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MBBS II MSS > L16 - BRACHIAL PLEXUS AND NERVE DISTRIBUTIONS > Flashcards

L16 - BRACHIAL PLEXUS AND NERVE DISTRIBUTIONS Flashcards

1
Q

List the components and location of the roots of brachial plexus?

A

Ventral rami of (C4) C5, 6, 7, 8, T1 (T2)

within prevertebral musculature

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2
Q

List the components and location of the Trunks of brachial plexus?

A

Trunks:

upper (C5, C6), middle (C7), lower (C8, T1)

posterior triangle of neck

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3
Q

List the components and location of the Divisions of brachial plexus?

A

Anterior, posterior

behind clavicle

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4
Q

List the components and location of the Cords of brachial plexus?

A

lateral, medial, posterior

upper half of axilla

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5
Q

List the components and location of the Branches of brachial plexus?

A

Nerve fibres from different spinal levels

Arise from all parts of the plexus, except divisions.

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6
Q

Which part of the arm is supplied by which part of the brachial plexus?

A
  • Anterior divisions: flexor compartment (richer nerve supply)
  • Posterior divisions: extensor compartment
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7
Q

What is the anterior wall of the Axilla?

A

pectoralis major, pectoralis minor (crosses 2nd part of axillary artery)

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8
Q

What is the posterior wall of the Axilla?

A

Posterior wall: latissimus dorsi, subscapularis, teres major

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9
Q

What is the medial wall of the Axilla?

A

Serratus anterior

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10
Q

What is the lateral wall of the Axilla?

A

long head of biceps, short head of biceps, coracobrachialis

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11
Q

List the branches from the Roots of the brachial plexus?

A

2

  • Dorsal scapular nerve (mainly C5)
  • Long thoracic nerve (C5,6,7)
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12
Q

List the branches from the upper trunk of the brachial plexus?

A

2

  • Suprascpular nerve (C5,6)
  • Nerve to subclavius (C5,6)
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13
Q

List the branches from the lateral cord of the brachial plexus?

A
  1. 5
    - lateral pectoral n. (C5, C6, 7)
    - musculocutaneous n. (C5, 6, 7)
    - lateral root of median n. (C6, 7)
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14
Q

List the branches from the Median cord of the brachial plexus?

A

4½

  • medial pectoral n. (C8)
  • medial cutaneous n. of arm (T1)
  • medial cutaneous n. of forearm (C8, T1)
  • ulnar n. ((C7), C8, T1)
  • medial root of median n. (C8, T1)
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15
Q

List the branches from the posterior cord of the brachial plexus?

A

5

  • upper subscapular n. (C5, 6)
  • thoracodorsal n. (C6, 7, 8)
  • lower subscapular n. (C5, 6)
  • axillary n. (C5, 6) *
  • radial n. (C5, 6, 7, 8, T1) *
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16
Q

Give the course and innervation of dorsal scapular nerve.

A

Branch from C5 root

Course: Posterior to back, does not pass through axilla

Supply:

  1. Levator scapulae
  2. Rhomboid major
  3. Rhomboid minor
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17
Q

Give the course and innervation of Long thoracic nerve.

A

Branch from C5,6,7 root

Course: vertically down, then over surface of serratus anterior

Supply:
Serratus anterior

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18
Q

What arises from long thoracic nerve injury?

A

Winging of scapula

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19
Q

Give the course and innervation of suprascapular nerve.

A

Branch from upper trunk

Course: Bound by superior transverse scapular ligamnet and converges into hole, Runs with suprascapular artery

Supply:

  1. Supraspinatus
  2. Infraspinatus
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20
Q

Give the origin and innervation of lateral pectoral nerve.

A

Branch from Lateral cord (C5,6,7)

Innervate pectoralis major

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21
Q

Give the course and innervation of musculocutaneous nerve.

A

Branch from anterior division of lateral cord (C5,6,7)

Course:
From muscle to skin, continues as lateral cutaneous nerve of forearm, 5 main terminal branches

Supply:
- Anterior flexor arm muscles: elbow flexors 
- Coracobrachialis
- Biceps brachii
- Brachialis 
Lateral skin of forearm
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22
Q

What is the consequence of damage to musculocutaneous nerve?

A

Affects flexion (brachioradialis), supination (biceps brachialis) of forearm + decrease sensation at lateral forearm

Compensated by other muscles that can flex the elbow **

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23
Q

Is damage to musculocutaneous nerve likely?

A

Well-protected (does not pass through any area which is vulnerable to damage), unless stab wound in axilla

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24
Q

What are the 2 parts of the median nerve and their origin?

A

1) C6,7&raquo_space; Lateral root of median nerve

2) C8, T1&raquo_space; Medial root of median nerve

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25
Q

Give the course of median nerve?

A

Anterior compartment of arm with no branches in arm

> > Half way down the arm, crosses brachial artery from LATERAL to MEDIAL

> > Carpal tunnel

> > hand

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26
Q

What muscles do the Median nerve innervate?

A

Supply all the muscles in the front of the forearm (except flexor carpi ulnaris and the medial half of the flexor digitorum profundus)

Supply 1st & 2nd lumbricals, and thenar muscles (except adductor of thumb).

27
Q

What skin does Median nerve innervate?

A

Lateral 2/3 of palm; palmar surfaces and nail-beds of lateral 3½ digits + dorsal surface of the distal 2 phalanges

28
Q

Where is the median nerve susceptible to damage?

A

Vulnerable at front of wrist

Damaged by:

1) Compression / swelling at carpal tunnel
2) Cuts at wrist

29
Q

What are the consequences of median nerve damage at the wrist ?

A
  1. Sensory loss
  2. Loss of muscular and joint proprioception
  3. Wasting of thenar eminence + Thumb adducted and laterally rotated (unopposed ADduction)
  4. Ulnar deviation of the wrist

3+4 = ape hand deformity

30
Q

What is Ape Hand deformity?

A

Median nerve palsy

Caused by wasting of thenar eminence

Thumb adducted and laterally rotated because Opponens pollicis muscle is paralyzed&raquo_space; no ABDUCTION

31
Q

What is the course of the ulnar nerve?

A

From anterior divisions of C8, T1, branch of medial cord

Travel down medial side of anterior compartment of arm, no branch in arm

> > pierce medial intermuscular septum to reach posterior compartment behind medial epicondyle of humerus

> > BACK to anterior compartment of forearm, superficial at wrist

32
Q

Where is the ulnar nerve suceptible to damage?

A

Behind medial epicondyle
or
Front of wrist: medial to ulnar artery, lateral to flexor carpi ulnaris tendon and pisiform bone

33
Q

What is Claw Hand deformity?

A

Damage to ulnar nerve, leading to motor loss involving fine movement of fingers

  • Wasting of Hypothenar muscles, Interosseous muscle (guttering)
  • Paralysis of lumbricals
  • unopposed long extensors at MCP joint (hyperextensions) & unopposed Long flexors at IP joints (flexion)
34
Q

What muscles are innervated by the ulnar nerve?

A

Not anything in the arm

Supplies 1½ muscles in forearm:

  • Flexor carpi ulnaris
  • Medial part of flexor digitorum profundus

+ most intrinsic muscles of the hand:

  • Hypothenar
  • 3rd, 4th lumbricals
  • Interosseous
35
Q

What skin regions are innervate by ulnar nerve?

A

1) Dorsal branch&raquo_space; Medial dorsum of hand

2) Superficial branch&raquo_space; Palmar aspect of medial 1½-2½ fingers

36
Q

Superficial ulnar nerve innervates the dorsal aspect of the medial 1½-2½ fingers. True or False?

A

False

Superficial ulnar nerve supplies the palmar aspect

dorsal aspect of the same fingers are supplied by a separate branch given off in the distal third of the forearm

37
Q

Give the origin and the innervation of Upper subscapular nerve?

A

Origin = Posterior cord (C5,6)

Supply: Subscapularis

38
Q

Give the origin and the innervation of Thoracodorsal nerve?

A

Posterior cord (C6,7,8)

Supply: Latissimus dorsi

39
Q

Give the origin and the innervation of Lower subscapular nerve?

A

Posterior cord (C5,6)

Supply Subscapularis

40
Q

What is the origin and course of the axillary nerve?

A

Origin = Posterior division C5,6 of posterior cord

Course: Leaves axilla by passing backward through the quadrilateral space&raquo_space; winds around the posterolateral aspect of surgical neck of humerus (may be affected by shoulder dislocation)

41
Q

What does axillary nerve innervate and what results from injury?

A

Supplies deltoid and teres minor, and a small area of skin on the lateral side of the arm near the insertion of the deltoid

Injury (from dislocation or swelling in quadrangular space): cannot abduct the arm beyond 45° (abduction initiated by supraspinatus)

42
Q

Give the origin and innervation of the Radial nerve?

A

Origin = Posterior division of C6,7,8 + T1 of posterior cord

Supply: All posterior muscles in arm and forearm (extensors)

Cutaneous branches to supply skin of the posterior and lateral surfaces of arm, back of forearm and a small area on dorsum of hand

43
Q

What is the course of the radial nerve?

A

From axilla to posterior side through triangular interval

> > Wind around back of humerus @ radial groove

> > Enter anterior compartment by piercing Lateral Intermuscular Septum above lateral epicondyle

> > Divide into deep and superficial branches at lateral epicondyle

> > Deep branch (dorsal interosseous nerve) pierces the supinator muscle and wraps around neck of radius (vulnerable here) to reach the posterior compartment of the forearm

> > Superficial branch (cutaneous) emerges in the snuff-box and gives off digital branches

44
Q

What is Wrist Drop syndrome?

A

Radial nerve damage

Paralysis of extensors of wrist and digits

45
Q

Median nerve lesions is the least severe. True or False?

A

False

Radial nerve damage is less disabling compared to median and ulnar nerve lesions

46
Q

What forms the boundaries of the carpal tunnel?

A

Roof = flexor retinaculum

Lateral = Hypothenar and Thenar muscles

Inferior = carpal bones

47
Q

What goes through the carpal tunnel? Does ulnar nerve go through it?

A

superficial to deep:

  • flexor digitorum superficialis tendons (four) (middle and ring finger more superficial to the index and little finger)
  • median nerve
  • flexor pollicis longus tendon
  • flexor digitorum profundus tendons (four)

Ulnar nerve passes outside

48
Q

Define dermatome. Define myotome.

A

An area of skin supplied by a single spinal (segmental) nerve

The amount of muscle supplied by a single spinal nerve, or the nerve roots responsible for particular movements

49
Q

Is the dermotomes of the limb the same as cutaneous innervation fields?

A

No

50
Q

List 3 ways to damage the radial nerve?

A

Humerus fracture
Prolong use of crutches
Saturday Night Syndrome

51
Q

What are axial lines and how are they arranged? What is the clinical use?

A

Line of junction of two dermatomes supplied from discontinuous spinal levels

not arranged segmentally in the limbs

Use in test for dermatome response to trace affected spinal level

52
Q

What are the 5 Areas where dermatomes can be tested for sensation with minimal overlap?

A 
C5 (upper lateral side of arm) 
C6 (pad of thumb) 
C7 (pad of index finger) 
C8 (pad of little finger) 
T1 (medial aspect of elbow)
53
Q

Do skin prick tests work for testing myotomes?

A

No

More complex and merged myotomes in limbs, no distinct areas

54
Q

What is the use of dermatomes and myotomes?

A

Test integrity of spinal nerves and level of a neurological lesion

Test integrity of segmental innervation across axial lines (checking for sensation to pin-prick and light touch) and testing which joint movements are impaired

55
Q

What is the ROM of the shoulder? Which nerves are responsible?

A

C5 > abduction& lateral rotation

C6,7,8 > adduction & medial rotation

C5,6,7,8 > flexion & extension

56
Q

What is ROM of elbow? Which nerves are responsible?

A

C5,6 > flexion

C7,8 > extension

57
Q

What is ROM of Forearm? Which nerves are responsible?

A

C6 > supination

C7,8 > pronation

58
Q

What is ROM of Wrist? Which nerves are responsible?

A

C6,7 > flexion & extension

59
Q

What is ROM of Fingers? Which nerves are responsible?

A

C7,8 > flexion& extension

60
Q

What is ROM of Intrinsic hand muscles? Which nerves are responsible?

A

T1 > abduction/adduction of digits II-IV

61
Q

What is the nerve damage from upper trunk lesion (e.g. from traction injury involving violent separation of head and neck)?

A

Upper roots C5, 6 commonly affected&raquo_space; Erb’s palsy

  • Injury of C5 causes shoulder to be medially rotated and adducted&raquo_space; No abduction and No lateral rotation
  • elbow flexion is weakened, forearm becomes pronated (“tip-taking position”)&raquo_space; Cannot supinate
  • Sensory loss on lateral aspect of upper arm (C5 dermatome)
62
Q

What is the nerve damage from lower trunk lesion?

A

Lower roots C8, T1 affected: Klumpke’s paralysis

  • Paralysis & wasting of intrinsic muscles of hand (T1).
  • Weakness in flexion of wrist and fingers (C8).
  • Loss of sensation on medial side of arm (T1), forearm and hand (C8).
  • Interruption of sympathetic outflow to orbit (T1)

> > Similar to ulnar paralysis + thenar muscle and digit flexor paralysis&raquo_space; Combined claw-hand and ape hand

63
Q

What are some possible causes of Lower trunk lesion?

A

breech presentation at birth&raquo_space; pull legs during birth causing damage

neurovascular compression by cervical rib

64
Q

What are the consequences of Interruption of sympathetic outflow to orbit due to T1 damage? (Klumpke’s paralysis)

A

Horner’s syndrome

constriction of pupil,

drooping of upper eyelid,

sinking in of the eyeball,

lack of sweating on the affected side of the face

MBBS II MSS (31 decks)

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