NERVOUS SYSTEMDr. Shabana AliIIMC

Divisipn Meninges

INTRODUCTION

Nervous system is divided Anatomically into:

1. Central Nervous System.2. Peripheral Nervous System.

Functionally it is divided into:1. Somatic Nervous System .2. Autonomic Nervous System .

1.Central nervous system

1.Brain and 2.spinal cord

Parts of brain Forebrain or prosencephalon Midbrain or mesencephalon Hindbrain or rhombencephalon

INTRODUCTION

Parts of hindbrain▪ Pons▪ Medulla oblongata▪ Cerebellum

2.spinal cord Starts at foramen

magnum and ends at L2 level.

2.Peripheral nervous system Twelve pairs of cranial nerves Thirty one pairs of spinal nerves

▪ Cervical – 8▪ Thoracic – 12▪ Lumbar – 5▪ Sacral – 5▪ Coccygeal – 1

Composition of a spinal nerve▪ Sensory fibres▪ Motor fibres▪ Autonomic fibres

Peripheral nervous system

Brain stemCranial nerves

Spinal cord

Coverings of the brain(Dap ) Dura mater---outermost Arachnoid mater---middle S2

LEVEL Pia mater---innermost----coccycx

Also cover the spinal cord after passing through foramen magnum

DURAL FOLDS

1.Falx cerebri2.Tentorium cerebelli3.Falx cerebelli

DURAL FOLDS

Falx cerebri

VENOUS SINUSES OF BRAIN

DURAL VENOUS SINUSES

LOBES OF THE BRAIN

CEREBRAL LOBES

Central sulcus

parietoocipital sulcus

Lateral sulcus

Cerebral lobes

AREAS IN THE CORTEX

Arteries of the brain

BLOOD SUPPLY OF CEREBRUM Ant cerebral Middle cerebral Post

cerebral

Spinal cord

Foramen magnum to lower border of L1 or upper border ofL2

COVERINGS OF THE SPINAL CORD DURA MATER ARACHNOID

MATER PIA MATER

SECTION THROUGH VERTEBRAL COLUMN

Vertebral body

pedicle

spinelamin

aGrey mater

White mater

Blood supply

Anterior and posterior spinal artery

Components of spinal nerve Ventral ramus and dorsal ramus

Spinal nerve

Divides into anterior and posterior rami Anterior --- -- body nerve plexus Posterior rami—sensory innervation to a

skin segment known as a dermatome

Ventral Roots The ventral (motor) roots consist of efferent fibers that convey output from the spinal

cord.

There are two components: (1) innervate voluntary striated

muscles, (2) influences to involuntary smooth

muscles,cardiac muscle, and glands

Voluntary muscles and spinal nerve root Ventral spinal root Muscles innervated C5–6 Biceps brachii (flexes elbow) C6–8 Triceps brachii (extends elbow) T1–8 Thoracic musculature T6–12 Abdominal musculature L2–4 Quadriceps femoris (knee jerk, patellar tendon

reflex) L5–S1–2 Gastrocnemius (ankle jerk, Achilles tendon reflex

Innervation by posterior ramus Dorsal spinal root Body region innervated C2 Occiput C4 Neck and upper shoulder T1 Upper thorax and inner side of

arm T4 Nipple zone T10 Umbilical girdle zone L1 Inguinal region L4 Great toe, lateral thigh, and

medial leg S3 Medial thigh S5 Perianal region

SECTION THROUGH SPINAL CORD

Autonomic nervous system Two parts

▪ Sympathetic▪ Parasympathetic

Functions of autonomic N S Involuntary Controls activities of heart, smooth

muscles of GIT, blood vessels & glands

Neuron

Smallest functional unit is neuron

It consists of cell body and cell processes

Types of neuron

Unipolar Bipolar Pseudo uni polar Multipolar

BONES AT THE BASE OF THE BRAIN