HUBS191 Neuro recap cards Flashcards
Vertebrae divisions
Cervical Thoracic Lumbar Sacrum Coccyx
Cervical
7
Thoracic
12
Lumbar
5
Spinal cord starts at….
foramen magnum
Spinal cord ends at…
Inferior border of L1 vertebrae
What is the spinal cord within?
Sack in the spinal cavity which is within the vertebrae and is filled with cerebrospinal fluid
Conus medlaris
End of the spinal cord is a tapered cone
Filum terminale
Extends from the conus medlars to the end of the spinal cavity
It is an extension of the meninges, anchors the spinal cord
How many pairs of spinal nerves are there?
31 pairs
Cervical spinal nerve pairs
8 pairs
Thoracic spinal nerve pairs
12 pairs
Lumbar spinal nerve pairs
5 pairs
Sacral spinal nerve pairs
5 pairs
Coccygeal spinal nerve pairs
1 pair
Spinal nerve exits
C1 nerve exits above the C1 vertebrae - all other spinal nerves exit below their corresponding vertebrae
Cauda equina
Large collection of nerves inferior to the end of the spinal cord
Peripheral nerve structure
Individual axons may be myelinated or unmyelinated
Axons are covered with endoneurium
Endoneurium covered axons (nerve fibres) are bundled together to form a fascicle
Fascicles are covered with perineurium
Fascicles bundle with each other and with blood vessels to form a nerve
Nerves are covered with epineurium
Bundles of axons in the CNS are called…
a tract
Dorsal side of spinal cord
Sensory (afferent)
Afferent information comes in through the dorsal root
Ventral side of spinal cord
Motor (efferent)
Efferent motor information leaves through the ventral root to the effectors
Somatic motor neurons in ventral form of spinal cord
Autonomic in lateral/ventrolateral horns of the spinal cord
Dorsal nerve roots
Flow of information is one way and the direction is IN
Ventral nerve roots
Flow of information is one way and the direction is OUT
Roots combine to form..
Spinal nerve and the flow of information is two ways therefore the direction is IN and OUT
Once spinal nerves leave the spinal column…
They branch into 2 branches - ventral and dorsal ramus (ramus = branch)
The ventral ramus communicates with the sympathetic chain via 2 sympathetic rami
Grey matter in the spinal cord
cell bodies
White matter in the spinal cord
axons
Ventral columns
White matter
Information descending
Dorsal columns
White matter
Information ascending
Lateral columns
Sensory and motor information are going up and down in both directions
Four lobes of the brain
Frontal
Parietal
Occipital
Temporal
Frontal lobe
Motor cortex Behaviour Mood Personality Language
Parietal lobe
Somatosensory cortex and also the association cortex (faces, shapes, words etc.)
Temporal lobe
Hearing and memory
Occipital lobe
Vision
Primary motor cortex
Execution of movement
Precentral gyrus - command from neuron here reaches other neuron, causing a somatic efferent neuron synapse on to a skeletal muscle
Pre-motor cortex
Planning of movement
Anterior part of the motor cortex - once you plan to do something, if you decide to execute the movement then the information is sent to the primary motor cortex which then sends the command to make the movement
Stretch reflex
Muscle spindles/stretch receptors are stimulated when the muscle is stretched. Results in nerve fibre activation and impulses sent from spindles to the spinal cord along afferent fibres. Information is processed at the level of the spinal cord which causes activation of motor neurons which causes contraction of the muscle to prevent overstretching
Withdrawl reflex
Painful stimuli triggers action potentials up afferent pain fibres which synapse in the spinal cord. Signals go up to the brain to alert of pain, to other levels of spinal cord to coordinate movement of other joints and onto efferent motor fibres within that spinal level. Stimulation of flexors and inhibition of extensors allows for withdrawal away from the painful stimulus.
Spinal reflex arc overview
Stimulation of receptor - activation of sensory neurons - information processing in CNS - activation of motor neuron - response in peripheral effector (contraction of agonist muscle and also inhibition of the antagonist muscle)
Integration of information … stimulus - afferent input via the dorsal root ganglion - up to the brain - modification of the response and travels back down (the afferent signal into the brain crosses at the spinal cord i.e. the stimulus is recorded in the brain at the opposite side of the brain that the stimulus was recorded.
Stretch and withdraw reflexes are a part of the …
Spinal reflex arc
Somatic sensory (afferent) division
Responsible for relaying information from the body to the CNS
Somatic motor (efferent) division
Responsible for sending out commands from CNS to the body, stimulating skeletal muscle contraction
Visceral sensory (afferent) division
Receptors receive stimulus that gets sent to the CNS
Sympathetic division (efferent)
Fight or flight response, prepares body for the stress response
e.g. increase heart rate, constricting blood vessels to skin and viscera to increase blood flow to muscles, decrease digestion and salivation, increase pupil size, increased sweating
Parasympathetic division (efferent)
Rest and digest response, prepares body for restful situations
e.g. decreases heart rate, increases gastric motility, decrease in pupil size, increase in salivation
Integration centres for autonomic and somatic are in the
CNS, but there actual location is in the PNS
Somatic neurons
Voluntary
Neuron 1 - upper motor neuron = myelinated by oligodendrocytes, all in the CNS
Neuron 2 - lower motor neuron = myelinated by Schwann cells, PNS, ACh on to effector cells
Parasympathetic neurons
Involuntary control
Neuron 1
Neuron 2 - Preganglionic neuron = myelinated, long axon, ACh
Neuron 3 - Postganglionic neuron = unmyelinated, short axon, ACh
Sympathetic neurons
Involuntary control
Neuron 1
Neuron 2 - Preganglionic = myelinated, short axon, ACh
Neuron 3 - Postganglionic = unmyelinated, long axon, NE released at synapse on to the effector
