Central Nervous System

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Questions and Answers

Which functional area of the cerebral cortex is primarily responsible for controlling voluntary movements?

Association areas

Cognitive areas

Motor areas (correct)

Sensory areas

What percentage of the brain's mass is accounted for by the cerebral cortex?

50%

60%

30%

40% (correct)

Which area of the cortex is involved in the planning of movements?

Frontal eye field

Premotor cortex (correct)

Primary motor cortex

Broca's area

Which hemisphere of the brain typically contains Broca's area?

Left Signup and view all the answers

What is the primary function of the primary motor cortex?

Conscious control of precise voluntary movements Signup and view all the answers

How do the two hemispheres of the brain generally function in relation to the body?

They control the opposite side of the body Signup and view all the answers

What role does the frontal eye field play in the cerebral cortex?

It manages visual attention and eye movement Signup and view all the answers

Which type of area in the cortex integrates diverse information?

Association areas Signup and view all the answers

What type of skills does the premotor cortex coordinate?

Learned and patterned motor skills Signup and view all the answers

Which type of area allows for conscious awareness of sensations?

Sensory areas Signup and view all the answers

What does the Central Nervous System (CNS) primarily consist of?

Brain and spinal cord Signup and view all the answers

What is the process of cephalization primarily associated with?

Elaboration of the anterior portion of the CNS Signup and view all the answers

Which of the following structures is NOT part of the surface anatomy of the brain?

Pons Signup and view all the answers

During which stage of embryonic development does the neural plate form?

During the first 26 days of development Signup and view all the answers

What structure develops from the fusion of the neural groove?

Neural tube Signup and view all the answers

What is a characteristic of the human brain compared to other species?

It exhibits the highest level of cephalization Signup and view all the answers

Which part of the CNS is responsible for coordination and balance?

Cerebellum Signup and view all the answers

What is the primary role of the ectoderm during the early stages of nervous system development?

To develop the neural plate Signup and view all the answers

At what embryonic day does the neural groove begin to form?

Day 19 Signup and view all the answers

The brain is composed of what type of tissue?

Wrinkled, pinkish gray tissue Signup and view all the answers

What is primarily found at the core of the spinal cord?

Gray matter surrounded by white matter Signup and view all the answers

Which ventricular component is NOT part of the brain's ventricular system?

The cerebral aqueduct Signup and view all the answers

Which of the following accurately describes the composition of the cerebral hemispheres?

Includes both gray matter and structures like gyri and sulci Signup and view all the answers

What is the primary function of the deep sulci in the cerebral hemisphere?

To divide the hemispheres into lobes Signup and view all the answers

Which lobe of the cerebral hemisphere is separated from the parietal lobe by the central sulcus?

Frontal lobe Signup and view all the answers

How much of the total mass of the brain is made up by the cerebral hemispheres?

Approximately 83% Signup and view all the answers

What separates the parietal and occipital lobes of the cerebral hemispheres?

Parieto-occipital sulcus Signup and view all the answers

Which statement about the cerebrum is true?

It includes nuclei and additional gray matter beyond the cortex. Signup and view all the answers

Which structure is NOT part of the brain's ventricular system?

Lateral aperture Signup and view all the answers

What type of matter surrounds the central cavity of the spinal cord?

Gray matter Signup and view all the answers

What sensory modalities does the primary somatosensory cortex primarily process?

Touch and proprioception Signup and view all the answers

What is the main function of the somatosensory association cortex?

To integrate sensory information for interpretation Signup and view all the answers

Where is the primary visual cortex located in the brain?

On the extreme posterior tip of the occipital lobe Signup and view all the answers

Which area is responsible for the perception of sounds such as pitch and rhythm?

Primary auditory cortex Signup and view all the answers

What type of information does the visual association area interpret?

Color, form, and movement Signup and view all the answers

Which of the following is NOT a function of the primary somatosensory cortex?

Receiving auditory feedback Signup and view all the answers

What does the auditory association area primarily store?

Memories of sounds Signup and view all the answers

Which area is associated with higher cognitive functions, such as decision making and social behavior?

Prefrontal cortex Signup and view all the answers

What key role does the general interpretation area serve in the brain?

Linking sensations to memories Signup and view all the answers

What distinguishes the auditory association area from the primary auditory cortex?

It allows perception of sound and stores auditory memories Signup and view all the answers

What function does cerebrospinal fluid (CSF) NOT perform?

Transmits electrical signals Signup and view all the answers

Which of the following best describes the role of the choroid plexuses?

Cleansing and filtering of cerebrospinal fluid Signup and view all the answers

How does the blood-brain barrier maintain the brain's environment?

By filtering bloodborne substances from neurons Signup and view all the answers

What is the primary function of the meninges?

To cover and protect the central nervous system Signup and view all the answers

Which layer of the meninges is the deepest and clings tightly to the brain?

Pia mater Signup and view all the answers

What mechanism allows the spinal cord's communication with the brain?

Nerve roots attached to the cord Signup and view all the answers

What does cerebrospinal fluid primarily resemble?

Blood plasma Signup and view all the answers

Which structure provides support and anchorage to the spinal cord?

Filum terminale Signup and view all the answers

What is the primary role of the epidural space in relation to the spinal cord?

Act as a cushion and support system Signup and view all the answers

How do the two layers of the dura mater function?

They separate to form dural sinuses Signup and view all the answers

Which structure allows for the absorption of cerebrospinal fluid into the venous blood?

Arachnoid villi Signup and view all the answers

What occurs when stress affects the blood-brain barrier?

It becomes less selective Signup and view all the answers

What is a characteristic feature of the cervical and lumbar enlargements of the spinal cord?

Emergence of limb nerves Signup and view all the answers

What is the role of the blood-brain barrier?

To protect the brain from harmful substances Signup and view all the answers

What is one characteristic of the composition of cerebrospinal fluid compared to blood plasma?

It has different ion concentrations Signup and view all the answers

Which of the following is NOT a function of the meninges?

Provide a blood supply to the brain Signup and view all the answers

Study Notes

The Central Nervous System

The CNS is comprised of the brain and spinal cord.
Cephalization is the elaboration of the anterior portion of the CNS, resulting in an increase in neurons in the head.
The human brain is the most complex example of cephalization.

Embryonic Development

The neural plate is formed from the thickening of the ectoderm along the dorsal midline during the first 26 days of development.
The neural plate invaginates to form a groove flanked by neural folds.
The neural groove fuses dorsally to form the neural tube.

Basic Pattern of the Central Nervous System

The spinal cord's central cavity is surrounded by gray matter, with white matter composed of myelinated fiber tracts located externally.
The brain is similar to the spinal cord but has additional gray matter.
The cerebellum has gray matter in nuclei, while the cerebrum also has nuclei and additional gray matter in the cortex.

Ventricles of the Brain

Ventricles are expansions of the lumen of the neural tube.
The ventricles include:
- The paired C-shaped lateral ventricles
- The third ventricle
- The fourth ventricle

Cerebral Hemispheres

They constitute the superior part of the brain and comprise 83% of its mass.
Cerebral hemispheres have ridges called gyri and shallow grooves called sulci.
Deep grooves in cerebral hemispheres are called fissures.

Major Lobes, Gyri, and Sulci of the Cerebral Hemisphere

Deep sulci divide the cerebral hemispheres into four major lobes:
- Frontal
- Parietal
- Temporal
- Occipital

Major Lobes, Gyri, and Sulci of the Cerebral Hemisphere (continued)

The central sulcus separates the frontal and parietal lobes.
The parieto-occipital sulcus separates the parietal and occipital lobes.
The lateral sulcus separates the parietal and temporal lobes.
The precentral and postcentral gyri border the central sulcus.

Cerebral Cortex

The cerebral cortex, the superficial gray matter, accounts for 40% of the brain's mass.
It enables sensation, communication, memory, understanding, and voluntary movements.
Each hemisphere operates contralaterally, controlling the opposite side of the body.

Functional Areas of the Cerebral Cortex

The three types of functional areas:
- Motor areas: control voluntary movement
- Sensory areas: provide conscious awareness of sensation
- Association areas: integrate diverse information

Cerebral Cortex: Motor Areas

Motor areas comprise:
- Primary (somatic) motor cortex
- Premotor cortex
- Broca's area
- Frontal eye field

Primary Motor Cortex

This area is located in the precentral gyrus.
It contains pyramidal cells with axons that compose the corticospinal tracts.
Allows conscious control of precise, skilled, and voluntary movements.

Premotor Cortex

This area sits anterior to the precentral gyrus.
Controls learned, repetitious, or patterned motor skills.
Coordinates simultaneous or sequential actions.
Involved in planning movements.

Broca's Area

Located anterior to the inferior region of the premotor area.
Usually present in the left hemisphere.
Functions as a motor speech area directing tongue muscles.
Becomes active when preparing to speak.

Frontal Eye Field

Located anterior to the premotor cortex and superior to Broca's area.
Controls voluntary eye movement.

Sensory Areas

Sensory areas include:
- Primary somatosensory cortex
- Somatosensory association cortex
- Visual and auditory areas
- Olfactory, gustatory, and vestibular cortices.

Primary Somatosensory Cortex

Located in the postcentral gyrus, this area:
- Receives information from the skin and skeletal muscles.
- Exhibits spatial discrimination.

Somatosensory Association Cortex

Located posterior to the primary somatosensory cortex.
Integrates sensory information.
Forms a comprehensive understanding of the stimulus.
Determines size, texture, and relationship of parts of the stimulus.

Visual Areas

The primary visual cortex:
- Located at the extreme posterior tip of the occipital lobe.
- Receives visual information from the retinas.
The visual association area:
- Surrounds the primary visual cortex.
- Interprets visual stimuli, including color, form, and movement.

Auditory Areas

The primary auditory cortex:
- Located at the superior margin of the temporal lobe.
- Receives information related to pitch, rhythm, and loudness.
The auditory association area:
- Located posterior to the primary auditory cortex.
- Stores memories of sounds and permits perception of sounds.
- Contains Wernicke's area.

Association Areas

Association areas comprise:
- Prefrontal cortex
- Language areas
- General (common) interpretation area
- Visceral association area

Prefrontal Cortex

Located in the frontal lobe.
Involved in intellect, complex learning abilities, personality, and judgment.
Responsible for working memory, abstract ideas, judgment, reasoning, and planning.
The most complex part of the cerebral cortex.

Language Areas

Language areas involve:
- Wernicke's area: responsible for speech understanding and sounds.
- Broca's area: responsible for speech production.
- Lateral sulcus: separates the frontal and temporal lobes.

General Interpretation Area

Receives information from all association areas.
Permits us to give meaning to information we receive.
Makes us aware of the objects around us.

Visceral Association Area

Located in the insular cortex, deep within the lateral sulcus.
Controls visceral functions like hunger, thirst, emotions, and autonomic nervous system regulation.

Cerebellum

Located behind the brain stem and below the cerebrum.
Controls equilibrium, posture, and fine motor coordination.
Aids in motor learning and planning.
Receives a copy of motor plans from the cerebrum.

Brain Stem

Contains:
- Midbrain
- Pons
- Medulla oblongata
Controls vital functions like respiration, heart rate, and blood pressure.
Responsible for reflexes.

Diencephalon

Located in the central core of the brain.
Contains:
- Thalamus: the relay center for sensory information.
- Hypothalamus: controls homeostatic functions like hunger, thirst, temperature regulation, and sleep.
Contains the epithalamus, which includes the pineal gland for hormone secretion.

Cranial Nerves

12 pairs of cranial nerves.
Mostly serve the head and neck regions.
Connect directly to the brain.

Spinal Cord

A column of nervous tissue that extends from the medulla oblongata.
Enclosed by vertebral column.
Transmits impulses to and from the brain.
Contains 31 pairs of spinal nerves.

Spinal Nerves

Serve the body periphery.
Formed from the fusion of dorsal and ventral roots.
Each nerve connects to the spinal cord by a pair of roots:
- Dorsal root: carries sensory information, which serves as an afferent pathway.
- Ventral root: carries motor information, which serves as an efferent pathway.

Peripheral Nervous System (PNS)

PNS includes all nervous tissue outside of the CNS.
Composed of:
- Cranial nerves
- Spinal nerves
- Ganglia: collections of neuron cell bodies outside the CNS.

Brain Protection

Brain is protected by bone, meninges, and cerebrospinal fluid (CSF)
Blood-brain barrier shields the brain from harmful substances

Meninges

Three membranes external to the CNS: dura mater, arachnoid mater, and pia mater
Functions:
- Cover and protect the CNS
- Protect blood vessels and enclose venous sinuses
- Contain CSF
- Form partitions within the skull

Dura Mater

Leathery and strong
Composed of two fibrous connective tissue layers
Layers separate in some areas to form dural sinuses

Arachnoid Mater

Loose brain covering
Separated from the dura mater by the subdural space
Has a wide subarachnoid space filled with CSF and large blood vessels
Arachnoid villi help CSF to be absorbed into venous blood

Pia Mater

Delicate connective tissue
Clings to the brain

Cerebrospinal Fluid (CSF)

Similar in composition to blood plasma, but with less protein and different ion concentration
Provides buoyancy to the CNS
Prevents brain from crushing under its own weight
Protects the CNS from trauma
Nourishes the brain and transports chemical signals

Choroid Plexuses

Clusters of capillaries
Form tissue fluid filters, which hang from the roof of each ventricle
Alter ion concentrations of the CSF
Remove CSF wastes

Blood-Brain Barrier

Protective mechanism for maintaining a stable brain environment
Separates bloodborne substances from neurons
Nutrients pass freely
Ineffective against substances that diffuse through plasma membranes
Stress increases permeability