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Medical Anatomy > Axilla and Brachial Plexus > Flashcards

Axilla and Brachial Plexus Flashcards

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USMLE® Step 1 flashcards
1
Q

Are the named arteries superficial or deep? Are they accompanied by veins?

A

The named arteries are deep

Superficial veins do not accompany named arteries

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2
Q

What are the main deep arteries?

A

Subclavian artery -> axillary artery -> brachial artery

Brachial artery splits into radial and ulnar arteries

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3
Q

What are the 2 main superficial veins? Which side of the arm are they on?

A

Basilic vein and cephalic vein
Basilic vein is on the medial (ulnar) side of the limb
Cephalic vein is on lateral (radial) side of limb

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4
Q

Where does the basilic vein pierce the fascia, and what fascia is this? What nerve passes through this same opening?

A

Basilic vein penetrates the fascia at the mid-arm area
It is the deep (brachial) fascia
The medial antebrachial cutaneous nerve passes superficially through the same opening of the brachial fascia

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5
Q

What does the basilic vein continue as?

A

Continues as the axillary vein

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6
Q

What vein connects the cephalic and basilic veins?

A

The median cubital vein

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7
Q

What is the nerve supply of the pectoralis major? What is its action?

A

Nerve supply is by the medial and lateral pectoral nerve

Action: Flexes, adducts, and medially rotates the humerus

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8
Q

What is the nerve supply of the pectoralis minor? What is its action?

A

Nerve supply is by the medial and lateral pectoral nerve

Action: Draws scapula downward and forward, stabilizes it

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9
Q

What fascia encloses the pectoralis minor?

A

Clavipectoral fascia

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10
Q

What is the clavipectoral fascia a thickening of, and where does the clavipectoral fascia extend?

A

Is a thickening of deep fascia and extends from clavicle to axillary fascia in floor of axilla

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11
Q

What two muscles does the clavipectoral fascia enclose?

A

Subclavius and pectoralis minor muscles

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12
Q

What is the name of the tough membrane between the subclavius and pectoralis minor? What fascia forms this tough membrane?

A

The name of the tough membrane is the costocoracoid membrane

Formed by clavipectoral fascia

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13
Q

What 3 structures pierce the costocoracoid membrane?

A

Cephalic vein
Lateral pectoral nerve
Thoracoacromial artery

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14
Q

What structures make up the deltopectoral triangle?

A

Clavicle
Deltoid muscle
Pectoralis major muscle

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15
Q

What is the nerve supply to the subclavius? What is its action?

A

Nerve supply is the nerve to the subclavius
Acts to depress the lateral end of the clavicle, pull the shoulders anteriorly, stabilizes the clavicle
(note: it does the same thing to the clavicle that the pec minor does to the scapula)

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16
Q

What are the anterior, posterior, and medial bones in the walls that make up the apex of the axilla? What is the base of the axilla?

A

Clavicle = anterior
Scapula = posterior
First rib = medial
So clavicle, scapula, and first rib make up the apex

Base is the fascia and skin of the armpit

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17
Q

What bone is in the anterior wall that forms the apex of the axilla, and what muscles are in the anterior wall of the axilla? What does one of these muscles form in the axilla?

A

Bone is the clavicle
The anterior wall is made of the pectoralis major and minor muscles
Lateral border of pec major forms anterior axillary fold

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18
Q

What bone is in the posterior wall that forms the apex of the axilla, and what muscles are in the posterior wall of the axilla? What do these muscles form in the axilla?

A

The bone is the scapula
The subscapularis, teres major, and latissimus dorsi muscles make up the posterior wall
The teres major and latisssimus dorsi muscles form the posterior axillary fold

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19
Q

What bone is in the medial wall that forms the apex of the axilla, and what makes up the medial wall of the axilla? What is the only major structure passing through the medial wall?

A

The first rib is in the medial wall
Medial wall is made up of ribs 1-5, intercostal muscles, and the serratus anterior
Intercostal brachial nerve

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20
Q

What forms the lateral wall of the axilla?

A

Intertubercular (bicipital) groove of the humerus

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21
Q

What is contained in the axilla?

A

Axillary artery and vein
Brachial plexus
(axillary artery and vein and brachial plexus are enclosed in axillary sheath, which is a continuation of prevertebral fascia in the neck)

Axillary lymph nodes

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22
Q

What are the 4 functions of the brachial plexus?

A
  1. Sensory innervation to the skin and deep structures
  2. Motor innervation to the muscles
  3. Vasomotor fibers to the blood vessels (postgang. sympth)
  4. Secretomotor fibers to the sweat glands (postgang. sympth)
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23
Q

The ventral rami of which spinal nerves contribute to the brachial plexus?

A

Brachial plexus is formed by the ventral rami of C5 to T1 (with contributions from C4 and T2)

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24
Q

What are the 5 trunks of the brachial plexus?

A

Superior Trunks: C5 and C6
Middle Trunk: C7
Inferior Trunks: C8 and T1

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25
Q

What are the 2 divisions of each trunk? What is another name for each of those divisions

A

Each of the superior, middle, and inferior trunks split into anterior and posterior division
The anterior division is the flexor part
The posterior division is the extensor part

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26
Q

What are the cords of the brachial plexus?

A

Posterior cord - all 3 posterior divisions of the 3 trunks
Lateral cord - anterior division of superior and middle trunk
Medial cord - anterior division of the inferior trunk

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27
Q

What are the terminal branches of each of the cords?

A

Lateral cord = musculocutaneous nerve and lateral root of the median nerve
Medial cord = Ulnar nerve and medial root of the median nerve
Posterior cord = radial and axillary nerves

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28
Q

What are the branches of the brachial plexus at the level of the roots? What do those branches supply? Which ventral rami of spinal nerves are they derived from?

A

Dorsal scapular nerve (C5) - supplies rhomboids and levator scapulae muscle
Long thoracic nerve (C5, C6, C7) - supplies serratus anterior muscle

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29
Q

What are the branches of the upper trunk (off of the superior trunk) of the brachial plexus? What do those branches supply? Which ventral rami of spinal nerves are they derived from?

A 
Nerve to the subclavius (C5 and C6) - supplies the subclavius (gives off accessory phrenic nerve branch which normally joins phrenic near first rib)
Suprascapular nerve (C5 and C6) - supraspinatous and infraspinatous muscles
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30
Q

What are all the branches of the lateral cord of the brachial plexus, and what muscles do these branches supply?

A

Lateral pectoral nerve - pectoralis major and minor muscles
Musculocutaneous nerve - muscles of the anterior arm compartment (ends as the lateral antebrachial cutaneous nerve)
Lateral root of the median nerve

31
Q

What are all the branches of the medial cord of the brachial plexus, and what muscles do these branches supply?

A 
Medial pectoral nerve - pectoralis major and minor muscles
Medial brachial cutaneous nerve
Medial antebrachial cutaneous nerve
Ulnar nerve
Medial root of the median nerve
32
Q

What are all the branches of the posterior cord?

A

Upper subscapular nerve - subscapularis muscle
Thoracodorsal nerve - latissimus dorsi muscle
Lower subscapular nerve - subscapularis muscle ad teres major muscle
Axillary nerve - teres minor and deltoid muscles (ends as upper lateral brachial cutaneous nerve)
Radial nerve - great extensor nerve of the upper limb**

33
Q

What is the great extensor nerve of the upper limb, and what part of the brachial plexus does it branch from?**

A

The great extensor nerve of the upper arm is the radial nerve, and is a branch of the posterior cord of the brachial plexus

34
Q

What is caused by a lesion to the nerve roots of C5 and C6?**

A

Erb-Duchenne’s Palsy

35
Q

What nerves are lesioned in Erb-Duchenne’s palsy, and what muscles are affected?**

A 
Suprascapular nerve (supraspinatous muscle  and infraspinatous muscle)
Subclavius nerve (subclavius muscle)
Musculocutaneous nerve (biceps brachii which is the supinator of the forearm, flexor of the forearm at the elbow, and weak flexor of the arm at teh shoulder, brachialis which is the chief flexor of the forearm at the elbow, and the coracobrachialis which flexes the arm at the shoulder)
Axillary nerve
36
Q

What 2 muscles does the suprascapular nerve innervate, and what do these muscles do? In which disease is this nerve affected?

A

Suprascapular nerve innervates the:

  • supraspinatous muscle which abducts the arm at the shoulder
  • infraspinatous muscle which is the lateral rotator of the arm at the shoulder

Affected in Erb-Duchenne palsy

37
Q

What muscle is innervated by the subclavius nerve, and what does this muscle do? In which disease is this nerve affected?

A

Subclavius nerve innervates the subclavius muscle which depresses the clavicle

Affected in Erb-Duchenne palsy

38
Q

What muscles are innervated by the musculocutaneous nerve, and what do these muscles do? In which disease is this nerve affected?

A

The musculocutaneous nerve innervates:

  • biceps brachii which is the supinator of the forearm, flexor of the forearm at the elbow, and weak flexor of the arm at the shoulder
  • brachialis which is the chief flexor of the forearm at the elbow
  • coracobrachialis which flexes the arm at the shoulder

Affected in Erb-Duchenne palsy

39
Q

What muscles are supplied by the axillary nerve, and what is the action of these muscles? In which disease is this nerve affected?

A

The axillary nerve innervates:

  • deltoid which is the abductor of the arm at the shoulder
  • teres minor which is the lateral rotator of the arm at the shoulder
40
Q

What is the result of Erb-Duchenne’s palsy? Which spinal nerve ventral rami are affected?

A

Results in the Waiter’s Tip position
The upper limb hangs limply by the side, medially rotated by the unopposed action of the pectoralis major
Forearm is pronated due to loss of action of the biceps (which is the supinator of the forearm)
There is loss of sensation on the lateral side of the arm

41
Q

What spinal root ventral rami are affected in Klumpke’s palsy?

A

Tearing of C8 and T1 roots of the plexus

42
Q

Which nerve is most affected in Klumpke’s palsy? What results?

A

The ulnar nerve which results in “claw hand”
Caused by hyperextension of metacarpophalangeal joints and flexion of the interphalangeal joints (ie hyperextension of knuckles and flexion of fingers)
Also causes loss of sensation along medial side of the arm of the upper limb

43
Q

Which muscles are impacted in Klumpke’s palsy?

A
  1. Extensor digitorum is unopposed by the lumbricals and interossei and exends the metacarpophalngeal joints
  2. Flexor digitorum superficialis and lateral portion of the flexor digitorum profundus are unopposed by the lumbricals and interossei and flex the middle and terminal phalanges respectively.
44
Q

What muscle is affected if there is a lesion of the long thoracic nerve? What is the impact of paralysis of this muscle?

A

The serratus anterior muscle is paralyzed

  1. The medial border of the scapula becomes prominent and protrudes posterior when someone pushes against a fixed object (because the scapula can’t be protracted, called Winging of the scapula)
  2. Because the scapula can no longer be fixed, the triceps brachii is seriously weakened.
  3. Abduction of the arm is impaired because of weakened upward rotation of scapula
45
Q

What is compromised in thoracic outlet syndrome?

A

Involves compression of the brachial plexus nerves, subclavian vessels, or both because of inadequate passageway just above first rib and behind clavicle

46
Q

What are the 3 passageways that the brachial plexus trunks and subclavian vessels course through from the base of the neck to the axilla? What makes up each passageway?

A

Interscalene triangle (most important)
-anterior scalene, middle scalene, and medial border of first rib
Costoclavicular triangle
-middle 3rd of clavicle, first rib, and upper border of scapula
Subcoracoid space
-beneath the coracoid process just deep to pec minor

47
Q

What does the axillary artery extend through, and what is it a direct continuation of? What muscle divides it into 3 parts?

A

Extends from the lateral border of the first rib to the inferior border of the teres major muscle
Is a direct continuation of the subclavian artery
Divided into 3 parts by the pectoralis minor muscle (first part is above the muscle, second part is behind the muscle, 3rd part is below the muscle)

48
Q

What are the branches of the axillary artery, and which part do they branch off of?

A

Superior thoracic artery branches off the 1st part
Thoracoacromial trunk and lateral thoracic artery branch off the 2nd part
Subscapular artery (gives rise to circumflex scapular artery and thoracodorsal artery) and the anterior/posterior circumflex humeral arteries branch off the 3rd part

49
Q

What part of the axillary artery does the lateral thoracic artery branch off of, and what does it supply?

A

The lateral thoracic artery is a branch of the 2nd part of the axillary artery and supplies the breast, pectoral muscles, serratus anterior, and contents of axilla

50
Q

What part of the axillary artery does the superior thoracic artery branch off of, and what does it supply?

A

Branches off the 1st part of the axillary artery and supplies the first 2 intercostal space and the serratus anterior muscle

51
Q

What part of the axillary artery is the subscapular artery a branch of, and what are the 2 main trunks that it divides into? What do both trunks supply?

A

The subscapular artery is a branch of the 3rd part of the axillary artery and branches into the:
circumflex scapular artery and the thoracodorsal artery
Supplies the latissimus dorsi muscle

52
Q

What part of the axillary artery are the anterior/posterior circumflex humeral arteries branching off of, which is larger, and what space does the posterior branch run into?

A

Branch of the 3rd part of axillary artery
Posterior circumflex humeral artery is larger
Posterior circumflex humeral artery runs in the quadrangular space

53
Q

What 2 things run in the quadrangular space?

A

Axillary nerve

Posterior circumflex humeral artery (of the 3rd part of axillary)

54
Q

Around what structure do the anterior and posterior circumflex humeral arteries pass around and anastomose with each other after passing around?

A

The surgical neck of the humerus

55
Q

What is the direct continuation of the basilic vein as the basilic vein crosses the lower border of the teres major?

A

Becomes the axillary vein
(note that the axillary artery becomes the brachial artery as it passes over the lower border of teres major, but there is no brachial vein, so the basilic vein becomes the axillary vein)

56
Q

What are the 3 tributaries of the axillary vein?

A

Venae comitantes of the brachial artery
Cephalic vein
Tributaries corresponding to branches of the axillary artery

57
Q

What are the 4 muscles that connect the upper limb to the vertebral column?

A
  1. Trapezius
  2. Latissimus dorsi
  3. Leator scapulae
  4. Rhomboid
58
Q

What does the trapezius muscle connect, what is its nerve supply, and what are the 4 fiber groups that control distinct actions?

A 
Connects upper limb to vertebral column
Supplied by the accessory nerve
Upper fibers - elevate scapula
Middle fibers - retract scapula
Lower fibers - depress scapula
Superior and inferior - upward rotation of the scapula (necessary for abduction)
59
Q

What does the latissimus dorsi connect, what is its nerve supply, and what is its action?

A

Connects upper limb to vertebral column
Supplied by the thoracodorsal nerve
Extends, adducts, and medially rotates the humerus

60
Q

What does the levator scapulae connect, what is its nerve supply, and what is its action?

A 
Connects upper limb to vertebral column
Supplied by the dorsal scapular nerve and ventral rami of C3, C4
Elevates scapula
Tilts glenoid cavity downward
helps retract the scapula
61
Q

What do the rhomboid muscles connect, what is its nerve supply, and what is its action?

A

Connects upper limb to vertebral column
Supplied by dorsal scapular nerve
Retracts the scapula and rotates the scapula inferiorly

62
Q

What muscles connect the upper limb to the thoracic wall?

A

Serratus anterior
Pectoralis muscles
Subclavius

63
Q

What does the serratus anterior connect, what is its nerve supply, and what does it do?

A

It connects the upper limb to the thoracic wall
Is supplied by the long thoracic nerve
Protracts the scapula, fixes scapula, rotates the glenoid cavity upward

64
Q

What are the 6 scapular muscles (intrinsic shoulder muscles)?

A 
Deltoid muscle
Supraspinatous
Infraspinatous
Teres minor
Teres major
Subscapularis
65
Q

What nerve supplies the deltoid muscle, and what is its action?

A

Supplied by the axillary nerve
Anterior fibers - flex and medially rotate the humerus
Middle fibers - abduct the humerus
Posterior fibers - extend and laterally rotate humerus
(all 3 work together with pure abduction)

66
Q

What is the nerve supply of the supraspinatous muscle, and what is its action?

A

Supplied by suprascapular nerve

Abducts the humerus

67
Q

What is the nerve supply of the teres minor, and what is its action?

A

Supplied by axillary nerve

Laterally rotates the humerus

68
Q

What is the nerve supply of the infraspinatous muscle, and what is its action?

A

Supplied by the suprascapular nerve

Laterally rotates the humerus

69
Q

What is the nerve supply of the teres major, and what is its action?

A

Supplied by the lower subscapular nerve

Extends, adducts, and medially rotates the humerus

70
Q

What is the nerve supply of the subscapularis, and what is its action?

A

Supplied by the upper and lower subscapular nerves

Medially rotates the humerus

71
Q

What are the borders of the quadrangular space, and what are its contents?

A

Superior - teres minor
Inferior - teres major
Medial - long head of triceps brachii
Lateral - surgical neck of humerus (which is a frequent site of fracture)
Contains the axillary nerve and the posterior circumflex humeral artery

72
Q

What are the borders of the triangular space, and what does it contain?

A

Teres minor, teres major, long head of triceps brachii

Contains circumflex scapular vessels (or their branches)

73
Q

What are the borders of the triangular internal (which is the most important space), and what are its contents**?

A

Teres major, long head of triceps brachii, and shaft of humerus
Contains the radial nerve** and the profunda brachii artery (aka deep brachial artery)

74
Q

If there is a fracture at the midshaft of the humerus, what nerve is in danger, and which space is it contained in?

A

The radial nerve is in danger

Contained in the triangular interval

Medical Anatomy (39 decks)

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