 7

What muscles are affected in Klumpke palsy?

Answer 7

Intrinsic hand muscles:

• lumbricals
• interossei
• thenar
• hypothenar

Question 8

How does Klumpke palsy present? Why?

Answer 8

Total claw hand; lumbricals normally flex MCP joints and extend DIP and PIP → MCP is extended and DIP/PIP are flexed

Question 9

What nerve injury leads to thoracic outlet syndrome?

Answer 9

Compression of lower trunk [of the brachial plexus] and subclavian vessels

Question 10

What spinal roots make up the upper, middle and lower trunks of the brachial plexus?

Answer 10

C5 & C6 => upper
C7 => middle
C8 & T1 => lower

Question 11

What trunks make up the lateral cord of the brachial plexus?

Answer 11

upper & middle

Question 12

What trunks make up the posterior cord of the brachial plexus?

Answer 12

upper, middle, and lower

Question 13

What trunks make up the medial cord of the brachial plexus?

Answer 13

the lower trunk only

Question 14

What nerves arise from the posterior cord of the brachial plexus? Do they lead to flexors or extensors?

Answer 14

axillary and radial

both → extensors

Question 15

Which cords give rise to the musculocutaneous nerve?

Answer 15

lateral cord

Question 16

Where does the long thoracic n. arise from?

Answer 16

C5, C6, C7 roots

Question 17

What are two causes of thoracic outlet syndrome?

Answer 17

Cervical rib injury

Pancoast tumor

Question 18

What muscles are affected in thoracic outlet syndrome?

Answer 18

Intrinsic hand muscles:

• lumbricals
• interossei
• thenar
• hypothenar

Question 19

What deficits are present in thoracic outlet syndrome?

Answer 19

atrophy of intrinsic hand muscles, ischemia, pain, and edema due to vascular compression

Question 20

What nerve is compromised in a patient presenting with a winged scapula?

Answer 20

long thoracic nerve

Question 21

What are two causes of injuries that lead to winged scapula?

Answer 21

1. axillary node dissection after mastectomy

2. stab wounds

Question 22

What muscle is affected in a patient with a winged scapula? What functional deficit results?

Answer 22

Serratus anterior → inability to anchor scapula to thoracic cage → can’t abduct arm above horizontal position

Question 23

Which cords give rise to the median nerve?

Answer 23

lateral and medial

Question 24

Which cords give rise to the ulnar nerve?

Answer 24

medial

Question 25

A patient presents with an atrophied shoulder. On physical exam they can't abduct their shoulder more than 15 degrees. There is also a loss of sensation over the shoulder and lateral arm. Which nerve is lesioned? What muscle is atrophied? What are some causes of this nerve injury?

Answer 25

Axillary nerve lesion (from C5-C6 roots); deltoid muscle; causes include fractured surgical neck of humerus and anterior dislocation of humerus

Question 26

A patient presents with wrist drop. What cord of the brachial plexus might be lesioned?

Answer 26

posterior cord

Question 27

What are the symptoms of a lesion to the musculocutaneous nerve?

Answer 27

loss of forearm flexion and supination | loss of sensation over lateral forearm

Question 28

Which spinal roots contribute to the musculocutaneous nerve?

Answer 28

C5-C7

Question 29

What is a common cause of injury to the musculocutaneous nerve?

Answer 29

compression of the upper trunk of the brachial plexus

Question 30

What are the spinal roots of the radial nerve?

Answer 30

C5-T1

Question 31

What symptoms are present in a radial nerve injury patient?

Answer 31

Wrist drop: loss of elbow, wrist, and finger extension ↓ grip strength (wrist extension necessary for maximal action of flexors) Loss of sensation over posterior arm/forearm and dorsal hand

Question 32

What are 2 causes of radial nerve injury?

Answer 32

1. Midshaft fracture of humerus 2. Compression of axilla e.g. due to crutches, sleeping with arm over chair ("Saturday night palsy"), or with someone laying on inner arm ("Honeymoon palsy").

Question 33

What are the symptoms of median nerve injury?

Answer 33

"Ape hand" and "Pope's blessing" Motor: Loss of wrist and lateral finger flexion, thumb opposition, lumbricals of 2nd and 3rd digits Sensory: loss of sensation over thenar eminence and dorsal and palmar aspects of lateral 3 1/2 fingers with proximal lesion Tinel sign (tingling on percussion) in carpal tunnel syndrome

Question 34

What are 3 causes of median nerve injury?

Answer 34

1. Supracondylar fracture of humerus (proximal lesion) 2. Carpal tunnel syndrome 3. Wrist laceration (distal lesion)

Question 35

What are 2 causes of axillary nerve injury?

Answer 35

1. fractured surgical neck of humerus | 2. anterior dislocation of humerus

Question 36

What are the spinal roots of the axillary nerve?

Answer 36

C5-C6

Question 37

What are the symptoms of axillary nerve injury?

Answer 37

1. flattened deltoid 2. loss of arm abduction at the shoulder (>15 degrees) 3. Loss of sensation over deltoid muscle and lateral arm

Question 38

What are the symptoms of an ulnar nerve lesion?

Answer 38

1. "ulnar claw" on digit extension 2. Radial deviation of wrist upon flexion (proximal lesion) 3. Loss of flexion of wrist and medial fingers, abduction and adduction of fingers (interossei), actions of medial 2 lumbrical muscles 4. Loss of sensation over medial 1 1/2 fingers including hypothenar eminence

Question 39

What are the spinal roots of the ulnar nerve?

Answer 39

C8 - T1

Question 40

What are two causes of injury to the ulnar nerve?

Answer 40

1. Fracture of medial epicondyle of humerus "funny bone" (proximal lesion) 2. Fractured hook of hamate (distal lesion)

Question 41

What are the symptoms of a lesion to the recurrent branch of the median nerve?

Answer 41

- "Ape hand" - loss of thenar muscle group: opposition, abduction, and flexion of thumb - no loss of sensation