Central Nervous System (CNS) Overview

Central Nervous System (CNS)

• Consists of the brain and spinal cord, housed within the cranial cavity and vertebral canal, respectively
• Processes and responds to sensory information and initiates motor functions

Structural Overview

• Grey matter: contains nerve cell bodies and dendrites; peripheral in the brain, central in the spinal cord
• White matter: composed mainly of myelinated nerve fibers; central in the brain, peripheral in the spinal cord

Development and Functional Organization

• CNS originates from a hollow neural tube, retaining cavities in the adult brain and spinal cord
• Developmental divisions:
  • Forebrain: includes cerebrum and diencephalon
  • Midbrain: connects forebrain and hindbrain
  • Hindbrain: comprises pons, medulla oblongata, and cerebellum
  • Brainstem: formed by midbrain, pons, and medulla

Brain Components

• Cerebrum:
  • Largest part, consisting of left and right hemispheres
  • Structure: surface layer of grey matter (cerebral cortex) and central core of white matter, with basal nuclei embedded within the white matter
• Diencephalon:
  • Located beneath the cerebrum
  • Includes structures like thalamus and hypothalamus
• Midbrain:
  • Connects forebrain to hindbrain
• Pons:
  • Part of hindbrain, connecting medulla to midbrain
• Medulla oblongata:
  • Controls vital autonomic functions
• Cerebellum:
  • Coordinates voluntary movements and balance

Cerebral Lobes

• Frontal lobe:
  • Responsible for voluntary motor functions, motivation, emotions, and self-awareness
• Parietal lobe:
  • Processes sensory information except for smell, hearing, and vision
• Occipital lobe:
  • Involved in visual processing
• Temporal lobe:
  • Manages smell, hearing, and memory functions
• Insula:
  • Submerged portion in the lateral sulcus, sometimes referred to as the 5th lobe
• Limbic lobe:
  • Encircles the diencephalon, associated with survival instincts and memory

Basal Ganglia

• Components:
  • Corpus striatum, claustrum, and amygdaloid body
  • Functionally, also involve the subthalamic nucleus and substantia nigra
• Function: influence motor performance, often referred to as extrapyramidal nuclei due to their role in motor control outside the pyramidal tracts

Key Functional Areas

• Motor control: managed by the frontal lobe and basal ganglia
• Sensory processing: primarily handled by the parietal, occipital, and temporal lobes
• Autonomic functions: regulated by the medulla oblongata
• Coordination and balance: controlled by the cerebellum

Diencephalon

• Located between the cerebrum and brainstem, largely obscured by the cerebral hemispheres
• Comprises several important structures:
  • Thalamus: forms the largest part of the diencephalon, functioning as a relay station for sensory impulses
  • Hypothalamus: regulates visceral activities via the autonomic nervous system and hormonal activities through the pituitary gland
  • Metathalamus: composed of the medial and lateral geniculate bodies, processing auditory and visual information, respectively
  • Epithalamus: includes the pineal gland and habenular nuclei, involved in emotional and visceral responses to odors
  • Subthalamus: associated with the basal ganglia, playing a role in controlling motor functions

Midbrain

• Smallest segment of the brainstem, lying just above the pons
• Houses the nuclei of cranial nerves III, IV, and V
• Features:
  • Cerebral aqueduct: runs through the midbrain, dividing it into the tectum (dorsal) and cerebral peduncles (ventral)
  • Tectum: contains the corpora quadrigemina, comprising superior and inferior colliculi, which process visual and auditory information, respectively
  • Cerebral peduncles: each peduncle includes the tegmentum and crus cerebri, separated by the substantia nigra

Pons

• Prominent part of the brainstem, connecting the midbrain to the medulla oblongata
• Features:
  • Ventral portion: contains pontine nuclei and descending fibers of the pyramidal tract, forming a corticopontocerebellar pathway
  • Dorsal portion (tegmentum): houses pontine sleep and respiratory centers, aiding in respiratory regulation in conjunction with the medulla

Medulla Oblongata

• Lower part of the brainstem, continuous with the spinal cord
• Key features and functions:
  • Ventral surface: features pyramids containing corticospinal tracts for skeletal muscle control, and olives with inferior olivary nuclei
  • Dorsal surface: contains cuneate and gracile tubercles overlying corresponding nuclei
  • Autonomic centers: controls vital reflexes, including heart rate, blood vessel diameter, breathing, swallowing, and reflexes like vomiting and coughing

Cerebellum

• Located dorsal to the pons and medulla
• Consists of two hemispheres and a central vermis
• Functions:
  • Equilibrium maintenance: involves involuntary control of somatic motor activities
  • Muscle tone and posture: essential for coordinated movements and maintaining balance
  • Surface structure: characterized by narrow transverse ridges called folia, separated by deep fissures

Base of the Brain

• Includes several important structures and surfaces:
  • Orbital and tentorial surfaces: surfaces of the frontal and temporal lobes of both cerebral hemispheres
  • Interpeduncular fossa: a rhomboidal space at the base of the brain
  • Ventral aspects: include the midbrain, pons, medulla oblongata, and cerebellum
  • Cranial nerve attachments: superficial attachment points for the cranial nerves

Central Nervous System (CNS)

• Consists of the brain and spinal cord, housed within the cranial cavity and vertebral canal, respectively
• Processes and responds to sensory information and initiates motor functions

Structural Overview

• Grey matter: contains nerve cell bodies and dendrites; peripheral in the brain, central in the spinal cord
• White matter: composed mainly of myelinated nerve fibers; central in the brain, peripheral in the spinal cord

Development and Functional Organization

• CNS originates from a hollow neural tube, retaining cavities in the adult brain and spinal cord
• Developmental divisions:
  • Forebrain: includes cerebrum and diencephalon
  • Midbrain: connects forebrain and hindbrain
  • Hindbrain: comprises pons, medulla oblongata, and cerebellum
  • Brainstem: formed by midbrain, pons, and medulla

Brain Components

• Cerebrum:
  • Largest part, consisting of left and right hemispheres
  • Structure: surface layer of grey matter (cerebral cortex) and central core of white matter, with basal nuclei embedded within the white matter
• Diencephalon:
  • Located beneath the cerebrum
  • Includes structures like thalamus and hypothalamus
• Midbrain:
  • Connects forebrain to hindbrain
• Pons:
  • Part of hindbrain, connecting medulla to midbrain
• Medulla oblongata:
  • Controls vital autonomic functions
• Cerebellum:
  • Coordinates voluntary movements and balance

Cerebral Lobes

• Frontal lobe:
  • Responsible for voluntary motor functions, motivation, emotions, and self-awareness
• Parietal lobe:
  • Processes sensory information except for smell, hearing, and vision
• Occipital lobe:
  • Involved in visual processing
• Temporal lobe:
  • Manages smell, hearing, and memory functions
• Insula:
  • Submerged portion in the lateral sulcus, sometimes referred to as the 5th lobe
• Limbic lobe:
  • Encircles the diencephalon, associated with survival instincts and memory

Basal Ganglia

• Components:
  • Corpus striatum, claustrum, and amygdaloid body
  • Functionally, also involve the subthalamic nucleus and substantia nigra
• Function: influence motor performance, often referred to as extrapyramidal nuclei due to their role in motor control outside the pyramidal tracts

Key Functional Areas

• Motor control: managed by the frontal lobe and basal ganglia
• Sensory processing: primarily handled by the parietal, occipital, and temporal lobes
• Autonomic functions: regulated by the medulla oblongata
• Coordination and balance: controlled by the cerebellum

Diencephalon

• Located between the cerebrum and brainstem, largely obscured by the cerebral hemispheres
• Comprises several important structures:
  • Thalamus: forms the largest part of the diencephalon, functioning as a relay station for sensory impulses
  • Hypothalamus: regulates visceral activities via the autonomic nervous system and hormonal activities through the pituitary gland
  • Metathalamus: composed of the medial and lateral geniculate bodies, processing auditory and visual information, respectively
  • Epithalamus: includes the pineal gland and habenular nuclei, involved in emotional and visceral responses to odors
  • Subthalamus: associated with the basal ganglia, playing a role in controlling motor functions

Midbrain

• Smallest segment of the brainstem, lying just above the pons
• Houses the nuclei of cranial nerves III, IV, and V
• Features:
  • Cerebral aqueduct: runs through the midbrain, dividing it into the tectum (dorsal) and cerebral peduncles (ventral)
  • Tectum: contains the corpora quadrigemina, comprising superior and inferior colliculi, which process visual and auditory information, respectively
  • Cerebral peduncles: each peduncle includes the tegmentum and crus cerebri, separated by the substantia nigra

Pons

• Prominent part of the brainstem, connecting the midbrain to the medulla oblongata
• Features:
  • Ventral portion: contains pontine nuclei and descending fibers of the pyramidal tract, forming a corticopontocerebellar pathway
  • Dorsal portion (tegmentum): houses pontine sleep and respiratory centers, aiding in respiratory regulation in conjunction with the medulla

Medulla Oblongata

• Lower part of the brainstem, continuous with the spinal cord
• Key features and functions:
  • Ventral surface: features pyramids containing corticospinal tracts for skeletal muscle control, and olives with inferior olivary nuclei
  • Dorsal surface: contains cuneate and gracile tubercles overlying corresponding nuclei
  • Autonomic centers: controls vital reflexes, including heart rate, blood vessel diameter, breathing, swallowing, and reflexes like vomiting and coughing

Cerebellum

• Located dorsal to the pons and medulla
• Consists of two hemispheres and a central vermis
• Functions:
  • Equilibrium maintenance: involves involuntary control of somatic motor activities
  • Muscle tone and posture: essential for coordinated movements and maintaining balance
  • Surface structure: characterized by narrow transverse ridges called folia, separated by deep fissures

Base of the Brain

• Includes several important structures and surfaces:
  • Orbital and tentorial surfaces: surfaces of the frontal and temporal lobes of both cerebral hemispheres
  • Interpeduncular fossa: a rhomboidal space at the base of the brain
  • Ventral aspects: include the midbrain, pons, medulla oblongata, and cerebellum
  • Cranial nerve attachments: superficial attachment points for the cranial nerves

Central Nervous System (CNS)

• Consists of the brain and spinal cord, housed within the cranial cavity and vertebral canal, respectively
• Processes and responds to sensory information and initiates motor functions

Structural Overview

• Grey matter: contains nerve cell bodies and dendrites; peripheral in the brain, central in the spinal cord
• White matter: composed mainly of myelinated nerve fibers; central in the brain, peripheral in the spinal cord

Development and Functional Organization

• CNS originates from a hollow neural tube, retaining cavities in the adult brain and spinal cord
• Developmental divisions:
  • Forebrain: includes cerebrum and diencephalon
  • Midbrain: connects forebrain and hindbrain
  • Hindbrain: comprises pons, medulla oblongata, and cerebellum
  • Brainstem: formed by midbrain, pons, and medulla

Brain Components

• Cerebrum:
  • Largest part, consisting of left and right hemispheres
  • Structure: surface layer of grey matter (cerebral cortex) and central core of white matter, with basal nuclei embedded within the white matter
• Diencephalon:
  • Located beneath the cerebrum
  • Includes structures like thalamus and hypothalamus
• Midbrain:
  • Connects forebrain to hindbrain
• Pons:
  • Part of hindbrain, connecting medulla to midbrain
• Medulla oblongata:
  • Controls vital autonomic functions
• Cerebellum:
  • Coordinates voluntary movements and balance

Cerebral Lobes

• Frontal lobe:
  • Responsible for voluntary motor functions, motivation, emotions, and self-awareness
• Parietal lobe:
  • Processes sensory information except for smell, hearing, and vision
• Occipital lobe:
  • Involved in visual processing
• Temporal lobe:
  • Manages smell, hearing, and memory functions
• Insula:
  • Submerged portion in the lateral sulcus, sometimes referred to as the 5th lobe
• Limbic lobe:
  • Encircles the diencephalon, associated with survival instincts and memory

Basal Ganglia

• Components:
  • Corpus striatum, claustrum, and amygdaloid body
  • Functionally, also involve the subthalamic nucleus and substantia nigra
• Function: influence motor performance, often referred to as extrapyramidal nuclei due to their role in motor control outside the pyramidal tracts

Key Functional Areas

• Motor control: managed by the frontal lobe and basal ganglia
• Sensory processing: primarily handled by the parietal, occipital, and temporal lobes
• Autonomic functions: regulated by the medulla oblongata
• Coordination and balance: controlled by the cerebellum

Diencephalon

• Located between the cerebrum and brainstem, largely obscured by the cerebral hemispheres
• Comprises several important structures:
  • Thalamus: forms the largest part of the diencephalon, functioning as a relay station for sensory impulses
  • Hypothalamus: regulates visceral activities via the autonomic nervous system and hormonal activities through the pituitary gland
  • Metathalamus: composed of the medial and lateral geniculate bodies, processing auditory and visual information, respectively
  • Epithalamus: includes the pineal gland and habenular nuclei, involved in emotional and visceral responses to odors
  • Subthalamus: associated with the basal ganglia, playing a role in controlling motor functions

Midbrain

• Smallest segment of the brainstem, lying just above the pons
• Houses the nuclei of cranial nerves III, IV, and V
• Features:
  • Cerebral aqueduct: runs through the midbrain, dividing it into the tectum (dorsal) and cerebral peduncles (ventral)
  • Tectum: contains the corpora quadrigemina, comprising superior and inferior colliculi, which process visual and auditory information, respectively
  • Cerebral peduncles: each peduncle includes the tegmentum and crus cerebri, separated by the substantia nigra

Pons

• Prominent part of the brainstem, connecting the midbrain to the medulla oblongata
• Features:
  • Ventral portion: contains pontine nuclei and descending fibers of the pyramidal tract, forming a corticopontocerebellar pathway
  • Dorsal portion (tegmentum): houses pontine sleep and respiratory centers, aiding in respiratory regulation in conjunction with the medulla

Medulla Oblongata

• Lower part of the brainstem, continuous with the spinal cord
• Key features and functions:
  • Ventral surface: features pyramids containing corticospinal tracts for skeletal muscle control, and olives with inferior olivary nuclei
  • Dorsal surface: contains cuneate and gracile tubercles overlying corresponding nuclei
  • Autonomic centers: controls vital reflexes, including heart rate, blood vessel diameter, breathing, swallowing, and reflexes like vomiting and coughing

Cerebellum

• Located dorsal to the pons and medulla
• Consists of two hemispheres and a central vermis
• Functions:
  • Equilibrium maintenance: involves involuntary control of somatic motor activities
  • Muscle tone and posture: essential for coordinated movements and maintaining balance
  • Surface structure: characterized by narrow transverse ridges called folia, separated by deep fissures

Base of the Brain

• Includes several important structures and surfaces:
  • Orbital and tentorial surfaces: surfaces of the frontal and temporal lobes of both cerebral hemispheres
  • Interpeduncular fossa: a rhomboidal space at the base of the brain
  • Ventral aspects: include the midbrain, pons, medulla oblongata, and cerebellum
  • Cranial nerve attachments: superficial attachment points for the cranial nerves