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Clinical Anatomy > Axilla II, Brachial Plexus, Arm > Flashcards

Axilla II, Brachial Plexus, Arm Flashcards

1
Q

What would injury to the superior trunk of the brachial plexus (C5 + C6 roots) present as?

A

Paralysis of:

  • Deltoid
  • Supraspinatus
  • Infraspinatus
  • Teres minor
  • Biceps
  • Brachialis
  • Brachioradialis
  • Erb-Duchenne’s palsy

Presentation:

  • ADducted shoulder joint (can’t ABduct)
  • Medial rotation (can’t laterally rotate)
  • Extended elbow (can’t flex forearm)
  • Waiter’s tip position
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2
Q

Common causes of injury to the superior trunk of the brachial plexus

A
  • Fall landing on shoulder/neck w/ hyperextension

- Delivery of baby by pulling on head + stretching neck,

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3
Q

What would injury to the inferior trunk of the brachial plexus (C8 + T1) present as?

A

Paralysis of:
- All small muscles of hand

Presentation:

  • Fingers of hand are noticeably bent
  • Claw hand
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4
Q

What is Erb-Duchenne’s palsy?

A
  • Superior trunk lesion
  • Involve C5 + C6 nerve roots
  • Mechanism: Injuries that widely separate neck + shoulder
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5
Q

Walk through the components of the brachial plexus

A

5 Roots:
- C5, C6, C7, C8, T1

3 Trunks:

  • Superior
  • Middle
  • Inferior

6 Divisions:

  • Anterior (each)
  • Posterior (each)

3 Cords:

  • Lateral
  • Medial
  • Posterior

6 Branches:

  • Musculocutaneous
  • Median
  • Ulnar
  • Radial
  • Axillary
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6
Q

What nerve branches off of nerve roots C5-C7?

A

Long thoracic nerve

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7
Q

What does the long thoracic nerve innervate?

A

Serratus anterior muscle

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8
Q

What 2 nerves immediately branch off of the C5 nerve root?

A
  • Dorsal scapular

- Phrenic

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9
Q

What 2 nerves branch off of the superior trunk?

A
  • Suprascapular

- Subclavius

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10
Q

What 3 nerves branch from the lateral cord?

A
  • Lateral pectoral nerve
  • Musculocutaneous nerve
  • Median nerve (lateral root)
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11
Q

What 5 nerves branch from the medial cord?

A
  • Median nerve (medial root)
  • Ulnar nerve
  • Medial pectoral nerve
  • Medial brachial cutaneous nerve
  • Medial antebrachial cutaneous nerve
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12
Q

What 5 nerves branch from the posterior cord?

A
  • Upper subscapular
  • Thoracodorsal
  • Lower subscapular
  • Radial
  • Axillary
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13
Q

What structure are the brachial plexus cords named in relation to?

A

Axillary artery

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14
Q

What are some additional contributions to the brachial plexus outside of C5-T1?

A
  • C4 to C5 (pre-fixed)

- T2 to T1 (post-fixed)

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15
Q

What is Klumpke’s palsy?

A
  • Inferior trunk lesion
  • Roots involved: C8 and T1
  • Mechanism: Injuries that cause excessive abduction of the arm
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16
Q

Common causes of injury to inferior trunk of brachial plexus (C8 + T1)

A
  • Hyperabduction of arm

- Pulling on prolapsed limb during baby delivery

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17
Q

Nerve avulsion

A
  • Dorsal + ventral roots of spinal nerves are completely torn away from spinal cord
  • No treatment available
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18
Q

Nerve rupture

A
  • Spinal nerve is completely torn at intervertebral foramen

- No treatment available

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19
Q

Nerve praxis/stretch

A
  • Spinal nerve is injured/damaged but not torn

- May heal on its own

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20
Q

Nerve neuroma

A
  • Scar tissue developed around nerve as it heals

- Can be debrided

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21
Q

What would injury to the long thoracic nerve present as?

A

Inability to:

  • Rotate scapula during ABduction
  • Difficulty raising arm above head (brushing hair)

Presentation:
- Medial winging scapula

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22
Q

Primary scapular winging causes

A
  • Dysfunction in one or more of the scapulothoracic stabilizers (serratus anterior, trapezius, rhomboids)
  • Muscular imbalance in scapular alignment
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23
Q

Secondary scapular winging causes

A
  • In association with other pathologies (subacromial bursitis, disorders of the glenohumeral joint)
24
Q

How to test for medial scapular winging

A
  • Arm flexion

- Push up motion against wall

25
Q

How to test for lateral scapular winging

A

Superior angle laterally displaced:

  • Arm ABduction
  • External rotation against resistance

Inferior angle laterally displaced:
- Arm extension from full flexion

26
Q

What would injury to the spinal accessory nerve present as?

A

Lateral winging scapula w/ superior angle displaced laterally

27
Q

What would injury to the dorsal scapular nerve present as?

A

Lateral winging scapula w/ inferior angle displaced laterally

28
Q

Median nerve palsy

A

Roots involved:
- C5-T1

Mechanism:

  • Lacerations at the wrist
  • Lacerations at the elbow

Paralysis of:

  • All pronator + flexor muscles of wrist + fingers (except for FCU + medial half of FDP)
  • 3 thenar muscles
29
Q

Long thoracic nerve lesion/injury

A

Roots involved:
- C5, C6, C7

Mechanism:
- Injury during surgery (iatrogenic injury)

Paralysis of:

  • Serratus anterior muscle
  • Inability to rotate scapula during abduction
  • Difficulty raising arm above head
30
Q

What would median nerve palsy present as?

A
  • Thenar atrophy

- Hand of papal benediction (after being asked to make a fist)

31
Q

Radial nerve palsy

A

Roots involved:
- C5-T1

Mechanism:

  • Fracture of the humerus
  • Poorly-fitted crutches
  • “Saturday night palsy” from drunkenness

Paralysis of:
- Extensors of wrist & fingers

32
Q

What would radial nerve palsy present as?

A

Wrist-drop after patient is asked to lift hand + fingers

33
Q

Ulnar nerve palsy

A

Roots involved:
- C7-T1

Mechanism:

  • Fracture of the medial epicondyle
  • Superficial cuts and stab wounds at the wrist

Paralysis of:

  • 1 and 1/2 muscles in the forearm (FCU, medial half of FDP muscles)
  • Hypothenar muscles, adductor pollicis muscle, all interosseous muscles
34
Q

What would ulnar nerve palsy present as?

A
  • Hypothenar atrophy
  • Ulnar claw-like hand
  • Unable to ABduct/ADduct fingers or thumb
  • Unable to flex digits 4-5
35
Q

Quick clinical test for axillary nerve

A

Abduct arm from 15-90 degrees

36
Q

Quick clinical test for musculocutaneous nerve

A

Flex elbow

37
Q

Quick clinical test for radial nerve

A

Extend wrist

38
Q

Quick clinical test for median nerve

A

Bring thumb in opposition with base of little finger

39
Q

Quick clinical test for ulnar nerve

A

ABduct + ADduct fingers (in anatomic plane)

40
Q

Hill-Sachs lesion (or fracture)

A
  • Cortical depression in posterolateral head of the humerus

- Results from forceful impaction of humeral head against anteroinferior glenoid rim when shoulder dislocates anteriorly

41
Q

What would an anterior inferior shoulder dislocation present as?

A
  • Axillary nerve palsy
  • “Regimental badge” - assess supero-lateral arm for absence of sensory nerve

Weakness in:

  • Abduction (15-90 degrees)
  • Flexion
  • Extension
  • External rotation
42
Q

Bankart lesion/fracture

A

Bony or cartilaginous fracture of anterior/inferior glenoid labrum

43
Q

How does an anterior glenohumeral dislocation usually occur?

A

Forced external rotation in abduction (e.g., blocking volleyball strike)

44
Q

What allows for blood supply to the arm if the axillary artery becomes compromised?

A
  • Retrograde flow through collateral circulation made possible by arterial anastomoses occuring around the scapula
  • Include dorsal scapular, suprascapular, subscapular nerves
45
Q

Biceps brachii (origin + insertion)

A

Origin:

  • Short head: Tip of coracoid process of scapula
  • Long head: Supraglenoid tubercle of scapula

Insertion:
- Tuberosity of radius + antebrachial fascia via bicipital aponeurosis

46
Q

Biceps brachii (function + innervation)

A

Function:

  • Supinates forearm
  • Flex forearm
  • Weakly flex arm

Innervation:
- Musculocutaneous nerve (C6) (C5)

47
Q

Brachialis (origin + insertion)

A

Origin:
- Distal 1/2 of anterior surface of humerus

Insertion:

  • Tuberosity of ulna
  • Coronoid process of ulna
48
Q

Brachialis (function + innervation)

A

Function:

  • Flex forearm
  • “One action, one joint muscle”

Innervation:
- Musculocutaneous nerve (C6) (C5)

49
Q

Coracobrachialis (origin + insertion)

A

Origin:
- Tip of coracoid process of scapula

Insertion:
- Middle 1/3 of medial surface of humerus

50
Q

Coracobrachialis (function + innervation)

A

Function:

  • Flex arm
  • Adduct arm

Innervation:
- Musculocutaneous nerve (C6) (C5,C7)

51
Q

Triceps brachii (origin + insertion)

A

Origin:

  • Long head: infraglenoid tubercle of the scapula
  • Lateral head: posterior surface of humerus superior to spiral groove
  • Medial head: posterior surface of humerus inferior to spiral groove

Insertion:
- Proximal end of olecranon

52
Q

Triceps brachii (function + innervation)

A

Function:

  • Extend arm
  • Extend forearm
Innervation: 
Radial nerve (C7, C8) (C6)
53
Q

Anconeus (origin + insertion)

A

Origin:
- Lateral epicondyle of humerus

Insertion:
- Lateral surface of olecranon

54
Q

Anconeus (function + innervation)

A

Function:

  • Assist triceps in extension of forearm
  • Prevents hyperextension of elbow

Innervation:
- Radial nerve (C7, C8, T1)

55
Q

What are the ulnar + median nerves doing in the arm?

A

Nothing, they are just “nerves of passage”, passing through on the way to the forearm.

56
Q

What nerve pierces the coracobrachialis muscle?

A

Musculocutaneous nerve

Clinical Anatomy (25 decks)

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