Session 1 - Anatomy of the CNS Flashcards
Give three differences between the CNS and PNS
CNS - Covered in meninge
PNS - Covered in Endoneurium, Perineurium & Epineurium
CNS - Complex
PNS - Limited in Function
CNS - Adaptable/Intelligent PNS - Dependent on CNS
What is the central nervous system divided into?
The brain and the spinal cord
Where does the anatomical border between the PNS and CNS lie?
At the Pia Mater
What two main sections is the PNS divided into?
Afferent and efferent sections
What does the efferent PNS divide further into?
The somatic and autonomic nervous system
Give three classes of neurones
Afferent neurones
Efferent neurones
Interneurones
Where do afferent neurones arise from?
A sense organ, with axons divergin in the CNS to come into contact with many other neurones
Where do efferent neurones arise from?
A cell body located within the CNS, upon which many other nerve cells converge
What are interneurones?
Make up 99% of the CNS and integrate input with output.
What are the two many parts of the CNS?
Neurones and Neuroglia
Give four differences between neurones and neuroglia
- General functions
- Ion channel expression
- Diseases that a) target them and b) they give rise
- Diversity of connections
Give four examples of neuroglia
Astrocytes
Oligodendrocytes
Ependymal cells
Microglial cells
Give threelimitations of the calvaria
- Limited volume/capacity
- No space for storage of energy reserves
- Meninges allow tracking of infection
Outline the layers of the meninges, including potential spaces
- Inner layer of Cranium
- Extradural Space
- Dura Mater (2 layers, periosteal layer and meningeal layer)
- Subdural space
- Arachnoid Mater
- Subarachnoind Space
- Pia Mater
- Brain Tissue
What are found in the subaracnoid space?
(place in which blood vessels are found, cushioned by CSF, and a site for intracranial bleeds)
What are the three main functions of CSF?
- Cushions the brain
- Maintains supply of metabolic substrate
- Dissolves and carries away products of metabolism from brain
Why is a stroke in the right brain worse than a stroke in the left?
Stroke in the right brain could effect the part of the parietal cortex responsible for the attention system
What is the “front” of the brain called anatomically?
Rostral
What are the three main anatomical features of the brain?
Gyri (folds), sulci (grooves) and fissures (clefts)
Give the five main parts brain can be divided up into
Cerebral hemispheres Thalamic masses Brainstem Cerebellum Cavities
What are the cerebral hemispheres separated by?
Longitudinal fissure and falx cerebri
How are the cerebral hemispheres connected?
By the corpus callosum and commissures
What are commissures?
Fibre tracts which span the longitudinal fissure
What does the frontal lobe contain?
Broca’s area, which is important for speech
What does the parietal lobe contain?
Wernicke’s area, important for comprehension of spoken language
What does the temporal lobe contain?
Area for perception of auditory signals
What is the role of the thalamus?
It is responsible for relaying and integrating information to different regions of the cerebral cortex from a variety of structures associated with sensory, motor, autonomic, and emotional processes.
What does the hypothalamus moderate?
temperature, endocrine functions, feeding, drinking, emotional states, and sexual behaviour
What is the role of the cerebellum?
integration, regulation, and co-ordination of motor processes
What are the three parts of the brain stem?
Midbrain
Pons
Medulla Oblongata
What does the midbrain do?
relays information for vision and hearing
What does the pons do?
It contains tracts passing through it as well as numerous nuclei for functioning in sleep, respiration, bladder control, and many others.
What does the medulla oblongata control?
autonomic function (such as respiration, cardiac centre and baroreceptors, and vomiting, coughing, sneezing, and swallowing centres) and connects the higher levels of the brain to the spinal cord.
What cranial nerves originate at midbrain?
→ CN III and IV form at the level of the midbrain
What cranial nerves originate at Pons?
→ CN V, VI, and VII form at the level of the pons
What cranial nerves originate at medulla?
→ CN VIII, IX, X, and XII form at the level of the medulla
What does the basal ganglia do?
• Basal Ganglia play an important role in the regulation and integration of motor functions, and are discussed in more detail later.
Where does the spinal cord extend to and from?
Foramen magnum -> L2
How long is the spinal cord?
42-45cm
Where are the two enlargements of the spinal cord?
Cervical enlargement at C4-T1 (Brachial plexus)
Sacral enlargement from T11-S1 (Lumbar and sacral plexus).
How does the conus medullaris move during development?
the tip of the conus medullaris is at L4-L5 level and gradually ascends until it lies at L2 level in adults
What are the group of nerve roots running in the lumbar cistern known as?
cauda equina
What is the filum terminlae?
a remnant of the caudal part of the spinal cord of the embryo and descends amongst the cauda equina
What is cauda equina syndrome?
results from dysfunction to the lumbar and sacral nerve roots in the lumbar vertebral canal, affecting the cauda equina. Cauda equina syndrome presents with dysfunction of the bladder, bowel, or sexual function, and sensory changes in saddle or perianal area, as well as potential back pain (with or without sciatic-type pain), sensory changes or numbness in the lower limbs, lower limb weakness, reduction or loss of reflexes in the lower limbs , or unilateral or bilateral symptoms.
What is a common cause of cauda equina?
caused by large central IV disc herniation at L4/5 or L5/S1 level, it can also be caused by tumours, direct trauma, spinal stenosis, or inflammatory disease. It is a medical emergency as if left untreated, patients can be left incontinent, affects motor function, and many other possible complications. Treatment is treating the underlying cause.
