Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neuroanatomy III > 25 - Lesions I > Flashcards

25 - Lesions I Flashcards

1
Q

What is a syndrome?

A

A disorder characterized by a set or pattern of symptoms

A “symptom complex”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When referring to a lesion, what does “ipsilateral deficits” mean?

A

The deficits appear ipsilateral (on the same side) as the lesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When referring to a lesion, what does “contralateral deficits” mean?

A

Deficits that appear contralateral (on the opposite side) as the lesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Paresis

A

Weakness (partial paralysis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Hemiparesis

A

Weakness of one side of the body (face, arm, leg)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Palsy

A

Weakness or no movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Paralysis

A

No movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Hemiplegia

A

No movement on one side of the body (face, arm, leg)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is Weber Syndrome?

A

A medial midbrain syndrome that occurs due to a lesion in the rostral (upper) midbrain (1) basis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the two main effects of Weber Syndrome?

A
  • Ipsilateral oculomotor nerve palsy
  • Contralateral hemiparesis

This means that in a patient with Weber Syndrome, you will see a weakness or inability to move the oculomotor nerve (little to no eye movement) on the same side as the lesion and a weakness of the skeletal muscles of the face, arm and leg on the opposite side of the body (contralateral to the lesion)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

If the lesion was on the left, what would be the effect on the oculomotor nerve?

A

Oculomotor nerve palsy on the LEFT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

If the lesion was on the left, what would be the effect on the lateral pterygoid?

A

A muscle of mastication

Weak lateral pterygoid on the RIGHT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

If the lesion was on the left, what would be the effect on the facial muscles?

A

Weak facial muscles on the LOWER RIGHT (upper muscles have “back up” innervation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

If the lesion was on the left, what would be the effect on the musculus uvulae?

A

The musculus uvulae, which lies entirely within the uvula, shortens and broadens the uvula

Remember that the musculus uvulae pulls the uvula towards itself

Weak musculus uvulae on the RIGHT

This means the uvula would deviate towards the left side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

If the lesion was on the left, what would be the effect on the genioglossus?

A

Muscle that functions in sticking out the tongue

Weak genioglossus on the RIGHT side

Since the genioglossus pushes the tongue toward the midline to protrude from the mouth, a weakness on the right side means the left genioglossus will overpower and the tongue will deviate to the right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

If the lesion was on the left, what would be the effect on the extremities?

A

Weak extremities on the RIGHT side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

We know that Weber Syndrome (medial midbrain syndrome) is due to a lesion in the rostral (upper) midbrain (1), but what would specifically cause this lesion?

A

Occlusion of vessels supplying the medial portions of the midbrain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which vessels supply the medial portions of the midbrain?

A
  • Branches of the posterior cerebral artery (PCA)
  • Top of the basilar artery

A vascular lesion involving the above vessels or their branches that infiltrate the rostral (upper) midbrain basis may result in lack of oxygen to major nerve fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which three sets of nerve fibers are affected due to an occlusion of the PCA or top part of the basilar artery?

A
  • Exiting root of the oculomotor nerve
  • Corticonuclear fibers
  • Corticospinal fibers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What type of fibers are found in the exiting root of the oculomotor nerve?

A

GSE and GVE fibers

GSE - general somatic efferent (skeletal muscle innervation)

GVE - general visceral efferent (autonomic fibers to smooth muscle)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does the oculomotor nerve innervate?

A

The IPSILATERAL eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What will occur if the oculomotor nerve is damaged as it exits the midbrain?

A
  • Ipsilateral paralysis of the levator palpebrae superioris (LPS) resulting in ptosis
  • Ipsilateral paralysis of all other extraocular muscles except LR6SO4
  • Eye cannot move medially or vertically
  • Eye is deviated down and out (lateral strabismus)
  • Patient will experience diplopia
  • Ipsilateral dilation of the pupil (mydriasis) which remains in this fixed, dilated position
  • Lens is flat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What do we call the paralysis of the ipsilateral eye muscles innervated by the oculomotor nerve?

A

Ipsilateral oculomotor nerve palsy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Which corticonuclear fibers will be affected in Weber syndrome?

A

The fibers that lie in the basis pedunculi (cerebral peduncles) prior to their distribution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

A lesion that damages teh corticonuclear (UMN) tract in the rostral (upper) midbrain (1) will damage what four nuclei?

A
  • Trigeminal motor nucleus
  • Facial nucleus
  • Nucleus ambiguus
  • Hypoglossal nucleus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Describe the trigeminal motor nucleus

A
  • Located in the midpons
  • Receives bilateral UMN projections, except for the LMNs that innervate the lateral pterygoid muscle
  • The lateral pterygoid muscle receives only contralateral projections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Describe the deficits that will occur with a lesion to the corticonuclear (UMN) tract on the LEFT side in relation to the trigeminal motor nucleus

A
  • Contralateral weakness and paralysis of the lateral pterygoid muscle
  • RIGHT lateral pterygoid will be affected and will be weak
    The jaw will deviate to the right side (weak side) on protrusion of the jaw
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Describe the facial nucleus

A
  • The upper half of the facial nucleus receives bilateral UMN projections
  • The lower half of the facial nucleus receives contralateral UMN projections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe the deficits that will occur with a lesion to the corticonuclear (UMN) tract on the LEFT side in relation to the facial nucleus

A
  • Contralateral weakness and paralysis of the muscles of the lower face
  • RIGHT LOWER facial muscles will be affected and will show weakness/paralysis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Describe the nucleus ambiguus

A
  • Receives bilateral (primarily contralateral) UMN projections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Describe the deficits that will occur with a lesion to the corticonuclear (UMN) tract on the LEFT side in relation to the nucleus ambiguus

A
  • Contralateral weakness and paralysis of the musculus uvulae will occur
  • The RIGHT musculus uvulae will be affected, uvula will be “pulled” to the innervated (intact) side and will deviate to the LEFT when saying “ahhhh”
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Describe the hypoglossal nucleus

A
  • Receives bilateral UMN projections, except for the LMN’s that innervate the genioglossus, which receives only contralateral UMN projections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Describe the deficits that will occur with a lesion to the corticonuclear (UMN) tract on the LEFT side in relation to the hypoglossal nucleus

A
  • Contralateral weakness/paralysis of genioglossus muscle will occur to the RIGHT side of tongue
  • The innervated/intact side “pushes” toungue to deviate toward the weak side (to the right) upon protrusion
  • The tongue will deviate to the RIGHT side
34
Q

Describe the corticospinal fibers affected from Weber Syndrome

A
  • Corticospinal fibers in the basis pedunculi (cerebral peduncles) ABOVE the pyramidal decussation (crossing) are affected by Weber Syndrome
35
Q

What is the result of a lesion affecting the corticospinal fibers prior to decussation?

A

Contralateral weakness (hemiparesis) of the extremities

36
Q

What is Claude Syndrome?

A

A central midbrain syndrome that occurs in the tegmentum of the midbrain

37
Q

What are the overall effects of Claude syndrome?

A
  • Ipsilateral oculomotor nerve palsy

- Contralateral ataxia and tremor of cerebellar origin

38
Q

Occlusion of which vessels will result in Claude syndrome?

A

Occlusion of vessels supplying the central portions of the midbrain

  • Branches of the posterior cerebral artery (PCA)
  • Top of basilar artery
39
Q

There are three structures that are affected by a Claude syndrome lesion and are responsible for the resulting deficits. What are they?

A

1 - Oculomotor nerve fasicles
2 - Red nucleus
3 - Cerebellothalamic fibers

40
Q

Which eye do the oculomotor nerve fascicles innervate?

A

The oculomotor NERVE innervates the IPSILATERAL eye

41
Q

What deficits result from damage to the oculomotor nerve fasicles?

A
  • Ipsilateral paralysis of the levator palpebrae superioris (LPS) resulting in ptosis
  • Ipsilateral paralysis of all extraocular muscles (ipsilateral oculomotor nerve palsy) except LR6SO4
  • Eye cannot move medially or vertically
  • Eye is deviated down and out (lateral strabismus)
  • Diplopia is experienced by patient
  • Ipsilateral dilation of the pupil (fixed mydriasis)
  • Lens is flat
42
Q

What is the red nucleus?

A

A structure in the rostral midbrain involved in motor coordination

There is nothing listed on the hand out in terms of deficits, but the red nucleus is damaged in Claude Syndrome

43
Q

What are cerebellothalamic fibers?

A

The cerebellum gives rise to a group of OUTPUT fibers called cerebellothalamic fibers

44
Q

What is the initial path of the cerebellothalamic fibers?

A

They exit the cerebellum and ascend to the midbrain via the superior cerebellar peduncle (SCP) at the level of the inferior colliculus

45
Q

Where do the cerebellothalamic fibers decussate?

A

When they reach the caudal midbrain, these fibers decussate in the decussation of the superior cerebellar peduncle (SCP) at the level of the inferior colliculus

46
Q

Where do the cerebellothalamic fibers go from here?

A

From here, these fibers continue their ascent to the thalamus which in turn projects to the motor cortex

47
Q

What does the motor cortex control?

A

Movement of the opposite side of the body

48
Q

With a lesion that is ROSTRAL to the superior cerebellar peduncle (SCP) decussation on the RIGHT, what will be damaged?

A

Cerebellothalamic fibers that are carrying information from the contralateral (LEFT) cerebellum

49
Q

What deficits will result from a lesion on the right side, rostral to the SCP?

A

Contralateral (LEFT) ataxia and tremor of cerebellar origin

50
Q

What is Benedikt Syndrome?

A

A medial midbrain lesion combined with a central midbrain lesion

51
Q

What is the overall result of Benedikt syndrome?

A
  • Ipsilateral oculomotor nerve palsy
  • Contralateral hemiparesis
  • Contralateral ataxia, tremor and involuntary movements
52
Q

The occlusion of which vessels results in this damage

A
  • Branches of the posterior cerebral artery (PCA)

- Top of basilar artery

53
Q

There are six structures that are affected by these lesions

A 
1 - Oculomotor nerve fascicles
2 - Corticonuclear fibers
3 - Corticospinal fibers
4 - Red nucleus 
5 - Cerebellothalamic fibers
6 - Substantia nigra
54
Q

What are the deficits that occur with damage to the oculomotor nerve fascicles?

A
  • Ipsilateral paralysis of the levator palpebre superioris (LPS causing ptosis
  • Ipsilateral paralysis of all extraocular muscles (ipsilateral oculomotor nerve palsy) except the LR6SO4
  • Eyes cannot move medially or vertically
  • Eye is deviated down and out (lateral strabismus)
  • Patient experiences diplopia
  • Ipsilateral dilation of the pupil (fixed mydriasis)
  • Lens is flat
55
Q

What deficits occur with damage to the corticonuclear fibers? Where in the tract does the damage occur?

A

The corticonuclear fibers are in the basis pedunculi (prior to their distribution)

CONTRALATERAL weakness and paralysis of the following muscles:

  • Lateral pterygoid muscle
  • Muscles of the lower face
  • Musculus uvulae
  • Genioglossus
56
Q

What deficits occur with damage to the corticospinal fibers? Where in the tract does the damage occur?

A

The corticospinal fibers are in the basis pedunculi (cerebral peduncles) and are damaged prior to their distribution

The result is contralateral weakness (hemiparesis) of the extremities

57
Q

What is the red nucleus?

A

A structure in the rostral midbrain involved in motor coordination

There is nothing listed on the hand out in terms of deficits, but the red nucleus is damaged in Claude Syndrome

58
Q

What is the origin of the cerebellothalamic fibers?

A

Cerebellum

59
Q

Where do the cerebellothalamic fibers exit the cerebellum?

A

Superior cerebellar peduncle

60
Q

What is the path of the cerebellothalamic fibers?

A

They ascend to the caudal midbrain where they decussate in the decussation of the superior cerebellar peduncle, located at the level of the inferior colliculus

61
Q

What occurs with a lesion to the cerebellothalamic fibers ROSTRAL to the superior cerebellar peduncle decussation?

A

Does this mean before or after the decussation? I’m guessing before because symptoms are contralateral.

Contralateral ataxia and tremor (of cerebellar origin) in the paretic (weak) limbs

Remember ataxia is lack of voluntary coordination of muscle movements

62
Q

Describe the relationship that the basal ganglia (including the substantia nigra) has on movement

A
  • Output from the RIGHT basal ganglia (including the substantia nigra) is projected to the RIGHT thalamus
  • The right thalamus in turn projects to the RIGHT motor cortex
  • The right motor cortex controls movement of the LEFT side of the body

So… movement of the left side of the body is influenced by the right basal ganglia (including the substantia nigra)

63
Q

What is the deficit that occurs with damage to the substantia nigra?

A

Contralateral involuntary movements occur (damaged substantia nigra)

64
Q

Compare the motor cortex, basal ganglia and cerebellum in terms of whether they control movement on the opposite side or ipsilateral side of the body

A

Motor cortex - opposite side of body
Basal ganglia - opposite side of body
Cerebellum - ipsilateral side of body

65
Q

Other than an arterial occlusion, what else can cause a midbrain lesion?

A

Demyelinating disease

66
Q

What’s an example of a demyelinating disease?

A

Multiple sclerosis

67
Q

If there is a demyelinating lesion in the caudal (lower) midbrain at the level of the inferior colliculus, where will this be in relation to the decussation of the superior cerebellar peduncle (SCP)?

A

ROSTRAL to the decussation

68
Q

A demyelinating lesion of the caudal midbrain at the level of the inferior colliculus, rostral to the decussation of the SCP will cause damage to which structures?

A
  • Cerebellothalamic fibers
  • Trochlear nucleus
  • Medial longitudinal fasiculus
69
Q

If there is a demyelinating lesion of the caudal midbrain at the level of the inferior colliculus, rostral to the decussation of the SCP on the LEFT side, what will be the effect on the cerebellothalamic fibers?

A

The cerebellothalamic fibers (from the superior cerebellar peduncle) will cause deficits in the RIGHT limbs

  • Intention tremor
  • Dysmetria
  • Dysdiadochokinesia
70
Q

Intention tremor

A
  • A tremor that increases in amplitude as the individual approaches the endpoint of deliberate and visually guided movement
  • An intention tremor is usually perpendicular to the direction of movement

So pretty much, you reach for something and when your hand gets close to the object you’re reaching for, the tremor gets stronger and jerks your hand back away from the object you’re reaching for.

71
Q

Dysmetria

A

A lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye

AKA “past pointing”

72
Q

Dysdiadochokinesia

A

Inability to perform rapid alternating movements such as rapid pronation and supination of the forearm (SPAL test)

73
Q

If there is a demyelinating lesion of the caudal midbrain at the level of the inferior colliculus, rostral to the decussation of the SCP on the LEFT side, what will be the effect on the trochlear nucleus?

A

The LEFT trochlear nucleus will be affected, but the left trochlear nucleus innervates the RIGHT SO4

The RIGHT eye will be deviated upward (hypertropic) and slightly outward (extorted)

74
Q

If there is a demyelinating lesion of the caudal midbrain at the level of the inferior colliculus, rostral to the decussation of the SCP on the LEFT side, what will be the effect on the medial longitudinal fasciculus (MLF)

A

LEFT internuclear ophthalmoplegia (INO) will occur

THe LEFT eye does not turn medially to gaze to the right

75
Q

Larger infarcts that involve the midbrain reticular formation will cause…

A

Impaired consciousness

76
Q

What are some examples of impaired consciousness that results from an infart involving the midbrain reticular fomation?

A
  • Somnolence
  • Delirium
  • Hallucinations
77
Q

What is Perinaud Syndrome?

A

Vertical gaze paralysis that occurs with a lesion in the dorsal rostral midbrain

(the back of the upper part of the midbrain (1))

78
Q

What structures are involved in Perinaud syndrome?

A
  • Vergence center
  • Oculomotor nucleus
  • EW-N
79
Q

What is the resulting deficit for damage to the vergence center in Perinaud syndrome?

A

The vergence center is located in a pretectal area just rostral to the superior colliculus

A deficit that results from damage to the vergence center is the inability to move the eyes vertically (up and down)

80
Q

What is the resulting deficit for damage to the oculomotor nucleus in Perinaud syndrome?

A

We’ve been through this many times… But here you go:

  • Ipsilateral paralysis of the levator palpebre superioris (LPS causing ptosis
  • Ipsilateral paralysis of all extraocular muscles (ipsilateral oculomotor nerve palsy) except the LR6SO4
  • Eyes cannot move medially or vertically
  • Eye is deviated down and out (lateral strabismus)
  • Patient experiences diplopia
  • Ipsilateral dilation of the pupil (fixed mydriasis)
  • Lens is flat
81
Q

What is EW-N?

A

Edinger–Westphal nucleus

AKA accessory oculomotor nucleus

82
Q

What is the Edinger–Westphal nucleus responsible for?

A

The Edinger–Westphal nucleus (accessory oculomotor nucleus) are the parasympathetic pre-ganglionic neurons that originate the oculomotor nerve. It supplies the iris sphincter muscle and the ciliary muscle.

Neuroanatomy III (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions