Concepts in Medical Neuroscience

By | January 20, 2014

Many of these notes are adapted from Dr. White's Coursera course titled "Medical Neuroscience."

1-2: Functional Microanatomy of Neurons

  • Neurons contain all the metabolic machinery common to other somatic cells (e.g., nuclei, mitochondria)
  • Most neurons are incredibly rich in endoplasmic riticulum for synthesis of lipid (smooth ER) and protein molecules (rough ER) and mitochondria for respiration
  • Spines - mushroom or filament shaped portrusions coming off of dendrites. Spines provide a locale of contact for other neurons. Other dendrites are smooth and don't have spines, meaning they are likely inhibitory neurons
  • Pyrimadal neurons - called so because of their pyramid shaped cell body. They have an apical dendrite extending from its apex (top) and then various other basal dendrites
  • Gray matter - cell bodies/dendrites/axon terminals; White matter - myelin (axons), glial cells
  • Synapses can either be at the end of an axon or along an axon
  • There are about the same number of excitatory interneurons as inhibitory interneurons
  • Afferent - sensory neuron (sending towards

1-3: Non Neuronal Cells of the CNS

  • Neuroglia support metabolic and signaling functions of neurons, participate in neuron circuit formation and synaptic plasticity, make myelin, contribute to formation of blood-brain barrier, participate in inflammatory response and phagocytosis, contribute to formation of scar tissue
  • Astrocyte - gray matter; help maintain ionic balance of extracellular fluids; take-up neurotransmitters from synaptic cleft; assist in formation of new synapses and circuits; contribute to blood-brain barrier; can develop into scar tissue
  • Oligodendrocyte - white matter; forms myelin in CNS (Schwann develops myelin in PNS); present antigens that influence the outgrowth of axons in developing/recovering brain
  • Microglia - mononuclear phagocyte; derived from hematopoietic precusor cells that migrate to the brain; exists as an amoeboid (activated as phagocytic) or ramified form (dormant); secrete cytokines
  • Glial Stem Cells - located near the ventricles; give rise to more stem cells, astrocytes, oligodendrocytes, or neurons
  • Blood brain barrier - permeability barrier between endothelium and extracellular space in neural tissue; formed by tight junctions; surrounded by astrocytic foot processes that disallow various substances from passing (e.g., water, toxic compounds)

1-4: Basic Orientation in the Human CNS

  • Anterior & Rostral - front; Posterior & Caudal - back;
  • Mid Sagittal Plane - divides left and right hemisphere and designates medial/lateral directionality
  • Superior & Dorsal - top; Inferior & Ventral - bottom

1-7: Finding the Central Sulcus

  • The cingulate gyrus is right above the corpus collosum
  • The cingulate sulcus is above the cingulate gyrus
  • There is a point when the cingulate sulcus, near the middle, forms a sharp vertical sulcus called the marginal branch of the cingulate sulcus
  • The space that is anterior to the marginal branch is the central sulcus
  • The arachnoid matter protects the cerebrum and under the arachnoid matter is about a millimeter of CSF
  • Postcentral gyrus is somatosensation

1-8: Ventral Surface of the Cerebral Hemispheres

Untitled1-9: Fingers to Gyri

1-10: Blood Supply to the Brain

Blood Supply to Brain

Untitled

1-11: Surface Anatomy of the Brainstem and Cranial Nerves

Brainstem

1-12: Cranial & Spinal Nerves, part 1

Below are the cranial nerves:

  • I. Olfactory nerve (sensory) - sense of smell
  • II. Optic nerve (sensory) - vision
  • III. Oculomotor nerve (motor) - eye movements
  • IV. Trochlear nerve (motor) - eye movements (intorsion, downward gaze)
  • V. Trigeminal nerve (sensory and motor) - somatic sensation from face, mouth, cornea
  • VI. Abducens nerve (motor) - eye movements (abduction or lateral movements)
  • VII. Facial nerve (sensory and motor) - muscles of facial expression; taste from anterior tongue; lacrimal and salivary glands
  • VIII. Vestibulochoclear (auditory) nerve (sensory) - hearing; sense of balance
  • IX. Glossopharyngeal nerve (sensory and motor) - sensation from posterior tongue and pharynx; taste from posterior tounge; carotid baroreceptors and chemoreceptors
  • X. Vagus nerve (sensory and motor) - autonomic functions of gut; sensation from larynx and pharynx; muscles of vocal cords; swallowing
  • XI. Spinal accessory nerve (motor) - shoulder and neck muscles
  • XII. Hypoglossal nerve (motor) - movements of tounge

Cranial Nerves Schematic

1-13: Cranial & Spinal Nerves, part 2

  • 31 spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal
  • The spinal cord has enlargement in the cervical region and the lumbosacral region to handle the circuitry of the arms and legs
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