Lecture 7 (2/10) Flashcards
Glial Cells
Main function is to protect and support neurons/nerve cells
Typically small in size
Do NOT transfer information, do NOT generate active electrical signals
2 Types:
Astrocytes
Oligodendrocytes
Astrocytes
One of 2 main types of Macroglia cells
Star-shaped cells with irregulars shaped cell bodies and numerous extensions
2 Main Classes:
Fibrous
Protoplasmic
Fibrous Astrocytes
A type of astrocyte; type of glial cell
Found in white matter
Protoplasmic Astrocyte
A type of astrocyte; type of glial cell
Found mostly in grey matter
Have shorter extensions
Associated with nerve cell bodies, dendrites, and synapses - they envelop synapses
Oligodendrocytes
One of 2 main types of Macroglia cells
Small, with few processes
Found in myelinated fiber tracts in the CNS
They wrap around axons and contribute to the formation of myelin sheaths
Multiple sclerosis involves the gradual death of these cells
Schwan
Macroglia cells/glial cells
Found in the PNS
Form myelin sheath around the axons of peripheral neurons
Ependymal
Macroglia cells/glial cells
Line the ventricles (cavities) which are filled with CSF
They produce/secrete CSF
Microglia
A class of glial cells
Found scattered through the brain
Look like a small, hair spider
Type:
Phagocyte
Macroglia
A class of glial cells
Includes: Astrocytes (fibrous & Protoplasmic) Oligodendrocytes Schwan Ependymal
Phagocyte
A type of microglia/glial cell
Cells that dispose of cellular debris; garbage collectors
Help seal off damaged brain tissue: rush to site of injury and clean up dead cells
Brain Stem
3 Main Parts:
Midbrain
Pons
Medulla Oblongata
Midbrain (General)
Part of the brain stem
Connects the brain stem to the diencephalon above and the pons below
Midbrain (Structures)
Cerebral Peduncle
Interpedunclur Fossa
Cranial Nerve IV
2 Important Nuclei:
Inferior Colliculus
Superior Colliculus
Cerebral Peduncles
Large swellings on the anterior, lateral surface of the midbrain
Interpedunculur Fossa
Deep grooves or sulci between the cerebral peduncles
Cranial Nerve III emerges from them
Inferior Colliculus
Important nucleus in the midbrain
Concerned with auditory info
The Lateral lemniscus is a tract that runs into the inferior colliculus and provides it with auditory information
Superior Colliculus
Important nucleus in the midbrain
Carries visual information to the midbrain
Pons
A portion of the brainstem
Cerebellar Peduncles connect the brainstem and cerebellum There are 3; Inferior Cerebellar Peduncle Middle Cerebellar Peduncle Superior Cerebellar Peduncle
Lesions on the anterior portion of the pons can cause Locked-in Syndrome.
Locked-in Syndrome
Caused by a lesion to the anterior portion of the pons
Patients with this condition are unable to talk even though they are conscious
Medulla Oblongata
Lies between the pons and the spinal cord
Main Structures: Pyramid Pyramidal Tract Nucleus Cuneatus Nucleus Gracilis Fasciculus Cuneatus Fasciculus Gracilis 5 Cranial Nerves (8-12)
Pyramid
A nucleus on the anterior surface of the Medulla
Axons of cells in the pre central gyrus travel through the pyramid on their way to the spinal cord
These axons form the Pyramidal Tract
Pyramidal Tract
A dense band of fibers made of axons that travel from the pre central gyrus on their way to the spinal cord
Pyramidal Decussation
Occurs when the axons traveling on the pyramidal tract reach the pyramid and switch sides
Nucleus Cuneatus & Nucleus Gracilis
Nuclei where cells traveling from the spinal cord pass through when traveling up to the cortex.
They form tracts called Fasciculus Cuneatus and Fasciculus Gracilis
Fasciculus Cuneatus & Fasciculus Gracilis
Bands created by cells from the spinal cord
These cells synapse with the Nucleus Cuneatus and the Nucleus Gracilis
Cranial Nerves in the Medulla
There are 5
Numbers 8-12
Damage to the Medulla
Causes Vertigo/dizziness, paralysis of the muscles in the throat/larynx, and combinations of sensory loss in limbs and face
Ventricles
Cavities
4 Main
2 Lateral Ventricles (one in each hemisphere)
1 Third Ventricle
1 Fourth Ventricle
Lateral Venticles
There are 2, 1 in each hemisphere
They are connected to the third ventricle by the Foramen of Monro
Foramen of Monro
Connects the lateral ventricle to the third ventricle
Third Ventricle
Located in the diencephalon
Connected to the fourth ventricle by the Cerebral Aqueduct
Cerebral Aqueduct
Connects the third and fourth ventricles
Fourth Ventricle
Located in the pons and the upper part of the medulla
Smallest ventricle
Ends in subarachnoid space
Choroid Plexus
Contained in ventricles
A spongey mass of tissue which is the primary producer of CSF
