Brachial plexus and nerve lesions

Question 1

what does the posterior cord supply?

Answer 1

extensors

Question 2

main nerves coming off the posterior cord?

Answer 2

axillary and radial nerves

Question 3

what does the lateral cord supply?

Answer 3

flexors

Question 4

what does the medial cord supply?

Answer 4

flexors

Question 5

roots of the axillary nerve?

Answer 5

Roots: C5 and C6.

Question 6

motor function of the axillary nerve?

Answer 6

Motor Functions: Innervates the teres minor and deltoid muscles.

Question 7

sensory function of the axillary nerve?

Answer 7

Sensory Functions: Gives off the superior lateral cutaneous nerve of arm, which innervates the inferior region of the deltoid (“regimental badge area”).

Question 8

roots of the musculocutaneous nerve?

Answer 8

C5, C6, C7

Question 9

motor function of the musculocutaneous nerve?

Answer 9

Innervates the brachialis, biceps brachii and coracobrachialis muscles.

Question 10

sensory function of the muscuocutaneous nerve?

Answer 10

Gives off the lateral cutaneous branch of the forearm, which innervates the lateral half of the anterior forearm, and a small lateral portion of the posterior forearm.

Question 11

roots of the median nerve?

Answer 11

C6 – T1. (Also contains fibres from C5 in some individuals).

Question 12

motor function of the median nerve?

Answer 12

Innervates most of the flexor muscles in the forearm, the thenar muscles, and the two lateral lumbricals associated with the index and middle fingers.

Question 13

sensory function of the median nerve?

Answer 13

Gives off the palmar cutaneous branch, which innervates the lateral part of the palm, and the digital cutaneous branch, which innervates the lateral three and a half fingers on the anterior (palmar) surface of the hand.

Question 14

roots of the radial nerve?

Answer 14

C5 – T1

Question 15

motor function of the radial nerve?

Answer 15

Innervates the triceps brachii, and the muscles in the posterior compartment of the forearm (which are primarily, but not exclusively, extensors of the wrist and fingers).

Question 16

sensory function of the radial nerve?

Answer 16

Innervates the posterior aspect of the arm and forearm, and the posterolateral aspect of the hand.

Question 17

roots of the ulnar nerve?

Answer 17

C8 and T1

Question 18

motor function of the ulnar nerve?

Answer 18

Innervates the muscles of the hand (apart from the thenar muscles and two lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum profundus.

Question 19

sensory function of the ulnar nerve?

Answer 19

Innervates the anterior and posterior surfaces of the medial one and half fingers, and associated palm area.

Question 20

which spinal levels contribute to the brachial plexus?

Answer 20

C5-T1

Question 21

what palsy is caused by damage to the upper brachial plexus roots?

Answer 21

C5/C6 injury leads to Erb-Duchenne Palsy

Question 22

what are the causes of upper root injury?

Answer 22

Shoulder dystocia (during delivery of the baby, a shoulder is stuck behind the mother’s pubic bone)

Tugging of the neck during delivery

stretching of the neck relative to the shoulder

Question 23

what nerves are affected by Erb’s palsy?

Answer 23

C5 or C6 roots: musculocutaneous
axillary
suprascapular
nerve to subclavius.

Question 24

what muscles are affected by Erb’s palsy?

Answer 24

Supraspinatus, infraspinatus, subclavius, biceps brachii, brachialis, coracobrachialis, deltoid and teres minor.

Question 25

what are the features of Erb's Palsy?

Answer 25

Wasted deltoid and biceps/brachialis Arm is pronated and medially rotated Elbow extended Dermatomal sensory loss "Waiter's tip" position: forearm is pronated due to the loss of biceps brachii. wrist is weakly flexed due to the normal increased tone of the wrist flexors relative to the wrist extensors

Question 26

what palsy is caused by injury to the lower Brachial plexus roots?

Answer 26

Klumpke's Palsy

Question 27

what is the cause of Klumpke's palsy?

Answer 27

excision abduction of the arm e.g. when breaking a fall by catching a branch, falls from ladders etc can occur during birth when the child's arm is pulled out (rare) this had a lower incidence than Erb's palsy

Question 28

which nerves are affected in Klumpke's Palsy?

Answer 28

Nerves derived from the T1 root – ulnar and median nerves.

Question 29

which root is more commonly affected in Klumpke's?

Answer 29

T1 (or can be C8 aswell)

Question 30

which muscles are affected in Klumpke's?

Answer 30

All the intrinsic hand muscles

Question 31

features of Klumpke's

Answer 31

Possible Horner's syndrome (if T1 affected) Intrinsic hand muscles paralysed “Claw Hand” supinated forearm with flexed wrist and fingers Dermatomal sensory loss (medial side of arm)

Question 32

what causes the "claw hand" in Klumpke's?

Answer 32

Unopposed action of the finger extensor muscles. The lumbrical muscles flex the metacarpophalangeal joints and extend the interphalangeal joints, so their paralysis will cause the opposite: extension of the MCP and flexion of the IP joints.

Question 33

how can the musculocutaneous nerve be damaged?

Answer 33

in surgery for breast cancer due to the location of lymph nodes shoulder dislocation weight lifters are prone to this

Question 34

what is the effect of a damage musculocutaneous nerve?

Answer 34

- Weak elbow flexion and supination - Absent biceps reflex - Lateral forearm sensory loss (lateral cutaneous nerve)

Question 35

how can the axillary nerve be damaged?

Answer 35

shoulder dislocations | humeral head and neck fractures

Question 36

what is the effect of axillary nerve damage?

Answer 36

- deltoid wastage (flat shoulder deformity alongside teres minor wastage) - Loss of abduction (from >15°) - Sensory loss on lateral upper arm in the Regimental badge patch

Question 37

what can cause a radial nerve injury?

Answer 37

injury to the axilla humeral shaft fracture fracture of the radial neck below the elbow

Question 38

what are the effects of a radial nerve injury?

Answer 38

- Wrist drop: cannot extend the wrist, elbow or fingers - muscle wastage (when the lesion is higher up) - Sensory loss to posterior forearm and dorsum of hand (anaesthesia) - loss of the power grip due to loss of wrist extension

Question 39

what are the causes of median nerve injury?

Answer 39

- supracondylar humeral fracture - wrist lacerations - carpal tunnel syndrome (compression)

Question 40

what are the effects of median nerve damage?

Answer 40

- Loss of sensation in lateral three and a half fingers - Loss of wrist flexion, elbow pronation, flexion of radial ½ of digits - Presence of “benediction sign” - Presence of ape hand deformity - loss of thenar eminence due to wasting

Question 41

what are the 4 pillars of the carpal tunnel?

Answer 41

hook of hamate pisiform crest of trapezium tubercle of scaphoid

Question 42

what are the causes of ulnar nerve injury?

Answer 42

- elbow fractures - wrist trauma (e.g. self harm) - funny bone trauma

Question 43

what are the effects of ulnar nerve damage?

Answer 43

- Sensory loss in medial 1½ fingers (palmar and dorsal) | - Ulnar claw

Question 44

ulnar claw

Answer 44

Hyper-extended 4th and 5th digits at MCP Hyper-flexed 4th and 5th digits at IPJs Weak thumb adduction “Froment’s sign” Claw worse on extension (unlike median nerve) the lumbricals contraction loss leads to no flexion at knuckles PAD and DAB affected

Question 45

what is the ulnar paradox?

Answer 45

claw deformity is more severe with wrist damage than with elbow damage "the closer to the paw, the worse the claw"

Question 46

what is the effect of damage to the long thoracic nerve?

Answer 46

winging of the scapula (unopposed action of the rhomboids pushes scapula back) paralysis of serratus anterior

Question 47

what is the function of the serratus anterior?

Answer 47

protect and stabilise the scapula

Question 48

proximal and distal attachment of the serratus anterior muscle?

Answer 48

upper 8/9 ribs | medial margin of scapula

Question 49

what can cause long thoracic nerve damage?

Answer 49

surgery for breast cancer

Question 50

what are the muscles of the rotator cuff? what is each muscle innervated by?

Answer 50

- Supraspinatus (suprascapular n) - Infraspinatus (suprascapular n) - Teres minor (axillary n) - Subscapularis (lower subscapular n)

Question 51

what is the function of the rotator cuff muscles as a whole?

Answer 51

keep the humeral head inside the glenoid fossa

Question 52

myotomes

Answer 52

the more distal the movement occurs at, the lower down the spinal root opposing movements tend to be innervated from adjacent spinal segments

Question 53

Shoulder Abduction

Answer 53

C5 (axillary)

Question 54

Shoulder Adduction

Answer 54

C6/7/8

Question 55

Elbow Flexion

Answer 55

C5 (musculocutaneous)

Question 56

Elbow extension

Answer 56

C7 (radial)

Question 57

Wrist Flexion & Extension

Answer 57

C6/7 (radial)

Question 58

Finger Flexion

Answer 58

C8 (median)

Question 59

Finger Extension

Answer 59

C7 (radial)

Question 60

Finger Abduction –

Answer 60

T1 (ulnar)

Question 61

Abductor pollicis brevis

Answer 61

T1 (median)

Question 62

which nerves are tested by the biceps jerk?

Answer 62

C5/C6

Question 63

what nerves are tested by the triceps jerk?

Answer 63

C6/C7

Question 64

what nerves are tested by the brachioradialis reflex?

Answer 64

C6/C7

Question 65

signs of tendon sheath infection

Answer 65

Finger held in flexion Swelling Tenderness along the flexor tendon sheath Pain with passive extension of the digit

Question 66

how can bacterial infection spread to the hand and wrist

Answer 66

FDM tendon sheath to ulnar bursa | FP tendon sheath to radial bursa

Question 67

why are flexor tendons enclosed in a sheath?

Answer 67

for lubrication and as a pulley

Question 68

frozen shoulder (Adhesive capsulitis”)

Answer 68

``` Seen in trauma Chronic pain and cramps, worse on moving NSAIDs and steroids can help Physiotherapy or manipulation under anaesthetic can help break up the adhesions Surgery only if very severe ```

Question 69

shoulder impingement

Answer 69

Tendons of rotator cuff become inflamed as they pass under the acromion Can be due to trauma or age-related degeneration Weakness, pain and reduced movement

Question 70

diagnosing and testing shoulder impingement

Answer 70

Hawkins-Kennedy test Treatment: - Conservative (PT and pain relief) - Steroid or local anaesthetic injection - Surgery if severe

Question 71

What is a colles fracture?

Answer 71

Fall onto outstretched arm with wrist extended | Distal radial fracture with dorsal displacement of the distal radial fragment (Dinner form deformity)

Question 72

why is a scaphoid bone fracture clinically significant?

Answer 72

Scaphoid bone supplied by radial artery branches Fracture in proximal 1/3 leads to avascular necrosis of proximal fragment (blood supply runs from distal to proximal) therefore snuff box injuries need to be taken seriously and an MRI may need to be done (x-ray can be non disclosing)

Question 73

acromioclavicular joint damage

Answer 73

Usually sports injuries where fall onto point of shoulder | Scapula forced downward and clavicle looks very prominent