Anatomy of brain and spinal cord

BMS 231: 2015/2016

DR SOBIA IKRAMDR AQEELA BANODR SADIA FARHAN

INTRODUCTION

• The brain is one of the most complex and magnificent organs in the human body.

• Our brain gives us awareness of ourselves and of our environment, processing a constant stream of sensory data.

• It controls our muscle movements, the secretions of our glands, and even our breathing and internal temperature.

• Every creative thought, feeling, and plan is developed by our brain. The brain’s neurons record the memory of every event in our lives.

INTRODUCTION

• Brain is a soft fragile organ that is protected in the bony structure called skull.

• Brain weighs about 3 pounds but it contains 100 billion cells.

• Acts as a command and control center for voluntary actions .

• Act as main coordinating center for automatic actions.

ANATOMY

Anatomically brain is divided into three parts

1. Cerebrum 2. Cerebellum 3. Brain stem

ALSO CONTAIN1. Grey matter2. White matter

3. Ventricles

4. Cerebrospinal fluid

ANATOMY

• Largest part of the brain• On the surface are present several elevations and

depressions called gyri and sulci. • Divided by inter hemisphere sulcus into1. Right hemisphere2. Left hemisphere Lt hemisphere Rt hemisphere

Cerebrum

Functions of cerebrum

• Act as integrating center for highly complex functions like

• Memory, learning, emotions, language and reasoning.

Cerebrum

Parts of cerebrumCerebrum is divided into four lobes by various

fissures1. Frontal lobe2. Parietal lobe3. Temporal lobe4. Occipital lobeAll the four lobes have different highly complex functions

Cerebrum

Parts of cerebrum

1. Frontal lobe• Planning, organizing and controlling• Cognition and memory2. Parietal lobe• Processing of sensory input• Body orientation• Recognition of somatic areas3.Occipital lobe• Primary visual perception area4. Temporal lobe• Auditory receptive area• Express behaviour• Language• Memory and information retrieval area

Cerebrum

CEREBELLUM

• Also called little brain• Present on the posterior and inferior part of the cerebrum• Has two hemispheres• Connected to the spinal cord through the medulla

oblongata.

Functions of cerebellum

1. The cerebellum plays an important role in motor control.

2. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses.

3. The cerebellum does not initiate movement, but it contributes to coordination, precision, and accurate timing.

CEREBELLUM

Brain stem

It is the part of the brain that connects the cerebrum to the

spinal cord.It consists of three parts:1. Mid brain2. Medulla oblongata3. pons

1. Mid brain

It is the smallest portion of the brain that act as a relay station for the auditory and visual informations.

It also control eye movements and body movements.

Brain stem

2. Pons

Pons, is the part of the brainstem lying above the medulla oblongata

The pons is a broad, horseshoe-shaped mass of transverse nerve fibres that connect the medulla with the cerebellum.

Brain stem

FUNCTIONS OF THE PONS1. Act as a connecting pathway for signals

between cerebrum and cerebellum2. Controls the respiration3. Responsible for consciousness4. Also play role in hearing

Brain stem

Medulla oblongata• The medulla oblongata is conical in shape.• Its broad part joins the pons above and narrow

part becomes continuous with the spinal cord.• The junction between medulla and spinal cord is

at the level of the upper border first cervical vertebra.

• Its length is about 3 cm and its width is about

2cm.

Brain stem

Functions of medulla oblongataMedulla oblongata involves in the regulation of1. Heart rate 2. Blood pressure3. Breathing4. Digestion5. Sleep and arousal

Brain stem

Ventricles and cerebrospinal fluid

VENTRICLES ventricles are the set of four cavities in the

brain parenchyma that intercommunicates with each other.

They are lined with the blood vessels that are called choroid plexuses, it secretes fluid called cerebrospinal fluid.

Four ventricles are 1. Two lateral ventricles2. Third ventricle3. Fourth ventricle

Ventricles and cerebrospinal fluid

Cerebrospinal fluid• A watery fluid that is continuously produced

and absorbed and that flows in the ventricles within the brain and around the surface of the brain and spinal cord.

• Abbreviated as CSF.

• CSF is produced by the choroid plexus, a series of infolded blood vessels that project into the cerebral ventricles, and it is absorbed into the venous system.

Ventricles and cerebrospinal fluid

FUNCTIONS OF CEREBROSPINAL FLUID• Absorbs physical shocks to the brain• Distributes nutritive materials to and removes

wastes from nervous tissue• Provides a chemically stable environment

Ventricles and cerebrospinal fluid

• Grey and white matters are present in both brain and spinal cord.

• Grey matter is composed of neuron cell bodies but white matter is composed of nerve fibers.

GREY AND WHITE MATTER

• If the spinal cord is cut in transverse section there is a tiny central canal which contains CSF.

• There is a dark portion of H-shaped or butterfly shaped “gray matter”, surrounded by a larger area of “white matter”.

GREY AND WHITE MATTER

The Spinal cord• The spinal cord is a

cylindrical grayish white structure that begins from medulla oblongata above and terminates below

• In adults: at the level of upper border of first lumber vertebra.

• In the young child it is relatively longer and ends at the upper border of third lumber vertebra

• Inferiorly the spinal cord tapers off into the structure called conus medullarius.

• The nerve roots of the lumbar and sacral regions are called cauda equina.

The Spinal cord

The Spinal cord

There are 31 pairs of spinal nerves.

Spinal Meninges• Membranes that covers the

spinal cords and its nerve roots are called spinal meninges.

• The outer layer is called dura mater. This is a tough, fibrous memebrane.

• The middle layer, the arachnoid, runs This is delicate and transparent.

• The innermost is called, pia mater. It is highly vascular and tightly attached to the spinal cord and its roots.

The Spinal cord

• That’s all about the brain and spinal cord.

• Its so easy isn't it?

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