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gross anatomy unit 2 > posterior triangle, axilla, and brachial plexus > Flashcards

posterior triangle, axilla, and brachial plexus Flashcards

1
Q

brachial plexus

A

the nerves are branches from ventral primary rami of C5-T1 exiting via intervebral foramine; rami branch and recombine forming brachial plexus

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2
Q

blood supply of the brachial plexus

A

from arteries branching from the aortic arch, the right brachipcephalic and left subclavian; vessels and nerves pass through two regions, the posterior triangle of the neck and the axilla

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3
Q

posterior traingle of the neck

A

more lateral; shaped roughly like a pyramid and lies between the large superficial mucles of the neck, sternocleidomastoid and trapezius (upper fibers); the third side of the triangle is the middle third of the clavicle, between the attachment sites of these muscles

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4
Q

boundaries of the posterior triangle

A

the posterior border of sternomastoid, anterior border of trapezius, and middle third of clavicle

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5
Q

superficial fascia of the neck

A

contains the platysma

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6
Q

platsyma

A

related to muscles of facial expression; innervated by a branch of the facial nerve (cranial nerve 7 or CN VII)

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7
Q

cutaneous nerves of the posterior triangle

A

supply skin below and behind the vertex-ear-chin line, down to the superclavicular region; these are branches of C2 and C3, radiating fromna point about halfway along the posterior border of the sternomastoid

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8
Q

external jugular vein

A

lies superficial to the sternomastoid

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9
Q

nerve that supplies sternomastoid and trapezius

A

cranial nerve XI

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10
Q

branch supplying the trapezius location

A

runs between the two layers of investing fascia across the posterior triangle.

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11
Q

CN XI

A

only has motor fibers; sensory fibers are part of the ventral primary rami of C2-C4

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12
Q

omohyoid

A

most inferior and most anterior muscles of the posterior triangle. it passes from the hyoid bone in the anterior f the neck to the scapula (omo=shoulder)

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13
Q

deep to the omohyoid

A

a second triangle formed by anterior and middle scalene muscles and the first rib

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14
Q

where does the anterior scalene attach

A

to a tubercle of the first rib.

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15
Q

`prevertebral fascia

A

covers the scalene muscles, levator scapulae, and the splenius muscle

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16
Q

subclavian artery and nerver components of the brachial plexus

A

pass between the anterior and middle scalene muscles and over the first rib to enter the axilla

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17
Q

left subclavian artery

A

a direct branch of the aorta,

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18
Q

right subclavian artery

A

passes behind the anterior scalene and goes over the first rib to become an axillary artery

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19
Q

axillary artery

A

crosses the teres major muscle to enter the arm as the brachial artery, the main supply to the upper limb.

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20
Q

phrenic nerve

A

(C3-5 to the diaphram) lies on the anterior surface of scalenus anterior, and is therefore at risk when anesthetic is injected into this region

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21
Q

thyrocervical trunk

A

deep to sternomastod; arises from the subclavian artery

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22
Q

transverse cervical and suprascapular arteries

A

arise in turn from the thyrocervical trunk; these arteries cross the posterior triangle to supply posterior muscles associated with the scapla: trapezius, the rhomboids, supraspinatus and infraspinatus; the arteries cross scalenus anterior superficial to the phrenic nerve

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23
Q

axillary vein

A

drains the upper limb, crosses the 1st rib to become the subclavian vein, and combines with the internal jugular vein draining the head to form the brachiocephalic vein

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24
Q

scalenus anterior

A

attaches to the first rib and separates the subclavian artery (posterior) from the subclavian vein (anterior)

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25
Q

how nerves and blood vessels leave the posterior traingle and enter the apex of the axilla

A

through the cervioaxillary canal, which is a triangle bounded by the middle of the clavicle, the first rib and the upper border of the scapula

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26
Q

anterior border of the axilla

A

a fold of skin covering the lower border of pectoralis major

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27
Q

posterior border of the axilla

A

a fold of skin covering the latissimus dorsi, teres major, and subscapularis muscles

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28
Q

lateral border of the axilla

A

bicipital groove of the humerus

29
Q

pectoralis major

A

attaches to the lateral lip of the bicipital groove of the humerus

30
Q

medial border of the axilla

A

the chest wall (ribs 1-4) covered by serratus anterior

31
Q

floor of the axilla

A

a sheet of tough fascia that bridges between the anterior and posterior folds

32
Q

vertical sheet of clavipectoral fascia

A

attaches to the clavicle and splits around the subclavius and pectoralis minor muscles

33
Q

suspensory ligament

A

a portion of the clavipectoral fascia; attaches to the fascia of the floor and raises the skin between the anterior and posterior borders into a dome - the armpit

34
Q

veins of the axilla

A

two veins lie in the superficial fascia of the upper limb and have no accompanying arteries; these are like the saphenous veins of the lower limb; the cephalic vein (named for its use in blood-letting to relive headaches) lies on the lateral side of the forearm and arm, closer to the head when the upper limb is abducted at the shoulder; the basilic vein (closer to the base) is superficial in the forearm but becomes the deep vein of the arm, accompanying the brachial artery; it continues into the axilla and becomes the axillary vein. the cephalic vein runs in the deltopectoral groove, between the deltoid and pectoralis major muscles, together with a branch of the thoracoacromial artery; the cephalic vein then pierces the clavipectoral fascia to join the axillary vein; a superficial vein must pierce the deep fascia at some point to join the system of deep veins

35
Q

lymph channels and lymph nodes of the axilla

A

these are divided into groups according to their locatio; lateral nodes receive lymph from the upper limb via channels along the axillary vein; pectoral nodes receive drainage from the thorax and are an important site of breast cancer metastasis

subscapular nodes (lying posterior) lie anterior to (deep to) the scapular

lymph from all fo these groups of nodes drains first into central nodes, then in apical nodes located along the axillary vein.

lymph from apical nodes on the right side drainsinto the subclavian trunk, while lymph on the left side drains into the throacic duct; the subclavian trunk and the thoracic duct join the venous system at the junction of the internal jugular and subclavian veins

36
Q

muscle in the axilla

A

coracobrachialis and the short head of the biceps

both arise from the carcoid process of the scapula and pass from the axilla to the arm.

37
Q

vascular contents of the axilla

A

subclavian artery and vein become the axillary artery and vein as they pass laterally over the first rib; for branches of axillary artery, it’s covenient to divide the artery into three parts, lying medial to, deep to, and lateral to, the pectoralis minor muscle. from the first part arise the superior (or supreme) thoracic, a small branch to the upper thorax that anastomoses with intercostal arteries.

38
Q

thoracoacromial artery

A

supplies the nearby pectoral and deltoid muscles, the acromian and the clavicle.

39
Q

lateral thoracic artery

A

supplies nearby muscles of the lateral thorax, latissimus dorsi and serratus anterior

40
Q

collateral circulation

A

an additional channel for blood that can compensate for a prtial block in the main channel

41
Q

arterial anastomoses

A

are common features of limb joints; allow collateral circulation

42
Q

anterior and posterior circumflex humeral arteries

A

wind around the humerus

43
Q

subscapular artery

A

supplies the subscapuls

44
Q

suprascapular artery

A

supplies the scapula

45
Q

circulation between the subclavian and axillary arteries

A

the suprascapular artery and the circumflex scapular artery anatomose with each other

  • dorsal scapular artery also participates in the anastomosis
46
Q

dorsal scapular artery

A

supplies the rhoboids

47
Q

collateral circulastion

A

an additional channel for blood that can compensate for a partial block in the main channel

arterial anatosomes allowing collateral circulation are common features of limb joints. other examples are found at elbow, hip, and knee joints

48
Q

basic motions at the shoulder, elbow, wrist and finger joints

A

extension and flexion

49
Q

flexion

A

performed by flexor muscles on the anterior side of the limb

50
Q

extension

A

performed by extensor muscles on the posterior side of the limb

51
Q

flexor muscle nerves

A

supplied by nerves on the anterior side of the limb

52
Q

extensor muscle nerves

A

supplied by nerves on the posterior side of the limb

53
Q

roots of the brachial plexus

A

ventral primary rami of spinal nerves C5 through T1, leaving intervertebral foramina; they are stacked on top of one another in a vertical plane in the neck

54
Q

trunks of the brachial plexus

A

as the roots pass into the posterior triangle, they form trunks still stacked in a vertical plane; C5 and C6 combine to form the upper trunk, C7 continues as the middle trunk, while C8 and T1 combine to form the lower trunk

55
Q

branches from anterior divisions of the trunks

A

will supply anterior compartment muscles (flexors)

56
Q

branches from posterior division of the trunks

A

will supply posterior compartment muscles (extensors)

57
Q

posterior cord

A

the three posterior division combine to form the posterior cord

58
Q

lateral cord

A

anterior division from the lower trunk forms the medial cord; made clear by standing in the anatomical position and abducting the upper limb; nerves from higher trunks (upper and middle) project out the (higher) lateral side of the arm, while nerves from the lower trunk become medial (lower side) on the arm

59
Q

2 general principles of nerves derived from the brachial plexus

A

1) more proximal muscles lie closer to the midline of the body and are supplied by nerves that arise from more proximal portions of the plexus
2) the most proximal muscles of the upper limb are located on the trunk and move the scapula as well as the humerus. these include pectoralis major and minor, latissimus dorsi, the rhomboids, levator scapulae, and serratus anterior

60
Q

nerves from the roots of the brachial plexus

A

dorsal scapular - C5 supplies rhomboids and levator scapulae, located high on the posterior chest wall (dorsal side of the body)
long thoracic - C5, C6, C7 supplies serratus anterior, located lower on the lateral chest wall

61
Q

nerves from the upper trunk of the brachial plexus

A

nerve to subclavius - to a small muscle just below the clavicle

suprascapular nerve - to supraspinatus and infraspinatus, muscles located on the superficial surface of the scapula. The suprrascapular artery supplies the same muscles

62
Q

nerves from the lateral cord (to anterior muscles and skin)

A

lateral pectoral nerve - to pectoralis major

musculocutaneous nerve - to flexor muscles of arm, then the lateral cutaneous nerve of forearm

lateral contribution to median nerve (anterior nerve of forearm and hand)

63
Q

nerves from the medial cord (to anterior muscles and skin)

A

medial pectoral nerve - to pectoralis major and minor
medial cutaneous

nerves of arm and forearm
medial contribution to median nerve

ulnar nerve - medial side of forearm and hand

64
Q

nerves from posterior cord (to posterior muscles and skin)

A

upper and lower subscapular nerves to subscapularis muscle and teres major

thoracodorsal nerve to latissmus dorsi, located on dorsal side of thorax

radial nerve to posterior extensor muscles of arm and forearm

axillary nerve to deltoid and teres mino

mnemonic ULTRA

65
Q

nerves in anterior divisions of C5-C6

A

run primarily in the multocutaneous nerve and supply more proximal muscles of the arm

66
Q

nerves in anterior divisions of C7-C8

A

run primarily in the median nerve and supply more distal muscles of the forearm and hand (primarily the thumb)

67
Q

nerves in anterior divisons of T1

A

run primarily in the ulnar nerve and supply distal muscles of the forearm and especially the intrinsic muscles of the hand

68
Q

upper brachial plexus injury (C5-C6)

A

caused by stretching of nerves associated with pulling the head away from the shoulder; e.g. difficult forceps deliveries and motorcycle accidents

damage to C5 and C6 fibers impairs function of proximal muscles - supraspinatus, deltoid, biceps and brachialis

loss of deltoid as an abductor lets the upper limb fall close to the side; loss of the biceps, the strong supinator, causes forearm to be pronated, the “waiter’s tip” position; the condition is Erb’s palsy.

69
Q

lower brachial plexux injury (C8-T1)

A

often caused by hyperabducting the arm, as in grabbing something overhead to avoid a fall; T1 supplies intrinsic muscles of the hadn which control movement at the metacarpophalangeal joints; a “claw hand” results from hyptextension of the fingers at the MP joints; the condition is called Klumpke’s palsy.

gross anatomy unit 2 (8 decks)

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