7). FIB Basal Ganglia, Thalamus, Somatosensory and Motor Pathways

Comprehensive review flashcards on neuroanatomy covering the thalamus, basal ganglia, somatosensory pathways, trigeminal sensory system, and motor pathways.

The __________ is a small, egg-shaped structure in the brain that acts as a relay station for most sensory information (except smell).

thalamus

The thalamus acts as a relay station for most sensory information, except __________.

smell

All visual information from the retina travels via the optic tracts to the __________ for processing before being sent to the primary visual cortex.

Lateral Geniculate Nucleus (LGN)

From the Lateral Geniculate Nucleus, visual information is sent to the primary visual cortex located in the __________ lobe.

occipital

The __________ colliculi are paired dorsal midbrain structures involved in processing optical stimuli, orienting attention, and coordinating eye and head movements.

superior

Superior colliculi are located on the dorsal aspect of the __________ structure of the brainstem.

midbrain

The basal ganglia are a subcortical collection of interacting clusters of cell bodies involved in __________, emotional, and motor circuits.

reward

The basal ganglia consist of six main subcortical structures: Caudate, Putamen, Nucleus Accumbens, Globus Pallidus, Substantia Nigra, and __________.

Subthalamic Nucleus

Disorders affecting the basal ganglia, such as __________ disease, can significantly disturb motor control including eye movements.

Parkinson's

The center of joy in the central nervous system is known as the __________.

Nucleus Accumbens

The __________ system gives "meaning" to what the eyes see by integrating raw visual data with emotions, memory, and behavior.

limbic

The somatosensory pathways consist of ascending pathways from the body to the __________ gyrus in the cerebral cortex.

postcentral

The DC/ML system stands for Posterior column–__________ lemniscus system.

medial

The DC/ML pathway carries __________ discriminative touch, pressure, proprioception, and vibration perception.

fine

The Anterolateral system (Spinothalamic tract) carries sensory signals for __________, temperature, and crude touch.

pain

Spino-cerebellar tracts carry __________ information to the cerebellum.

proprioception

Merkel's disks, Meissner's corpuscles, Ruffini endings, and Pacinian corpuscles are classified as __________.

mechanoreceptors

Nociceptors consist of __________ nerve endings.

free

Thermoreceptors in the skin are __________ nerve endings.

specialized

Proprioceptors are found deep in __________ and joints to sense body position and movement.

muscles

For sensory signals from the body, the cell bodies of first-order neurons are located in the __________ root ganglion.

dorsal

For sensory signals from the face, the cell bodies of first-order neurons are located in the __________ ganglion.

Trigeminal

First-order neurons begin the sensory journey by carrying signals from sensory receptors to the __________.

central nervous system (CNS)

Second-order neurons relay sensory signals from the first-order neuron to the __________.

thalamus

For body somatosensation, second-order neuron cell bodies are located in the dorsal horn of the spinal cord or __________ nuclei.

medullary

For facial somatosensation, second-order neuron cell bodies are located in the trigeminal sensory nuclei in the __________.

brainstem

Third-order neurons transmit sensory signals from the thalamus to the __________ cortex.

cerebral

For sensory signals from the body, third-order neurons originate in the __________ nucleus of the thalamus.

Ventral posterolateral (VPL)

For sensory signals from the face, third-order neurons originate in the __________ nucleus of the thalamus.

ventral posteromedial (VPM)

The somatosensory cortex pathway proceeds from primary somatosensory cortex to secondary somatosensory cortex in the parietal operculum, then to the posterior parietal lobule areas $5$ and __________.

$$7$$

The muscle spindle is the major __________ receptor within muscles.

stretch

Stresses and forces at tendons and joints are monitored by Golgi tendon organs and __________ afferents.

joint

Proprioceptive information from the spinocerebellar tract primarily targets the __________ for minute-by-minute feedback.

cerebellum

The proprioceptive spinocerebellar tract arises primarily from $A\alpha$ afferents, which are the largest and __________ axons.

fastest

Nerve fibers of type $A\alpha$ have a diameter of __________ and a conduction velocity of $70\text{--}120\,\text{m/s}$.

$$12\text{--}20\,\mu\text{m}$$

According to the nerve fiber classification, type $A\beta$ fibers carry pressure and touch, with a conduction velocity of __________.

$$30\text{--}70\,\text{m/s}$$

Type $A\gamma$ nerve fibers innervate the __________ and have a diameter of $3\text{--}6\,\mu\text{m}$.

muscle spindle

Type $A\delta$ nerve fibers carry touch, cold temperature, and __________ pain.

fast

Type B nerve fibers carry autonomic signals with a conduction velocity of __________ and diameter of $< 3\,\mu\text{m}$.

$$3\text{--}15\,\text{m/s}$$

Type C nerve fibers carry autonomic signals and __________ pain, with a conduction velocity of $0.7\text{--}2.3\,\text{m/s}$.

slow

Any sensory system going to the cerebral cortex crosses over because the cerebral cortex operates on a __________ basis.

contralateral

The discriminative touch system decussates high in the __________.

medulla

The pain system decussates low, in the __________.

spinal cord

Fibers of the proprioceptive system going to the cerebellum operate on an __________ basis.

ipsilateral

The three main branches of the trigeminal nerve are Ophthalmic ($V1$), Maxillary ($V2$), and __________.

Mandibular ($V3$)

Ophthalmic division of the trigeminal nerve is designated as __________.

$$V1$$

Cell bodies of first-order trigeminal neurons reside in the Trigeminal ganglion, also known as the Semilunar or __________ ganglion.

Gasserian

The four nuclei associated with the trigeminal system are Mesencephalic nucleus, Sensory nucleus, Motor nucleus, and __________ nucleus.

Spinal

The primary mechanoreceptor present in the periodontal ligament (PDL) is the __________ ending.

Ruffini

In the trigeminal pathway for touch and proprioception, second-order neurons are located in the __________ sensory nucleus.

Main

In the trigeminal pathway for pain and temperature, second-order neurons are located in the __________ nucleus.

Spinal Trigeminal

The corneal blink reflex tests the function of Cranial Nerve __________.

$$V$$

The corneal blink reflex is mediated by poly-synaptic connections in the brainstem between the trigeminal nerve ($CN\,V$) and the __________ nerve ($CN\,VII$).

facial

Trigeminal Neuralgia is also known by the French term __________.

Tic Douloureux

Pain attacks in Trigeminal Neuralgia typically last for __________ duration.

$$< 1\,\text{minute}$$

In Trigeminal Neuralgia, pain is most often in the distribution of the Maxillary or __________ branch.

Mandibular

Trigeminal Neuralgia onset is typically after age __________.

$$40$$

Stretch reflexes are elicited in response to stimuli to tendons and are __________ in synaptic complexity.

monosynaptic

The withdrawal reflex and corneal blink reflex are classified as __________ reflexes.

polysynaptic

Motor pathways that control voluntary movement are categorized as __________ tracts.

pyramidal

The __________ tract controls voluntary muscles of the head and face.

Corticobulbar

The __________ tract controls voluntary movement of the trunk and limbs.

Corticospinal

Motor innervation from the corticobulbar tract to cranial nerve nuclei is primarily bilateral, with the exception of cranial nerve nucleus __________.

$$7$$

Corticobulbar upper motor neuron axons descend within the internal capsule to the medial part of the cerebral peduncle, known as the __________.

Crus cerebri

Approximately __________ percent of corticospinal axons decussate in the lower medulla to form the lateral corticospinal tract.

$$85\%$$

The uncrossed fibers of the corticospinal tract ($15\%$) form the __________ corticospinal tract.

Anterior

Damage to Upper Motor Neurons can result in exaggerated muscle reflexes, known as __________ paralysis.

spastic

Loss of Lower Motor Neurons leads to weakness, muscle twitching, and atrophy, known as __________ paralysis.

flaccid

The presence of a __________ reflex (where the great toe flexes upward and toes fan out) indicates damage to the corticospinal tract.

Babinski's

Decorticate rigidity occurs with lesions located above the __________ nuclei, whereas decerebrate posture occurs with lesions between those nuclei and the vestibular nuclei.

red