Transcript The Nervous System Chapter 8

Anatomy Nervous System Lab
Divisions of the Nervous
System
 Central nervous system – brain &
spinal cord
 Peripheral nervous system –
cranial nerves & spinal nerves
The Brain
 Brain stem
 medulla oblongata (M.O.)
Cerebrum
 pons
 midbrain
 Diencephalon
T
H
M
 thalamus
PP
 hypothalamus
midbrain
Cerebellum
 mamillary bodies
 epithalamus (pineal gland)
pons
m.o.
 Cerebrum
 Cerebellum
The Brainstem
 medulla oblongata (M.O.)
 pons
 midbrain –
 cerebral peduncle
 cerebral aqueduct of
midbrain
 corpora
quadrigemina
pons
 superior colliculi
Cerebral
peduncle
Cerebral
aqueduct of
midbrain
m.o.
 inferior colliculi
The Diencephalon
 thalamus
 hypothalamus
 mamillary bodies
T
H
M
infundibulum
P
 connects to
pituitary gland via
infundibulum
 epithalamus (pineal
gland)
The Diencephalon
Intermediate mass of
Thalamus
Pineal gland
Hypothalamus
Infundibulum
Pituitary gland
Cerebrum
convolutions
gyrus
sulcus
(separated
from cerebrum
by transverse
fissure)
4 lobes per hemispherefrontal, parietal,
temporal, occipital
The Cerebrum
corpus callosum
septum
pellucidum
fornix
The Cerebellum
 gray matter “folia”
 white matter “arbor
vitae”
 separated from
cerebrum by transverse
fissure
Transverse
fissure
 2 hemispheres
connected by “vermis”
The Spinal Cord
 Begins at foramen magnum & ends at
L2 vertebral level by forming conus
medularis
 Has 2 thickened areascervical enlargement - supplies
nerves to upper extremity
lumbar enlargement - supplies
nerves to lower extremity
 Made up of 31 spinal cord
segments
Cross Sectional Anatomy of the Spinal
cord segments
Posterior median sulcus
Dorsal root
Dorsal root
ganglion
Posterior column
Posterior gray horn sensory
Central canal
Lateral column
Gray commissure
Anterior column
Lateral gray horn (T1-L2, S2S4) - autonomic
Anterior gray horn motor
Spinal nerve
Ventral root
Anterior median fissure
The Spinal Cord & Spinal Nerves
• Each spinal cord segment gives off a
pair of spinal nerves
• each spinal nerve forms from union
of dorsal/ventral root of spinal cord
segment & exits between vertebra at
IVF
• 8 pair cervical spinal nerves – 1st cervical nerve
exits between occipital bone & C1, 8th cervical
nerve exits the IVF between C7-T1
• 12 pair thoracic spinal nerves
• 5 pair lumbar nerves
• 5 pair sacral nerves
• 1 pair coccygeal nerves
Below the conus medularis,
spinal nerves must angle
downward (in the
subarachnoid space) before
exiting their IVF. These spinal
nerves make up the cauda
equina
Cauda equina
The Central Nervous System
CNS well protected by bones (cranial & vertebrae),
CT meninges, & cerebrospinal fluid (CSF)
Meninges – Connective tissues that surround
and protect the brain and spinal cord (CNS)
3 layers:
• Dura Mater
• Arachnoid
• Pia Mater
Meninges
2
layers thick
around brain with
creation of dural
sinuses between
layers; dural folds
into fissures of brain
Dura Mater – tough,
fibrous outer layer
Dural folds and dural
sinuses
Superior sagittal sinus
Falx cerebri
Inferior sagittal sinus
Tentorium cerebelli
Straight
sinus
Confluence
of sinuses
Transverse
sinus
Sigmoid sinus
Dural folds and dural sinuses
Superior sagittal sinus
Falx cerebri
Inferior sagittal sinus
Straight sinus
Confluence of sinuses
Transverse sinus
Meninges- Dura mater
1
layer around spinal cord with
epidural space external
Meninges
Arachnoid – “spidery” web-like middle layer
Pia Mater – delicate, thin inner layer;
 filum terminale - extension of
pia mater extends from tip of
cord to coccyx to anchor cord
in place;
 denticulate ligaments anchor
cord laterally
Meninges
Subarachnoid space – between arachnoid & pia
mater; contains cerebral spinal fluid (CSF)
Subarachnoid space
(blue space)
Cerebrospinal Fluid (CSF)
clear, colorless fluid formed by filtration of blood
plasma by choroid plexuses within ventricles of the
brain.
 functions in protection of CNS, support, nutrient
supply, waste removal
CSF Circulation
Lateral ventricle (behind
septum pellucidum)
Third ventricle
Aqueduct
of midbrain
Fourth ventricle
Lateral ventricles (in
cerebral hemispheres) 
interventricular foramen
 third ventricle (in
diencephalon around
thalamus)  cerebral
aqueduct of midbrain 
fourth ventricle (between
pons/cerebellum) 
subarachnoid space &
central canal of SC
Reabsorption of CSF through
arachnoid granulations (arachnoid
villi) of dural sinuses (superior
sagittal sinus)  into cerebral veins
(space around & within
thalamus & hypothalamus)
Cranial Nerves
 12 pairs of nerves that connect to the brain; provide
motor, sensory &/or autonomic (parasympathetic)
function
Spinal nerves
& Plexuses
(Intercostal nerves)
(Common peroneal nerve)