Introduction to the Nervous System:

CNS: Brain & Spinal Cord;

PNS: Somatic Nerves;

Meninges;

Dural Venous sinus;

and Cranial Fossae

by

Dr. Gun Anantasomboon

Human Gross Anatomy I for DT student (ANA 227)

July 1, 2013

Anatomy Unit, Faculty of Science

Rangsit University

Human Brain & Spinal Cord

Lecture outline:

3 Cranial Fossae Location & Parts of the Brain

- Cerebrum

- Diencephalon

- Cerebellum

- Brainstem

Cranial Nerves

Spinal Cord & Spinal Nerves

Meninges (Cranial & Spinal parts)

Blood supply of the brain

- The Circle of Willis

Ventricular System &

CSF Circulation

:

( )

2.

3 ( )

4 (Meninges) 3

5.

6.

cerebrospinal fluid &

CSF circulation)

Organization of the nervous system

1.

Central nervous system, CNS)

Brain

Spinal cord

(Nervous system)

2.

Peripheral nervous system, PNS)

, 12 cranial nerves

, 31 (spinal n.)

* autonomic nervous system)

: - Sympathetic nervous system

- Parasympathetic nervous system

Diencephalon

CNS:

- Brain:

- Spinal cord

PNS:

- Cranial nerves

- Spinal nerves

ANS:

- Sympathetic n. - Parasympathetic n.

SC begins at foramen magnum

SC ends at L1-2 vertebral level

Spinal cord

Cerebrum,

Diencephalon,

brainstem,

Cerebellum

Protection of the CNS:

- Bones: Brain skull

Spinal cord - vertebrae

(body & vertebral arch)

vertebral canal

- Meninges - Dura

- Arachnoid

- Pia & *dentate ligament - Cerebrospinal fluid (CSF)

within Subarachnoid space

(and ventricular system &

central canal of SC)

floating SC & Brain

(exmp. Brain 1.5 kg

0.3 kg in CSF)

Cranial Bone & Base of Skull

Brain is located in the cranial cavity, covering by cranial bones,

on base of skull.

frontal b.

ethmoid b.

sphenoid b.

parietal b.

temporal b.

occipital b.

Cranial cavity:

- anterior cranial fossa

- middle cranial fossa

- posterior cranial fossa

anterior cranial fossa

bed for frontal lobe

middle cranial fossa

bed for temporal lobe

posterior cranial fossa

bed for cerebellum

The Cranial fossae

CNS is neuroectodermal origin.

Developmental Anatomy of the CNS

Neural tube CNS:

- Cranial neural tube

Brain

- Caudal neural tube

Spinal cord

Developmental Anatomy of the CNS

Development of the Central Nervous System (CNS)

(form the Neural tube of embryo to the Brain & Spinal cord of adult)

Cerebrum

Diencephalon

Cerebellum

Brainstem:

- midbrain

- pons

- medulla oblongata

Spinal cord

CNS

slender nerve column

vertebral canal

medulla oblongata,

foramen magnum

L1-L2 vertebrae

: Cervical enlargement

: Lumbar enlargement

: Conus medullaris

: Filum terminale (end at S 2)

: Cocygeal ligament

Spinal cord (

1.

(both voluntory & involuntory)

2.

Reflex activities)

3. neurons ;

: sensory neurons dorsal horn

: intermediate neuron

: motor neuron (lower) -

Spinal cord (

The Spinal Cord

Meniges covering

Subarachnoid space

lumbar cistern

External morphology &

Different levels of SC

(C, T, L, S, Co)

Anterior / Posterior of SC

Ending of SC = conus medullaris

= L1-2 vertebra

Nerve roots

- Ventral n. roots

- Dorsal n. roots

& spinal ganglion/ or DRG DRG derived from neural crest cells of the neuroectoderm

Spinal nerves (31 pairs: C-8; T-12; L-5; S-5; Coc-1)

DRG

Lumbar cisterna (subarachnoid space at L2-S2)

Dural sac at SC terminal

- coccygeal ligament

Cauda equina

(collection of L-S nerve rootlets)

- ventral n. roots

- dorsal n. roots

Filum terminalae (pia mater)

Collection of Cerebrospinal fluid

(CSF) within lumbar cisterna

*Clin. Note: Lumbar puncture

usually perform at between L3-L5 CSF examinations:

- RBC = CNS vessel rupture

- CSF pressure

- pathogens in CSF

- etc.

Coccygeal ligament

Filum terminalae

Cross-section of the spinal cord

White matter

- anterior funiculus

- posterior funiculus

- lateral funiculus

(a)

(b)

Gray matter:

- ventral (anterior) horn

- dorsal (postrior) horn

- lateral horn : T 1-L2

Rami of Spinal Nerves

Branches of a Spinal Nerve

1. Anterior ramus - Intercostal nerves (T1-T11) run between the ribs

costae and subcostal nerve (T12) runs below the twelfth rib

2. Posterior ramus

- Medial

- lateral branches

1

2

Sensory Area distribution of a Spinal Nerve

http://www.bartleby.com/107/209.html

Nerve Plexuses

Ventral rami branch and anastomose repeatedly to form 5 nerve plexuses

cervical - C1 to C 5

supplies neck and phrenic nerve to the diaphragm

Brachial - C5 to T 1

supplies upper limb, some of shoulder and neck

Lumbar - L1 to L 4

supplies abdominal wall, anterior thigh and genitalia

Sacral - L4, L5 and S 1 to S 4

supplies remainder of lower trunk and lower limb

Coccygeal - S4, S5 and C 0

Diagram the Brachial plexus

Brachial plexus -C5-C8, T1-provides entire nerve supply of arm a. Axillary nerve -deltoideus and teres minor b. Musculocutaneous nerve -flexors of arm and forearm c. Radial nerve -muscles of posterior arm and forearm d. Median nerve -anterior forearm and some palm muscles e. Ulnar nerve -anteromedial muscles of forearm, most

The Cranial Nerves

CN.I olfactory n.

CN.II optic n.

CN.III oculomotor n.

CN.IV trochlear n.

CN.V trigeminal n.

CN.VI abducent n.

CN.VIII vestibulocochlear n.

(auditory n.)

CN.IX glossopharyngeal n.

CN.X vagus n.

CN.XI accessory n.

CN.XII hypoglossal n.

* CN.III CN.XII are arise from brainstem.

12 pairs:

Brain composes of functional parts:

Diencephalon

Brainstem

cerebellum

Spinal cord

Anterior Posterior

1. Cerebrum & Basal ganglia

2. Diencephalon

- Thalamus

- Hypothalamus

- Epithalamus

- Subthalamus

3. Brainstem

- Mid brain

- Pons

- Medulla oblongata

4. Cerebellum

5. Reticular formation

6. Limbic system

Cerebrum can be clearly divided as 5 lobes

frontal lobe parietal lobe

temporal lobe occipital lobe

insula lobe

corpuscallosum

septum pellucidum 1. Frontal lobe

2. Parietal lobe

3. Temporal lobe

4. Occipital lobe

5. Insula lobe

6. Limbic lobe

Lateral fissure

longitudinal fissure

Neuroanatomy: ANA 225

Neuroanatomy: ANA 225

Basal ganglia

deep cerebral nuclei

white matter

cerebral hemisphere

-

(learned-coordinated

movement)

The Basal ganglia = Deep cerebral nuclei: - caudate - putamen

- globus pallidus

- amygdaloid nucleus

Play a role in motor control system

Diencephalon 1. Thalamus

2. Epithalamus

3. Hypothalamus

4. Subthalamus

body

movement

basal ganglion,

cerebellum,

motor area

cerebrum

Reticular formation

brainstem

1.

2. ANS e.g., cardiovascular,

respiratory, gastrointestinal activities)

3. arousal

system or awareness

(emotion)

memory

limbic lobe: parahippocampal &

cingulate gyri ; hippocampus

Limbic system

Cerebellum

hemispheres

vermis

flocculo-nodular lobe

1. coordination)

2.

Proprioceptor impulse)

3.

semicircular canal)

Brainstem:

- Midbrain

- Pons

- Medulla oblangata

Anterior view

4th ventricle

pyramid

olive

cerebral peduncle

mamillary body

pituitary stalk

Midbrain

cerebrum pons

(cerebral aqueduct) &nerve

fibers cerebrum (e.g., Pons, medullar

oblongata, cerebellum spinal cord)

relay stations

nuclei 3, 4 (CN III, CN IV)

Anterior view

Posterior view

Pons

cerebellum, midbrain,

medulla oblongata

nerve fibers

Pons cerebellum

(fibers from higher levels

spinal cord) pons

relay stations

Medulla oblongata

cranium foramen

magnum

- cardiovascular center

- respiratory center

- reflex centers of vomiting,

coughing, sneezing and

swallowing

The Cranial Nerves

CN.I olfactory n.

CN.II optic n.

CN.III oculomotor n.

CN.IV trochlear n.

CN.V trigeminal n.

CN.VI abducent n.

CN.VIII vestibulocochlear n.

(auditory n.)

CN.IX glossopharyngeal n.

CN.X vagus n.

CN.XI accessory n.

CN.XII hypoglossal n.

* CN.III CN.XII are arise from brainstem.

12 pairs:

(The Meninges)

1.Dura mater

2. Arachnoid mater -

3. Pia mater -

Subarachnoid space

CSF

Subdural space

Cranial meninges Epidural space (potential space)

1. Dura mater

dense fibrous tissue

2

(periosteal layer)

(periosteum )

(menigeal layer)

meningeal dura 2

inner dura

1.1) falx cerebri

-

1.2) falx cerebelli

-

1.3) tentorium cerebelli

- &

dura

vertebral canal

Epidural space

The Dural Venous Sinuses

2. Arachnoid mater

fibrous CNT, reticular

fibers

subarachnoid space

(CSF)

3. Pia mater

CNT

filum

terminale arachnoid

dura mater coccyx

epidural space 1. Spinal dura mater

Spinal meninges

Ventricles of brain

and the cerebrospinal fluid

Right and left lateral ventricles

- cerebral hemisphere

third ventricle

interventricular foramen

Third ventricle

- thalamus

- fourth ventricle

cerebral aqueduct

Fourth ventricle

- Diamond -shaped

cerebral aqueduct

- cerebellum pons

- subarachnoid space

foramen of Margendie

2 foramen of Luskchka

The Cerebrospinal Fluid (CSF)

choroid plexuses

lat., 3 rd & 4 th ventricles

, ,

albumin, globulin , ,

creatine, urea

leukocytes (lymphocyte)

Ventricular System & CSF Circulation

CSF = cerebrospinal fluid

Choroid plexuses ***

Lateral ventricles (Rt. & Lt.)

interventricular foramen/ f. of Monro

Third ventricle

cerebral aqueduct

Fourth ventricle

central canal of spinal cord

foramen of Magendie subarachnoid space of brain & spinal cord

foramen of Lushka

Choroid plexuses are found

at lateral, third, and fourth

ventricles.

CSF

Site of the formation

and circulation patterns

of cerebrospinal fluid