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Anatomy Exam 3 > Axilla and Arm > Flashcards

Axilla and Arm Flashcards

1
Q

Overview of axilla

  • What are the anterior and posterior boundaries of the axilla?
  • What is the axillary sheath?
A

Overview of axilla

  • Boundaries:
    • Pectoralis major forms the anterior axillary fold (when you grab your armpit, this is what you’re grabbing)
    • Latissimus dorsi and teres minor form the posterior axilary fold
    • Midaxillary lines starts at the midpoint of the axilla and runs down the length of the torso
  • Axillary sheath
    • Thick layer of fascia enclosing: axillary artery, axillary vein, distal portion of brachial plexus
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2
Q

Axillary artery

  • What artery is before and after and where does the name change?
  • What are the branches for each of the three parts?
  • What is the location of the parts in relation to pectoralis minor?
  • What does each branch supply?
  • What are the borders of the quadrangular space?
  • What passes through the space leaving the axilla?
A

Axillary artery

  • Continuation of the subclavian artery (changes name at 1st rib)
  • Becomes the brachial artery at inferior border of teres major
  • Subdivided based on the relationship to pectoralis minor:
    • First part (one branch)
      • Proximal to pectoralis minor
      • Superior thoracic artery: supplies 1st - 2nd intercostal spaces
    • Second part (two branches)
      • Deep to pectoralis minor
      • Thoracoacromial artery: supplies pectoral muscles and deltoid
      • Lateral thoracic artery: supplies serratus anterior and pectoral muscles (courses with long thoracic nerve, which also supplies serratus anterior)
    • Third part (three branches)
      • Distal to pectoralis minor
      • Subscapular artery
        • Circumflex scapular artery: supplies scapular region (goes lateral)
        • Thoracodorsal artery: supplies latissimus dorsi (goes inferior and travels with thoracodorsal nerve, which also supplies latissimus dorsi)
      • Anterior circumflex humeral artery:
        • Supplies shoulder and arm
        • Anastomoses with posterior circumflex humeral artery
      • Posterior circumflex humeral artery:
        • Supplies shoulder and arm
        • Anastomoses with anterior circumflex humeral artery
        • Travels with the axillary nerve through the quadrangular space
        • Borders of the quadranular space:
          • Teres minor (superior)
          • Teres major (inferior)
          • Humerus (lateral)
          • Long head of triceps brachii (medial)

Both the anterior and posterior circumflex humeral arteries wrap around the surgical neck of the humerus and they anastomose

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3
Q

Blood supply to the posterior shoulder

  • Subscapular artery is a branch of?
  • What are the two branches of the subscapular artery?
  • Thyrocervical trunk is a branch of?
  • What are the two branches of the thyrocervical trunk?
  • What are the two branches that come off of one of those branches?
A

Blood supply to the posterior shoulder

  • Axillary artery:
    • Subscapular artery
      • Circumflex scapular artery
      • Thoracodorsal artery
  • Subclavian artery
    • Thyrocervical trunk
      • Transverse cervical artery
        • Superficial branch
        • Dorsal scapular artery
      • Suprascapular artery
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4
Q

Axillary vein

  • Formed by a union of what two veins?
  • Becomes subclavian vein where?
  • What are the three major tributaries?
A

Axillary vein

  • Formed by union of brachial veins and basilic vein at the inferior border of teres major
  • Becomes subclavian vein at the level of the 1st rib
  • Major tributaries:
    • Brachial veins (deep)
    • Basilic vein (superificial and medial)
    • Cephalic vein (superficial and lateral)
    • Additional veins parallel branches of axillary artery
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5
Q

The brachial plexus: overview

  • Roots: Located? Ventral rami of?
  • Trunks: Located? Spinal levels of the 3 trunks?
  • Divisions: Located? Made up of?
  • Cords: Located? Named according to? Spinal levels of the 3 cords?
A

The brachial plexus: overview

  • Roots
    • In the neck
    • Ventral rami of C5-T1
  • Trunks
    • In the neck
    • Formed by merged roots
    • Superior trunk (C5-6)
    • Middle trunk (C7)
    • Inferior trunk (C8-T1)
  • Divisions
    • Deep to clavicle
    • Each trunk splits into anterior and posterior division
  • Cords
    • Distal to clavicle
    • Formed by merged divisions
    • Named according to their position relative to the axillary artery
    • Lateral cord: anterior divisions of superior and middle trunks (C5-7)
    • Medial cord: anterior division of inferior trunk (C8-T1)
    • Posterior cord: posterior divisions of all trunks (C5-T1)
      • All 3 posterior divisions merge together to form the posterior cord
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6
Q

The brachial plexus: branches

  • What are the two branches of the roots?
    • Motor innervation to?
    • What does each travel with?
    • What causes a winged scapula?
  • What is the branch of the superior trunk?
    • Motor?
    • Travels with?
A

The brachial plexus: branches

  • Branches of the roots
    • Dorsal scapular nerve
      • Motor: levator scapulae and rhomboid major/minor
      • Travels with dorsal scapular artery, medial to the medial border of the scapula
    • Long thoracic nerve
      • Motor: serratus anterior
      • Travels with the lateral thoracic artery along the midaxillary line, on the superficial surface of serratus anterior
      • Lesion of the long thoracic nerve results in a “winged scapula” because serratus anterior fixes scapula to the thoracic cage
  • Branches of the superior trunk
    • Suprascapular nerve (C5-6)
      • Motor: supraspinatus and infraspinatus
      • Travels with the suprascapular artery (Army over Navy)
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7
Q

The brachial plexus: terminal branches of the lateral cord

  • What are the two terminal branches that each of the three cords gives rise to?
  • What are the three terminal branches of the lateral cord?
  • Motor and sensory of each?
  • What is carpal tunnel syndrome?
A

The brachial plexus: terminal branches of the lateral cord

  • LMM: lateral cord gives rise to the musculocutaneous and median nerves
  • MUM: medial cord gives rise to ulnar and median nerves
  • PAR: posterior cord gives rise to axillary and radial nerves
  • Terminal branches of the lateral medial cords form an M

Lateral cord

  • Musculocutaneous nerve (most lateral nerve of the plexus)
    • Motor: anterior compartment of the arm
    • Sensory: near the elbow, terminates as the lateral cutaneous nerve of the forearm, which innervates skin of the lateral forearm
  • Contributes to the median nerve (_m_edian travels _m_idline down the arm, it is the middle of the M)
    • Motor: most of the muscles of the anterior compartment of the forearm and some intrinsic hand muscles
    • Sensory: skin of part of hand
    • Carpal tunnel: compression of median nerve as it passes deep to the flexor retinaculum at the wrist
  • Lateral pectoral nerve
    • Motor: pectoralis major
    • There may be a communicating branch between the lateral and medial pectoral nerves
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8
Q

The brachial plexus: terminal branches of the medial cord

  • What are the two main branches of the medial cord?
  • What are the other three branches?
  • Motor and sensory?
  • Which one can be compressed, funny bone?
A

The brachial plexus: terminal branches of the medial cord

MUM: medial cord gives rise to ulnar and median nerves

Medial cord

  • Contributes to the median nerve
  • Ulnar nerve (most medial of the plexus)
    • Motor: 1.5 muscles of anterior forearm and most intrinsic hand muscles
    • Sensory: skin of part of hand
    • Very superficial as it crosses the elbow joint, it can be compressed here (“funny bone”)
  • Medial pectoral nerve
    • Motor: pectoralis major and minor
  • Medial cutaneous nerve of the arm
    • Sensory: skin of medial arm
  • Medial cutaneous nerve of the forearm
    • ​Sensory: skin of the anterior arm and medial forearm

*** “Medial” in the name because they are coming off the medial nerve

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9
Q

The brachial plexus: terminal branches of the posterior cord

  • What are the two main branches of the posterior cord?
  • What are the other three branches?
  • Motor and sensory?
  • How would the structures in the quadrangular space and radial groove be damaged?
A

The brachial plexus: terminal branches of the posterior cord

PAR: posterior cord gives rise to axillary and radial nerves

Posterior cord

  • Axillary nerve (C6-5)
    • Exits axilla posteriorly through the quadrangular space (with posterior circumflex humeral vessels)
    • Structures in the quadrangular space are susceptible to damage with a fracture of the surgical neck of the humerus
    • Motor: deltoid and teres minor
    • Sensory: skin on the lateral aspect of the shoulder
  • Radial nerve
    • Courses in radial groove on posterior aspect of humeral shaft (with deep artery and vein of the arm)
    • Structures in radial groove are susceptible to damage with a midshaft fracture of the humerus
    • Motor: muscles of the posterior arm and forearm
    • Sensory: skin of the posterior arm, forearm, and hand

*** Going from proximal to distal:

  • Upper subscapular nerve
    • Motor: subscapularis (superior part)
  • Thoracodorsal nerve
    • ​Motor: latissimus dorsi
    • Travels with thoracodorsal artery
  • Lower subscapular nerve
    • ​Motor: subscapularis (inferior part) and teres major
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10
Q

Brachial plexus injuries

  • What do C5-6 and C7-8 innervate?
  • What is an injury to C5-6 called and look like?
  • What is an injury to C8-T1 called and look like?
A

Brachial plexus injuries

  • C5-6 innervate muscles around the shoulder/arm, while C7-8 innervate muscles in the hand
  • Erb’s palsy: injury to C5-6, waiter’s tip position, with adducted and medially rotated GHJ and extended elbow joint
  • Klumpke’s palsy: injury to C8-T1, claw hand, affects intrinsic hand muscles
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11
Q

Muscles of the anterior compartment of the arm

  • Innervation rule? Action rule?
  • What are the three muscles?
  • Origin, insertion, and innervation?
  • What does the biceps reflex test test?
  • Side note: what are the three muscles that attach to the coracoid process?
A

Muscles of the anterior compartment of the arm

  • Innervation rule:
    • Musculocutaneous nerve (C5-7)
  • Action rules:
    • Flex GHJ and elbow joint
    • Supinate forearm

Coracobrachialis (crosses GHJ anteriorly)

  • Origin: coracoid process of scapula
  • Insertion: midshaft of anterior humerus
  • Action: flex GHJ

Biceps brachii (2 headed muscle, crosses the GHJ)

  • Origin:
    • Short head: coracoid process of scapula
    • Long head: supraglenoid tubercle of scapula, tendon passes through the intertubercular groove to get to the supraglenoid tubercle
  • Insertion:
    • Radial tuberosity and fascia of forearm via bicipital aponeurosis
  • Action:
    • Flex elbow joint
    • Supinate forearm
    • Weakly flex GHJ
    • (Lift dumbell, turn door handle)
  • Note: the biceps reflex test can be used to assess the musculocutaneous nerve and the C5-6 spinal segments

Brachialis (does NOT cross GHJ)

  • Origin: distal half of humerus
  • Insertion: ulnar tuberosity
  • Action: flex elbow joint

*** FYI: coracobrachialis, biceps brachii, and pec minor are the three muscles that attach to the coracoid

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12
Q

Muscules of the posterior compartment of the arm

  • Innervation rule? Action rule?
  • What is the one muscle in the posterior compartment of the arm?
  • What are their three branches?
  • Origin, insertion, and action?
  • What two things does the triceps reflex test test?
  • What is the small muscle posterior to the elbow joint that stabilizes the elbow joint? Innervated by?
A

Muscles of the posterior compartment of the arm

  • Innervation rule: radial nerve (C6-8)
  • Action rules:
    • Extend elbow
    • Extend GHJ

Triceps brachii

  • Origin:
    • Long head: infraglenoid tubercle of scapula
    • Lateral head: posterior humerus
    • Medial head: posterior humerus
  • Insertion:
    • Olecranon process of ulna
  • Action:
    • Extend elbow joint
    • Extend GHJ (via long head)
  • The triceps reflex test can be used to assess the radial nerve and the C7-8 spinal segments
  • Anconeus (radial nerve C7-T1), a small muscle posterior to the elbow joint, is also in this compartment and stabilizes the elbow joint
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13
Q

Arteries of the arm

  • Where does the axillary artery change to brachial artery?
  • Brachial artery
    • Supplies?
    • How can you control hemorrhages in the distal UE?
    • What two arteries does it give rise to?
    • What does the first artery supply and where does it course?
    • What is susceptible to a midshaft fracture of the humerus?

Deep veins

  • Typically are?
  • Communicate with?
A

Arteries of the arm

  • At the inferior border of teres major, axillary artery changes to brachial artery
  • Brachial artery
    • Supplies arm
    • Blood pressure is measured from brachial artery
    • Mid arm compression of brachial artery aids in controlling hemorrhages in the distal UE
    • Gives rise to:
      • Deep artery of the arm
        • AKA profunda brachii artery
        • Primary blood supply to the posterior arm
        • Courses in the radial groove of the humerus with the radial nerve
        • Structures in the radial groove are susceptible to damage with a midshaft fracture of the humerus
      • Ulnar collateral arteries
        • Anastomose around elbow joint

Deep veins

  • Accompany arteries and have the same names
  • Typically paired
  • Communicate with superficial veins
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Anatomy Exam 3 (5 decks)

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