14.1a Central Nervous System - Cortex

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General Training Module CENTRAL NERVOUS SYSTEM RK 1

Unit 10 – Nervous System:

Unit 10 – Nervous System Part A – Central Nervous System Part B – Peripheral Nervous System Part C – Autonomic Nervous System Part D – Sensory Organs & Systems

The Nervous System – Contents :

The Nervous System – Contents Overview of the Nervous System & its components The Central Nervous System The Brain and its parts The Spinal Cord an its parts The Meninges of the CNS The ventricles of the Brain, The Spinal Canal & Cerebro - Spinal Fluid (CSF)

An Overview of the Nervous System:

An Overview of the Nervous System

The Nervous System:

The Nervous System The Central Nervous System (CNS): The Brain The Spinal Cord The Peripheral Nervous system (PNS): Somatic Nerves: Cranial Nerves – 12 pairs Spinal Nerves – 31 pairs The Autonomic Nervous System (ANS) - Sympathetic component ( thoraco -lumbar) Parasympathetic component ( cranio -sacral) Visceral Sensory Nervous System

The Nervous System:

The Nervous System The nervous system receives information from: The external environment (sensory input from our sensations – five sensory organs) as well as from The internal environment (Visceral pain, CO2 levels, Hormone levels etc , temperature,) Neural Chemical Thermal

The Nervous System:

The Nervous System The Central Nervous System Information Action Changes in the Internal Environment From External Environment 5 sensory organs From Internal Environment Neural Chemical Thermal Peripheral Nervous System Autonomic Nervous System Visceral Afferent System Physical activity  +/- Changes in external Environment Somatic Nervous System Somato -sensory Nervous System Processing Brain & the Spinal Cord

Terminology:

Terminology Information Reception Action/Response Processing INPUT AFFERENT SENOSRY OUTPUT E FFERENT MOTOR CNS P NS ACENDING DESCENDING

Organization of the Nervous System:

1. The Central Nervous System (CNS) The Brain – gives off cranial nerves of the PNS The Spinal Cord – gives off the spinal nerves of the PNS 2. The Peripheral Nervous System (PNS) Somatic Nervous System (Sensory –Motor Nervous system) Motor Nervous System Somato -Sensory Nervous System – Somatic Sensation Visceral Nervous System The Autonomic Nervous System (ANS) – Sympathetic ( Thoraco -Lumbar) & Parasympathetic ( Cranio -Sacral) components Visceral Afferent Nervous System – Visceral Sensation Organization of the Nervous System Peripheral Nerves (Spinal/Cranial) Visceral Nerves Cranial Nerves Has all 3 components: Somatic, Autonomic and Visceral

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Cranial Nerves have all three components: (1) Somatic Nervous System; (2) Autonomic and (3) Visceral Afferent System Somatic Nervous Syste m The diagram illustrates the concepts of each component given above but is not anatomically correct Afferent Visceral Nervous Syste m (Spinal)

The Nervous System:

The Nervous System This information is transmitted to the Central Nervous System: Mostly by Sensory Nerves (information from the external environment via the five sensory organs) As well as Chemical or thermal signals obtain from the blood (information form the internal environment)

The Nervous System:

The Nervous System This information is then processed and in the central nervous system Appropriate responses are generated thereafter to alter: Activity of skeletal muscles therefore creating changes in the external environment as well as Activity of Smooth muscles in internal tissues/organs changing the internal environment! Chemical changes like secretion of hormones

The Nervous System:

The Nervous System Based on the above respective functions carried out by different parts, the nervous system is divided into two main parts: The Central Nervous System The Peripheral Nervous system

The Central Nervous System (CNS): :

The Central Nervous System (CNS): The central nervous system is so named because it integrates information it receives from, and coordinates and influences the activity of, all parts of the body It consists of: The Brain The Spinal Cord

The Peripheral Nervous System:

The Peripheral Nervous System The peripheral nervous system (PNS) is the part of the nervous system that consists of the nerves and ganglia  outside the  brain and spinal cord .   The main function of the PNS is to connect the central nervous system (CNS) to the limbs and organs, essentially serving as a communication path going back and forth between the brain and spinal cord with the rest of the body .

The Autonomic Nervous System:

The Autonomic Nervous System The autonomic nervous system (ANS) is a division of the peripheral nervous system that influences the function of internal organs .   The autonomic nervous system is a control system that acts unconsciously and regulates bodily functions such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal.

The Visceral Nervous System:

The Visceral Nervous System This is the   part of the nervous system that carries Visceral A fferent F ibers   that conduct sensory impulses (usually visceral pain or reflex sensations) from the viscera, glands, and blood vessels to the central nervous system .   Though they are physically travel along with the nerves of the Autonomic Nervous system they are considered to be part of the visceral nervous system, not the autonomic nervous system. Unlike the efferent fibers of the autonomic nervous system, the afferent fibers are not classified as either sympathetic  or parasympathetic .

The Central Nervous System (CNS):

The Central Nervous System (CNS) The Brain & the Spinal Cord

The Brain:

The Brain

Parts of the Brain:

FORE-BRAIN: Cerebrum (& Diencephalon) MID-BRAIN PONS MEDULLA OBLONGATA HIND-BRAIN: cerebellum BRAIN STEM Parts of the Brain

The Brain:

The Brain DIENCEPHALON

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Parts

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CEREBRUM CEREBELLUM BRAIN STEM

Cerebrum:

Cerebrum

Cerebrum:

Cerebrum The cerebrum consists of two cerebral hemispheres that are separated in the midline by the longitudinal cerebral fissure It’s surface has convolutions or gyri and sulci or fissures to increase the surface area of the brain

Cerebral Hemispheres:

Cerebral Hemispheres Three (3) main sulci divides each hemisphere into several lobes that has taken the name of the skull bone corresponding to that area The Sulci are: Central Sulcus Lateral sulcus Parieto -occipital sulcus (1) Central sulci (2) Laterla Sulci (3) Parieto -occipital sulci

Lobes in Cerebral Hemispheres:

Lobes in Cerebral Hemispheres These lobes are: Frontal lobe Parietal lobe Temporal lobe Occipital lobe

White & Grey Matter:

White & Grey Matter The outer layer of the cerebrum has a large amount of nerve cell bodies concentrated This peripheral area is called Cerebral cortex. These areas are grey in colour. Therefore the periphery of the cortex is called Grey Matter

White & Grey Matter:

White & Grey Matter The fibres from these nerve cells connect different lobes of the brain as well as the brain and the spinal cord. They are usually white in colour. Therefore this inner parts of the brain with fibres of nerve cells are called white matter

White & Grey Matter:

White & Grey Matter

White & Grey Matter:

White & Grey Matter

White & Grey Matter:

White & Grey Matter

Functions of the Cerebrum:

Functions of the Cerebrum Three main types of functions are associated with the cerebral hemispheres: Higher Mental Activities : Memory, intelligence, thinking, reasoning, learning moral sense, sense of responsibility. Sensory Perception (Sensory Cortex) : Touch, pain, heat and cold; sight, hearing, taste and smell and also the position of joints and movement of muscles Initiation and Control of Voluntary Muscle contractions (Motor Cortex)

Functional Areas of the Cerebral Cortex:

Functional Areas of the Cerebral Cortex FRONTAL LOBE: Motor Area or Cortex – in the pre-central area lies immediately anterior to the central sulcus In the lower part of the Motor area near the lateral sulcus is the Motor Speech Area ( Broca’s Area). It p roduces speech Anterior to Motor area is the Pre-motor area influence and coordinate the activity of motor area to generate patterns of movement. Eg : manual dexterity Anterior to this the remainder of the frontal lobe or the pole greater in humans than in other mammals and is associated with Complex Social behavior.

Functional Areas of the Cerebral Cortex:

Functional Areas of the Cerebral Cortex PARIETAL LOBE: Sensory Area or Cortex – in the post-central area. Lies immediately posterior to the central sulcus . Lower part of this area is the Sensory Speech (Wernicke’s) Area extending below to the Temporal Lobe as well. This is concerned with recognizing & understanding speech (Spoken Language) In the deep layers of sensory area just above the lateral sulcus lies the Taste Area. Area behind this part forms the major part of the parietal lobe and is associated with sensory memory .

Functional Areas of the Cerebral Cortex:

Functional Areas of the Cerebral Cortex TEMPORAL LOBE: Part of the Sensory Speech Area Auditory Area lies immediately below the lateral sulcus in the temporal lobe. Deep in the temporal lobe lies the Olfactory Area which is associated with smell.

Functional Areas of the Cerebral Cortex:

Functional Areas of the Cerebral Cortex OCCIPITAL LOBE: Visual Area lies behind the parieto -occipital sulcus in the Occipital lobe.

Cortical Areas:

Cortical Areas

Cerebral Nuclei or Ganglia:

Cerebral Nuclei or Ganglia In addition to the neurones in the cortical grey matter there are collections of neurones lying in the deeper parts of the cerebral hemispheres. They are known as either ganglia or nuclei There are several important such ganglia: Basal Ganglia (or neuclei ) Thalamus Hypothalamus

Basal Ganglia:

Basal Ganglia

Basal Ganglia:

Basal Ganglia They consist of a complex group of nuclei They lie deep within the cerebral hemispheres at their base. They are involved in maintaining skeletal muscle tone and coordinating movement among other functions. If control is absent or inadequate movements may become jerky, clumsy or uncoordinated.

Basal Ganglia:

Basal Ganglia The basal ganglia are associated with a variety of functions including: Control of voluntary motor movements Procedural   learning Routine behaviours or "habits" such as  teeth grinding Eye movements   Action selection Cognition   Emotion

Basal Ganglia:

Basal Ganglia In terms of anatomy, the basal ganglia are divided into four distinct structures, depending on how close to the top of the head they are: The   striatum: Caudate Nucleus & Putamen   The   Globus Pallidum : GP externa & interna The S ubstantia N igra The S ubthalamic Nucleus.

Basal Ganglia:

Basal Ganglia In terms of anatomy, the basal ganglia are divided into four distinct structures, depending on how close to the top of the head they are: Two of them, the striatum and the  pallidum , are relatively large; The other two, the substantia nigra and the subthalamic nucleus, are smaller. In the illustration, two coronal sections of the human brain show the location of the basal ganglia components.

Basal Ganglia:

Basal Ganglia Striatum Globus Pallidus ( Gpe & Gpi ) 3. Sub Thalamic Nuclei (STN) 4. Substantia Niagra (SN)

Terminology – Basal Ganglia:

Terminology – Basal Ganglia Corpus Striatum Striatum = Striate Nucleus = Neostriatum Dorsal Striatum (divided into 2 by internal capsule) Caudate Nucleus Putamen Ventral Striatum Nucleus accumbens Olfactory tubercle Globus Pallidus Globus Pallidus Externa ( GPe ) Globus Pallidus Interna ( GPi ) Sub Thalamic Nuclei (STN) Substantia Nigra (SN) Lentiform Nucleus

Thalamus:

Thalamus Two groups of nerve cells and fibers lying in each cerebral hemisphere on either side of the third ventricle Sensory inputs coming from the skin, special senses and viscera first go through the thalami on either side before they are redistributed to the cerebrum

Hypothalamus:

Hypothalamus Has several groups of nerve cells and is located anterior and inferior to the thalamus, immediately above the pituitary gland. It is linked to the anterior lobe of the pituitary gland by blood vessels and the posterior lobe of the pituitary by nerve fibers. This way the hypothalamus influence these pituitary lobes.

Hypothalamus:

Hypothalamus It also controls the autonomic nervous system : C ontrol of hunger T hirst B ody temperature H eart and blood vessels and D efensive reactions such as those associated with fear and rage

Limbic System:

Limbic System This is a system of interconnecting ganglia and network of nerves in the brain Located sub-cortically at the border between the cerebral hemispheres and the brain stem. It regulates and associated with emotions and feelings and responses in relation to them, Regulates the visceral autonomic processes of the body.

Limbic System:

Limbic System Some of the emotions the limbic system is associated with are Instinct and mood. The basic emotions (fear, pleasure, anger) and It drives (hunger, sex, dominance, care of offspring).

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Fornix

Ventricles of the Brain :

Ventricles of the Brain There are four irregular shaped cavities within the brain which are know as ventricles They contain cerebro -spinal fluid (CSF) They are: The right and left lateral ventricles The third ventricle The fourth ventricle

Ventricles of the Brain :

Ventricles of the Brain

Lateral Ventricles of the Cerebral Hemispheres:

Lateral Ventricles of the Cerebral Hemispheres

Neurotransmitters of the Brain:

Neurotransmitters of the Brain # Neurotransmitter The Part Effect 1. Glutamate Most parts of the Brain – The predominant neurotransmitter Inputs from the cortex and the thalamus to the Striatum and Subthalamic Nuclei Excitatory Effect 2. GABA (Gamma Amino Butyric Acid) Most Neurones in the Basal Ganglia Ouput from the striatum, pallidum and Substantia Nigra Inhibitory effect 3. Dopamine Projections from Substantia Nigra to Dorsal Striatum Modulatory Effect 4. Acetylecholine External inputs to the striatum Inter-striatal neurons. Straitum has one of the highest amount to cholinergic fibers though overall cholinergic activity in the brain is at a very low level.

End of Unit 10 – Part A1:

End of Unit 10 – Part A1

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