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Anatomy III > Upper plexuses > Flashcards

Upper plexuses Flashcards

1
Q

Differentiate btw afferents and efferents of the PNS.

A
  • afferents = sensation, 1 neuron, perikaryon in ganglion (spinal ganglion)
  • efferents = motor innervation, 1 neuron, perikaryon in ventral horn, pseudounipolar
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2
Q

Which cranial nerve has bipolar neurons?

A

n. facialis

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3
Q

Define segmental innervation.

Where can it be seen most prominently?

A

peripheral nerve of 1 segment innervates area (esp. dermatomes) of same segment

→ trunk, nn. intercostales

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4
Q

What are dermatomes?

Briefly describe the innervation of the different segments.

A

area of skin that is mainly supplied by a single spinal nerve

BUT: C1 doesn’t have a dermatome

<u>NOTE:</u> V1 - 3 refer to skin innervation by division of <strong>n. V</strong>

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5
Q

Explain generally how a plexus is formed.

A

spinal nerves enter plexus segmentally seperated, exchange fibers, leave as mixed-segmental peripheral nerves

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6
Q

What is a segment-indicating muscle?

List for C5 - C7.

A

mainly innervated by one distinct spinal nerve

→ can indicate lesion in that very segment

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7
Q

What is a segment-indicating muscle?

List for C8, L3-4.

A

mainly innervated by one distinct spinal nerve

→ can indicate lesion in that very segment

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8
Q

What is a segment-indicating muscle?

List for L5 - S2.

A

mainly innervated by one distinct spinal nerve

→ can indicate lesion in that very segment

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9
Q

Explain the general pathway of spinal nerves.

A
  1. ventral motor + dorsal sensory root unite
    → spinal nerve in canalis vertebralis
  2. give off r. meningeus: enters canalis vertebralis again → supplies periostium, meningi + intervertebral disks
  3. spinal nerves bifurcate into r. anterior + r. posterior
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10
Q

Explain the function of rr. posteriores of the cervical spinal nerves.

A

all sensory except C1

  • C1 = n. suboccipitalis: motor inn. of deep short nuchal mm. + m. semispinalis capitis
  • C2 = n. occipitalis major: skin inn. - vertex
  • C3 = n. occipitalis tertius: skin inn. caudal + medial to C2
  • C4 - 8 = skin inn. of nuchal region caudally
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11
Q

Which structure can be frequently seen next to n. occipitalis major?

A

a. occipitalis

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12
Q

Explain the function of rr. posteriores of the thoracic - sacral spinal nerves.

A
  • T1-12 = skin + motor inn. of autochthonal back mm.
  • L1 - S5 = nn. clunium superiores + medii: skin inn. of pelvis, gluteal region

skin innervation of the back

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13
Q

Explain the pathway of rr. anteriores of the thoracic region.

A

only rr. anteriores that do NOT participate in formation of plexus

→ form nn. intercostales on inner wall of thorax, run at superior border of rib

  • Th1 - 6: end at sternum
  • Th7 - 12: after sternum downwards to linea alba

→ r. cutaneus lateralis + r. cutaneus ant. innervate pleura + peritoneum

3 = r. ant., 5 = r. cutaneus lat., 6 = r. cutaneus ant.

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14
Q

Differentiate btw the general function of nn. intercostales.

A

innervate intercostal mm. + resp. dermatomes

Th1 - 6: end at sternum

  • ALSO: mm. serrati post. sup. + inf.

Th7 - 12: after sternum downwards to linea alba

  • ALSO: abdominal mm.

→ give off r. cutaneus lateralis + r. cutaneus ant. innervate pleura + peritoneum

3 = r. ant., 5 = r. cutaneus lat., 6 = r. cutaneus ant.

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15
Q

Which nn. intercostales have a special role?

A
  • 1st: participates in plexus brachialis
  • 2nd (+3rd): sensory collateral to upper limb, hence n. intercostobrachialis → anastomoses w/ n. cutaneus brachii medialis
  • 12th: under last rib, hence n. subcostalis

3 = r. ant, 4 = n. intercostobrachialis

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16
Q

Which nerves form plexus cervicalis?

Where is it located?

General functions.

A

rr. anteriores of C1 - 4
form plexus cervicalis deep to m. sternocleidomastoideus btw mm. scaleni and m. levator scapulae in trigonum colli laterale

→​ infrahyoid mm. + sensory innervation of cervical region

​<u>NOTE:</u> prominent <strong>ansa cervicalis profunda</strong>

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17
Q

Which muscular branches are given off by plexus cervicalis?

A
  • branches to
    • mm. scaleni
    • deep nuchal mm.
    • m. sternocleidomastoideus
    • m. trapeziuse
  • ansa cervicalis (profunda)
  • n. phrenicus
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18
Q

What is ansa cervicalis profunda?

Spinal origin?

Pathway + function.

A

loop formed by plexus cervicalis
radix superior (C1, 2) runs parallel to n. XII, then anastomoses w/ radix inferior (C3, 4) ventrally to v. jugularis/a. carotis communis

→ m. geniohyoideus + infrahyoid mm.

1 = n. XII, 2 = radix sup., 3 = radix inf., 4 = branches to infrahyoids

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19
Q

Describe the pathway of n. phrenicus

A

branch of plexus cervicalis (C3 - 5)

  1. runs on m. scalenus ant. downwards
  2. enters thorax btw a. + v. subclavia
  3. then btw pleura + pericardium in ant. mediastinum
  4. leaves thorax at apex of heart (left)/ foramen venae cavae (right) to diaphragm

​1 = n. phrenicus, 2 = m. scal. ant., 3 = a. subcl., 4 = v. subcl.

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20
Q

Which branches are given off by n. phrenicus?

Function?

A
  • rr. perciadiaci → pericardium, pleura
  • rr. phrenicoabdominales → peritoneum

⇒ motor/sensory innervation of diaphragm
(3, 4 and 5 keep diaphragm alive)

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21
Q

Which sensory branches are formed by plexus cervicalis?

Spinal origin.

A

​4 branches

  • n. occipitalis minor (C2): dorsally to m. sternoc.
  • n. auricularis magnus (C2, 3): crosses m. sternoc. superiorly
  • n. transversus colli (C2, 3): crosses m. sternoc. inferiorly, forms ansa cervicals superficialis
  • nn. supraclaviculares (C3, 4): to clavicle, upper chest, shoulder

cf. picture

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22
Q

What is a common feature of all sensory branches of plexus cervicalis?

A

exit all together at post border of m. sternocleidomastoideus

= punctum nervosum/Erb’s point

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23
Q

What is ansa cervicalis superficialis?

A

neural anastomosis of n. transversus colli from plexus cervicalis and r. colli n. facialis

→ superficial loop

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24
Q

Where does plexus brachialis originate from?

Explain its general pathway.

A

(mainly) C5 - T1

  1. originates in trigonum colli laterale
  2. runs together with a. subclavia through hiatus scalenus to form 3 trunci
  3. rearrangement to 3 fasciculi dorsally to clavicle, accompanying a. axillaris
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25
Q

What is scalene hiatus?

Contents?

A
  • ant.: m. scalenus ant.
  • post.: m. scalenus med.
  • inf.: 1st rib

→ contains fibers of plexus brachialis + a. subclavia

26
Q

What are the 3 trunci of plexus brachialis?

Spinal origin?

A
  • truncus superior (C5 - 6)
  • truncus medius (C7)
  • truncus inferior (C8 - T1)

REMEMBER: 2, 1, 2

27
Q

Which structures are formed by the 3 trunci of plexus brachialis?
At which level?

Spinal origin?

A

at level of clavicle
rearrangement of fibers of trunci to fascicles
→ named in relation to a. axillaris

  • fasciculus lat. = first 2 trunci
  • *→** C5 - 7
  • fasciculus post. = all 3 trunci
  • *→** C5 - T1
  • fasciculus med. = last truncus
  • *→** C8 - T1
28
Q

List all branches directly originating from the trunci of plexus brachialis.

Spinal origin?

A
  • n. thoracicus longus (C5 - 7)
  • ​n. dorsalis scapulae (C3 - 5)
  • n. subclavius (C4 - 6)
  • n. suprascapularis (C4 - 6)
  • short branches to mm. scaleni + m. longus colli (C5 - 8)
29
Q

Nerve?

Function + pathway.

A

n. thoracicus longus (C5 - 7)

pierces m. scalenus medius, runs downwards dorsally on inner thoracic wall

→ m. serratus ant.

30
Q

Nerve?

Pathway + function.

A

n. dorsalis scapulae (C3 - 5)

runs on m. scalenus med., pierces m. levator scapulae to reach medially to rhomboids

→ m. levator scapulae, mm. rhomboidei

31
Q

Right nerve?

Pathway + function.

A

n. subclavius (C5 - 6)

might give off branch to n. phrenicus (shown here)

→ m. subclavius

32
Q

Nerve?

Pathway + function.

A

n. suprascapularis (C4 - 6)

runs dorsally through incisura scapulae to

→ m. supra- and infraspinatus

33
Q

List all branches originating from the fasciculi of plexus brachialis that are responsible for innervation of mm. of the shoulder girdle.

Spinal origin?

A
  • n. pectoralis lat. (C5 - 7)
  • n. pectoralis med. (C8 - T1)
  • nn. subscapulares (C5 - 7)
  • n. thoracodorsalis (C5 - 8)
  • n. axillaris (C5 - 6)
34
Q

Pointing at 2 nerves. Which one originates from the more cranial spinal nerves?

Pathway + function.

A

n. pectoralis lat. (C5 - 7)

originates in trigonum deltoideopectorale from fasciculus lat.

→ m. pectoralis maj.

35
Q

Pointing at 2 nerves. Which one originates from the more caudal spinal nerves?

Pathway + function.

A

n. pectoralis med. (C8 - T1)

originates in trigonum deltoideopectorale from fasciculus med.

→ m. pectoralis min.

36
Q

Nerves?

Pathway + function.

A

nn. subscapulares (C5 - 7)

mostly 2, originate from fasciculus post., run to

→ m. subscapularis (sometimes also m. teres major)

37
Q

Pointing at right nerve.

Pathway + function.

A

n. thoracodorsalis (C6 - 8)

accompanies a. thoracodorsalis caudally to come to lie medially to m. latissimus dorsi

→ m. latissimus dorsi + m. teres major

38
Q

Nerve?

Pathway, branches + function.

A

n. axillaris (C5 - 6)

originates from fasciculus post., runs in dorsal direction → giving off n. cutaneus brachii lat. sup. → lateral upper half of arm

runs together w/ a. circumflexa humeri post. through quadrangular space → ​m. deltoideus + m. teres minor

39
Q

List all branches of fasciculus posterior.

Spinal origin?

A
  • n. axillaris (C5 - 6)
  • n. radialis (C5 - T1)
  • nn. subscapulares (C5 - 7)
  • n. thoracodorsalis (C6 - 8)
40
Q

Nerve?

Pathway.

A

n. radialis (C5 - T1)

  1. continuation of fasciculus post., enters together w/ n. medianus and n. ulnaris sulcus bicipitalis medialis
  2. together w/ a. profunda brachii dorsally to triangular interval
  3. enters sulcus n. radialis
  4. emerges sup. to cubital region, reaches it laterally btw m. brachioradialis and m. brachialis to bifurcate into terminal nerves
41
Q

What are the borders of the triangular interval?

Contents.

Other names?

A

= triceps hiatus

  • cran.: m. teres major
  • med.: humerus
  • lat.: caput longum m. tricipitis brachii

→ contains a. profunda brachii + n. radialis

42
Q

What is the general function of n. radialis?

A
  • ALL extensors of forearm, hand, finger
  • sensory innervation of
    • lat. side of arm
    • dorsally 2,5 radial fingers
43
Q

Which branches are given off by n. radialis?

A

in craniocaudal direction, 7 branches

  • n. cutaneus brachii post.
  • n. cutaneus brachii lat. inf.
  • branches to m. triceps brachii
  • n. cutaneus antebrachii post.
  • branches to m. brachioradialis, m. extensor carpi radialis long., brev.
  • 2 terminal branches
    • ​r. superficialis
    • r. profundus

lower mm. branches not shown

44
Q

Describe the sensory innervation of n. radialis.

A

4 branches

  1. n. cutaneus brachii post.: dorsal arm
  2. n. cutaneus brachii lat. inf.: lat. arm
  3. n. cutaneus antebrachii post.: rad. side of forearm
  4. r. superficialis + nn. digitales dorsales: dorsum of hand + 2,5 fingers - middle phalanges

​

45
Q

Nerve?

Pathway + function.

A

n. radialis r. superficialis
originates from n. radialis after bifurcation in cubital region

  1. accompanies a. radialis
  2. exits dorsally at lower 2/3 of forearm
  3. gives off nn. digitales dorsales at dorsum of hand

→ sensory innervation of dorsal 2,5 fingers - middle phalanges

11

46
Q

Nerve?

Pathway, branches + function.

A

n. radialis r. profundus
originates from n. radialis after bifurcation in cubital region, pierces m. supinator in canalis supinatorius, then

  • mm. branches to all remaining extensors
  • terminates as n. interosseus antebrachii post.
    → sensory innervation of dorsum of wrist
47
Q

How do you call the fascia of m. supinator?

A

Frohse-Fränkel arcade

48
Q

List all branches of fasciculus lateralis.

Spinal origin?

A
  • n. musculocutaneus (C5 - 7)
  • n. medianus, radix lateralis (C6 - 7)
  • n. pectoralis lat. (C5 - 7)
49
Q

Nerve?

Pathway + function.

A

n. musculocutaneus (C5 - 7)

from fasciculus lateralis, pierces m. coracobrachialis, then

  • branches to flexors of arm + m. coracobrachialis
  • exits as n. cutaneus antebrachii lat. → sensory innervation of radial side of forearm
50
Q

Nerve?

Pathway + function.

A

n. medianus

  1. radix lat. (C6 - 7) from fasciculus lat., radix med. (C8 - T1)
  2. sulcus bicipitalis medialis w/ n. ulnaris till cubital region
  3. emerges btw heads of m. pronator teres
  4. runs btw sup. and deep. flexors of fingers to hand
  5. through canalis carpi → terminal branches

→ most flexors of forearm + thenars + mm. lumbricales I, II, sensory innervation of radial 3,5 fingers on palmar side

51
Q

Which branches are given off by n. medianus?

Where?

A

in craniocaudal direction

  • mm. branches for flexors of forearm (exc. m. flexor carpi ularnis + uln. part of m. flexor digitorum prof.
  • n. interosseus antebrachii ant.
  • r. palmaris: before retinaculum flexorum
  • 3 nn. digitales palmares communes: in palm of hand
52
Q

Which mm. are innervated by n. medianus (directly and indirectly)?

Differentiate (7, 4).

A

forearm - most flexors, all pronators

  • m. flexor carpi radialis
  • m. flexor digitorum profundus, radial half
  • m. flexor digitorum superficialis
  • m. flexor pollicis longus
  • m. palmaris longus
  • m. pronator quadratus
  • m. pronator teres

​thenar mm. - exc. adductor + lumbricales

  • m. abductor pollicis brevis
  • m. flexor pollicis brevis, caput superficiale
  • m. opponens pollicis
  • mm. lumbricales I, II
53
Q

Nerve?

Pathway + function.

A

n. interosseus antebrachii ant.

originates from n. medianus, runs together w/ a. interossea ant. on membrana interossea to m. pronator quadratus

→ m. flexor pollicis longus, m. pronator quadratus, m. flexor digitorum profundus (radial parts)

54
Q

What is the function of nn. digitales palmares communes?

A

3 nn., branches of n. medianus

  • branches to innervate thenar (exc. adductor) + mm. lumbricales I, II
  • r. communicans to n. digitalis communicans IV of n. ulnaris
  • 7 nn. digitales palmares proprii to provide sensory inn. of radial 3,5 fingers on palmar side, terminal phalanges also on dorsal side
55
Q

List all branches of fasciculus medialis w/ their respective spinal orgins.

A

all from C8 - T1

  • n. medianus, radix medialis
  • n. ulnaris
  • n. cutaneus brachii medialis
  • n. cutaneus antebrachii medialis
  • n. pectoralis medialis
56
Q

Nerve?

Pathway.

A

n. ulnaris

from fasciculus medialis C8 - T1, runs in sulcus bicipitalis medialis w/ n. medianus, pierces septum intermusculare brachii med., runs to epicondylus medialis in sulcus n. ulnaris, together w/ a. ulnaris through Guyon’s canal, then branches into terminal nn.

57
Q

Which branches are given off by n. ulnaris?

Where?

A

in craniocaudal direction, 6 branches

  • r. articularis cubiti: in elbow joint
  • mm. branches for m. flexor carpi ulnaris, ulnar half of m. flexor digitorum profundus
  • r. dorsalis n. ulnaris: dorsally, at half of forearm
  • r. palmaris: before retinaculum flexorum
  • r. profundus: terminal branch
  • r. superficialis: terminal branch

r. articularis cubiti not shown

58
Q

Which mm. are innervated by n. ulnaris (directly and indirectly?

A

2 forearm mm.

  • m. flexor carpi ulnaris
  • m. flexor digitorum profundus, ulnar half

hypothenar

  • m. flexor brevis digiti minimi
  • m. abductor digiti minimi
  • m. opponens digiti minimi

further hand mm.

  • mm. interossei
  • mm. lumbricales III, IV
  • m. flexor pollicis brevis, caput profundum
  • m. adductor pollicis
59
Q

Which nn. are responsible for sensory innervation of n. ulnaris?

Explain.

A
  • r. dorsalis n. ulnaris: to dorsal side of hand, branches into nn. digitales dorsales
  • r. palmaris: innervation of hypothenar
  • r. superficialis: terminal branch, gives off n. digitalis palmaris communis + 3 nn. digitales palmares proprii

→ ulnar half of 2,5 fingers dorsally, 1,5 ulnar fingers ventrally

60
Q

Nerve?

Pathway + function.

A

r. profundus n. ulnaris
= motor terminal branch

runs w/ arcus palmaris profundus

→ hypothenar, mm. interossei, mm. lumbricales III, IV, m. adductor pollicis, m. flexor pollicis brevis, caput profundum

<u>NOTE:</u> r. superficialis = sensory terminal branch

61
Q

Nerve?

Pathway + function.

A

n. cutaneus brachii medialis

from fasciculus medialis C8 - T1, anastomoses w/ n. intercostobrachialis (of 2nd/3rd n. intercostalis), branches in axillary region

→ dermal innervation of medial side of arm (cf. picture, 1)

62
Q

Nerve?

Pathway + function.

A

n. cutaneues antebrachii med.

from fasciculus medialis C8 - T1, runs in sulcus bicipitalis medialis, pierces together w/ v. basilica the fascia, branches into r. volaris and r. ulnaris

→ dermal innervation of ulnar side of forearm (cf. picture, 2)

Anatomy III (13 decks)

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