Week 1 Flashcards
What are meninges?
Connective tissue surrounding and providing protection to the CNS
Where do C1-7 pass through the intervertebral foramen?
Above their appropriate vertebrae
Where do C8- Coc 1 pass through the intervertebral foramen?
Below their appropriate vertebrae
What is the upper limit of the spinal cord?
Its junction with the medulla oblongata
Where is the lower limit of the spinal cord in a newborn infant?
L3/4 vertebral level
Where is the lower limit of the spinal cord in an adult?
L1/L2 border (as you grow vertebra get bigger??)
What are the alar and basal plates?
Dorsal and ventral aspects of the spinal cord during development, giving rise to the dorsal (alar) and ventral (basal) horns
What are the main features of grey matter?
Dorsal horn, intermediate horn (connects the two horns) and ventral horn
What are the main features of white matter?
Dorsal funiculus, lateral funiculus and ventral funiculus
What is the dorsal for responsible for?
Receiving sensory information from periphery
In which segments ate the dorsal and ventral horns much bigger?
Cervical and lumbar segments, due to innervation of limbs
What is the outer meningeal layer?
The dura mater, a thick inelastic membrane which fuses with the endosteum of cranium at the foramen magnum
What separates the dura and the vertebrae
Epidural space
What is the middle meningeal layer?
Arachnoid mater, a thin, fibrous membrane that bridges the subarachnoid space which contains cerebrospinal fluid
What is the innermost meningeal layer?
Pia mater- a unicellular membrane enveloping the spinal cord which forms 21 denticulate ligaments laterally and is spirited from the spinal cord by the subpial space
What is CSF and where is it made?
A filtrate of blood, made in the choroid plexus within the ventricular system of the brain
How much CSF is produced each day?
500ml, about 140ml of which circulates throughout the subarachnoid space and is reabsorbed into the venous drainage system of the head
What is the purpose of CSF?
Affords mechanical and immunological protection to the brain and spinal cord
What is found in the sub-arachnoid space?
Blood vessels (?) and trabeculae of the arachnoid mater
What plexus of veins exists in the epidural space, and what is its significance?
Vertebral/Batson venous plexus (batson’s veins), major route in spread of cancer form deep pelvic regions due to lack of valves
What is the arterial arrangement in the thoracic section?
2 posterior spinal arteries, anterior spinal artery
What artery supplies the lower 1/3 of the spinal cord, and what is its clinical importance?
Artery of Adamkiewicz, arises from L posterior intercostal artery and is important in anterior spinal artery syndrome leading to loss of urinary and/or decal continence and impaired motor function of legs/spasticity
What is the clinical importance of the lumbar cistern?
Site for epidural injections at L3/4 or L4/5 (supracristal line passes through body of L4) as well as spinal tap (lumbar puncture), allowing withdrawal and measurement of CSF pressure
Where do sensory roots originate?
Dorsal horn?
Where do motor roots originate?
Ventral horn?
What is the purpose of the myelin sheath of A fibres?
Speeding up conduction of electrical impulses
What is the ascending pathway for discriminative touch?
Dorsal column pathway (medial lemniscus pathway)
What is the ascending pathway for pain?
Spinothalamic pathway
What is the descending pathway for voluntary motor functions?
Corticospinal and corticobulbar tracts
What is equilibrium potential?
Membrane potential where number of ions entering the cell equals number of ions leaving the cells
What does the destination of current din an axon depend on?
Axon diameter and number of open pores/channels in membranes
Where can charge travel in axons?
Along axon or out of axon via membrane
What covers axons to increase speed of conduction?
Myelin. Gaps between are called nodes of Ranvier
What are supporting neuronal cells known as?
Glial cells
What does grey matter contain?
Most of the neurone cell bodies and their dendritic processes
What does white matter contain, and why does it appear white?
Axons, and the lipid-rich myelin sheaths around the axons accounts for the white appearance of white matter
What are oligodendrocytes?
Cells responsible for the formation of myelin sheaths in the CNS
What are astrocytes?
Highly branched cells that pack the interstices between the neurones, their processes and oligodendrocytes, providing mechanical support as well as mediating the exchange of metabolites between neurones and the vascular system. Furthermore, astrocytes form part of the blood-brain barrier as well as playing an important part in repair of CNS tissue after damage
What are microglia?
CNS representatives of the monocyte-macrophage system and have defence and immunological functions
What are ependymal cells?
Cells making up a specialised endothelium which lines the ventricles and spinal canal
What is one of the main motor pathways?
Pyramidal tract- this passes form the cortex down through the brainstem, crosses the midline and activates the motoneurons in the spinal cord
What are the 5 types of neurotransmitters?
Cholinergic (ACh), biogenic amines (catecholamines, 5-HT/serotonin), amino acids (glutamate +, GABA -), neuropeptides (endogenous opioids) and miscellaneous (gases: NO, pruines: adenosine, ATP)
What are the sensory receptors from A-alpha fibres?
Proprioceptors of skeletal muscle
What are the sensory receptors from A-beta fibres?
Mechanoreceptors of skin
What are the sensory receptors from A-delta fibres?
Pain, temperature
What are the sensory receptors from C fibres?
Temperature, pain, itch
What basic structures comprise a neuron?
Dendrites, cell body, axon and axon terminal
Describe the medial lemniscal pathway:
Axon (A-beta myelinated fibres) from the periphery projects to the lumbar spinal cord via the dorsal roots. The axon branches into the spinal cord (come back to this), and has an ascending branch which projects into the brainstem, through the dorsal funiculus. The axon then reaches the dorsal column nuclei where it terminates. The second neuron crosses to the opposite side (known as internal arcuate fibres) of the medulla, where it then projects into the thalamus. The third neuron projects from the thalamus to the sensory cortex of the brain via the internal capsule
Describe the spinothalamic pathway:
The primary afferent fibre (A-delta or C axons) projects to the spinal cord, and terminates in the dorsal horn. Primary afferent fibres synapse with the second axon which crosses to the opposite side of the lumbar spine, where it then projects up to the thalamus. The second axon synapses with the third axon which travels to the sensory cortex via the internal capsule