Neuroscience 2:
Lecture 1: Topography of the Brian and the Spinal Cord
Importance of the Brain and Spinal Cord
- They are both constituted from unique collection of tissues of the NS
- The NS is unique for being the most sophisticated product of evolution
- When the brain and spinal cord are taken together, they:
o Constitute the main substance of the NS
o Make up what is referred to as the CNS
o Are responsible for carrying out and co-ordination all body’s functions
NS is made up from a large number of cells, the entire NS is complex
CNS is different from the PNS but there is a boundary where they cross (there is a continuum).
They can work together; the boundary is a site of all sorts of functions of the NS
The boundary is called the Redlich-Obersteiner’s Zone. Afferent system is a sensory system and the
efferent system is the motor system.
The Efferent can be split into the somatic and the autonomic NS. The afferent NS can be split into
sympathetic/ parasympathetic and the enteric NS.
CNS is characterized by encasement of the cranial and the vertebral column. There is a soft tissue
encasement in the meninges, and it is suspended in the CSF. IT is responsible for the sophisticated
functions of the NS.
Peripheral NS:
12 pairs of Cranial Nerves
31 pairs of Spinal Nerves
25 pairs of Autonomic Ganglia
31 pairs of Sensory Ganglia
Nerve plexuses
Enteric Nervous System
Cell types in the CNS:
2 broad types:
- Neurons (10%) = responsible for sophisticated function
- Neuroglia (90%)
Multiple differences between the cell types:
- General functions
- Ion channel expression (Glial cells have no Na+ channels)
- Diseases that target them and that they give rise to
- Diversity of Connections
General Anatomy of a Neuron:
Myelinated:
Presence of a cell body and axon. Dendrites are not required but can be present. Single axon can
eventually be branched out to affect many targets. Axon can be myelinated by the glial cells and this
transmits impulses much faster.
CNS – Oligodendrocytes provide Myelination
PNS – Schwann Cells provide Myelination
Unmyelinated section is the Node of Ranvier. The myelination provides saltatory conduction. The
initial segment of the axon is never myelinated, and it expressed Na+ channels to allow the initiation
of an AP.
Cranium, Calvaria and the Brain:
,External Appearance of the Skull:
Closed box formed of 4 major bones: Frontal, Parietal, Temporal and Occipital. These bones forma a
cavity integrally. The floor is formed from some of the major bones and also others: Frontal,
Occipital, Ethmoid, Sphenoid, Vomer, Nasal etc.
There are 22 bones.
Without the Mandible, the rest will be called a Cranium.
External Appearance of the Calvaria:
- Immovable joints of the skulls are called sutures.
- Cranial suture are fibrous joints
- There are many sutures to the calvaria.
3 important Sutures: Sagittal (anterior to posterior), Coronal and Parieto-Occipital or Lambdoid.
Coronal and Sagittal meet at the Bregman Point
Lambdoid and Sagittal Sutures meet at the Lambda Point
Positioning of these points is important for surgery.
Internal Appearances of the Roof of the Calvaria:
- The Skull Vault
- Flat on the Inside
- Generally Featureless
- Imprints of BV are present
- Foramina for Emissary Veins
, - Granular Pits
Internal Appearances of the Base of the Calvaria
- Irregular Shape
- Divisible into Cranial Fossae
- Anterior Fossa, Middle Fossa and Posterior Fossa. There are boundaries.
External Appearance of the Cranial Base:
- Irregular in Appearance
- Divisible into the anterior, middle and posterior
Anterior: Alveolar Arches of Maxilla to Posterior Edge of Hard Palate
Middle: Posterior Edge of hard palate to anterior edge of foramen magnum
Posterior: Lies behind the middle part
Brain:
Functions as a single organ. Anatomically, it has a bilateral structure. The two sides are
morphologically symmetrical but functionally, there is an asymmetry in specialization. The left and
right brain are connected.
The brain consists of:
- Cerebral Hemisphere
- Thalamic Masses
- Brainstem (Midbrain, Pons, Medulla)
- Cerebellum
- Cavities (Ventricles)
Cerebral Cortex:
It has many lobes which make up the cerebral hemispheres. There are 4 major lobes: Frontal Lobe,
Parietal Lobe, Temporal Lobe and Occipital Lobe. There are other smaller lobes as well
Left to Right Brain:
There is laterization of function with respect to some modalities. Information is shared but some
functions are dominant to more of one side of the brain. Some modalities are presented bilaterally.
The attention system is commanded by the right side of the brain.
Implications:
Outcomes of stroke damage in the parietal cortex depends on whether it is the left or the right brain
that is injured. Right brain losses tend to be permanent and is more sever
Orientation in the Brain:
The anatomical orientation of the forebrain and the brain stem are different
, Appearance of the Adult Brain: Dorso-Lateral Aspect:
- Highly Convoluted
Convolutions consist of:
Groves/Depressions known as Sulci (Major Sulci are known as Fissures)
Ridges or Elevations known as Gyri
Large Sulci are invariable between individual. They are used a important landmarks in brain
mapping for surgery.
Divisions of the Cerebral Cortex:
2 bilaterally symmetrical hemispheres
- Longitudinal Fissures and Falx Cerebri divides the cortex into: Right and Left hemispheres
- Hemispheres are normally interconnected by the Corpus Callosum and Commissures
(anterior/posterior). It allows communications between the different brains.
Appearance of the Adult Brain: Medial Aspect
- More Marked and Complex Presentation
- Shows Segmentation
- Segments are visible from embryonic stages
They are called vesicles:
3 are initially seen but then an additional 2 appear later. They are 3 primary vesicles and 5
secondary vesicles.
Features of the Adult Brain:
5 major neuro-anatomical segments:
Segmentation of the Adult brain is easily discernible:
Forebrain: Telencephalon/ Diencephalon
Midbrain: Mesencephalon
Hindbrain: Pons/ Medulla
Midbrain and Hindbrain together give the Brainstem
Lecture 1: Topography of the Brian and the Spinal Cord
Importance of the Brain and Spinal Cord
- They are both constituted from unique collection of tissues of the NS
- The NS is unique for being the most sophisticated product of evolution
- When the brain and spinal cord are taken together, they:
o Constitute the main substance of the NS
o Make up what is referred to as the CNS
o Are responsible for carrying out and co-ordination all body’s functions
NS is made up from a large number of cells, the entire NS is complex
CNS is different from the PNS but there is a boundary where they cross (there is a continuum).
They can work together; the boundary is a site of all sorts of functions of the NS
The boundary is called the Redlich-Obersteiner’s Zone. Afferent system is a sensory system and the
efferent system is the motor system.
The Efferent can be split into the somatic and the autonomic NS. The afferent NS can be split into
sympathetic/ parasympathetic and the enteric NS.
CNS is characterized by encasement of the cranial and the vertebral column. There is a soft tissue
encasement in the meninges, and it is suspended in the CSF. IT is responsible for the sophisticated
functions of the NS.
Peripheral NS:
12 pairs of Cranial Nerves
31 pairs of Spinal Nerves
25 pairs of Autonomic Ganglia
31 pairs of Sensory Ganglia
Nerve plexuses
Enteric Nervous System
Cell types in the CNS:
2 broad types:
- Neurons (10%) = responsible for sophisticated function
- Neuroglia (90%)
Multiple differences between the cell types:
- General functions
- Ion channel expression (Glial cells have no Na+ channels)
- Diseases that target them and that they give rise to
- Diversity of Connections
General Anatomy of a Neuron:
Myelinated:
Presence of a cell body and axon. Dendrites are not required but can be present. Single axon can
eventually be branched out to affect many targets. Axon can be myelinated by the glial cells and this
transmits impulses much faster.
CNS – Oligodendrocytes provide Myelination
PNS – Schwann Cells provide Myelination
Unmyelinated section is the Node of Ranvier. The myelination provides saltatory conduction. The
initial segment of the axon is never myelinated, and it expressed Na+ channels to allow the initiation
of an AP.
Cranium, Calvaria and the Brain:
,External Appearance of the Skull:
Closed box formed of 4 major bones: Frontal, Parietal, Temporal and Occipital. These bones forma a
cavity integrally. The floor is formed from some of the major bones and also others: Frontal,
Occipital, Ethmoid, Sphenoid, Vomer, Nasal etc.
There are 22 bones.
Without the Mandible, the rest will be called a Cranium.
External Appearance of the Calvaria:
- Immovable joints of the skulls are called sutures.
- Cranial suture are fibrous joints
- There are many sutures to the calvaria.
3 important Sutures: Sagittal (anterior to posterior), Coronal and Parieto-Occipital or Lambdoid.
Coronal and Sagittal meet at the Bregman Point
Lambdoid and Sagittal Sutures meet at the Lambda Point
Positioning of these points is important for surgery.
Internal Appearances of the Roof of the Calvaria:
- The Skull Vault
- Flat on the Inside
- Generally Featureless
- Imprints of BV are present
- Foramina for Emissary Veins
, - Granular Pits
Internal Appearances of the Base of the Calvaria
- Irregular Shape
- Divisible into Cranial Fossae
- Anterior Fossa, Middle Fossa and Posterior Fossa. There are boundaries.
External Appearance of the Cranial Base:
- Irregular in Appearance
- Divisible into the anterior, middle and posterior
Anterior: Alveolar Arches of Maxilla to Posterior Edge of Hard Palate
Middle: Posterior Edge of hard palate to anterior edge of foramen magnum
Posterior: Lies behind the middle part
Brain:
Functions as a single organ. Anatomically, it has a bilateral structure. The two sides are
morphologically symmetrical but functionally, there is an asymmetry in specialization. The left and
right brain are connected.
The brain consists of:
- Cerebral Hemisphere
- Thalamic Masses
- Brainstem (Midbrain, Pons, Medulla)
- Cerebellum
- Cavities (Ventricles)
Cerebral Cortex:
It has many lobes which make up the cerebral hemispheres. There are 4 major lobes: Frontal Lobe,
Parietal Lobe, Temporal Lobe and Occipital Lobe. There are other smaller lobes as well
Left to Right Brain:
There is laterization of function with respect to some modalities. Information is shared but some
functions are dominant to more of one side of the brain. Some modalities are presented bilaterally.
The attention system is commanded by the right side of the brain.
Implications:
Outcomes of stroke damage in the parietal cortex depends on whether it is the left or the right brain
that is injured. Right brain losses tend to be permanent and is more sever
Orientation in the Brain:
The anatomical orientation of the forebrain and the brain stem are different
, Appearance of the Adult Brain: Dorso-Lateral Aspect:
- Highly Convoluted
Convolutions consist of:
Groves/Depressions known as Sulci (Major Sulci are known as Fissures)
Ridges or Elevations known as Gyri
Large Sulci are invariable between individual. They are used a important landmarks in brain
mapping for surgery.
Divisions of the Cerebral Cortex:
2 bilaterally symmetrical hemispheres
- Longitudinal Fissures and Falx Cerebri divides the cortex into: Right and Left hemispheres
- Hemispheres are normally interconnected by the Corpus Callosum and Commissures
(anterior/posterior). It allows communications between the different brains.
Appearance of the Adult Brain: Medial Aspect
- More Marked and Complex Presentation
- Shows Segmentation
- Segments are visible from embryonic stages
They are called vesicles:
3 are initially seen but then an additional 2 appear later. They are 3 primary vesicles and 5
secondary vesicles.
Features of the Adult Brain:
5 major neuro-anatomical segments:
Segmentation of the Adult brain is easily discernible:
Forebrain: Telencephalon/ Diencephalon
Midbrain: Mesencephalon
Hindbrain: Pons/ Medulla
Midbrain and Hindbrain together give the Brainstem
