Quiz 1 Flashcards
Somatosensory Pathways
Posterior Column–Medial Lemniscal pathway: proprioception, vibration, fine/discriminate touch
Anterolateral pathways: pain, temperature, crude touch
Muscle Fibers
Type I: red (myoglobin), slow-twitch, rich in lipids, mitochondria, and oxidative enzymes. Sustained force.
Type II: white, fast-twitch, rich in glycogen and glycolytic enzymes. Rapid force.
Herniation
Subfalcine herniation of the cingulate gyrus under the falx cerebri —> compresses branches of the anterior cerebral artery (ACA).
Transtentorial (uncal) herniation of the medial temporal lobe against the tentorium cerebelli —> compresses the 3rd cranial nerve and/or the posterior cerebral artery (PCA).
Tonsillar herniation of cerebellar tonsils through the foramen magnum —> compress medullary respiratory centers, a particularly life-threatening situation***
Cranial Nerves
I: olfactory: smelling (sensory)
II: optic: vision (sensory)
III: occulomotor: eye movements (motor)
IV: trochlear: eye movements (motor)
V: trigeminal: facial sensations and mastication (sensory and motor)
VI: abducens: eye movements (motor)
VII: facial: facial movements, some taste (sensory and motor)
VIII: vestibulocohlear: balance, hearing (sensory)
IX: glosopharyngeal: taste, tongue movements (sensory and motor)
X: vagus: parasympathetic, also laryngeal muscles (sensory and motor)
XI: spinal accessory: neck movements (motor)
XII: hypoglossal: tongue movement ( motor)
Midbrain - surface anatomy
Dorsal: inferior and superior colliculi –> form tectum
- also lateral and medial geniculate nuclei
ventral: cerebral peduncle (different from cerebellar peduncles in pons**)
Cranial nerve exits from spinal
4 CN are above pons (I, II, III, IV).
(III and IV exit the midbrain)
4 CN exit the pons (V, VI, VII, VIII).
4 CN are in medulla (IX, X, XI, XII).
4 CN nuclei are medial (III, IV, VI, XII).
“Factors of 12, except 1 and 2.”
Pons - surface anatomy
Superior, middle and inferior cerebellar peduncles
Medulla surface anatomy
ventral: inferior olive (lateral), pyramid (medial)
dorsal: Dorsal column tubercles: nucleus cuneatus (lateral) and nucelus gracilis (medial)
lower down, fasciculus gracilis (medial) and fasiculus cuneatus (lateral)
Corticospinal tracks in the brainstem
- Midbrain: crus cerebri
- Pons: basilar part of pons
- Medulla: pyramid
neurotransmitters
glutamate - excitatory –>
glycine is inhibitiry in spina cord, GABA everywhere else
mechanoreceptors
encapsulated receptors:
- Meissners corpuscle: vertically oriented, stroking of skin, stronger at onset and rapidly adpating
- Merkels disk - right angles, pressure, maintained response, slowly adapting
- Ruffini:
- Pacinian:
- Free nerve ending: pain and temp - C and A delta fibers
sensory pathway (DC-ML)
first order is dorsal root ganglion
send order is
- gracile nucelus: medial, thin slice, lower limbs
- cuneate nucleus: lateral, thicker wedge, upper limbs
MRI weighting
T1: longitudinal magnetization recovery time
- short = bright
- long = dark
CSF is dark gray, gray matter is darker than white matter
good for anatomy, poor contrast of pathology
hem. is bright
T2: tranverse magnetization dephases
- short= dark
- llong= light
CSF is white, gray matter is ligther than white matter
great for contrast with pathologic tissue**
most tumors and lesions have water – so bright
hem is dark in this case
gradient recall - GRE — good for bleed and flow - floing blood is brighter ‘
FLAIR - makes CSF very dark - makes it easier to see lesions near flui - ventricles, etc.
DWI - surpresses water
DTI - vectors, surgical planning
embryonic origians of neurons
Excitatory: glutamate, migrate radially from ventricular zone, perpedicualr to surface
Inhibitory: GABA, migrate tangentially from subcortical, parellel to surface
Thalamic connections to cortex
Specific:
- relay affertents from specific thalamic nuclei, go to a special place in the cortex, - layer VI
- excitatory - glutamine
Non-specific: - diffuse, - depending on NTs - can be inhibitory or excitatory - noradrenergic connections in locus ceruleus are important -- vigilance -
