Neuroanatomy Flashcards
What is the lateral border of the thalamus?
PLIC
What is medial to the ALIC?
Caudate nucleus
What is 1. medial 2. lateral to the caudate nucleus?
- lateral ventricle
2. ALIC
what is the blood supply to the internal capsule (Putamen, Caudate Nucleus, Globus Pallidus)?
Lenticulo Striate branches from MCA
what is the embryological origin of the pons and cerebellum?
Metencephalon - from the rhombencephalon
What is the embryological origin of the medulla?
Myelencephalon - from the rhombencephalon
What are the divisions of the posterior funiculus?
Lateral - Cuneatus (T7- higher)
Medial - Gracilis (T7- below)
Describe the Dorsal Column/Medial lemniscus pathway
- nerves carry fine touch, propriception, vibration
- Upper body (T7-up) goes through fasiculus cuneatus
- Lower body (T7-down) goes through fasculus gracilis - Internal arcuate fibers cross in the CAUDAL MEDULLA and enter the medial lemniscus on the contralateral side
- Fibers go to the VPL in the thalamus and
- 3rd order neurons send fibers to postcentral gyrus of cerebral cortex
Describe the Anterior Lateral system
Conducts pain, temperaturs, crude touch information
- First order - DRG (Adelta, C fibers)
- Neuron splits in dorsal horn, travel 1-3 segments up and down (Lissauer’s tract)
- Fibers Cross immediately in the VENTRAL WHITE COMMISSURE
- Ascend in the ALS and synpase in the VPL
- VPL to somatosensory cortex
Besides the VPL, what other areas do the second order neurons of the ALS synapse with?
- periaquaductal gray matter in the mid brain (descending pain control)
- reticular formation, intralaminar thalamic nucleus (emotional and arousal aspects of pain)
Describe the Orofacial touch and vibration pathway?
- Nerves in the Trigeminal ganglion projects in the PONS
- Synapses in the Chief Sensory Nuclei Ipsilaterally
- Neurons sent bilaterally into VPM of thalamus through Dorsal trigeminothalamic tract
- Third order projects to the primary somatosensory cortex
Describe the Orofacial pain and temperature pathway?
- Nerves in the trigeminal ganglion project to the Brainstem where it synapses ipsilaterally
- Second order neurons cross controlaterally and ascend in the ventral trigeminal tract
- synpases in the VPM
- third order neuron projects axon to synapse in the primary somatosensory cortex
What part of the visual field is carried in Meyer’s loop?
Superior field
What part of the visual field is the occipital lobe superior to the calcarine fissure responsible for?
Inferior field
Where in the occipital lobe does Meyer’s loop synapse?
Below calcarine fissure
Describe the Corticobulbar spinal tract
Motor Fxn
1. Fibers from the corona radiata in the Precentral gyrus travel in Posterior Limb (Corticospinal tract) and Genus (Corticobulbar tract)
2. Mid brain: Corticospinal fibers form middle 1/3 of crus cerebri; Corticobulbar fibers are medial crus cerebri
3. Pons: fibers spread out
4. Medulla: fibers coalesce into Medullary Pyramids: Most fibers CROSS HERE at pyramidal decussation
5. crossed fibers: Lateral corticospinal tract
uncrossed fibers: anterior corticospinal tract
6. Anterior corticospinal fibers cross midline at level of motor fxn
What motor fxns are controlled by:
- Lateral corticospinal tract
- Anterior corticospinal tract
- Extremities - most important!!
2. Axial muscles
What are the 3 grouping categories of the 3 components of the Basal ganglia?
Neostriatum = Caudate nucleus + putamen
Paleostriatum = Globus pallidus
Lentiform Nucleus = Globus pallidus + putamen
Describe the Direct pathway of the Basal ganglia (what is the fxn)
Initiates movement
- Cerebral cortex sends signal to Neostriatum (CN, Putamen
- Neostriatum inhibits GPM (gpm inhibits Va/Vl motor thalamus)
- Motor Thalamus is disinhibited and movement is caused
What substance do neostriatal neurons of the basal ganglia secrete?
GABA (inhibitory) - inhibits GPM in direct pathway
How does dopamine affect the direct and indirect pathways of the basal ganglia? what releases it?
released by substantia Nigra compacta cells
Direct: released onto Neostriatal neurons = facilitates response to direct pathway, easier to start movment
Indirect: inhibits indirect pathway harder to stop movement
Describe the Indirect pathway of the Basal ganglia (what is the fxn)
Stops movement
- Cerebral cortex sends signal to the Neostriatum (CN, putament)
- Neostriatum inhibits GPL (gpl inhibits Subthalamic nucleus)
- STN is disinhibited which signals more strongly to the GPM (GPM inhibits motor thalamus)
- Motors thalamus is inhibited
What happens when the Substantia Nigra is damaged?
slower, lack of movements
Parkinsons disease
