Functional Neuroanatomy Flashcards
Which levels of the SC have a lateral horn?
Thoracic and S2-4
Where is spinothalamic / anterolateral tract found in the brain stem?
Found laterally in brain stem, close to medial lemniscus in midbrain.
Pathway for fine touch, vibration, and position from face
Synapses in ipsi trigeminal ganglion, crosses, and ascends in trigeminothalamic tract, which starts medial and then gets more lateral by the time it reaches the thalamus.
Pathway for pain, temp, and gross touch form face
Enters pons via trigeminal nerve but descends down into medulla or upper cervical SC and synapses in spinal trigeminal nucleus. Synapses, crosses, and ascends in trigeminothalamic tract
Pathway for viscerosensation
Viscerosensation ascends in viscerosensory tracts to solitary nucleus, synapses and projects bilaterally via solitariothalamic tracts, ultimately projecting to insula
Paraesthesia vs Dysesthesia
- Paraesthesia – dysfunction of peripheral somatosensory axon causing spontaneous or evoked positive somatosensory sxs that are not unpleasant / painful.
- Dysesthesias are unpleasant / painful
Allodynia
Perception of pain to stimuli that are not normally noxious
Cell pathway for vision
Photoreceptors synapse on retinal bipolar cells, which synapse on retinal ganglion cells, whose axons travel to the thalamus
Pathway from frontal eye field
- Frontal eye field → contralateral pontine horitzontal gaze center (aka pontine paramedian reticular formation / PPRF) → abducens nucleus → left lateral rectus.
- Pontine horizontal gaze center also projects to oculomotor nucleus on other side via medial longitudinal fasciculus
Where are vertical gaze and convergence centers found?
Vertical gaze center found in upper brainstem and is composed of nuclei near oculumotor nucleus. Projects to oculomotor and trochlear nuclei to cause conjugate vertical gaze. This area is also responsible for convergence.
- Tropia
- Phoria
- Exotropia
- Esotropia
- Hypertropia
- Hypotropia
- Skew
- Tropia = fixed dysconjugacy
- Phoria = intermittent dysconjugacy
- Exotropia = deviation of an eye laterally
- Esotropia = deviation of an eye medially
- Hypertropia = deviation of an eye superiorly
- Hypotropia = deviation of an eye inferiorly
- Skew = vertical dysconjugacy
Pupillary light reflex
Visual info for conscious info goes to lateral geniculate nucleus in thalamus. Unconcious info goes to bilateral pretectal nuclei, each of which receives light info from both eyes. Pretectal nuclei then project short distance to Edinger Westphal nucleus, which contains preganglionic parasympathetic neurons. These axons travel w/ ipsi occulomotor nerve to synapse on ciliary ganglion, which contains postganglionic parasympathetic neurons, which project to iris to innervate iris sphincter muscle (smooth muscle).
Term for pupils that aren’t the same size
anisocoria
Pupillary dark reflex
Info sent to hypothalamus. Sympathetic tract from hypothalamus down to T1 to synapse on lateral horn (preganglionic). Second neuron runs up sympathetic chain and ascends back to superior cervical ganglion. 3rd neuron (postganglionic) hitches a ride on arteries (carotid, etc), then finally reaches the pupil to innervate the iris dilator muscle.
Whole pathway is ipsilateral.
Corneal (blink) reflex
Mechanoreceptors trigger ipsi trigeminal nerve to brainstem. Efferent response involves bilateral facial nerves causing strong eye closure
Sound transmission to cochlea
Malleus, incus, stapes vibrate oval window. Endolymph vibrates the basilar membrane.
Which nerve innervates tensor tympani? Stapedius?
Tensor tympani innervated by CN V. Stapedius innervated by CN VII.