Neuroanatomy 1 Flashcards
Anatomical orientation: the location of the nervous system
- The nervous system (of vertebrates) comprises a
central division and a peripheral division
Central division:
- The central nervous system (CNS) comprises the brain
and spinal cord
Peripheral divison:
- The peripheral nervous system PNS) is defined as the
nerves connecting the central nervous system to the
body (the periphery), and includes a number of
neuronal clusters (ganglia) at specific locations along
these peripheral nerves.
Define two basic types of cells that comprise the CNS
> Neurons: functional cells that create the action potentials that communicate with other neurons that allow to do things – electrically excitable
> Glia: support, nourish and protect the neurons
Compare the CNS axis in humans/vertebrates vs quadrapeds
- The central nervous system (of vertebrates) is
elongated - The rostrocaudal “neuraxis” of quadrupeds is
essentially horizontal, so “up” and “down”
directions are dorsal and ventral (resp.) - The neuroaxis is essentially vertical in humans but
is rotated anteriorly at the rostral end
List the wider cells of the CNS
- Neurons
- Glia
- Microglia
- Oligodendrocyte
- Astrocyte
Be able to identify regions of brain and describe them
Telencephalon
1. Cerebrum
- composed of cerebral cortex (info retrieval),
everything that goes into the cerebral cortex is
conscious, the rest in subconscious
Diencephalon
2. Thalamus: important in sensory processing - sends
sensory signals to parietal lobe containing map of
body, guiding where action needs to occur
3. Hypothalamus: important in automatic functions
such as temperature regulation, and cardiovascular
control - regulates endocrine system and pituitary
(hormones) and ANS (SNS (fight/flight) and PNS
(rest&digest)
Mesencephalon
4. Midbrain
Metencephalon
5. Pons
6. Cerebellum (motor activity)
- tone
- balance
- coordination
Myencephalon
6. Medulla oblongata
Other:
1.. Pineal gland - part of epithalamus
2. Brainstem (heart rate, breathing, blood pressure,
reflexes of head & neck, houses nuclei of cranial
nerves)
- midbrain
- Pons
- Medulla oblongata
3. Pituitary gland
4. Central canal
Be able to identify lobes of brain and describe them
Brain lobes;
1. Frontal lobe
- Pre-frontal cortex (conscious intellect)
- motor cortex (conciously initiates movement)
- higher order reasoning
2. Parietal lobe
- somato-sensory cortex (recieves signals on temp,
touch, pain, pressure)
3. Occipital lobe
- Visual association area
- Primary-visual cortex - vision
4. Temporal lobe
- hear
Define the terms Sulcus, Gyri and Fissures and list them in the brain
- Suclus, Gyri and Fissures refer to the folded surface of
the cerebral cortex increasing its SA
The folded cerebral cortex surface has:
> Grooves = sulcus
> Ridges = Gyri
> Fissures = Deeper grooves
Longitudinal fissure - seperates into left and right hemispheres
Some terms:
Lateral sulcus - separates frontal and parietal from temporal
Parietal-occipital sulcus - seperates parietal and occipital lobes
Precentral gyrus - before central sulcus
Postcentral gyrus - ridge after central sulcus
Most primary cortices are located around the deepest sulci/fissures such as:
> The central sulcus: is surrounded by primary s
somatomotor & somatosensory cortices and
separates frontal and parietal lobes. The primary
somatomotor cortex is located in frontal lobe in the
precentral gyrus and somatosensory cortex in the
postcentral gyrus in the parietal lobe.
> The lateral fissure: is surrounded by primary auditory
and gustatory cortices
> The calcarine sulcus: surrounded by the primary visual
cortex
Define precentral sulcus, post central sulcus and parietal occipital sulcus
o Precentral sulcus is the location of the primary motor cortex – the movement of limbs
o Post central sulcus is the location of your primary sensory cortex – sensory neurons
o Parietal occipital sulcus – sperate the parietal lobe from grey occipital lobe
What are meninges and its three membranes
The three membranes that wrap the CNS
o All three meninges: dura mater, arachnoid mater and pia mater.
- Dura mater
o Sitting over the cerebrum, a fibrous and strong layer, that wraps around the brain and spinal cord
> Sub-dural space
- Arachnoid membrane
- a thin, transparent, web-like layer of the meninges -
has web-like connective tissue projections (called trabeculae) adhering to pia mater, it is situated between the dura mater and pia
mater, that surrounds the brain and spinal cord,
containing cerebrospinal fluid in the subarachnoid
space.
- a thin, transparent, web-like layer of the meninges -
> . The subarachnoid space is filled with cerebrospinal
fluid (CSF)
- Pia mater
- delicate, connective tissue, innermost, tiny blood
vessels, adheres to all gyri, sulci, fissure surfaces (like wet tissue)
- delicate, connective tissue, innermost, tiny blood
Describe the common CNS Herniations (rupture)
- Subfalcine: common, headache contralateral leg weakness
- Transtentorial: Occulomotor paresis (dilated pupil, contralateral hemiparesion
- Tonsillar: Obtundation
Where does CSF come from and what is its role?
What are the 4 ventricles and how do they interact?
o CSF production occurs from blood in the ventricular system of the brain
o Each hemisphere has a lateral ventricle which comes together to form a third ventricle
Beneath the “corpus callosum” sits the lateral ventricle
- Lateral ventricle communicates with the third ventricle
via the IV (intraventricular) foramen
- Third ventricle communicates through the cerebral
aquiduct with the 4th ventricle
- 4th ventricle communicates with the subarachnoid space
choroid plexus
That specialised capillary bed is designed to filter blood and make CSF – as blood flows in the capillary bed, the pressure in the choroid plexus forces some of the plasma-like substance out of the blood into the ventricles, the ventricles fill up, the chambers in the brain fill up and the blood flows off to the venous system
Blood is being made as a filtrate from blood through the choroid plexus within the ventricular system
o Arachnoid granulations:
CSF from the choroid plexus flows around the space around the brain and fills up the arachnoid granulations increasing the pressure and forcing the CSF out into the Venus system back into the blood from which it came
CSF provides that extra level of protection for the brain
CSF:
- Choroid plexus produces CSF (enables CNS to float) and filters blood plasma into subarachnoid space
> choroid plexuses are located in each ventricle
- CSF from the choroid plexus of lateral ventricle joins CSF produced by choroid plexus of 3rd ventricle which join with the CSF at the 4th ventricle
- 4th ventricle has openings called median aperture and lateral apertures that commucate with subarachnoid space
CSF role:
- cushions and gives buoyancy to the brain and spinal cord - reduces weight of brain and spinal cord
What is hydrocephalus and how is it treated?
- Hydrocephalus is excessive buildup of CSF
- A catheter draining CSF from the ventricles into the
peritoneal cavity to treat hydrocephalus
> Tube inserted into lateral ventricle through hole in
skull
> Drainage tube, usually introduced into peritoneal
cavity, with extra length to allow for the growth of
child
Name and describe 4 dural folds
Dural folds
- Falx cerebri
> Separates the right and left cerebral hemispheres.
> sickle shaped
> largest dural infolding
> located at the longitudinal fissure
- Tentorium cerebelli
> Separates the occipital lobes from the cerebellum.
- Falx cerebelli
> Separates the right and left cerebellar
hemispheres.
- Diaphragma sellae
> Covers the hypophysial fossa (sella turcica) of the
sphenoid bone, containing the pituitary gland.
Compare the structure of myelin in the PNS and CNS
and describe myelin’s functional importance
- Made of oligodendrocytes (in the CNS) and Schwann
cells (in the PNS) are glial cells that provide insulation
(electrical insulation to help neurons in axon flow
faster) to nerve axons - The lipid bilayers of oligodendrocyte cell membrane
that form this insulation (the myelin sheath) give the
axonal bundles a white appearance, and hence fibre
tracts in the brain and spinal cord are called “white
matter”.
o Unlike electrical insulation, myelin isn’t continuous
o It is formed in segments along the axon, with each section from a separate glial cell and the intervening gaps are called nodes of Ranvier (important as they contain ion channels needed for axonal conduction)
o Hence, in a myelinated axon, the electrical signals propagate faster as they effectively jump from node to node
