Dr. Ali Mohsin

(M.Sc., Ph.D. Anatomy, Histology & Embryology)

Neuroanatomy-1: Introduction(figures)

Neuroanatomy: Introduction

Dr. Ali Mohsin

Human brain

Hu

man

nervo

us system

Hu

man

brain

, spin

al cord

, &

spin

al nerve ro

ots

Human nervous system

Nervous System

Central (CNS) Peripheral (PNS)

Cranial NervesSpinal Cord

Spinal Nerves

Brain

Nervous System

Forebrain Midbrain

Cerebrum Diencephalon

Hindbrain

Pons CerebellumMedulla Oblongata

Brainstem

Autonomic Nervous System (ANS)

Somatic Nervous System (SNS)

Sympathetic Nervous System

Parasympathetic Nervous System

Enteric Nervous System

Motor Pathway Sensory Pathway

Anatomic classification

Functional classification

Nervous System Classifications

Neu

ral tub

e

Spin

al Co

rdB

rain

CN

S develo

pm

ent

Forebrain

Midbrain

Hindbrain

CNS development

CNS development

Motor & sensory columns in the brainstem

Neurons: parts, morphological & functional classifications

• Glial cells: supportive cells to the neurons.

Nervous tissue. N: neuron, G: glial cells, Np:neuropil (dendrites & axons

Nervous System Function

Grey matter• The grayish zone of the CNS. It consists of a huge number of

neuronal bodies (perikarya) & dendrites, glial cells, & the initial unmyelinated segments of axons.

• It occupies the outer zone (cortex) of the cerebrum & cerebellum, & the inner zone of the rest of the CNS.

• The thickness of the cortex varies from 1.5 to 4.5 mm. being thickest over the crest of a gyrus and thinnest in the depth of a sulcus.

• Exists also as deeper nuclei.

White matter• Whitish part of the CNS. It consists of aggregation of (myelinated)

nerve fibers (axons) & glial cells. No perikarya (cell bodies).

• It occupies the interior of the cerebrum & cerebellum, & the exterior of the rest of the CNS.

• White matter fibers:

o Association fibers (blue arrow)

o Commissural fibers (green arrow)

o Projection fibers (red arrow)

Association FibersCommissural FibersProjection Fibers

•N

erve: an aggregatio

n o

f nerve fib

ers (axon

s) in th

e PN

S

•G

anglio

n: an

aggregation

of n

erve cell bo

dies (p

erikarya) in th

e PN

S

•Tract (fascicu

lus): an

aggregation

of n

erve fibers in

the C

NS, h

aving th

e sam

e origin

& term

inatio

n, &

serving th

e same fu

nctio

n.

•Fu

nicu

lus (co

lum

n): a large b

un

dle o

f wh

ite matter w

hich

may co

nsist

of several fu

nctio

nally d

ifferent tracts o

r fasciculi.

•R

eticular fo

rmatio

n: a regio

n in

the b

rain stem

& u

pp

er spin

al cord

co

nsistin

g of a gro

up

of in

tercon

nected

neu

ron

s intersp

ersed am

on

g n

erve fibers.