Neuroanatomy

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This article covers very basic neuroanatomy. It is essential to have a good grasp on neuroanatomy and neurohistology... before doing neuropathology.

This article has some overlap with the neurohistology article, as there isn't a clear divider between microscopic and macroscopic.

Anatomy

General

  • Central nervous system (CNS): Brain, spinal cord.
  • Cortex:
    • Cerebral lobes: Frontal, parietal, temporal, occipital, insula.
  • Diencephalon: Thalamus, hypothalamus.
  • Mesencephalon: Colliculi (superior, inferior).
  • Metencephalon: Pons, cerebellum.
  • Myelencephalon: Medulla.
  • Ventricular system:
    • Lateral ventricles, interventricular foramen, third ventricle, cerebral aquaeduct, fourth ventricle, subrachnoid space.
  • Meninges:
    • Outer Covering, CSF circulation, buoyancy of brain.
    • Falx cerebri (between hemispheres), Tentorium cerebelli (separates cerebellum).

  • Brain: Top view

  • Brain: Bottom view

  • Brain: Lateral view

  • Orientation planes (WC/blausen staff)

  • Gray and white matter


Important

  • Basal ganglia
    • Includes: Nucleus caudatus, putamen, pallidum, subthalamus, substantia nigra
    • Part of the forebrain.
    • Caudate nucleus + putamen = striatum.
    • Pallidum + putamen = lenticular nucleus.

  • Schematic overview (WC/blausen staff)

  • Section with descriptions (WC/SMH)

  • Uncus (as in uncal herniation).

  • Position of the uncus

  • Uncus bottom view (WC/Anatomist90)

  • Cerebellar tonsils (as in tonsillar herniation).
  • Hippocampus (as in hippocampal sclerosis).

  • Location of the hippocampus in the brain (WC/Washington irving)

  • Hippocampus is marked blue on this coronar section (PLoS/Talbot et al.)

  • Macroscopic specimen after formalin fixation showing hippocampus in coronar section (WC)

  • Longitudinal fissure - divides cerebrum into hemispheres.

  • Animation showing position of longitudinal fissure in the brain (WC)

  • Superior view on longitudinal fissure (WC)

  • Lateral sulcus (Sylvian fissure, lateral fissure) - separates temporal lobe from frontal lobe & parietal lobe.

  • Animation showing position of lateral sulcus in the brain (WC)

  • Fixated brain, lateral view. The sulcus centralis is marked with 5 (WC)

  • Central sulcus - separate parietal lobe from frontal lobe.

  • Animation displaying position of central sulcus (WC)

  • Superior view on central sulcus (WC)

  • Fixated brain, lateral view. The sulcus centralis is marked with 6 (WC)

  • Brain stem = medulla oblongata, pons, mesencephalon (midbrain).[1]

  • The three distinct parts of the brainstem are colored in this sagital section of a human brain (WC)

  • Anterior view on a formalin fixated brainstem (WC).

  • Coronal section through brainstem and hemispheres (WC)

Less important

Glomeruli of Arnold

  • Over lies hippocampus.

Calcarine cortex

Nucleus accumbens

  • Abbreviated NAcc - inferior-medial to where the internal capsule ends; anterior of optic chiasm.

  • NAcc - sagittal. (WC)

  • NAcc - frontal. (WC)

Nucleus basalis of Meynert

  • Abbreviated NBM.
  • Inferior of the globus pallidus; makes acetylcholine.

  • NBM - very low mag. (WC)

  • NBM - intermed. mag. (WC)

Locus ceruleus

See also: Neurohistology#Locus_ceruleus.
  • Blue dots - anterior to 4th ventricle in the pons.

Images:

Other - trivia

  • Claustrum - thin band of grey mater in the external capsule; function uncertain.[2]
  • Nerve root vs. nerve:[3]
    • Nerves have epineurium.
    • Nerve roots do not have epineurium.

Notes:

  • Nerve anatomy:[4]
    • Nerve (surrounded by epineurium) -> Fascicle (surrounded by perineurium) -> Nerve fibre (surrounded by endoneurium).

Vascular structures

  • Posterior cerebellar arteries.
    • Inferior of posterior cerebral arteries.
  • Anterior inferior cerebellar arteries.
    • Branch off basilar artery.
  • Posterior inferior cerebellar arteries - AKA PICA.
    • Branch off vertebral arteries.

Images

  • Circle of Willis. (WC)

www:

Meninges

Deep to superficial:

  1. Pia mater.
  2. Arachanoid membrane.
    • Subarachanoid space - contains blood vessels.
  3. Dura mater.
    • Tough outer covering.

Lesion location in relation to meninges

Locations:[5]

  1. Intra-axial = inside the (middle) of spinal cord/brain.
    • AKA intramedullary.
  2. Intradural = not intra-axial, but deep to the dural.
    • AKA extramedullary.
    • AKA extra-axial.
  3. Extradural = outside of dura.
  • The above descriptors are often found in radiology reports.

DDx based on location[6]

Intra-axial:[7]

  • Glioma (astrocytoma, oligodendroglioma, ependymoma).
  • Non-glial tumours (hemangioblastoma, CNS lymphoma).
  • Metastases.
  • Non-tumour:

Intradural:

Extradural:

Neuropathological dissection (autopsy)

Brain fixation after removal: Usually 14 days

  • Check brain for:
    • Lesions
    • edema (might be not visible but tissue is softer than normal)
    • hemorrhage
    • Discolorations
    • Asymmetry (midline shift)
    • herniation (subfalxial, uncal, tonsillar)
    • vascular abnormalities

  • Asymmetry (midline shift) indicating lesions (stroke, tumor)

  • Brain hemorrhage

  • Atrophy: widespread sulci, often seen in neurodegenerative diseases

  • Brown discolorations indicating demyelinisation


Sampling - sections (autopsy)

See autopsy.

Standard histologic sections:

Site Routine[8] Head injury[9] Epilepsy[10] Dementia[11]
Frontal cortex Y [1] Y - bilateral parasagittal [2] N Y - middle frontal gyrus [1]
Cingulate gyrus N N Y - parasagittal [1] Y [1]
Basal ganglia &
internal capsule 		Y [1] Y - bilateral with corpus callosum [2] Y - caudate, putamen,
globus palidus [1] 		Y - putamen,
globus palidus [1]
Basal ganglia,
internal capsule,
thalamus 		N Y [2] N N
Temporal lobe N N Y - superior & middle temporal gyri [2] Y - superior & middle temporal gyri [1]
Hippocampus Y [1] Y - bilateral [2] Y - also parahippocampal gyri [2] Y - also parahippocampal gyri [1]
Splenium of corpus callosum N Y [1] N N
Parietal lobe N Y - centrum semiovale (unilateral) [1] N Y - inferior [1]
Occipital cortex Y [1] N N Y [1]
Midbrain Y [1] Y [1] N Y [1]
Cerebellum (with
dentate gyrus) 		Y [1] Y - bilateral [2] Y - also vermis [2] Y [1]
Pons N Y [1] N Y [1]
Medulla Y [1] Y [1] N Y [1]
Total sections [7] [15] [8] [11]

An absolute minimum:[12]

  1. Hippocampus.
  2. Cerebral cortex.
  3. Brainstem (midbrain).
  4. Cerebellum.

See also

References

  1. ↑ Martini, Frederic H. (2003). Fundamentals of Anatomy & Physiology (6th ed.). Benjamin Cummings. pp. 466. ISBN 978-0805359336.
  2. ↑ URL: http://commons.wikimedia.org/wiki/File:Telencephalon-Horiconatal.jpg. Accessed on: 22 September 2010.
  3. ↑ MUN. 25 November 2010.
  4. ↑ Martini, Frederic H. (2003). Fundamentals of Anatomy & Physiology (6th ed.). Benjamin Cummings. pp. 438. ISBN 978-0805359336.
  5. ↑ URL: http://www.nervous-system-diseases.com/spine-tumor.html. Accessed on: 21 September 2010.
  6. ↑ URL: http://www.nervous-system-diseases.com/spine-tumor.html. Accessed on: 21 September 2010.
  7. ↑ Perry, Arie; Brat, Daniel J. (2010). Practical Surgical Neuropathology: A Diagnostic Approach: A Volume in the Pattern Recognition series (1st ed.). Churchill Livingstone. pp. 57. ISBN 978-0443069826.
  8. ↑ Burton, Julian L.; Rutty, Guy N. (2010). The Hospital Autopsy A Manual of Fundamental Autopsy Practice (3rd ed.). Oxford University Press. pp. 164. ISBN 978-0340965146. }}
  9. ↑ Burton, Julian L.; Rutty, Guy N. (2010). The Hospital Autopsy A Manual of Fundamental Autopsy Practice (3rd ed.). Oxford University Press. pp. 176. ISBN 978-0340965146. }}
  10. ↑ Burton, Julian L.; Rutty, Guy N. (2010). The Hospital Autopsy A Manual of Fundamental Autopsy Practice (3rd ed.). Oxford University Press. pp. 179. ISBN 978-0340965146. }}
  11. ↑ Burton, Julian L.; Rutty, Guy N. (2010). The Hospital Autopsy A Manual of Fundamental Autopsy Practice (3rd ed.). Oxford University Press. pp. 180. ISBN 978-0340965146. }}
  12. ↑ MUN. 15 November 2010.

External links

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