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OFS3 > Brachial plexus > Flashcards

Brachial plexus Flashcards

1
Q

Where does the dorsal scapular nerve originate from?

A

from the C5 root

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2
Q

Where does the long thoracic nerve originate from?

A

from the C, C6, C7 root

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3
Q

Where does the suprascapular nerve originate from?

A

from the upper trunk

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4
Q

Where does the lateral pectoral nerve originate from?

A

from the lateral chord

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5
Q

Where does the upper supscapular nerve originate from?

A

posterior chord

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6
Q

Where does the lower supscapular nerve originate from?

A

posterior chord

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7
Q

Where does the thoracodorsal nerve originate from?

A

posterior chord

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8
Q

Where does the medial cutaneous nerve of the arm originate from?

A

medial chord

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9
Q

Where does the medial cutaneous nerve of the forarm originate from?

A

medial chord

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10
Q

Where does the medial pectoral nerve originate from?

A

medial chord

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11
Q

What does the dorsal scapular nerve innervate?

A

rhomboid major + minor, levator scapulae

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12
Q

What does the long thoracic nerve innervate?

A

supplies serratus anterior , descends posterior to roots of brachial plexux + anterior to root of scalenus posterior muscles, course along chest wall in srface of serratus anterior muscle

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13
Q

What is a pathology associated with the long thoracic nerve?

A

paralysis of the serratus anterior + winged scapula

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14
Q

What does the suprascapular nerve innervate?

A

supraspinatus + infraspinatus
bring sensation to acromioclavicular + glenohummeral joints

course: after branching from brahcial plexus, ollow suprascapular artery + vein laterally, posterior to deep trapezius, until superior margin of scapula, passes through scapular notch, enter supraspinous fossa

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15
Q

What does the lateral pectoral nerve innervate?

A

pectorallis major

communicating branch to medial pectral nerve forms loop (ansa pectoralis), branches from medial chord of brachial plexus, pass inferiorly piercing clavicopectoral fascia, pierce deep surface of pectoralis muscle

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16
Q

What does the medial pectoral nerve innervate?

A

pectoralis minor

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17
Q

What is the course of the media pectoral nerve?

A

arises from medial cord of brachial plexus, posteriorly to axillary artery
supplies pectoralis minor + major. Curves anteriorly to lie between axillary artery + vein
receives communicating branch from lateral pectoral nerve (ansa pectoralis)
enters deep surface of pectoralis minor.

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18
Q

What are the specificities of the Upper (superior) subscapular nerve?

A

smaller than inferior
enters subscapularis fossa
frequently double.

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19
Q

What does the Lower (inferior) subscapular nerve supply?

A

supplies lower part of subscapularis

ends in teres major (sometimes supplied by separate branch)

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20
Q

What does the Thoraco-dorsal nerve(C6-C8) supply?

A

supplies latissimus dorsi.

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21
Q

What does the musculocutaneous nerve innervate?

A

provides sensory innervation to lateral aspect of forearm. (NB.has a varied anatomical course. Can interact with median nerve –> adheres + exchanges fibres)
coracobrachialis, biceps brachii, brachialis muscles

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22
Q

What is the course of the musculocutaneous nerve?

A

arises from anterior division of lateral cord of BP (contains fibers from spinal roots C5, C6 and C7)
leaves axilla
pierces coracobrachialis muscle
passes down arm anterior to brachialis muscle but deep to biceps brachii
innervates both
emerges laterally to biceps tendon
continues into forearm as lateral cutaneous nerve

23
Q

What are pathologies associated with the musculocutanous nerve?

A

well protected within axilla: most common cause stab wound to axilla region.

Motor functions: coracobrachialis, biceps brachii, brachialis muscles paralysed. Flexion at shoulder weakened, but can still occur due to pectoralis major. Flexion at elbow also affected, but can still be performed: brachioradialis. Supination of affected limb greatly weakened but produced by supinator muscle.

Sensory functions: Loss of sensation over lateral side of forearm.

24
Q

What does the axillary nerve innervate?

A

Motor Functions: innervates deltoid muscles (innervated by anterior terminal branch of axillary nerve) + teres minor (rotator cuff –> stabilizes glenohumeral) innervated by posterior terminal branch of axillary nerve

Sensory Functions: via posterior terminal branch after innervation of teres minor–>continues as upper lateral cutaneous nerve of arm–> innervates skin over inferior portion of deltoid (‘regimental badge area’).

25
Q

What does axillary nerve damage lead to?

A

sensation at regimental badge impaired/absent + paraesthesia (pins and needles) in distribution of axillary nerve.
Lesion caused by dislocation of shoulder joint /fracture of surgical neck of humerus.
Injury of the axillary nerve–>deltoid atrophy, weakness in abduction from 15 degrees to 90 degrees, loss of cutaneous sensation over lower half of deltoid.

26
Q

What is the quadrangular space and what are its boudaries?

A

gap in muscles of posterior scapular region: pathway for neurovascular structures to move from axilla to posterior shoulder + arm.
Boundaries:
SUP: Subscapularis + teres minor //
INF: Teres major //
LAT: Surgical neck of humerus //
MED: Long head of triceps brachii// axillary nerve + posterior circumflex humeral artery pass through space.

27
Q

What is the trajectory of the axillary nerve?

A

• formed within axillary region, direct continuation of posterior cord of BP, contains fibres from C5+C6 nerve roots.
• after formation: axillary nerve posterior to axillary artery + anterior to subscapularis
descends to inferior border of subscapularis muscle
exits axilla posteriorly via quadrangular space.
Followed by posterior circumflex humeral artery.

28
Q

What is the trajectory of the median nerve?

A

• Originates from BP in axilla
descends down arm lateral to brachial artery
Halfway down arm: crosses over brachial artery
becomes situated medially
enters anterior compartment of forearm via cubital fossa.
• Before entering cubital fossa innervates: pronator teres, Flexor carpi radialis, Palmaris longus, flexor digitorum superficialis
In cubital fossa: nerve medial to brachial artery-> enters forearm between humeral + ulnar heads of pronator teresthere: anterior interosseous branch (supplies deep muscles in anterior forearm) given off
courses along anterior elbow through 2 heads of pronator teres
into forearm beneath edge of fibrous arch of flexor digitorum superficialis
in forearm between flexor digitorum profundus + flexor digitorum superficialis
enters hand via carpal tunnel
terminates by dividing into 2 branches:

29
Q

What are the 2 branches of the median nerve and what do they innervate?

A

Recurrent branch (Innervates thenar muscles: Abductor pollicis brevis, flexor pollicis brevis, opponens pollicis)

Palmar digital branch (Inner fingertips of lateral three and half digits + distal phalanges of same fingers on dorsal side of hand. Also innervates lateral two lumbrical muscles)

30
Q

What is the carpal tunnel and how is it related to the median nerve?

A

formed by carpal bones (floor), transverse carpal ligament (roof), scaphoid + trapezium (radial side), pisiform + hook of the hamate (ulnar side).
Median nerve subdivides into digital + muscular branches (recurrent branch) when exiting carpal tunnel.

31
Q

How is the Palmar branch (distal branch) of the median nerve formed?

A

released before entering retinaculum flexorum.

32
Q

What is the Anterior interosseous nerve formed from the medial nerve?

A

branches posteriorly from median nerve between two heads of pronator teres: proximal, deep branch, innervates deep flexors.

33
Q

What is the trajectory of the radial nerve?

A

• Roots: C5-T1, arises in axillary region (situated posteriorly to axillary artery)
exits axilla inferiorly (via triangular interval)supplies branches to long + medial heads of triceps brachii
descends down posterior aspect of arm (travels in shallow depression within surface of humerus: radial groove: separates medial and lateral heads of triceps)
On lateral side of arm passes anteriorly through lateral intermuscular septum
enters anterior compartment
lies between brachialis + brachioradialis (posterior comp. of forearm) which attaches to lateral supraepicondylar ridge of the humerus
enters forearm anterior to lateral epicondyle of humerus, deep to brachioradialis muscle
terminates by dividing into 2 branches:

34
Q

What are the 2 branches arrising from the radial nerve and what do they innervate?

A

o Deep branch (motor) – innervates most muscles in posterior compartment of forearm.
o Superficial branch (sensory) – contributes to cutaneous innervation of hand + fingers

35
Q

The sensory branches of the radial nerve are released in 2 location, where?

A
  • Sensory branches released in upper arm (AXILLA)–>Posterior cutaneous nerve of the arm
  • Sensory branches released in SPIRAL GROOVE –>Lower cutaneous nerve of arm + Posterior cutaneous nerve of forearm
36
Q

What accompanies the radial nerve during its course in the upper arm?

A

During course in upper arm: accompanied by deep branch of brachial artery.

37
Q

What is the triangular interval?

A

formed by shaft of humerus, inferior margin of teres major muscle, lateral margin of long head of triceps bracchi.

38
Q

What are the motor functions of the radial nerve?

A

Innervates triceps brachii, extensor muscles in posterior compartment of forearm. In upper arm, innervates 3 heads of triceps brachii (acts to extend arm at elbow). Also gives rise to branches that supply brachioradialis + extensor carpi radialis longus (posterior forearm). Terminal branch of radial nerve, deep branch, innervates remaining muscles of posterior forearm. These muscles act to extend at wrist + finger joints, supinate forearm.

39
Q

When deep branch of radial nerve penetrates supinator muscle of forearm, it is called the _____________

A

posterior interosseous nerve.

40
Q

What are the sensory functions of the radial nerve?

A

Innervates posterior aspect of arm + forearm + the posterior lateral aspect of hand. Superficial branch (sensory) in antero-lateral aspect of forearm deep to brachioradialis + contributes to cutaneous innervation of hand + fingers.

41
Q

What does a lesion in the axilla region of the radial nerve lead to ?

A

radial nerve damage by dislocation at shoulder joint/fracture of proximal humerus. Occa. injured via excessive pressure on nerve within axilla (eg. badly fitting crutch).
o Motor functions: triceps brachii + muscles in posterior compartment affected–> patient unable to extend at elbow, wrist, fingers. UNOPPOSED FLEXION OF WRIST OCCURS, KNOWN AS WRIST-DROP.
o Sensory functions: all 4 cutaneous branches of radial nerve affectedloss of sensation over lateral + posterior upper arm, posterior forearm, dorsal surface of lateral three and a half digits.

42
Q

What does a lesion in the spinal grove of the radial nerve lead to ?

A

• In Radial Groove radial nerve tightly bound within spiral groove of humerus–> susceptible to damage with a fracture of humeral shaft.
o Motor functions: triceps brachii weakened, but not paralysed (branches to long + medial heads of triceps arise proximal to radial groove).Muscles of posterior forearm mainly affected –>patient unable to extend at wrist + fingers –> unopposed flexion of wrist occurs, known as wrist-drop.
o Sensory functions: cutaneous branches to arm already arisen –> superficial branch of radial nerve damaged –> sensory loss on dorsal surface of lateral 3 and half digits + associated palm area.

43
Q

What is the trajectory of the ulnar nerve?

A

• posteromedial to brachial artery in anterior compartment of upper 1/2 arm
pierces medial intermuscular septum at arcade of Struthers, medial to the triceps
At elbow passes posterior to medial epicondyle(nerve easily palpable +vulnerable to injury)
enters forearm
passes through cubital tunnel
in forearm passes between 2 heads of flexor carpi ulnaris
travels alongside ulna, lying over flexor digitorum profundus
there: gives off 3 branches: muscular branches (proximal) +palmar cutaneuos branch + dorsal cutaneous branch (distal)
5 cm proximal to wrist releases Palmar cutaneous branch (innervates skin of medial half of palm) + Dorsal cutaneous branch (arises 5 cm. proximal to wrist + provides sensory innervation to medial portion of IV and all Vth finger)

44
Q

3 branches of the ulnar nerve arise in the forarm, what are their names?

A

muscular branch
superficial terminal branch
deep branch

45
Q

What does the msucular branch of the ulnar nerve innervate?

A

innervates 2 muscles in anterior compartment of forearm (FLEXOR CARPI ULNARIS + FLEXOR DIGITORUM PROFUNDUM).

46
Q

What is the trajectory of the muscular branch of the ulnar nerve?

A

• At wrist ulnar nerve travels superficially to FLEXOR RETINACULUM
enters hand via ulnar canal (or Guyon’s canal: fascia, superficial part of flexor retinaculum, which bridges over ulnar neurovascular bundle + attaches to radial side of pisiform
tunnel
occasional site of ulnar nerve entrapment)
finishes in hand
superficial + deep branch:

47
Q

What does the superficial terminal branch of the ulnar nerve supply?

A

supplies palmaris brevis + medial palmar skin

48
Q

What is the trajector of the superficial terminal branch of the ulnar nerve?

A

Divides into 2 palmar digital nerves (supply medial side of little finger) + common palmar digital nerve (sends twig to median nerve + divides into 2 proper digital nerves to supply adjoining sides of little + ring fingers.) Proper digital branches distributed like those derived from median nerve.

49
Q

What does the deep branch of the ulnar nerve innervate?

A

muscles of hypothenar eminence + intrinsic muscles of hand

50
Q

How does the ulnar nerve innervate the hand?

A

majority of intrinsic hand muscles innervated by deep branch of ulnar nerve. Hypothenar muscles (Flexor digiti minimi brevis, abductor digiti minimi, opponens digiti minimi): group of muscles associated with little finger

innervated by the ulnar nerve

also innervates medial two lumbrical + interossei of the hand + adductor pollicis + palmaris brevis

51
Q

What is the cubital tunnel?

A

space through which ulnar nerve passes posterior to medial epicondyle of humerus.

52
Q

What are the boundaries of the cubital tunnel?

A

Roof: cubital tunnel retinaculum (ligament of Osborne), extends from olecranon to medial epicondyle anconeus epitrochlearis (when present)
Lateral wall: olecranon process
Medial wall: medial epicondyle
Floor: elbow joint capsule, posterior band of medial collateral ligament of elbow joint

53
Q

What are the 3 pathologies associated with the ulnar nerve?

A
  • narrowing of scalene space by cervical rib: pain irradiating along arm + circulatory impairment
  • thoracic outlet syndrome: thoracic outlet compressed area: impingement between rib and clavicle
  • costoclavicular syndrome: narrowing of costoclavicular space.

OFS3 (15 decks)

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