Nervous System and Nerves Flashcards
Define the neuron and glial cells.
Neuron refers to the functional unit of the NS - important for electrical activity and communication.
Glial cells refer to supporting cells of the NS. Examples such as:
- Astrocytes: important for synapsis function and blood-brain barrier
- Oligodendrocyte: myelin production
- Microglial cells: immune cells of the NS
Mention the features of the cerebrum.
- Gyri: ridge of the cerebral cortex
- Sulci: depression/groove in the cortex - surrounds a gyri
- Fissures: larger sulci
Function: increase surface area - allow higher cognitive processes
Corpus collosum
Myelinated axons that connects the brain’s hemispheres
What is meninges? Mention the layers of the meninges.
Meninges refers to the protective layers around the brain. It consists of:
- Dura Mater
- Arachnoid Membrane
- Pia Mater
Mention the features and importance of dura mater.
It is important for brain protection - thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord.
Sites such as Falx cerebri, tentorium cerebelli, and falx cerebelli, where the dura mater sits on a fissure/sulci, are prone to subdural hematoma. Herniations may occur when swelling pressure squishes the brains at theses sites.
Mention the features and importance of the arachnoid membrane.
It is separated form the dura mater by the subdural space. Arachnoid villi are present and acts as drainage sites for CSF to the circulatory system.
Describe CSF and how it is being produced and retrieved in the brain.
Cerebral Spinal Fluid fills up the subarachnoid space - surrounding the brain and the spinal cord. It is produced by the the Coroid Plexus in the brain’s ventricles. Pressure in the space forces it back through the arachnoid villi. This features maintain a steady-state system.
Mention the features of the pia mater.
It sits on the brain and separated from the arachnoid membrane by the subarachnoid space.
Mention the lobes of the brain.
- Frontal
- Parietal
- Occipital
- Temporal
Differ between “grey” and “white” matter.
Grey matter refers to the site of the CNS where the cell bodies of the neuron sits. White matter refers to the myelinated axons - which is made up of fatty substances.
Mention the members of the diencephalon.
- Hypothalamus
- Thalamus
- Pineal Gland
Mention the members of the brainstem. Explain as well brainstem’s importance.
- Midbrain (Mesencephalon)
- Pons (“Bridge”)
- Medulla oblongata (myelencephalon)
It has centres that control breathing and other vital functions.
Mention the members of the spinal cord. Describe a feature of regarding the thickness of the cord.
- Cervical cord & nerves
- Cervical enlargement: due to limbs => more neurons
- Thoracic cord & nerves
- Lumbar cord & Nerves
- Lumbar enlargement: due to limbs => more neurons
- Sacral cord & Nerve
- Coccygeal cord & nerve
Myelin sheath is produced by __________ in the CNS and ________ in the PNS.
Oligodendrocytes, Schwann Cells
Explain how conus medullaris arises.
Conus medullaris refers to the site where the spinal cord ends (around the L2). Cauda equina, or nerve root extensions project beyond the conus medullaris until it is anchored by the filum terminale to the sacrum
It arises due to the developmental consequence during the first trimester, where the spinal cord stopped growing even though the foetus continues to elongate. This causes the cord to terminate at a higher vertebral level – Note: all vertebral nerve still exists
Mention the categorical levels of nervous connective tissue.
Nerve fibres are encased in endoneurium. These fibres form fasicles - which itself is encased in perineurium. A group of these fasicles form the nerve/axon which itself is encased by the epineurium.
There are ____ pairs of spinal nerves. Mention them.
31 Pairs
- 8 pairs of cervical nerves (C1-C8)
- 12 pairs of thoracic nerves (T1-T12)
- 5 pairs of lumbar nerves (L1-L5)
- 5 pairs of sacral nerves (S1-S5)
- 1 pair of coccygeal nerves (Co1)
Note: there are only 30 pairs of vertebras (only 7 cervical vertebrae) - C1 arises from above the vertebrae
Mention the orientation of the peripheral nerve axons in terms of its constituents and their features.
Peripheral nerve axons are made up of both sensory and motor neurons, which are separated as it joins the CNS in the spinal cord.
The ventral (anterior) roots are considerd to be motor neurons. The nuclei are located in the ventral horns.
The dorsal (posterior) roots are considered to be sensory neurons. The ganglion forms in the periphery with the axons continuing into the dorsal horns of the cord.
Define dermatome and myotome.
Dermatome is an area of skin that is mainly supplied by a spinal nerve
Myotome is the group of muscles that single spinal nerve innervates
Define the ANS. Compare it with the somatic nervous system.
The autonomic nervous system mediates unconscious homeostatic control of organ and body physiology.
Compared to the SNS, the ANS has two neurons connecting the CNS and the effector. Parasymphatetic neurons has a longer pre-ganglionic neuron, with the ganglion located nearer to the effector. Sympathetic neuron has a short pre-ganglionic neuron, with the ganglion sitting next to the spinal cord.
Describe the features of the parasympathetic ANS.
The parasympathetic ANS arise from the craniosacral outflow. The visceral efferent axons then go through the ventral roots to synapse with the post-synaptic ganglion in the ganglia near the effector.
Describe the features of the sympathetic autonomic NS.
The Sympathetic ANS arise from the thoracolumbar outflow of the spinal cord. Cell-bodies of the pre-ganglionic neuron lies in the lateral horn of the cord’s grey matter.
These neurons then collects into the symphathetic ganglion (part of the sympathetic trunk) where it synapses with the post-ganglionic neurons to continue onto the effectors.
The connection between the spinal nerves and the sympathetic trunk/ganglia is called the communicating rami (rami communicantes)
Mention the Cranial Nerves and its associative functions/purposes.
Cerebral Hemisphere
- I - Olfactory
- II - Optic
Midbrain
- III - Oculomotor: eye movement
- IV - Trochlear: eye movement
Pons
- V - Trigeminal: face
- VI - Abducens: eye movement
- VII - Facial: fascial muscle, taste, saliva production
- VIII - Vestibulocochlear: hearing and balance
Medulla
- IX - Glossopharyngeal: taste, innervate pharynx
- X - Vagus: parasympathetic to lungs, heart, gut
- XI - Accessory: muscle in the neck and trap
- XII - Hypoglossal: tongue movement
Describe the processing arrangement of the grey matter in the spinal cord.
Grey Matter:
- Dorsal/Posterior Horn: sensory processing
- Lateral Horn: autonomic processing
- Ventral/Anterior Horn: motor processing
