OCB03-2004 Flashcards
Define a PNS neuron.
A neuron with any part outside the brain or spinal cord
Define a CNS neuron.
A neuron entirely contained within the brain and/or spinal cord
What are the two divisions of the autonomic NS?
Parasympathetic
Sympathetic
What two structures make up the CNS?
Brain
Spinal cord
What is contained in grey matter?
Cell bodies of neurons
What is contained in white matter?
Myelinated axons
What is the distribution of grey and white matter in the brain?
Cortex = grey matter
White matter on the inside
What is the distribution of grey and white matter in the spinal cord?
White matter peripherally
Grey matter forms characteristic H shape
Where does the parasympathetic system originate?
Cranial nerves
Sacral nerves
(Cranio-sacral)
Where does the sympathetic system originate?
T1-L2
What are the functions of the cranial part of the parasympathetic system?
Constrict pupils (miosis)
Stimulate salivation
Slow heartbeat
Constrict airways
Stimulate stomach and intestinal activity
Stimulate gall bladder
Inhibit glucose release
What are the functions of the sacral part of the parasympathetic system?
Contract bladder
Promote erection of genitals
What are the functions of the thoracic part of the sympathetic system?
Dilate pupils (mydriasis)
Inhibit salivation
Increase heartbeat
Relax airways
Inhibit stomach and intestinal activity
Inhibit gall bladder
Stimulate glucose release
What are the functions of the lumbar part of the sympathetic system?
Relax bladder
Promote ejaculation and vaginal contraction
What forms the hindbrain?
Pons
Medulla
Cerebellum
What is another term for forebrain?
Endbrain
Telencephalon
What are the three main anatomical compartments of the brain?
Forebrain
Midbrain
Hindbrain
Which surface of the brain is ventral?
Underside
Which side of the brain is dorsal?
Upper side
What is a sagittal plane?
Plane that runs through the midline
Why is the coronal plane considered to be a transverse plane?
Flexion of brain during development
How many pairs of spinal nerves are there normally?
31
How many spinal nerves are in each vertebral area (ie cervical, thoracic…)?
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
At what level does the spinal cord end?
L1/L2
Through what structure do spinal nerves leave the vertebral column?
Intervertebral foramen
What is the cauda equina?
Region of spinal nerves with no spinal cord in the vertebral column
What is the clinical significance of the cauda equina?
Able to perform a lumbar puncture to sample CSF safely/without damaging spinal cord
Describe the location of lower motor neurons.
Soma in ventral horns
Axons project through ventral root to join with dorsal roots
Terminate at neuromuscular junction
Describe the location of sensory neurons in the spinal cord.
Soma in dorsal root ganglion
Axon comes in from a sensory-specific receptor
Axon travels via dorsal root into dorsal horn
How do nerves enter/leave the spinal cord?
As rootlets
How to the rootlets change as you progress down the spinal cord and why?
Become more oblique in angle
Due to difference in lengths of spinal cord and vertebral column
What are the main lobes of the cerebrum?
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe
What is the frontal lobe responsible for?
Executive functions
Thinking, planning, organising, problem solving
Emotions, behavioural control, personality
Motor cortex = movement
In which lobe is the motor cortex found?
Frontal lobe
What separates the frontal and parietal lobes?
Central sulcus/fissure
What separates the motor and sensory cortices?
Central sulcus/fissure
What is the temporal lobe responsible for?
Memory
Understanding
Language
What is the parietal lobe responsible for?
Perception/sensation = sensory cortex
Arithmetic and spelling
In which lobe is the sensory cortex found?
Parietal lobe
What is the occipital lobe responsible for?
Vision
What separates the temporal lobe from the frontal and parietal lobes?
Lateral sulcus/fissure (Sylvian fissure)
What are gyri?
Ridges of the cerebral cortex
What are sulci?
Grooves of the cerebral cortex
What are fissures?
Deeper grooves in the brain
What is the purpose of gyri and sulci?
Increase surface area to allow more neuronal material to fit into the cranial vault
What is the ventricular system?
Interconnected chambers important in the production and transit of CSF
What is the spinal canal?
Central canal of spinal cord containing CSF
Describe the structure of the ventricular system.
One lateral ventricle in each hemisphere
Each connected to the third ventricle by the interventricular foramen
Third ventricle connected to fourth ventricle by the cerebral aqueduct
What forms the walls of the third ventricle?
Diencephalon on each side
What shape are the lateral ventricles?
C-shaped with posterior horns
Which ventricles sit in the midline?
Third and fourth
Describe the position of the fourth ventricle.
Posterior to pons
Anterior to cerebellum
How does CSF escape the ventricular system?
Foramina in the fourth ventricle
What are the foramina leaving the fourth ventricle?
Central canal of medulla
Median foramen of Magendie
Lateral foramina of Luschka
What synthesises CSF?
Choroid plexus
How does the choroid plexus look?
Bubbly
Cauliflower-like
What type of cells make up the choroid plexus?
Specialised ependymal cells
What are the functions of CSF?
Buoyancy - reduces weight of brain from 1.3kg to 30g to prevent ventral neurons being squashed
Protection - hydrostatic buffer against cranium
Removal of waste products - eventually returns to venous bloodstream
How much CSF is produced per day?
~500ml
What can failure of CSF reabsorption cause?
Hydrocephalus - CSF pushes brain cortex outwards which pushes against unfused skull plates
How could you treat hydrocephalus?
Stent to remove excess CSF
Surgically
What are the meninges?
Outer protective layers of CNS
What are names of the meninges?
Pia mater
Arachnoid mater
Dura mater
Which layer of the meninges cannot be seen with the naked eye?
Pia mater
Describe the pia mater.
Innermost layer of meninges
Fine, delicate, about 2 cells thick
Describe the arachnoid mater.
Silky, web-like
Closely associated with dura mater
What is the glia limitans?
Outer layer of brain/cortex made up of glial cells (esp. astrocytes)
Describe the dura mater.
Tough, hardy
Closely associated with arachnoid mater and the periosteum (in the cranial region)
2 layers in skull which separate to form venous sinuses
What are the two layers of the dura mater?
Periosteal
Meningeal
Why is the dura mater not closely attached to the periosteum of the vertebral column?
Allows spine to bend easily
What is the subarachnoid space?
Space between pia mater and arachnoid mater
Contains CSF
How is CSF reabsorbed?
Moves from subarachnoid space into venous sinuses (mainly superior sagittal sinus) via arachnoid granulations/villi
Where are the arachnoid granulations particularly abundant?
Along the superior sagittal sinus