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Structure And Function 2-3 > Brainstem Anatomy > Flashcards

Brainstem Anatomy Flashcards

1
Q

What are the pyramids in the medulla

A

The descending axons of the corticospinal tract

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2
Q

Where do the axons or the corticospinal tract originate

A

The sensorimotor strip= broadmans areas 4,3,1, and 2.

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3
Q

Describe the tract of the axons of the corticospinal tract once they leave the sensorimotor strip

A

They course down ipsilaterally through the posterior limb of the interior capsule, the middle 1//3 of the crus cerebri, the pons, and emerge on the ventral surface of the medulla as the pyramids

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4
Q

Where do the axons of the corticospinal tract cross in the brainstem

A

The pyramidal decussation, which is the caudal most medulla.

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5
Q

After they decussate in the medulla, where do the axons of the corticospinal tract take place in the spinal cord and wat are they then called

A

They will take up a lateral position in the spinal cord and will travel as the lateral corticospinal tract before exiting at appropriate levels onto LMNs in the lateral part of the anterior horn of the spinal cord grey matter

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6
Q

A patient with a unilateral lesion above the decusation of the pyramids will show what motor signs and symptoms on what side of the body

A

Contralateral

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7
Q

A patient with a unilaterally lesion caudal to the pyramids wil show signs and symptoms on what side of the body

A

Ipsilateral

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8
Q

What type of information do the spinothalamics relay

A

Information about pain and temperature

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9
Q

Describe the pathway of the spinothalamic pathway, specifically the lateral spinothalamic tract

A

1st order neurons are found in the DRG, axons enter the SC, ascend 1-2 segments, and synapse on lamin of reed 1,2, and 5. Axons of 2nd order neurons cross immediately and the up ventrolateralposition in the spinal cord and ascend as the lateral spinothalamic tract.

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10
Q

What will the anterolateral system be called int he rostral medulla

A

The spinal lemniscus

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11
Q

How will a patient present if they have a unilateral lesion of the sympathetic axons passing through the medulla on their way to the intermediolateral cell column (T1-L2)

A

Ipsilateral horners syndrome=miosis, ptosis, and anhydrosis

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12
Q

Which axons are heavily myelinated

A

Aa and Ab

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13
Q

What information do the dorsal columns carry

A

Fine touch, vibration, and conscious proprioception ipsilaterally

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14
Q

Describe the pathway of the dorsal columns

A

1st order neurons (DRG) will travel ipsilaterally in the SC as the fasiculus gracillis(medial) and cuneatus(lateral) and synapses int he nucleus gracilis/cuneatus in the medulla. These axons will then cross immediately (called the internal arcuate fibers) and then be known as the medial lemniscus projecting to S1

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15
Q

Where is the leg represented in the dorsal columns and the medullary dorsal column nuclei

A

Medially

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16
Q

After the second order neurons have entered the medial lemniscus, where is the leg represented

A

Ventrally/laterally in the pons

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17
Q

What does the dorsal motor nucleus control

A

Viscera of the thorax and abdomen

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18
Q

Nucleus ambiguous is the outflow of what cranial nerves

A

IX and X

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19
Q

What type of gaze center will be in the pons

A

Horizontal gaze center

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20
Q

Which cranial nerve can give you a false localizing sign

A

CN VI

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21
Q

What is the motor component of CN 5

A

Innervation of the muscles of mastication and a small portion of the acoustic reflex.

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22
Q

What are the sensory components of CN5

A

Pain, temperature, fine touch, vibration, conscious proprioception, and unconscious proprioception

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23
Q

Where is the spinal tract and the spinal nucleus of CN V and what is to function

A

Located in the medulla, and it is responsible for processing and conveying pain and temperature information front he head/face to higher order structures in the brain

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24
Q

Describe the course of the pathway for the spinal tract/nucleus of CN V

A

1st order lie in the trigeminal ganglion (A delta and C axons), central processes enter the brainstem at the pons and descend int he dosolateral area of the brainstem as the spinal trigeminal tract to synapse int he spinal trigeminal nucleus(corresponds to the dorsolateral fasiculus of lissaur). Central processes form the spinal trigeminal neuron (2nd order) decussate and ascend as the TTT and synapse int he medial division of the ventral posterior nucleus (VPM) in the thalamus.

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25
Q

What will the result of a lesion of the spinal tract of V result in

A

Loss of pain and temperature in the ipsilateral face

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26
Q

What will the result of a lesion of the TTT result in

A

Contralateral loss of pain and temperature because the TTT, by definition, is a crossed pathway.

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27
Q

What is the function of Clarke’s Nucleus and where would you expect to find it

A

Located in the spinal cord levels (C8-L2) receives proprioceptive info collateral s and sends axons to the inferior cerebellar peduncle to the cerebellum. 2d order neurons will make put he cuneocerebellar tract which relays proprioceptive info C8 and up

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28
Q

What level of the brainstem would you expect to find the hypoglossal nucleus.

A

Most medial in the dorsal medulla just ventral to the 4th ventricle.

29
Q

What isn’t he one muscle of the tongue that is not innervated by CN 12

A

Palatoglossus

30
Q

UMN lesion of CN12 results in what

A

Contralateral weakness of the genioglossus resulting in tongue deviation away from the weak side and away from the side off the lesion

31
Q

A unilateral lesion of the LMN of CN 12 will result in what

A

Atrophy and fasiculation with the tongue deviating to the side of the lesion

32
Q

Where does the dorsal motor nucleus of CN X lie

A

The dorsal medulla lateral to the hypoglossal nucleus

33
Q

Where is the nucleus ambiguous located and what does it contain

A

It contains the LMS of IX and X that innervate the soft palate, larynx, pharynx, and upper esophagus,, and it lies dorsal to the inferior olive and medial tot he spinal trigeminal tract/nucleus of the anteriolateral system of the medulla

34
Q

Lesions of the nucleus ambiguous will result in what clinical presentation

A

Dysphagia(trouble swallowing), dysphonia(difficulty speaking), dyspnea(difficulty breathing), and a deviated uvula towards the normal side. Also a loss of the gag reflex

35
Q

Where is the localization of the vestibular nuclei and what is the clinical presentation of a lesion involving it

A

Located int he dorsal medulla and vertigo is how it would present clinically

36
Q

What in the major blood supply to the vestibular nuclei

A

The PICA

37
Q

What isn’t he major blood supply ot the dorsal and ventral cochlear nulcei

A

The AICA

38
Q

What will a unilateral lesion of the dorsal and ventral cochlear nuclei result in

A

Ipsilateral deafness

39
Q

What is the main function of the medullary reticular formation

A

It contains the cardiovascular and respiratory centers

40
Q

What CN’s are contained int he pontine tegmentum of the caudal pons

A

CN’s 6 and 7 as well as the ascending sensory pathways (denial and spinal lemniscus)

41
Q

Unilateral lesion of VI results in what

A

Medial strabismus (bc of unopposed medial rectus) and horizontal diplopia

42
Q

Why can CN 6 give a false localizing sign

A

In exits the brain stem and travels a long distance in the subarachnoid space. Issues here can show LMN signs for 6 but not be from issues in the brainstem

43
Q

Where is the horizontal gaze center located

A

The pons

44
Q

A unilateral lesion in the caudal pons involving the motor nucleus of CN 7 will result in what

A

Paralysis of the entire face ipsilateral to the lesion

45
Q

Where is the trapezoid body located and what does it do

A

It is involved in auditory system projections. And axons of the dorsal and ventral cochlear nucleus ducussate in the lower part of the pontine tegmentum

46
Q

What is the function of the superior oligarchs nucleus SON

A

It plays a role in sharpening the tonotopy of the auditory system as well as in the acoustic reflex

47
Q

What is the MCP and what does it do

A

The middle cerebellar peduncle allows the cerebral cortex to communicate with the cerebelllum

48
Q

Where is the chief (principal, main, superior,pontine) sensory nucleus of V located, and what is its main function

A

It is located in the rostral/midpons and it relays information about discriminative touch, vibration, and conscious proprioception from the face

49
Q

Describe the course of sensory information from the face

A

Afferent axons from all 3 division of V enter the lateral pons and synapse in the chief sensory nucleus of V. 2nd order neurons them decussate and ascent to the VPM via the TTT. The VPM then projects to the primary somatosensory cortex

50
Q

What is the nucleus locus coeruleus, where does it lie, and what is its clinical correlation

A

It is found in the dorsolateral part of the rostral pontine tegmentum and it is involved in arousal, response to stress, pain modulation, mood, and it is one of the nuclei that undergo degeneration in both Alzheimer’s and Parkinson’s disease.

51
Q

What are the fascicles of the pontine nuclei involved in

A

Corticospinal and corticobulbar tracts and some send collaterals to the cerebellum

52
Q

What is the function of the superior coliculus

A

It plays a role in visual reflexes and facilitates sudden, reactive, fovation

53
Q

What are the main outputs of the superior coliculus

A

To the cervical spinal cord(turn head), horizontal and vertical gaze centers (conjugate eye movements) and the the pulvinar (relay visual info to the extrastriate visual cortex)

54
Q

What is one of the main functions of the inferior coliculus

A

It is involved in auditory reflexes and relays auditory information to the thalamus

55
Q

Where is the occulomotor nuclear complex located

A

Dorsi medially in the midbrain at the level of the superior colliculus

56
Q

A unilateral lesion of the LMN of 3 result in what

A

Occulomotor opthalmoplegia

57
Q

Where is the troclear nucleus located

A

The dorsal midbrain at the level of the inferior colliculus

58
Q

What are the major structures associated with the midbrain tegmentum

A

CN 3/4, PAG, ascending/descending fibers ofthe superior cerebellar peduncle, the red nucleus, medial/spinal/lateral lemniscus, TTT, and medial longitudinal fasiculus

59
Q

Unilateral LMN lesions of CN 4 result in what

A

Contralateral extortion and elevation of he eye (due to the unopposed action of the IO)

60
Q

What are the major contents of the PAG

A

Mesencephallic nucleus of V(unconscious proprioception), neurons of descending regulation of the lateral spinothalamic tract, and the vertical gaze center

61
Q

What is the function of the superior cerebellar peduncle

A

It connects the cerebellum with the red nucleus of the midbrain and the motor relay nuclei of the thalamus. It decussate in the midbrain at the level of the inferior colliculus

62
Q

What is the function of the red nucleus

A

It rexevies input from the cerebellum and its output is art of the indirect corticospinal tract

63
Q

What is a rubral tremor

A

A tremor of the contralateral upper arm resulting from a lesion of the red nucleus

64
Q

Unilateral lesion above the red nucleus produce what

A

Decorticating posturing contralaterally (flexion of the. Arm and extension of the leg)

65
Q

A unilateral lesion below the red nucleus(but above the vestibular nucleus) result in what

A

Decerebrate posturing contralaterally (extension of both arm and leg) because of unopposed activity of the vestibulospinal tracts

66
Q

What are the major components of the basal midbrain

A

The substanitia nigra and the crus cerebri

67
Q

What are the major components of the substantia nigra

A

The pars compacta and th pars reticularis

The pars compacta (Dopamine) degeneration results in Parkinson’s

68
Q

What NT does the pars reticularis utilize

A

GABA

69
Q

What are the functional distinctions of the crus cerebri (3)

A

The middle 1/3 contains the descending corticobulbar and corticospinal tract axons

Middle 1/3 containsdescending axons from the frontal lobe on their way to the pons

Lateral 1/3 contain axons from the parietal, occipital, and temporal lobes on their way to the pons

Structure And Function 2-3 (14 decks)

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