Neuroanatomy

Question 1

Striatum

Answer 1

Caudate+Putamen

Question 2

Lentiform

Answer 2

Globus pallidus+Putamen

Question 3

Direct pathway

Answer 3

Projects from cortex -(+)-> striatum -(-)-> GPi/SNr -(-)-> thalamus (+). Named because signal heads directly to GPi/SNR.
(+) Glu, (-) GABA
Increases excitatory thalamic output to the cortex
INCREASES MOTOR ACTIVITY
Dopamine from SNc acts on striatum via D1 receptors, enhancing response to glutamate, resulting in increased motor activity

Question 4

Indirect pathway

Answer 4

From cortex -(+)-> striatum -(-)->GPe -(-)-> STN -(+)->GPi/SNr -(-)-> thalamus (+).
Detours at GPe and STN.
(+) Glu, (-) GABA
Decreases excitatory thalamic output to the cortex
DECREASES MOTOR ACTIVITY
Dopamine from SNc acts on striatum via D2 receptors, decreasing response to glutamate, resulting in increased motor activity

Question 5

Striatal projects in the basal ganglia

Answer 5

Primarily inhibitory

Question 6

Dopamine in the direct pathway

Answer 6

From substantia nigra, pars compacta → striatum (via nigrostriatal projections)
Enhances striatal response to glutamate via D1 receptors (more activation)
Increases GPi and SNr inhibition by striatum
INCREASES MOTOR ACTIVITY

Question 7

Dopamine in the indirect pathway

Answer 7

Substantia nigra, pars compact → striatum (via nigrostriatal projections
Decreases striatal response to glutamate via D2 receptors
Decreases striatal inhibition on GPe→Increases STN inhibition by GPe→Decreases activation of GPi and SNr
INCREASES MOTOR ACTIVITY

Question 8

Acetylcholine in BG

Answer 8

Aspiny neurons - striatal interneurons, release ACh
Excite both pathways – BU prefer the indirect pathway
Anticholinergic medications (trihexyphenidyl, benztropine, procyclidine) can be beneficial in Parkinson’s disease

Question 9

Primary output nuclei from the basal ganglia

Answer 9

The internal segment of the globus pallidus sends outputs to the thalamus through the ansa lenticularis and the lenticular fasciculus.
Each enters into the thalamic fasciculus to synapse on VL (ventrolateral) and VA (ventral anterior) of the thalamus.
VA nucleus of the thalamus later projects to the premotor cortex and is responsible for initiating movement
VL nucleus of the thalamus projects to the primary motor, supplementary motor, and premotor cortices and assists with initiation and learning of skilled movements.<p></p>

Question 10

Parkinson’s disease BG lesio

Answer 10

SNc degeneration: Loss of dopamine→net inhibition of the thalamus
DECREASES MOTOR ACTIVITY

Question 11

Hemiballismus BG lesion

Answer 11

Subthalamic nucleus lesion → reduced thalamic inhibition
INCREASES MOTOR ACTIVITY CONTRALATERAL TO THE LESION

Question 12

Huntington’s disease BG lesion

Answer 12

Degeneration of striatal neurons in caudate and putamen
More severe damage to the indirect pathway→reduced thalamic inhibition
INCREASES MOTOR ACTIVITY
**Eventually all striatum degenerates à hypokinetic, parkinsonian

Question 13

Basal ganglia circuity other. name

Answer 13

Cortico-striato-thalamo-cortical

Question 14

<p>D2 receptors and prolactin</p>

Answer 14

<p>D2 receptors are found in the pituitary gland; activity at D2 receptors in the pituitary inhibits prolactin release, hence the hyperprolactinemia seen in patients taking antipsychotics (which antagonize D2 receptors).</p>

Question 15

VPM thalamus

Answer 15

Somatosensory information from the contralateral face
-Pain (spinal nucleus of CN V)
-Temperature (spinal nucleus of CN V)
-Fine touch (chief sensory nucleus of CN V)
-Proprioception (mesencephalic nucleus of CN V)
Taste
Visceral pain

Question 16

VPL thalamus

Answer 16

Somatosensory information from the contralateral body

The ventral posterolateral (VPL) nucleus is involved in sensory relay from the body, while the ventral posteromedial (VPM) nucleus is involved in sensory relay from the face, both of which project to the somatosensory cortex.

Question 17

Cheiro-Oral Syndrome

Answer 17

Lacunar syndrome
Contralateral sensory deficits of the hemi-mouth and hand/fingers
Localizes to the VPM and VPL nuclei of the thalamus

Question 18

Thalamic astasia

Answer 18

Lesion to the VPL, supplied by posterior choroidal artery branches of the posterior cerebral artery
Cannot stand or sit unassisted
Fall backwards or to the side opposite of the lesion
Varying degrees of sensory loss
Normal strength

Question 19

Thalamic Vascular Supply

Answer 19

Posterior communicating artery
PCA
Anterior choroidal artery (Lateral thalamus - LGN)

Question 20

Lateral Geniculate Nucleus thalamus

Answer 20

Visual relay nucleus
Optic tract -> LGN -> primary visual cortex

Question 21

Medial Geniculate Nucleus thalamus

Answer 21

Auditory relay nucleus
Inferior colliculus -> MGN -> primary auditory cortex

Question 22

Dorsal medial thalamus

Answer 22

Innervates the entire pre-frontal cortex
Receives input from the amygdala
Involved in control of affect, behavior, executive function
Lesion -> disinhibition, poor executive function

Question 23

Anterior nucleus thalamus

Answer 23

Involved in memory
Hippocampus, hypothalamus, mammillary bodies (mammillothalamic tract) -> AN -> cingulate gyrus
Part of Papez circuit, limbic system
Lesion -> amnesia

The anterior nucleus is mostly involved in limbic relay and memory formation (part of Papez circuit).

Question 24

Fatal familial insomnia

Answer 24

Preferentially affects:
Dorsomedial nucleus (receives input from the amygdala)
Anterior nucleus

Question 25

Pulvinar thalamus

Answer 25

Reciprocal connections with the occipital, parietal and posterior temporal lobes
LGN, MGN, superior colliculur ->pulvinar->integrates visual, auditory and somatosensory input

The pulvinar is involved in processing visual info and sensory integration.

Question 26

Cerebellar anatomy

Answer 26

Question 27

Cerebellum input/output

Answer 27

Input
Inferior and middle cerebellar peduncles

Output
Superior Cerebellar Peduncle

Question 28

Superior cerebellar peduncle

Answer 28

Formed by fibers from the dentate, emboliform, globose and fastigial nuclei

Dentatorubrothalamic tract:
• Fibers enter and surround the contralateral red nucleus
• Effects synergy of movement

Fastigial nucleus: assist in coordinating eye movements and some autonomic functions

Question 29

Cerebellar vascular supply

Answer 29

Superior cerebellar peduncles = SCA
Middle cerebellar peduncles = AICA (+ some SCA)
Inferior cerebellar peduncles = PICA

Question 30

Palatal myoclonus

Answer 30

Rhythmic jerking of the palate & pharyngeal structures
Persists in sleep
Lesions of the triangle of Guillian-Mollaret
Pathology disinhibits the inferior olivary nucleus

The triangle begins in the inferior olive which projects via the inferior cerebellar peduncle to the contralateral dentate nucleus
The dentate nucleus projects via the superior cerebellar peduncle to the ipsilateral red nucleus
The ipsilateral red nucleus completes the triangle by projecting to the ipsilateral inferior olive via the central segmental tract

Question 31

Cellular layers of the cerebellum

Answer 31

Molecular layer
-Basket (-) & stellate cell bodies (-)
-Parallel fibers
-Purkinje cell dendrites (-)
Purkinje cell layer
-Purkinje cell bodies (-)
Granule layer
-Golgi cells (-) & granule cells (+)

(-): inhibitory, (+) excitatory
Climbing and mossy fibers - interneurons that are also (+)

Input: mossy and climbing fibers
Output: Purkinje cells - only cells to emerge from cerebellar cortex and project to the deep cerebellar nuclei

Excitatory: mossy, climbing, granule cells
Inhibitory: Stellate, basket, golgi, purkinje

Question 32

Extraocular muscles

Answer 32

Superior oblique: Depression/intorsion - CN IV
Inferior oblique: Elevation/extorsion - CN III

Superior rectus: Elevation/intorsion - CN III
Inferior rectus: Depression/extorsion - CN III

These do not have a secondary action and only work in the horizontal plane
Medial rectus: Adduction - CN III
Lateral rectus: Abduction - CN VI