Name the skull bones and sutures (For bones, name from posterior to anterior and superior to inferior)
Sutures:
Medial sagittal - Saggital suture
Anterior coronal - Coronal suture
Posterior horizontal - Lambdoid suture
Lateral sagittal - Squamous suture
Bones:
Occipital, Parietal, Temporal, Frontal
Inferior to frontal - Sphenoid
Anterior to Sphenoid - Zygomatic
Anterior to Zygomatic (in eye) - Lacrimal
Anterior to Lacrimal - Maxilla
Anterior to Maxilla - Nasal
inferior to Maxilla - Mandible
Located at the spinal cord - Vertebra
What are the meninge layers?
Dura mater - toughest and most external layer
Arachnoid mater - Thin layer that lines the underneath of the dura mater
Subarachnoid space - Space between the arachnoid mater and pia mater that is filled with CSF
Pia mater - Thin layer that lines the brain
Name the make-up of the ventricular system and the location of cerebrospinal fluid production/location. What are the functions of the CSF?
Ventricles - (2) Lateral ventricle, (1) Third ventricle, (1) Fourth ventricle
The CSF is produced by the choroid plexus and is found within the subarachnoid space.
CSF is used for (A) Impact absorption, (B) Osmotic homeostatis [balance salt + water in nervous system -> balance in pressure], (C) Waste disposal, (D) Neurotrophic factor secretion [help neurons stay healthy]
What is the glymphatic system?
The glymphatic system is a waste clearance system that uses the pressure gradient from blood to push CSF around the brain and clear plaque and waste.
Why is the retina considered as a part of the CNS?
- They cannot spontaneously regenerate their axons after optic nerve injury
- Myelinated by oligodendrocytes
- Astrocytes and microglia are found in the retina
- Aqueous humor [fluid in eye] is similar to CSF
- Retina and optic nerve extend from the brain during development
How are neurons mapped to different positions within a cross-section of spinal cord?
Inside the spinal cord, there are different zones of grey matter (I-X). In the dorsal horn, sensory neurons will synapse with distinct interneurons arranged in different zones. Furthermore, in the ventral horn, motor neurons innervating to from the neighbouring muscles are located next to each other. If the motor neurons were scrambled in the ventral horn, the motor behavior is altered.
Describe the mouse motor neuron scrambling experiment.
- Label the different motor neurons in the lumbar ventral horn by using cholera toxin B (CTB)
Label muscle region with CTB by injecting CTB in muscle, which lets it enter the axon terminal and travel to the nuclei - Delete a single trancription factor (FOXP1), this affects the positioning of these neurons
- Mouse no longer moves properly
Describe the changes in white and grey matter in the spinal cord.
When we are at the cervical, we have the most white matter as it carries information from all spinal cord segments up to the brain and the least in the caudal segments as they only carry information to their own segments. Furthermore, the cervical and lumbar segments have the largest ventral horn as they require more fine-motor movements since they innervate the hands and toes.
Name the different glial cells and their functions (mention phenotype when applicable)
[Glia makes up ~50% of the CNS]
Ependymal cells: found in the ventricle wall and choroid plexus within the brain and spinal cord
-> Secrete most of the fluid that becomes CSF through the glymphatic system
Schwann cells: found in the PNS
-> myelinate one axon, support and guide axon regeneration
Oligodendrocytes: found in the CNS
-> myelinate multiple axons
Myelin is a lipid substance that provide electrical insulation and supplies axons with nutrients and neurotrophic factors
Microglia: Found in the CNS
-> Scavenging of invaders and mediating inflammation, participate in neuron/neurite plasticity, or synpatic remodeling/pruning.
[phenotypes]
M1 -> inflammation and neurodegeneration
M2 -I inflammation and promotes neural repair
Astrocytes: Most populous glia cell in the CNS
-> Modulate neurotransmitssion and regulating ion homeostasis and brain metabolism, altering blood vessel diameter, maintain blood-retinal barrier, synaptic and neuron growth and connectivity, manage CSF flow rate in the glymphatic system, Form glial scar around nerve injuries (astrogliosis).
[phenotype]
A1 -> inflammation and neurodegeneration
A2 -I inflammation and promotes neural repair
Muller cells: Found in the retina. In zebrafish, the cells are pluipotent and can turn into any retinal (stem) cells after retinal injury.
-> an astrocyte-like cell that can undergo gliosi
Describe the pupillary light reflex pathway.
- Photoreceptors are stimulated by light and makes an action potential
(rods = light detection, cones = color detection) - Photoreceptor release excitatory neurotransmitter glutamate at their axon terminal
- Bipolar cells are stimulated and relay visual information to retinal ganglion cells(RGC) by releasing glutamate in their axon terminal
- Retinal ganglion cells(RGC) is stimulated and relaty the visual information to the brain via the optic nerve (a bundle of axons)
Extra:
Ciliary ganglion neurons are effector neurons that synapse with ciliary muscles and adjust the pupil size
Spinal cord anatomy and knee-jerk reflex
