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326 > The Axilla and Brachial Plexus > Flashcards

The Axilla and Brachial Plexus Flashcards

1
Q

Define: axilla

A

pyramidal space inferior to the glenohumeral joint

passageway for neurovascular structures that supply the upper limb and anterior + posterior thorax

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2
Q

What forms the borders of the axilla

A

Anterior border
* pec minor

Posterior border
* subscapularis

base
* posterior axillary fold - latdorsi and teres major (primarily teres major
* anterior axillary fold - pec major

lateral wall
* intertubercular groove/sulcus

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3
Q

axillary artery
* travels where
* arises from where
* gives rise through?
* what are the 3 parts of the axillary artery

A
  • through axilla
  • arises from subclavian artery at the first rib
  • gives rise to brachial artery at the inferior border of teres major
  • 1st part: proximal to pec minor; 2nd part: deep to pec minor; 3rd part: distal to pec minor
  • lateral border of rib 1 divides subclavian and axillary artery
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4
Q

What are the two main terminal branches of the brachial artery

A

radial and ulnar artery

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5
Q

How do we anatomically describe the axillary vein?

A

The axillary vein is anatomically described using the same borders as the axillary artery, but in reverse:

  • The axillary vein arises from the** basilic vein** at the inferior border of teres major, and drains into (and continues as) the subclavian vein, at the first rib.
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6
Q

What drains into the axillary vein?

A

Cephalic lateral (superficial),
Brachial middle (deep)
Basilic medial (superficial)

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7
Q

Where can you find lymphatics in the upper limb

A

axilla has a dense collection of lymph nodes

The lymphatics of the upper limb travel closely with veins (“shadow” veins).

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8
Q

The plexes innervating the limbs arises from the _______ rami

A

anterior

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9
Q

dorsal vs ventral root

A

dorsal: sensory (posterior)

ventral: motor (anterior)

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10
Q

Are the dorsal and ventral ramus mixed?

A

Yes - they contain motor and sensory axons

not to be confused with dorsal and ventral ROOTS

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11
Q

Spinal nerve

Myotome

Dermatome

A

Spinal nerves arise from a segment of spinal cord.
Spinal nerves are mixed and innervate a distinct region of muscle and skin.
Myotome: unilateral portion of skeletal muscle innervated by a single spinal nerve.
Dermatome: unilateral portion of skin innervated by a single spinal nerve

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12
Q

Motor nerves arise from and sensory nerves project to the spinal nerves between ___ and ___

A

C5
T1

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13
Q

What are the 5 anatomical divisions of the brachial plexus

A

Real Teachers Drink Cold Beer

5 Roots (anterior rami)
3 Trunks
3 Divisions (3 anterior divisions and 3 posterior divisions)
3 Cords (lateral posterior, medial)
5 Branches

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14
Q

Brachial plexus
* emerges between
* deep to
* overlying

A
  • the scalenes
  • the clavicle and pectoralis minor
  • subscapularis
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15
Q

What portions of the brachial plexus does the axilla contain?

A

cords and branches

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16
Q

What forms the M of the brachial plexus

A
  • musculocutaneous nerve
  • lateral and medial root that feeds into median nerve ( do not confuse with anterior rami roots. these link the lateral/medial cords to the median nerve)
  • ulnar nerve
17
Q

The axillary nerve arises from the ____ cord ____ (distally/proximally) in the plexus

A
  • posterior
  • proximally
18
Q

What does the axillary nerve innervate?

A

deltoid and teres minor

19
Q

The radial nerve arises from the ____ cord and travels ____

A

posterior

distally

20
Q

What does the radial nerve innervate?

A
  • posterior arm (all 3 heads of triceps)
  • brachialis (often dually innervated)
  • posterior forearm (extensors and supinators)
21
Q

What is the wrist drop posture indicative of?

A

radial nerve injury

22
Q

The musculocutaneous nerve arises from the ____ cord to innervate _____.

Sensory innervation is _____

A

lateral

arm flexors (coracobrachialis, biceps both heads, brachialis)

note that sensation innervation is distal to the innervation of the arm flexors (distal to elbow); and on the anterior surface of the arm

23
Q

The median nerve arises from the ____ cords and travels ____. It innervates ____

A

lateral and medial

distally through the upper limb

anterior forearm (flexors and pronators) and thenar muscles

24
Q

What are some signs of median nerve injury?

A

thenar atrophy

loss in sensation in first and second finger

**ape hand deformity: **Ape hand deformity is a condition in which the thumb is permanently rotated and adducted, resulting in a loss of its opposable function

25
Q

The ulnar nerve arises from the ____ cords and travels ____. It innervates ____

A

medial

distally through the upper limb

medial flexors (flexor carpi ulnaris and medial half of flexor digitorum profundus), intrinsic hand muscles

26
Q

What are some signs of ulnar nerve injury?

A

loss in sensation of pinky

claw hand deformity

interosseous atrophy

27
Q

What are 2 main patterns of injury to the brachial plexus

A

superior (upper) plexus injury
* fall where head is forcefully pulled away from trunk; tractions upper portion of plexus
* vaginal injury can also cause brachial plexus injury; tugging on head during birth.

inferior (lower) plexus injury
* yanking the lower plexus away from the body; falling and catching self on tree
* tugging on the arm of a baby during birth. separating arm from body

28
Q

What are the different mechanisms of injury to the brachial plexus

A
  • avulsion (spinal cord)
  • stretch
  • rupture (more distal)
29
Q

Describe Erb’s palsy
* how does it happen
* what does it preferentially affect
* what is the classic sign of it. why do you see this deformity

A
  • damage to upper plexus (aka as upper trunk palsy)
  • head is pulled away from shoulder during birth
  • preferentially affects C5 and C6
  • Waiter’s tip
  • loss of innervation to the abductors, lateral rotators of the arm, forearm flexors, and wrist extensors
30
Q

Describe Klumpke’s palsy
* what does it preferentially affect
* what is the classic sign of it. why do you see this deformity

A
  • AKA lower trunk palsy
  • C8 and T1
  • claw hand
  • loss of innervation to the pronators and intrinsic hand muscles (especially distal digit extenders)
31
Q

What spinal cord roots are associated with: musculocutaneous nerve

A

C5, C6, C7

32
Q

What spinal cord roots are associated with: axillary nerve

A

C5, C6

33
Q

What spinal cord roots are associated with: median nerve

A

C6-T1

34
Q

What spinal cord roots are associated with: radial nerve

A

C5-T1

35
Q

What spinal cord roots are associated with: ulnar nerve

A

C8 and T1

36
Q

Describe oxygenated blood flow through the arm

A
  • Left subclavian artery (SCA) arises from aortic arch. Right SCA arises from brachiocephalic trunk

past rib 1, SCA continues as the axillary artery

past the lower border of the tendon of teres major, axillary artery continues as brachial artery

around the elbow, brachial artery divides into radial (lateral) and ulnar (medial) arteries

37
Q

Describe deoxygenated blood flow through the arm

A

Divided into superficial and deep

Deep and superficial veins drain into the axillary veins which continue as left and right subclavian veins, then brachiocephalic veins, and into superior vena cava

326 (32 decks)

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