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BLOCK 1: L7-8 Nerves of the Upper Limb

Terms in this set (52)

Spinal nerves C___ - C___ exit (above/below) respective vertebrae
Spinal nerve C____ exits (above/below) below the 7th cervical vertebra
Spinal nerves T1 - Co1 exit (above/below) respective vertebrae
C1 - C7, above
C8, below
below
C1 spinal nerve exits between ________ bone and ___________ vertebra

C8 spinal nerve exits between __________ vertebra and _________ vertebrae
occipital, 1st cervical

7th cervical, 1st thoracic
The fibers of the brachial plexus originate from which spinal nerves?
C5 - T1
The UPPER trunk of the brachial plexus has fibers from which spinal nerves?

The MIDDLE trunk of the brachial plexus has fibers from which spinal nerves?

The LOWER trunk of the brachial plexus has fibers from which spinal nerves?
C5 - C6

C7

C8 - T1
The LATERAL cord of the anterior division of the brachial plexus contains fibers from which spinal nerves?

The MEDIAL cord of the anterior division contains fibers from which spinal nerves?

The POSTERIOR cord of the POSTERIOR division contains fibers from which spinal nerves?
C5 - C7

C8- T1

C5 - T1
Which nerves stem from the posterior cord of the brachial plexus?
Axillary n.
Radial n.
Which nerves stem from the lateral cord of the brachial plexus?
Musculocutaneous n.
Medial n.
Which nerves stem from the medial cord of the brachial plexus?
Median n.
Ulnar n.
Which nerves of the brachial plexus form "The M"?
Musculocutaneous n.
Median n.
Ulnar n.
The posterior cord of the brachial plexus is deep to which artery?

A) Brachial
B) Axillary
C) Carotid
D) Ulnar
E) Radial
B) Axillary
Which nerve branches off spinal nerve C5 of the brachial plexus?
Which muscles are innervated?
Dorsal scapular n.
Rhomboid major and minor, levator scapulae
Which nerve branches off spinal nerves C5-C7 of the brachial plexus?
Which muscles are innervated?
Long thoracic n.
Serratus anterior
A patient presents with a winged left scapula from paralysis of a muscle after they underwent a radical mastectomy.
Which nerve may have been damaged?
Which muscle is most likely paralyzed causing a winged scapula?
Long thoracic n.
Serratus anterior
• Damage during lymph removal during surgery
Which nerves branch off the upper trunk (C5-6) of the brachial plexus?
Which muscles are innervated?
Suprascapular n.
supraspinatus & infraspinatus

n. to subclavius
subclavius
Which nerve branches off the lateral cord (C5-7) of the anterior division of the brachial plexus?
Which muscles are innervated?
Lateral pectoral n.
pectoralis major
Which nerves branch off the medial cord (C8-T1) of the anterior division of the brachial plexus?
Which muscles are innervated?
Medial pectoral n.
pectoralis major & minor

Medial brachial cutaneous n.
skin of medial arm

Medial antebrachial cutaneous n.
skin of medial forearm
Which nerves branch off the posterior cord (C5-T1) of the brachial plexus?
Which muscles are innervated?
Upper subscapular n.
subscapularis

Lower subscapularis n.
subscapularis & teres major

Thoracodorsal n.
latissimus dorsi
Which muscles are innervated by the axillary nerve (C5-6)?
Where does this nerve provide sensation to?
teres minor
deltoid

superior arm (lateral)
Which muscles are innervated by the radial nerve (C5-6)?
Posterior compartment muscles arm & forearm
Where does radial nerve provide sensation to?
posterior/lateral arm, posterior forearm, lateral dorsum hand.

splits:
• Superficial branch: sensory to posterior hand (lateral side)
• Deep branch: Muscles of posterior forearm compartment
Which nerve pierces the supinator muscle and emerges as posterior interosseous n.?
Radial n. (C5-T1)
A patient has a radial nerve lesion in the axilla from crutch use and often falling asleep in a chair.
This patient likely has loss of which muscles and inability to do which actions?
• extensors in arm and forearm
• can't extend elbow, wrist, CMC and MCP joints
A patient cannot extend the wrist, CMC, and MCP joints and complains of sensory loss in the forearm and hand. However, their triceps seem to be unaffected. You suspect they have a radial nerve lesion.
Where would this lesion most likely be found?
What injury most likely caused this lesion?
• Radial groove of humerus
• humeral midshaft fracture
A patient complains of sensory loss in the dorsal hand and extending into the forearm although they can still use their hand normally. You notice they are wearing a watch very tightly compressed to their arm.
Which nerve is most likely compressed?
radial nerve, superficial branch
Which nerve pierces coracobrachialis on way to innervate biceps and brachialis?
Musculocutaneous nerve (C5-C7)
The musculocutaneous nerve (C5-C7) innervates which muscles of the arm?
It gives sensory to which part of the body?
anterior compartment:
• coracobrachialis
• biceps brachii
• brachialis

Lateral forearm
The _______ nerve innervates most muscles of anterior forearm and lateral hand and gives sensory to the lateral palm, digits I-III and lateral ½ of digit IV.
Median n.
The median nerve runs between the 2 heads of the ___________ muscle and innervates the most anterior forearm muscles.
It gives off the ________________ nerve which innervates deep anterior compartment muscles.
pronator teres
anterior interosseous
The median nerve enters the hand via the carpal tunnel and innervates __________ muscles (except the ______ head of the _______) and lumbricals _____ & _____
thenar
deep, FPB
1, 2
What nerve is affected by pronator teres syndrome?
median n.
What condition results from median nerve damage at the elbow, preventing the full flexion of all digits?
Which digits cannot be flexed?
"Hand of Benediction"
cannot flex digits I-III
A patient with a "Hand of Benediction" has most likely lost function of which muscles of digit I?
• flexor pollicis longus (flexion)
• thenar muscles (flexion, abduction)
A patient with a "Hand of Benediction" has most likely lost function of which muscles of digit II-V?
• flexor digitorum superficialis (Digit II-V flexion)
• lateral ½ flexor digitorum profundus (Digit II & III flexion)
• lateral 2 lumbricals (Digit II & III flexion)
A patient has nerve damage due to fractures of their radius. You ask the patient to make an "OK" sign and the patient makes a "pinch" sign instead. Which nerve is most likely damaged from their injury?

A) Musculocutaneous
B) Radial
C) Ulnar
D) Axillary
E) Median
E) Median
• anterior interosseous n.
A patient has nerve damage due to fractures of their radius. You ask the patient to make an "OK" sign and the patient makes a "pinch" sign instead. The patient most likely has muscle deficits in all of the following muscles except?

A) Lateral 1/2 of flexor digitorum profundus
B) Pronator quadratus
C) Flexor carpi radialis
D) Flexor pollicis longus
E) None of the above
C) Flexor carpi radialis
A patient with carpal tunnel syndrome most likely has motor deficits of which muscles?
Where would they have sensory deficits?
• thenar muscles and lumbricals 1 & 2
• lateral palm, digits I-III and lateral ½ of digit IV.
What are the tests for carpal tunnel?
• Phalen's test: forced flexion for 30-60 seconds
• Tinel's test: tapping over flexor retinaculum

• Positive signs: tingling/numbness over median nerve distribution
The ulnar nerve provides motor function to which muscles?
1 & ½ muscles in forearm; hypothenar and most deep muscles of hand
The ulnar nerve provides sensory function to which parts of the hand?
medial hand (anterior and posterior) including digit V and medial side of digit IV
The ________ nerve crosses the elbow joint posteriorly (medial side) and runs between and innervates the ___________ muscle and medial ½ of ______________ muscle
Ulnar n.
flexor carpi ulnaris
flexor dig. profundus
The ulnar nerve enters the hand via the ____________ and innervates muscles of which compartments and lumbricals?
Guyon's canal

hypothenar, adductor, interosseous

lumbricals 3-4
Cubital tunnel syndrome occurs from compression of the __________ n. from entrapment in cubital tunnel (passage through fascia and flexor tendons at ulnar groove).

What causes this condition?

Patients with this have motor deficits in the forearm and hand and sensory deficits of the medial hand and digits ____ and _____
Ulnar n.

direct pressure, hypertrophy of forearm flexors, or tension on nerve from extended flexion of elbow (while sleeping, etc)

IV and V
A patient presents with a "claw hand" and has a flexed thumb when asked to hold a piece of paper (Froment's sign). Which nerve is most likely damaged?

A) Ulnar
B) Radial
C) Axillary
D) Musculocutaneous
E) All of the above
A) Ulnar
A patient presents with a "claw hand" and has a flexed thumb when asked to hold a piece of paper (Froment's sign).
Describe the loss of function and associated muscle for each of the following digits.
• Digit 1
• Digit 2-3
• Digit 4-5
• Digit 1: loses adduction (adductor pollicis)

• Digit 2-3: lose adduction & abduction (palmar & dorsal interossei mm.)

• Digit 4-5: lose all intrinsic hand muscles and all forearm flexors except flexor digitorum superficialis (median n.)
A patient complains of weakness in intrinsic hand muscles and parenthesia of skin on medial hand and digits IV-V. They explain that they have been training for a road cycling competition for the past few months. You suspect the patient has been putting direct pressure on Guyon's canal. What nerve is likely affected my compression?

A) Radial
B) Axillary
C) Musculocutaneous
D) Ulnar
E) Median
D) Ulnar
An infant presents with "waiter's tip" hand (Erbs-Duchenne's Palsy). You suspect injury to the upper trunk of the brachial plexus from forced increased angle between the head and neck during delivery. Which nerves and associated muscles are likely affected by this injury?
• Axillary n. (Deltoid, teres minor)
• Suprascapular n. (Supraspinatus, infraspinatus)
• Musculocutaneous n. (coracobrachialis, biceps brachii, ½ brachialis)
• Radial n. (C5-C6 fibers to posterior forearm)
Describe "waiter's tip" hand
• Arm adducted and medially rotated
• weakened elbow flexion & supination
• flexed wrist
An infant presents with "waiter's tip" hand. You suspect injury to the upper trunk of the brachial plexus from forced increased angle between the head and neck during delivery. Which actions and associated muscles are affected by this injury?
• Paralysis of abductors (deltoid, supraspinatus)
• Weakened lateral rotation (deltoid, infraspinatus, teres minor)
• Weakened elbow flexion and supination (biceps brachii,
• Weakened wrist extensors
An infant with "waiter's tip" hand most likely has loss of sensation in C___ and ___ dermatomes (lateral upper limb)
5 and 6
Klumpke's Palsy results from injury to the which part of the brachial plexus?

Motor function of which muscles are lost?
What are the signs of motor deficit?

Damage to spinal nerve _____ can impact sympathetic innervation causing Horner's syndrome.
How is this presented in patients with this condition?
lower trunk (C8-T1)

All intrinsic muscles of hand
All fingers "clawed"

T1
permanently constricted iris and droopy eyelid
General pattern of myotomes:
• Back, Shoulder & Arm = ____ to ____
• Forearm = ____ to ____
• Intrinsic Hand = ____ to ____
C5-C6
C6-C8
C8-T1
Pin prick tests can be used to assess spinal nerve damage.
Upper limb test points:
• C5
• C6
• C7
• C8
• T1
• C5 lateral cubital fossa
• C6 thumb
• C7 middle finger
• C8 5th finger
• T1 medial cubital fossa
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