Mix Examples- Neural Control and Coordination Questions in English

(C) $(i)$ Correct: The $Ramus$ $dorsalis$ (dorsal ramus) is a mixed nerve containing both sensory and motor fibres.
(ii) Incorrect: Preganglionic nerve fibres arise only from specific segments of the spinal cord (thoracolumbar and craniosacral regions).
(iii) Correct: There are $31$ pairs of spinal nerves in humans.
(iv) Incorrect: The somatic nervous system transmits impulses from the $CNS$ to skeletal muscles,not visceral organs.
$(v)$ Incorrect: Reflex actions are involuntary,automatic,and rapid responses to a stimulus,not thoughtful or voluntary.

(B) Cranial nerves are classified as sensory,motor,or mixed based on their function.
$i$. Pathetic (Trochlear nerve,$IV$): Motor nerve.
$ii$. Trigeminal (Cranial nerve $V$): Mixed nerve (sensory and motor).
$iii$. Facial (Cranial nerve $VII$): Mixed nerve (sensory and motor).
$iv$. Auditory (Vestibulocochlear nerve,$VIII$): Sensory nerve.
$v$. Glossopharyngeal (Cranial nerve $IX$): Mixed nerve (sensory and motor).
Therefore,the mixed cranial nerves are $ii$ (Trigeminal),$iii$ (Facial),and $v$ (Glossopharyngeal).

(D) Alzheimer's disease is a progressive neurodegenerative disorder characterized by the following features:
$1$. It involves the loss of cholinergic and other neurons in the $CNS$ (Central Nervous System),which leads to a decline in cognitive functions such as thinking,memory,and reasoning.
$2$. $A$ hallmark pathological feature is the accumulation of amyloid-beta protein plaques in the brain.
$3$. Statement $(a)$ is incorrect because the degeneration of dopamine-producing neurons is characteristic of Parkinson's disease,not Alzheimer's.
$4$. Statement $(b)$ is incorrect as it is primarily a neurodegenerative/cognitive disorder,not a physical disorder in the general sense.
Therefore,statements $(c)$,$(d)$,and $(e)$ are correct.

(A) The cranial nerves are a set of $12$ pairs of nerves that emerge directly from the brain. The sequence is as follows:
$I$: Olfactory
$II$: Optic
$III$: Oculomotor
$IV$: Trochlear
$V$: Trigeminal
$VI$: Abducens
$VII$: Facial
$VIII$: Vestibulocochlear (Auditory)
$IX$: Glossopharyngeal
$X$: Vagus
$XI$: Spinal accessory
$XII$: Hypoglossal
Therefore,$II$ is Optic,$III$ is Oculomotor,$VI$ is Abducens,and $XI$ is Spinal accessory. The correct option is $A$.

(C) Statement-$I$ is correct: Parkinson's disease is a neurodegenerative disorder primarily caused by the loss of dopaminergic neurons in the substantia nigra of the brain.
Statement-$II$ is correct: Cocaine acts as a stimulant by blocking the reuptake of dopamine in the synaptic cleft,which leads to an increased concentration and prolonged effect of dopamine in the brain's reward pathways.
Therefore,both statements are correct.

(C) The cranial nerves involved in the movement of the eye muscles are the Oculomotor $(III)$,Trochlear $(IV)$,and Abducens $(VI)$ nerves.
$1$. Oculomotor nerve $(III)$: Innervates most of the extrinsic eye muscles.
$2$. Trochlear nerve $(IV)$: Innervates the superior oblique muscle of the eye.
$3$. Abducens nerve $(VI)$: Innervates the lateral rectus muscle of the eye.
$4$. The Hypoglossal nerve $(XII)$ is the $12^{th}$ cranial nerve and it primarily controls the muscles of the tongue,not the eye muscles.
Therefore,the Hypoglossal nerve does not innervate eye muscles.

(A) Cranial nerves are classified based on their function into sensory,motor,and mixed nerves.
$1$. Sensory nerves carry impulses from sense organs to the brain (e.g.,$I, II, VIII$).
$2$. Motor nerves carry impulses from the brain to muscles or glands (e.g.,$III, IV, VI, XI, XII$).
$3$. Mixed nerves contain both sensory and motor fibers (e.g.,$V, VII, IX, X$).
- Trigeminal $(V)$: Sensory for face,motor for chewing.
- Facial $(VII)$: Sensory for taste,motor for facial expression.
- Glossopharyngeal $(IX)$: Sensory for taste and pharynx,motor for swallowing.
- Vagus $(X)$: Sensory and motor for visceral organs.
Therefore,the correct option is $A$.