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Neuroanatomy TOTD #15🧵
The inner ear #tweetorial--it packs a large functional punch for its small size-strap in!
#meded #FOAMed #FOAMrad #medtwitter #medstudents #radiology #neurorad #HNrad #radres #neurology #ENT #temporalbone #neurosurgery #neuroanatomy #neuroanatomyTOTD
1/24
The inner ear #tweetorial--it packs a large functional punch for its small size-strap in!
#meded #FOAMed #FOAMrad #medtwitter #medstudents #radiology #neurorad #HNrad #radres #neurology #ENT #temporalbone #neurosurgery #neuroanatomy #neuroanatomyTOTD
1/24
To evaluate the t-bone, best to compartmentalize--external/middle/inner ear (IE). See previous #tweetorial of the ME. The IE is difficult as most structures are obliquely oriented (at different obliquities!)-and can be hard to see on standard views. 2/24
IE communicates with ME via oval&round windows (which allow for transmission&dissipation of sonic vibrations). IE houses sensory organs for hearing/balance/sensing motion. The cochlear&vestibular nerves (CNVIII) transmit signals to the brain via the int auditory canal (IAC). 3/24
Neuroanatomy TOTD #12
The green structure is the amygdala (amygdaloid body) and the yellow structure is the stria terminalis (ST).
1/18
#meded #FOAMed #FOAMrad #medtwitter #medstudents #radiology #neurorad #radres #neurology #neurosurgery #neuroanatomy #neuroanatomyTOTD
The green structure is the amygdala (amygdaloid body) and the yellow structure is the stria terminalis (ST).
1/18
#meded #FOAMed #FOAMrad #medtwitter #medstudents #radiology #neurorad #radres #neurology #neurosurgery #neuroanatomy #neuroanatomyTOTD
Time for a deep dive into limbic networks. Bear with me—this is a fun subject. I got carried away preparing slides—it’s hard to know when to stop!
2/18
2/18
The amygdala is an almond-shaped collection of gray nuclei/subnuclei deep to the uncus and ant to hippocampus in the med temporal lobe. Involved in multiple functions: memory modulation, emotional learning and responses, +important connections w/ the olfactory bulb/cortex.
3/18
3/18
Neuroanatomy TOTD #10🧵Â
1/5 Small gray matter structure at the junction of the thalamus and midbrain is the subthalamic nucleus (STN).
#meded #FOAMed #FOAMrad #medtwitter #medstudents #radiology #neurorad #radres #neurology #neurosurgery #neuroanatomy #neuroanatomyTOTD
1/5 Small gray matter structure at the junction of the thalamus and midbrain is the subthalamic nucleus (STN).
#meded #FOAMed #FOAMrad #medtwitter #medstudents #radiology #neurorad #radres #neurology #neurosurgery #neuroanatomy #neuroanatomyTOTD
2/5...The STN is functionally a node within the basal ganglia (BG) INDIRECT LOOP. STN contains excitatory glutaminergic neuronsâžžoutput to the GABA neurons of GPi, which in turn have inhibitory effect on thalamic outputs to the motor cortex.
3/5...Loss of nigrostriatal input in Parkinsons Dzâžžincreased inhibitory output from GPiâžždecreased thalamic stimulation of the motor cortex (through both direct and indirect loop circuits). Makes sense that DBS treatments were initially directed at disrupting activity in GPi.
Neuroanatomy TOTD #9🧵
1/6 The trigeminal n. courses anteriorly➡️prepontine cistern➡️into Meckel’s cave (green), which lies at the medial floor of middle cranial fossa at the petrous apex.
#meded #FOAMed #FOAMrad #neurorad #neurology #neurosurgery #neuroanatomy #neuroanatomyTOTD
1/6 The trigeminal n. courses anteriorly➡️prepontine cistern➡️into Meckel’s cave (green), which lies at the medial floor of middle cranial fossa at the petrous apex.
#meded #FOAMed #FOAMrad #neurorad #neurology #neurosurgery #neuroanatomy #neuroanatomyTOTD
2/6...Meckel’s cave (MC) is open to the subarachnoid space at its posterior margin (and is therefore filled with CSF). The trigeminal (Gasserion) ganglion lives in MC. Superiomedial to MC (and sharing a dural border), is the cavernous sinus. #radres #neurorad
3/6...Coursing anteriorly, the V1 and V2 branches of CNV exit MC to travel within the lateral wall of the cavernous sinus. V3 courses inferiorly to exit the middle cranial fossa through foramen ovale, without involving the cavernous sinus.
Neuroanatomy TOTD #7🧵
1/7 The cavernous sinuses (CS) are outlined on either side of the sella. The ICA & cranial nerves 3,4,6,V1,V2 travel through the CS.
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1/7 The cavernous sinuses (CS) are outlined on either side of the sella. The ICA & cranial nerves 3,4,6,V1,V2 travel through the CS.
#meded #FOAMed #FOAMrad #radres #neurorad #medtwitter #radiology #neurology #neurosurgery #neuroanatomy #neuroanatomyTOTD
2/7...CN 3,6,V1 travel between two dural layers in the lateral wall of the CS. V2 often travels in the the inferolateral wall of the CS (sometimes inferior to the CS). Cranial nerve 6 floats freely in the CS (why CS pathology often selectively affects CN6).
3/7...Note that: postganglionic sympathetic inputs to the orbit (originating from the sup cervical ganglion) ascend with the ICA, branch off the ICA in the CS, and then join branches of CN3 (to sup tarsal muscle) and V1 (pupillary dilation).
Neuroanatomy TOTD #6
a) Ant choroidal artery infarct, involving the post limb of the internal capsule
b) Sup hypophyseal artery aneurysm—medially directed from the supraclinoid ICA
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a) Ant choroidal artery infarct, involving the post limb of the internal capsule
b) Sup hypophyseal artery aneurysm—medially directed from the supraclinoid ICA
#meded #FOAMed #FOAMrad #radres #neurorad #radiology #neurosurgery #neuroanatomy #neuroanatomyTOTD
ICA segments: C1 (cervical) becomes C2 (petrous) in the carotid canal of the petrous bone. Becomes C3 (lacerum) as it exits the carotid canal above the foramen lacerum. Becomes C4 (cavernous segment above the petrolingual ligament through the cavernous sinus.
...C5 (clinoid) above proximal to the distal dural ring. C6 (ophthalmic) is truly intracranial. C7 (communicating) distal to the Pcomm. Alternative segmentation schemes include C1-C4 (cervical, petrous, cavernous, supraclinoid/terminal)
Neuroanatomy TOTD #5
The indicated bundle is the anterior commissure (AC), located at the ant border of the 3rd ventricle, at the sup margin of the lamina terminalis.
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The indicated bundle is the anterior commissure (AC), located at the ant border of the 3rd ventricle, at the sup margin of the lamina terminalis.
#meded #FOAMed #FOAMrad #radres #neurorad #medtwitter #radiology #neurosurgery #neuroanatomy #neuroanatomyTOTD
The AC runs across the midline in front of the anterior columns of the fornix, behind the basal forebrain and beneath the anterior limb internal capsule and basal ganglia, surrounded by the bed nucleus of the stria terminalis.
The AC connects areas of the bilateral temporal poles and orbitofrontal cortex. Function is not entirely understood but it is thought to be important in the olfactory pathway and pain sensation, among other things.
Neuroanatomy TOTD #4
1/5 Answer: The orange structure is the cavernous sinus (CS), a paired dura-lined venous cavity on either side of the sella. The sinuses are split into numerous “caves” by fibrous septae (hence the name). #neuroanatomy #neurorad #medtwitter #neuroanatomyTOTD
1/5 Answer: The orange structure is the cavernous sinus (CS), a paired dura-lined venous cavity on either side of the sella. The sinuses are split into numerous “caves” by fibrous septae (hence the name). #neuroanatomy #neurorad #medtwitter #neuroanatomyTOTD
2/5 Note that the paired sinuses are often variably connected by “intercavernous sinuses”. While the CS is often taught for its relationship to the ICA and cranial nerves, I find that medical students and residents rarely understand the flow of blood through the sinus.
3/5 The CS receives blood from sup. and inf. ophthalmic veins draining the orbit--This is how a facial/orbital infection spreads intracranially to CS (classic #usmle ?). The sphenoparietal sinus as well as the superficial middle and inferieor cerebral veins also feed into the CS.
Neuroanatomy TOTD #3
1/6 The superior frontal sulcus courses in the AP direction, and terminates at the precentral sulcus posteriorly. The central sulcus is immediately posterior to the precentral, and the postcentral immediately posterior to the central.
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1/6 The superior frontal sulcus courses in the AP direction, and terminates at the precentral sulcus posteriorly. The central sulcus is immediately posterior to the precentral, and the postcentral immediately posterior to the central.
#meded #FOAMed #FOAMrad
2/6 "Upper T sign" or "L sign"
The SFS intersects the precentral s
Central sulcus is just posterior
The SFS intersects the precentral s
Central sulcus is just posterior
3/6 "Lower T sign" or "M sign"
The IFS terminates at the precentral s.
Central sulcus is just posterior
The IFS terminates at the precentral s.
Central sulcus is just posterior
