Nervous System

Nervous System

Nervous System

The nervous system is responsible for controlling much of the body, both through somatic (voluntary) and autonomic (involuntary) functions It is very important in helping to maintain balance of the body Made up of nerve tissue neurones and neuroglia

Nervous system enables the body to react to continuous changes in its internal and external environment

Division of nervous system:

• Nervous system is divided
• Structurally into
• Central nervous system
• Peripheral nervous system
• Functionally into
• Somatic

Autonomic

Present in the cranial cavity

Surrounded by three layers of meninges

Don’t get confused about simple anatomy on parts of the brain- fore brain,mid brain and hind brain

• brain has 2 hemispheres namely right and left hemisphere

has 4 lobes namely occipital lobe,pariental lobe,frontal lobe and temporal lobe

Brain and spinal cord composed of grey mater and white mater

• Grey mater formed by nerve cell bodies

White mater formed by interconnecting fibre tract system

Brain

Forebrain (prosencephalon)-cerebrum,thalamus+hypothalamus form limbic system(regulation of thirst, hunger, mood) and basal ganglia (reward processing, habit formation, movement and learning Midbrain(mesencephalon)-tectum,tegmentum Hind brain (rhombencephalon)- cerebellum,pons,medulla oblangata Applied anatomy:degeneration of basal ganglia cells uncoordinated movements of skeletal muscles e.g in Parkinson’disease NB: midbrain, pons and medulla form the brain stem

Development of brain

Nervous System

v vv

The diencephalon is located at the center of the brain, and its name (Greek for “between-brain”) reflects that.

It’s surrounded by the brain stem and cerebellum on the bottom and the cerebral cortex on top.

The corpus callosum is the bridge between the left and right sides of the brain

The corpus callosum (Latin for "tough body")

The Meninges

The central nervous system consists of the brain and spinal cord.

The brain and spinal cord are completely covered by three membranes, the meninges lying between the skull and the brain, and between vertebrae and the spinal cord.

• o Dura mater
• o Arachnoid mater

o Pia mater

Ventricular system

Ventricular system is a communicating system of cavities underlined by choroid plexus which produce cerebrospinal fluid and transport it around the cranial cavity.

• They are lined by ependymal cells.
• There are ventricles:-
• Lateral ventricles
• Third ventricle
• Fourth ventricle

Central Canal.

Ventricles of the Brain

• Within the brain there are four irregular shaped cavities containing cerebrospinal fluid.
• They are called ventricles, these are
• o Right and left lateral ventricles

o third ventricle and fourth ventricle

lateral ventricles

• lateral ventricles are the two largest cavities of
• the ventricular system of the human brain and

contain cerebrospinal fluid (CSF).

Each cerebral hemisphere contains a lateral ventricle, known as the left or right ventricle They open into the 3rd ventricle through the interventricular foramina (of monro).

They are separated from each other by a thin membrane, the septum lucidium,and are lined by ciliated epithelium (ependymal cells).

3rd ventrical It is a cavity situated below the lateral ventricles between the two parts of the thalamus.

Fourth ventricle

It is situated below and behind the third ventricle, between the cerebellum and pons.

It communicates with the subarachnoid space by 3 foramina in its roof, and continuous below with central canal of the spinal cord The fourth ventricle contains cerebrospinal fluid. It has a diamond shape and is located in the upper portion of the medulla

CEREBRAL SPINAL FLUID

It is also found inside the subarachnoid space of the meninges which surrounds both the brain and the spinal chord.

In addition, a space inside the spinal chord called the central canal also contains cerebrospinal fluid CSF is produced mainly by a structure called the choroid plexus in the lateral, third and fourth ventricles. A small amount is also produced by ependymal cells.

Ependymal cell,

type of neuronal support cell (neuroglia) that forms the epithelial lining of the ventricles (cavities) in the brain and the central canal of the spinal cord.

Composition of CSF

• It consists of
• Water
• Mineral salts
• Glucose
• Plasma proteins: small amount of albumin and globulin
• Small amount of creatinine, urea
• A few leukocytes

It is slightly alkaline

Functions of CSF

Applied anatomy

Hydrocephalus

PNS

12 pairs of cranial nerves—leave the brain and pass through the foramina in the skull 31 pairs of spinal nerves—leave the spinal cord and pass through intervertebral foramina

Cranial nerve

any of the nerves that arise in pairs from the lower surface of the brain one on each side and pass through openings in the skull to the periphery of the body and that comprise 12 pairs.

They can be classified as sensory nerves, motor nerves, or a combination of both, primarily responsible for the sensory and motor functions of the head and neck (one of these nerves targets organs in the thoracic and abdominal cavities as part of the parasympathetic nervous system).

spinal cord

• cervical segments
• thorathic segments
• lumbar segments
• sacral segments

coccygeal segements

Origin of spinal nerves

Spinal nerves

• Actions of the spinal nerves Level Motor Function
• C1–C6: Neck flexors
• C1–T1: Neck extensors
• C3, C4, C5=Phrenic nerve Supply diaphragm (mostly C4)
• C5, C6: Move shoulder, raise arm (deltoid); flex elbow (biceps)
• C5,C6,C7=long thoracic nerve motor to Serratus anterior
• C6 Externally rotate (supinate) the arm
• C6, C7: Extend the elbow and wrist (triceps and wrist extensors); pronate wrist

C7, C8: Flex wrist; supply small muscles of the hand

T1–T6 Intercostals and trunk above the waist

• T7–L1 Abdominal muscles
• L1–L4 Flex thigh

L2, L3, L4 Adduct thigh; extend leg at the knee (quadriceps femoris) L4, L5, S1 Abduct thigh; flex leg at the knee (hamstrings); dorsiflex foot (tibialis anterior); extend toes L5, S1, S2 Extend leg at the hip (gluteus maximus); plantar flex foot and flex toes

Nervous System

The nervous system is responsible for controlling much of the body, both through somatic (voluntary) and autonomic (involuntary) functions.

• It is very important in helping to maintain balance of the body.

Made up of nerve tissue-neurone and neuroglia Nervous system enables the body to react to continuous changes in its internal and external environment.

Division of nervous system.

• Nervous system is divided into:
• Structurally
• Central nervous system.
• Peripheral nervous system
• Functionally
• Somatic

Autonomic

Brain Present in the cranial cavity.

Surrounded by 3 layers of meninges.

Don't get confused about simple anatomy on parts of the brain- fore brain, mid brain and hind brain.

• Brain has 2 hemispheres namely right and left hemisphere

Has 4 lobes namely occipital lobe, Pariental lobe, Frontal lobe and Temporal lobe

Brain and spinal cord composed of grey mater and white mater.

• Grey mater formed by nerve cell bodies.
• White mater formed by interconnecting fibre tract system.
• Brain.
• Fore brain – Cerebrum, thalamus, hypothalamus form limbic system.
• Midbrain – tectum, tegmentum.
• Hind brain – cerebellum, pons, medula oblangata form brain stem.
• The corpus callosum is the bridge between the left and right sides of the brain.

The corpus callosum (Latin for "tough body").

Diencephalon.

The diencephalon is located at the center of the brain, and its name (Greek for “between-brain”) reflects that.

It’s surrounded by the brain stem and cerebellum on the bottom and the cerebral cortex on top.

Hypothalamus.

A part of the brain that is in the forebrain, it is located below the thalamus and the cerebrum.

The hypothalamus contains several important centers which control body temperature, thirst, hunger ,water balance and sexual function. It is also closely connected with emotional activity and sleep and works with the pituitary gland.

Meninges of the Brain.

The central nervous system consists of the brain and spinal cord.

The brain and spinal cord are completely covered by three membranes, the meninges lying between the skull and the brain, and between vertebrae and the spinal cord.

• Dura mater.
• Arachnoid mater.

Pia mater.

Ventricular system

Ventricular system is a communicating system of cavities underlined by choroid plexus which produce cerebrospinal fluid and transport it around the cranial cavity.They are lined by ependymal cells.

• Within the brain there are four irregular shaped cavities containing cerebrospinal fluid.
• They are called ventricles, these are:-
• Right and left lateral ventricles

Third ventricle and fourth ventricle

Lateral ventricles.

• Lateral ventricles are the two largest cavities of
• The ventricular system of the human brain and

contain cerebrospinal fluid (CSF).

Each cerebral hemisphere contains a lateral ventricle, known as the left or right ventricle.

They open into the 3rd ventricle through the interventricular foramina (of monro).

They are separated from each other by a thin membrane, the septum lucidium, and are lined by ciliated epithelium.

3rd Ventrical is a cavity situated below the lateral ventricles between the two parts of the thalamus.

CEREBRAL SPINAL FLUID (CSF).

Nervous System

CSF, It is also found inside the subarachnoid space of the meninges which surrounds both the brain and the spinal chord. In addition, a space inside the spinal chord called the central canal also contains cerebrospinal fluid.

CSF is produced mainly by a structure called the choroid plexus in the lateral, third and fourth ventricles. A small amount is also produced by ependymal cells.

• Composition of CSF
• It consists of:-
• Water
• Mineral salts
• Glucose
• Plasma proteins: small amount of albumin and globulin
• Small amount of creatinine, urea
• A few leukocytes

It is slightly alkaline

Peripheral Nervous System.

12 pairs of cranial nerves—leave the brain and pass through the foramina in the skull 31 pairs of spinal nerves—leave the spinal cord and pass through intervertebral foramina

Spinal Cord

Spinal nerves

• Actions of the spinal nerves Level Motor Function.
• C1–C6: Neck flexors.
• C1–T1: Neck extensors.
• C3, C4, C5: Supply diaphragm (mostly C4).
• C5, C6: Move shoulder, raise arm (deltoid); flex elbow (biceps).
• C6: Externally rotate (supinate) the arm.
• C6, C7: Extend the elbow and wrist (triceps and wrist extensors); pronate wrist.

C7, C8: Flex wrist; supply small muscles of the hand

DERMATOMES.