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Directional terms

Supporting structures

Meninges

  • Dura mater (‘tough mother’)
  • Arachnoid membrane
  • Subarachnoid space
  • Pia mater (‘gentle mother’)

Ventricular system

  • Also known as cerebral ventricles
  • Lateral (1st & 2nd)
  • 3rd
  • Cerebral aqueduct
  • 4th

  • Ventricles filled with cerebrospinal fluid (CSF)
    • CSF clears metabolites during sleep (Xie et al., 2013)?

Blood Supply

  • Carotid & vertebral arteries converge on Circle of Willis
  • Anterior, Middle, and Posterior Cerebral arteries main output

Blood/brain barrier

  • Cells forming blood vessel walls tightly packed
  • Active transport of molecules typically required

Area Postrema

  • In brainstem, blood-brain barrier thin
  • Chemoreceptors detect toxins, trigger emesis if necessary

Organization of the Nervous System

https://www.pastmedicalhistory.co.uk/the-nervous-system-of-harriet-cole/

https://www.pastmedicalhistory.co.uk/the-nervous-system-of-harriet-cole/

Organization of the CNS

Major division Ventricular Landmark Embryonic Division Structure
Forebrain Lateral Telencephalon Cerebral cortex
Basal ganglia
Hippocampus, amygdala
Third Diencephalon Thalamus
Hypothalamus
Midbrain Cerebral Aqueduct Mesencephalon Tectum, tegmentum
Hindbrain 4th Metencephalon Cerebellum, pons
– Mylencephalon Medulla oblongata

Hindbrain

  • Hindbrain: structures adjacent (or caudal to) 4th ventricle
    • Medulla oblongata
    • Cerebellum
    • Pons

Medulla oblongata

  • Cardiovascular regulation
  • Muscle tone
  • Fibers of passage
    • Ascending fibers (from body), a.k.a. afferents
    • Descending fibers (exiting brain), a.k.a., efferents

Cerebellum

  • “Little brain”
  • Dorsal to pons
  • Movement coordination, simple learning

Pons

  • Bulge on brain stem
  • Neuromodulatory nuclei (e.g., 5-HT, NE, ACh, DA)
  • Relay to cerebellum

Midbrain

  • Tectum (roof), dorsal
  • Tegmentum (floor), ventral

Tectum

  • “Roof” of the midbrain
  • Superior and inferior colliculus (colliculi is plural)
  • Reflexive orienting of eyes, head, ears

Tegmentum

  • “Floor” of the midbrain
  • Species-typical movement sequences
  • Neuromodulatory nuclei
    • Norepinephrine (NE)
    • Serotonin (5-HT)
    • Dopamine (DA) – from ventral tegmental area (VTA)

Forebrain

  • Diencephalon
  • Telencephalon

Diencephalon

  • Thalamus
  • Hypothalamus

Thalamus

  • Input to cortex
  • Functionally distinct nuclei (collection of neurons)
    • Lateral geniculate nucleus (LGN), vision
    • Medial geniculate nucleus (MGN), audition
    • Pulvinar, attention?

Hypothalamus

  • Five Fs: fighting, fleeing/freezing, feeding, and reproduction
  • Controls pituitary gland (“master” gland)
    • Anterior pituitary (indirect release of hormones)
      • e.g., Corticotropin Releasing Hormone (CRH) -> release of cortisol from Adrenal Cortex
    • Posterior pituitary (direct release of hormones)
      • Oxytocin
        • Vasopressin (aka, Arginine Vasopressin – AVP; Anti-diuretic Hormone – ADH)

Telencephalon

  • Basal ganglia
  • Hippocampus, amygdala
  • Cerebral cortex

Basal Ganglia

  • Skill and habit learning
  • Linked to Tourette syndrome, obsessive-compulsive disorder (OCD), addiction, movement disorders
  • Example: Parkinson’s Disease

  • Striatum
    • Caudate nucleus
    • Putamen
  • Globus pallidus
  • Subthalamic nucleus
  • Substantia nigra (tegmentum)

Hippocampus

  • Medial to lateral ventricles
  • Memories of specific facts or events; place memory in non-human animals
  • Fornix projects to (mammillary bodies of) hypothalamus

Amygdala (“almond”)

  • Physiological state, behavioral readiness, affect
  • NOT the fear center! (LeDoux, 2015).

Cerebral Cortex

  • Cerebral hemispheres
  • Groove (sulcus or sulci)
  • Bumps (gyrus or gyri)
  • Grey vs. white matter
  • Lobes

Lateral view

Medial view

Nissl stain

Lobes of the cerebral cortex
  • Frontal
  • Temporal
  • Parietal
  • Occipital
  • Names derive from bones of the skull

Longitudinal fissure

  • Also known as superior longitudinal fissure
  • Divides the cerebral hemispheres

Lateral sulcus/fissure

  • Also known as Sylvian Fissure
  • Divides frontal from temporal lobe

Central sulcus

  • Also known as Rolandic Fissure or Fissure of Rolando
  • Divides frontal from parietal lobe

Frontal lobe
  • Anterior to central sulcus
  • Superior to lateral fissure
  • Dorsal to temporal lobe

Inferior Frontal Gyrus (IFG)

Middle Frontal Gyrus (MFG)

Temporal lobe
  • Ventral to frontal, parietal lobes
  • Inferior to lateral fissure

  • Primary auditory cortex (A1)
  • Object, face recognition
  • Storage of memories about events, objects
  • Amygdala, hippocampus

Inferior Temporal Gyrus (ITG)

Entorhinal Cortex (ER)

Parietal lobe
  • Caudal to frontal lobe
  • Dorsal to temporal lobe
  • Posterior to central sulcus

  • Primary somatosensory cortex (S1)
  • Perception of spatial relations, action planning

Inferior Parietal Lobule

Superior Parietal Lobule

Occipital lobe
  • Caudal to parietal & temporal lobes

  • Primary visual cortex (V1)
  • Secondary visual areas (V2…V7)

Insular cortex (insula)
  • medial to temporal lobe
  • deep inside lateral fissure

  • Primary gustatory cortex
  • Self-awareness, interpersonal experiences, motor control, interoception
Brodmann Areas

  • Cytoarchitectonic (cellular architecture) differences in cerebral cortex
  • Numbered areas, e.g. V1 == Area 17

White matter pathways

  • Brainstem
  • Projection fibers
  • Association fibers
  • Commissural fibers

(Oishi, Faria, Zijl, & Mori, 2010), Chapter 3, Figure 1.

Brainstem projections

  • Corticospinal tract (descending/efferent)
  • Dorsal column/medial lemniscus (ascending/afferent)
  • Superior/inferior cerebellar peduncles (from/to cerebellum)

(Oishi et al., 2010), Chapter 3, Figure 8.

Projection fiber tracts

  • Internal capsule
    • Thalamic radiation
    • Cortico-{pontine, bulbar, reticular} tracts

(Oishi et al., 2010), Chapter 3, Figure 11.

Cortical white matter tracts

  • Superior/inferior longitudinal fasciculus
  • Superior/inferior fronto-occipital fasciculus
  • Cingulum, fornix (hyp-hip), stria terminalis (hyp-amyg)

Commissural fibers

  • Corpus callosum
  • Anterior commissure (AC)
  • Posterior commissure (PC)

Anterior, Posterior Commissures

Spinal cord

  • Spinal column w/ vertebrae
  • Cervical (8), thoracic (12), lumbar (5), sacral (5), coccygeal (1)
  • Spinal segments & 31 nerve pairs
  • Cauda equina

  • Spinal segments (rostral to caudal) ennervate specific body segments
  • When focusing on the skin, these are called dermatomes

  • Dorsal/Ventral
    • Dorsal root (sensory)
    • Ventral root (mostly motor)
  • Grey (interior) vs. white matter (exterior)
    • Cerebral cortex opposite (grey exterior, white interior)

Organization of the PNS

Somatic division

Cranial nerves

  • Afferents (input), efferents (output), or mixed
  • Innervate head and neck
  • Olfactory (I), optic (II), (VIII) auditory, vagus (X), etc.
  • Spinal nerves

Spinal nerves

Autonomic nervous system

  • CNS & PNS components
  • Controls “vegetative functions”
    • Limited voluntary control
  • Two divisions
    • Sympathetic
    • Parasympathetic

Sympathetic division

  • Prepares body for action
  • “Fight or flight”
  • Spinal cord
    • ganglion chain along spinal column to End organs
  • Neurotransmitters (NTs)
    • Preganglionic: ACh
    • Post: NE

Parasympathetic division

  • “Around” sympathetic
  • Restorative function
  • “Rest & digest”
  • Spinal cord (or Vagus n.) -> ganglia near end organs -> end organ
    • NT: ACh

References

Berntson, G. G., Cacioppo, J. T., & Quigley, K. S. (1991). Autonomic determinism: The modes of autonomic control, the doctrine of autonomic space, and the laws of autonomic constraint. Psychological Review, 98(4), 459–487. https://doi.org/10.1037/0033-295X.98.4.459

LeDoux, J. (2015, August 10). The Amygdala Is NOT the Brain’s Fear Center. Psychology Today. Retrieved from https://www.psychologytoday.com/blog/i-got-mind-tell-you/201508/the-amygdala-is-not-the-brains-fear-center

Oishi, K., Faria, A. V., Zijl, P. C. van, & Mori, S. (2010). MRI atlas of human white matter. Academic Press.

Xie, L., Kang, H., Xu, Q., Chen, M. J., Liao, Y., Thiyagarajan, M., … others. (2013). Sleep drives metabolite clearance from the adult brain. Science, 342(6156), 373–377. https://doi.org/10.1126/science.1241224