Psychobiology part 2 unit 3

Question 1

What is the primary function of the spinal cord?

Answer 1

The spinal cord serves as the primary communication pathway between the brain and the body, transmitting sensory and motor information. It also controls reflex actions independently of the brain.

Question 2

How many pairs of spinal nerves are there, and what is their role?

Answer 2

There are 31 pairs of spinal nerves, each corresponding to a segment of the spinal cord. These nerves are responsible for transmitting sensory information to the spinal cord and motor commands from the spinal cord to muscles.

Question 3

What is the difference between sensory and motor nerves in the spinal cord?

Answer 3

Sensory Nerves: Carry sensory information from the body to the spinal cord through the dorsal roots.
Motor Nerves: Carry motor commands from the spinal cord to muscles through the ventral roots.

Question 4

What is the difference between grey matter and white matter in the spinal cord?

Answer 4

Grey Matter: Composed of neuronal cell bodies and dendrites, located centrally in the spinal cord, responsible for processing information.
White Matter: Composed of myelinated axons that transmit signals between spinal cord segments and the brain.

Question 5

How is the spinal cord protected?

Answer 5

The spinal cord is protected by the spinal column (vertebrae), meninges (three layers of membranes), and cerebrospinal fluid (CSF), which cushions the cord.

Question 6

How is the spinal cord protected?

Answer 6

The spinal cord is protected by:

Spinal/Vertebral Column:

Composed of 24 vertebrae:
Cervical (neck)
Thoracic (chest)
Lumbar (lower back)
Sacral & Coccygeal (pelvic region, fused vertebrae)
The spinal cord passes through the spinal foramen (hole in the center of each vertebra).
Meninges: Three layers of protective membranes.

Cerebrospinal Fluid (CSF): Cushions and nourishes the spinal cord.

Question 7

What are the cervical and lumbar enlargements of the spinal cord responsible for?

Answer 7

The cervical enlargement supplies the upper limbs, and the lumbar enlargement supplies the lower limbs.

Question 8

How are spinal nerves organized?

Answer 8

Each spinal nerve consists of a dorsal root (sensory nerves) and a ventral root (motor nerves), which join together to form a mixed spinal nerve that carries both sensory and motor information.

Question 9

What happens if the spinal cord is damaged at a specific segment?

Answer 9

Damage to a segment of the spinal cord can result in the loss of sensation and motor control from that segment and all regions below it.

Question 10

Whats the main pathway of
communication between the brain and the head?

Answer 10

Through cranial nerves

Question 11

What do the terms dorsal and ventral refer to in the context of the spinal cord?

Answer 11

Dorsal: Refers to the back side of the body or spinal cord. The dorsal root of the spinal cord carries sensory information from the body to the spinal cord.

Ventral: Refers to the front or belly side of the body. The ventral root of the spinal cord carries motor information from the spinal cord to the muscles, enabling movement.

Question 12

What are ascending and descending pathways in the spinal cord?

Answer 12

Ascending Pathways: These pathways carry sensory information from the body to the brain. They transmit signals such as touch, pain, and temperature from the spinal cord to the brain for processing.

Descending Pathways: These pathways carry motor information from the brain to the spinal cord. They transmit signals that control voluntary movement from the brain to muscles in the body.

Question 13

What is the spinal column, and how does it protect the spinal cord?

Answer 13

The spinal column is a series of bones (vertebrae) stacked on top of each other. It protects the spinal cord, which runs through the center of these bones. The column is made up of:

Cervical vertebrae (neck)

Thoracic vertebrae (upper back)

Lumbar vertebrae (lower back)

At the bottom, the sacral and coccygeal vertebrae are fused together. The spinal cord passes through an opening in the middle of each vertebra called the spinal foramen.

Question 14

What are the enlargements of the spinal cord, and why do they exist?

Answer 14

The spinal cord has two enlargements where it thickens to accommodate more nerves for the limbs:

Cervical Enlargement:

Location: Neck region
Function: Innervates the upper limbs (arms, shoulders, hands).
Lumbar Enlargement:

Location: Lower back region
Function: Innervates the lower limbs (legs, hips, feet)

Question 15

What are dorsal root ganglia?

Answer 15

Dorsal root ganglia are clusters of sensory nerve cell bodies located outside the spinal cord. They collect sensory information from the body and send it to the spinal cord.

Question 16

What are ventral roots, and why are spinal nerves considered mixed?

Answer 16

Ventral Roots:

Contain efferent motor neurons that send commands from the CNS to the body.
Include:
Motor neurons: Control skeletal muscles for voluntary movements.
Preganglionic neurons: Part of the autonomic nervous system, regulating involuntary functions (e.g., heart rate, digestion).
Their cell bodies are located in the grey matter of the spinal cord.
Spinal Nerves Are Mixed:

Formed by the fusion of:
Dorsal roots: Carry sensory signals to the spinal cord (afferent pathway).
Ventral roots: Carry motor signals out of the spinal cord (efferent pathway)

Question 17

What is a dermatome in relation to the spinal cord?

Answer 17

A dermatome is a specific area of the body that is innervated by a single spinal nerve. Sensory information from each dermatome is carried back to the spinal cord via the corresponding spinal nerve.

Question 18

How do dermatomes overlap, and what does this mean for spinal nerve damage?

Answer 18

Dermatome divisions overlap slightly, so if one spinal nerve is damaged, sensation in the corresponding area of the body may not be completely lost, as neighboring dermatomes can still provide sensory input.

Question 19

What is the central canal in the spinal cord?

Answer 19

The central canal is a small, fluid-filled channel that runs through the center of the spinal cord. It is filled with cerebrospinal fluid (CSF) and helps cushion and protect the spinal cord.

Question 20

What are the central canal, grey matter, and white matter in the spinal cord?

Answer 20

Central Canal:

A small hollow tube in the center of the spinal cord.
Part of the ventricular system, where cerebrospinal fluid (CSF) flows, providing cushioning and nutrients.
Grey Matter vs. White Matter:

Grey Matter: Internal in the spinal cord, forming an H-shape (or butterfly). Contains neuron cell bodies for signal processing.
White Matter: External in the spinal cord. Contains axon tracts (wires) for transmitting signals.
Brain vs. Spinal Cord:

Spinal Cord: Grey matter is internal, white matter is external.
Brain: Grey matter is external, white matter is internal.

Question 21

What are the four protrusions of the spinal cord?

Answer 21

The spinal cord grey matter has four protrusions where the grey matter expands into the horns of the spinal cord:

Dorsal Horn: Processes sensory information.
Ventral Horn: Contains motor neurons that send signals to muscles.
Lateral (Lateral means toward the side, away from the center of the spinal cord) Horn: Found in thoracic and lumbar regions, involved in autonomic functions.
Central Canal: Contains cerebrospinal fluid and runs through the center of the spinal cord.

Question 22

What are Rexed’s laminae in the spinal cord, and how are they organized?

Answer 22

The spinal cord’s dorsal and ventral horns are divided into layers of cells called Rexed’s laminae. These layers, numbered I to X, are organized from the back (dorsal) to the front (ventral). Each layer helps categorize the cell bodies in the spinal cord based on their roles and characteristics

Question 23

What types of sensory information are processed in the dorsal horn of the spinal cord?

Answer 23

In the dorsal horn, the most dorsal laminae process somatosensory information (e.g., sensations from skin, joints, and muscles), while more ventral laminae process visceral sensory information (e.g., sensory signals from internal organs).

Question 24

What is the function of Lamina VII in the spinal cord?

Answer 24

Lamina VII spans the dorsal and ventral horns of the spinal cord.
Middle segments (thoracic): Contains preganglionic sympathetic neurons (control “fight-or-flight” responses).
Sacral segments: Contains preganglionic parasympathetic neurons (control “rest-and-digest” responses).

Question 25

What role does the ventral horn play in movement, and what happens in motor neuron disease?

Answer 25

The ventral horn contains motor neurons that control voluntary movement. These motor neurons are affected in motor neuron disease, which leads to muscle weakness, reduced muscle control, and muscle wasting.

Question 26

How is spinal cord white matter organized?

Answer 26

White matter in the spinal cord is organized into dorsal, lateral, and ventral columns, with axons grouped into ascending (sensory) and descending (motor) tracts that communicate between the spinal cord and other parts of the CNS.

Question 27

What do ascending tracts in the spinal cord carry, and how are they organized?

Answer 27

Ascending tracts carry different types of somatosensory information to the brain. For example,

the spinothalamic tract carries pain, temperature, and touch information, while

the fasciculus gracilis and fasciculus cuneatus carry proprioception and fine touch information.

Question 28

Does all ascending information reach consciousness?

Answer 28

No, some ascending information reaches consciousness (e.g., when it reaches the cerebral cortex), while other information does not (e.g., when it goes to the cerebellum).

Question 29

What are the spinothalamic tract, fasciculus gracilis, and fasciculus cuneatus?

Answer 29

Spinothalamic Tract: Carries pain, temperature, coarse touch, and pressure information from the body to the brain.

Fasciculus Gracilis: Located in the dorsal column, it carries information about proprioception (body position) and fine touch from the lower body.

Fasciculus Cuneatus: Also part of the dorsal column, it carries similar information about proprioception and fine touch, but from the upper body.

Question 30

What do descending white matter tracts control?

Answer 30

Descending white matter tracts originate in the cerebral cortex and brainstem, controlling movement, muscle tone, spinal reflexes, autonomic functions, and modulating sensory signals to the brain.

Question 31

How are the 2 descending tracts categorized in the spinal cord?

Answer 31

Lateral Column Tracts (e.g., lateral corticospinal, rubrospinal): Control voluntary limb movements.

Ventromedial Column Tracts (e.g., ventral corticospinal, tectospinal, vestibulospinal, reticulospinal): Control automatic movements, reflexes, and unconscious coordination for posture and balance.

Question 32

What are interneurons, and why are they important?

Answer 32

Interneurons are neurons entirely contained within the spinal cord’s grey matter.
They connect sensory neurons (incoming signals) to motor neurons (outgoing commands).
They play a critical role in reflex movements, ensuring quick responses to stimuli.

Question 33

What is a monosynaptic reflex arc, and how does it work?

Answer 33

A monosynaptic reflex involves just one connection (synapse) between two neurons:
Sensory neuron: Detects the stimulus and sends the signal to the spinal cord.
Motor neuron: Receives the signal and activates the muscle.
Example: The knee jerk reflex—a simple and fast response.

Question 34

Can reflexes be overridden by the brain? How?

Answer 34

Reflexes can be overridden if the stimulus isn’t too intense.
The cortex (brain) sends signals through descending tracts to activate inhibitory interneurons.
Inhibitory interneurons block the reflex action by stopping the motor neuron from sending a signal to the muscle.

Question 35

What is a reflex, and how does it work?

Answer 35

A reflex is an automatic, involuntary response to a stimulus. It occurs through the spinal cord without the need for conscious thought, involving a simple pathway known as the reflex arc.

Question 36

What is a polysynaptic reflex, and how does it work?

Answer 36

A reflex involving more than one synapse, with at least three neurons:
Sensory neuron: Detects harmful stimuli and sends a signal to the spinal cord.
Interneuron: Processes the signal and relays it to the motor neuron.
Motor neuron: Activates a flexor muscle, causing it to contract and withdraw from harm.
Example: The withdrawal reflex (e.g., pulling your hand away from a hot iron).

Question 37

What are the main components of a reflex arc?

Answer 37

A reflex arc includes:

Sensory receptor (detects stimulus)
Afferent neuron (sends signal to spinal cord)
Interneuron (integrates information in the spinal cord)
Efferent neuron (carries motor command)
Effector organ (produces response, such as muscle contraction).

Question 38

What are the two main types of reflexes?

Answer 38

Monosynaptic Reflex: Involves only one synapse between the sensory and motor neuron (e.g., knee-jerk reflex).
Polysynaptic Reflex: Involves one or more interneurons between sensory and motor neurons (e.g., withdrawal reflex).

Question 39

What is the role of interneurons in reflexes?

Answer 39

Interneurons relay signals between sensory and motor neurons, particularly in polysynaptic reflexes, helping coordinate more complex reflex actions like withdrawal from pain.

Question 40

How does the withdrawal reflex work?

Answer 40

The withdrawal reflex is a polysynaptic reflex that occurs when a painful stimulus (e.g., touching something hot) triggers a rapid withdrawal of the affected body part, usually involving a reciprocal inhibition to relax the opposite muscle group.

Question 41

What are the main functions of the brainstem?

Answer 41

The brainstem controls basic life functions, such as breathing, heart rate, and sleep. It also acts as a relay center for sensory and motor pathways between the brain and spinal cord.

Question 42

What are the three main parts of the brainstem?

Answer 42

The brainstem consists of the midbrain, pons, and medulla oblongata, each playing a role

in sensory processing,
motor control, and
autonomic functions.

Question 43

What is the role of the brainstem in cranial nerve function?

Answer 43

The brainstem is the location of most cranial nerves and their nuclei.
It serves as the hub for cranial nerves controlling head, neck, and some internal organ functions.

Question 44

What are cranial nerve nuclei, and what are their roles?

Answer 44

Cranial Nerve Nuclei: Clusters of cell bodies located in the brainstem.
Roles:
Motor Function:
Contain cell bodies of motor neurons that send signals to muscles in the head, neck, or internal organs.

Sensory Function:
Contain cell bodies that receive sensory input (e.g., touch, pain, taste, sound) from the head and neck.

Question 45

What is the role of the medulla oblongata in the brainstem?

Answer 45

The medulla oblongata regulates vital functions like heart rate, blood pressure, and respiration. It also controls reflexes such as swallowing and vomiting.

Question 46

What does the pons do in the brainstem?

Answer 46

The pons is involved in regulating sleep, respiration, and facial movements, and it connects the upper and lower parts of the brain.

Question 47

What are pontocerebellar fibres, and where are they located?

Answer 47

Pontocerebellar fibres are a network of axons located in the pons (part of the brainstem).
They form a transverse system (running side-to-side) that acts as a communication bridge.
These fibres connect the cerebral cortex (responsible for planning movements) with the cerebellum (responsible for coordinating and refining those movements).

Question 48

What is the function of the midbrain?

Answer 48

The midbrain plays a key role in vision, hearing, motor control, and regulating sleep/wake cycles. It connects the forebrain and hindbrain and is involved in processing auditory and visual information.

Question 49

What is the tectum, and what are its roles?

Answer 49

Part of the midbrain, located behind the cerebral aqueduct.
Contains two swellings:
Superior Colliculus: Involved in the visual system (e.g., eye movements, visual reflexes).
Inferior Colliculus: Involved in the auditory system (e.g., sound localization).

Question 50

What is the tegmentum, and what are its key components?

Answer 50

The tegmentum is the ventral part of the midbrain, located below the tectum.
Contains important nuclei:
Reticular Formation: Sleep, arousal, attention, and motor functions.
Periaqueductal Grey Matter: Pain modulation and primitive behaviors.
Red Nucleus: Coordinates voluntary limb movements. the origin of axons that constitute one of
the major descending pathways that takes motor
information from the cortex to the spinal cord – the
rubrospinal tract

Substantia Nigra: important
connections with the basal ganglia
(caudate nucleus + putamen), and is
involved in the voluntary control of
movement
Involved in movement control; linked to Parkinson’s disease.

Question 51

What is the reticular formation and what role does it play?

Answer 51

The reticular formation is a network of neurons in the brainstem responsible for regulating arousal, alertness, and sleep. It acts as a filter, controlling the flow of sensory information to the cortex.

Question 52

What is the periaqueductal grey matter and its role in the brain?

Answer 52

The periaqueductal grey matter (PAG) surrounds the cerebral aqueduct and is crucial for pain modulation and defensive behavior. It plays a role in the body’s response to stress and pain, including the activation of the “fight or flight” response. such as
aggression and mating.

Question 53

What is the red nucleus, and what does it do?

Answer 53

The red nucleus is a structure in the tegmentum of the midbrain.
It is the starting point of the rubrospinal tract, a major descending pathway.
The rubrospinal tract carries motor signals from the cerebral cortex to the spinal cord, helping to coordinate limb movements.

Question 54

What function does the substantia nigra serve in the brain?

Answer 54

The substantia nigra has important
connections with the basal ganglia
(caudate nucleus + putamen) an is involved in voluntary movement and The neural connections between the substantia nigra and the basal ganglia
use dopamine, is implicated in diseases like Parkinson’s due to its role in dopamine production.

Question 55

What are the key structures found in the midbrain?

Answer 55

The midbrain contains the superior colliculus (involved in visual processing) and the inferior colliculus (involved in auditory processing), both of which play roles in integrating sensory information and coordinating movement.

Question 56

What behavioral responses does the periaqueductal grey matter (PAG) influence?

Answer 56

The PAG is involved in the fight or flight response, defensive behaviors, and pain relief. It activates motor pathways to coordinate responses to stress, including freezing or fleeing from threats.

Question 57

What is the role of dopamine produced by the substantia nigra?

Answer 57

Dopamine produced by the substantia nigra is critical for voluntary movement control, influencing motor coordination and the ability to perform smooth, purposeful movements.

Question 58

How does damage to the substantia nigra affect movement?

Answer 58

Damage to the substantia nigra, as seen in Parkinson’s disease, leads to a dopamine deficiency, resulting in symptoms such as tremors, rigidity, and difficulty initiating movements.

Question 59

What is the relationship between the midbrain and the brainstem?

Answer 59

The midbrain is a part of the brainstem, serving as the connection between the hindbrain and forebrain and playing an essential role in motor coordination, sensory processing, and regulating autonomic functions.

Question 60

How does the substantia nigra contribute to motor control in coordination with the basal ganglia?

Answer 60

The substantia nigra releases dopamine to the basal ganglia, which helps coordinate smooth, controlled voluntary movements. Disruption in this system, such as in Parkinson’s disease, impairs movement initiation and control.

Question 61

How many cranial nerves are there, and where do they originate?

Answer 61

There are 12 cranial nerves, and they originate from the brainstem, except for the olfactory and optic nerves, which are connected to the forebrain.

cranial nerve I attaches to the
olfactory bulb (important for olfaction) and
cranial nerve II attaches to the thalamus

Question 62

What are the general functions of cranial nerves?

Answer 62

Cranial nerves are responsible for sensory functions (e.g., vision, hearing, taste) and motor functions (e.g., eye movement, facial expressions, swallowing). Some cranial nerves also regulate autonomic functions, like heart rate and digestion.

Question 63

What is the difference between cranial nerve nuclei and cranial nerves?

Answer 63

Cranial Nerve Nuclei:

Located inside the brainstem.
Clusters of neuron cell bodies that act as control centers.
Sensory nuclei receive information; motor nuclei send commands.
Cranial Nerves:

Located outside the brainstem, extending to the body.
Bundles of axons that act as wires, carrying information to and from nuclei.
Can be sensory, motor, or mixed.
Analogy:

Nuclei are the control rooms inside a factory; cranial nerves are the delivery trucks transporting signals

Question 64

What are sensory cranial nerve nuclei, and what do they do?

Answer 64

Sensory cranial nerve nuclei: Receive sensory information from the head and send it to the brain.
Key Nuclei and Their Functions:

Trigeminal Sensory Nucleus:
Processes pain, temperature, and touch from the head.
Vestibular Nuclei:
Handle information about the motion and position of the head (from the inner ear).
Cochlear Nuclei:
Process auditory information (sound) from the inner ear.
Nucleus Solitarius:
Receives taste information

Question 65

What is the somatic efferent column, and what does it control?

Answer 65

Part of the cranial motor nuclei, controlling eye and tongue movements.
Includes:
Oculomotor, Trochlear, and Abducens nuclei: Move the eyes.
Hypoglossal nucleus: Moves the tongue.

Question 66

What is the branchiomotor column, and what does it control?

Answer 66

Part of the cranial motor nuclei, controlling face, throat, and voice movements.
Includes:
Trigeminal Motor Nucleus: Moves jaw and mouth.
Facial Motor Nucleus: Moves facial muscles.
Nucleus Ambiguus: Moves throat (pharynx) and voice box (larynx).

Question 67

What is the parasympathetic column, and what does it control?

Answer 67

Part of the cranial motor nuclei, controlling involuntary functions:
Edinger-Westphal Nucleus: Adjusts pupil size.
Superior & Inferior Salivatory Nuclei: Control tears and saliva.
Dorsal Motor Nucleus of the Vagus: Regulates internal organs (e.g., heart, lungs, digestion).

Question 68

What is the function of cranial nerve I (Olfactory nerve)?

Answer 68

The olfactory nerve (CN I) is responsible for the sense of smell. It transmits sensory information from the nasal cavity to the brain.

Question 69

What is the function of cranial nerve II (Optic nerve)?

Answer 69

The optic nerve (CN II) transmits visual information from the retina to the brain. It is crucial for vision.

Each eye has one optic nerve that carries visual
information primarily to the lateral geniculate nucleus in
the thalamus, before being sent to the primary visual
cortex

Question 70

What is the role of cranial nerve III (Oculomotor nerve)?

Answer 70

The oculomotor nerve (CN III) is a motor nerve with two main roles:

Motor Functions:

Controls most of the eye muscles that move the eyeball.
These motor fibers originate from the oculomotor nucleus in the midbrain.
Parasympathetic Functions:

Regulates the iris muscles, enabling the pupillary light reflex (constricts the pupil in response to light).
Adjusts the ciliary muscles, which change the lens thickness for focusing on near or far objects.
These parasympathetic fibers originate from the Edinger-Westphal nucleus, also in the midbrain.

Question 71

What does cranial nerve IV (Trochlear nerve) control?

Answer 71

The trochlear nerve (CN IV) controls the superior oblique muscle of the eye, which allows for downward and inward eye movements. This nerve originates from the trochlear nucleus

Question 72

What is the function of cranial nerve V (Trigeminal nerve)?

Answer 72

Sensory:

Composed of ophthalmic, maxillary, and mandibular nerves.
Carries somatosensory information from the face and scalp, cornea, nasal cavity, mouth (teeth, gums, and sinuses).
Attaches to the trigeminal sensory nucleus.
Motor:

The mandibular nerve controls mastication muscles, the soft palate, digastric muscle, and tensor tympani muscles.
Originates from the trigeminal motor nucleus.

Question 73

What is the role of cranial nerve VI (Abducens nerve)?

Answer 73

The abducens nerve (CN VI) is a motor nerve that:

Controls the lateral rectus muscle, responsible for moving the eye outward (abduction, or away from the nose).
It ensures smooth lateral eye movements.
This nerve originates from the abducens nucleus in the brainstem

Question 74

What is the main function of cranial nerve VII (Facial nerve)?

Answer 74

Sensory Fibers:

Receive taste from the anterior two-thirds of the tongue and palate.
Carry touch, pain, and pressure sensations from the external ear.
Signals attach to the nucleus solitarius.
Motor Fibers:

Control facial muscles for expressions (e.g., smiling, frowning).
Signals originate from the facial motor nucleus.
Parasympathetic Fibers:

Stimulate lacrimal glands (tears) and salivary glands (saliva).
Signals originate from the superior salivatory nucleus.

Question 75

What does cranial nerve VIII (Vestibulocochlear nerve) do?

Answer 75

The vestibulocochlear nerve (CN VIII) is responsible for hearing (via the cochlear branch) and balance (via the vestibular branch), transmitting auditory and equilibrium information.

The vestibular nuclei send axons to the cerebellum,
allowing the control of equilibrium (balance). The cochlear nerve carries auditory information (i.e. what
we hear) from the cochlea in the inner ear and attaches to
the cochlear nuclei

Question 76

What is the function of cranial nerve IX (Glossopharyngeal nerve)?

Answer 76

The glossopharyngeal nerve (CN IX):

Sensory: Provides taste sensation to the posterior one-third of the tongue and sensation to the pharynx.

Motor: Involved in swallowing and saliva secretion from the parotid gland.

Autonomic: Helps regulate blood pressure and respiration through baroreceptors and chemoreceptors.

Question 77

What is the role of cranial nerve X (Vagus nerve)?

Answer 77

• Cranial nerve X (vagus nerve) contains sensory, motor and
  parasympathetic nerve fibres

Somatosensory Fibers:

Carry sensations (touch, pain, pressure) from:
Pharynx, larynx, oesophagus, tympanic membrane (eardrum), auditory canal, and external ear.
Terminate in the trigeminal sensory nucleus.
Visceral Sensory Fibers:

Transmit sensory information from abdominal organs (e.g., intestines).
Terminate in the nucleus solitarius.

Question 78

What are the motor and parasympathetic functions of cranial nerve X (Vagus nerve)?

Answer 78

Motor Fibers:

Innervate the soft palate, pharynx, larynx, and upper oesophagus.
Important for swallowing and speech.
Originate from the nucleus ambiguus.
Parasympathetic Fibers:

Regulate the cardiovascular, respiratory, and gastrointestinal systems.
Originate from the dorsal motor nucleus of the vagus.

Question 79

What does cranial nerve XI (Accessory nerve) control?

Answer 79

The accessory nerve (CN XI) controls the sternocleidomastoid and trapezius muscles, allowing for head movement and shoulder elevation.

Question 80

What is the function of cranial nerve XII (Hypoglossal nerve)?

Answer 80

The hypoglossal nerve (CN XII) controls the muscles of the tongue, allowing for movement required for speech, swallowing, and food manipulation.