Organisation Of The Nervous System Flashcards
What are the basic divisions of the nervous system?
CNS (Central Nervous System): Brain and spinal cord.
• PNS (Peripheral Nervous System): Motor and sensory neurons.
What are the sub-divisions of the autonomic nervous system?
Parasympathetic: Rest and digest (e.g., constricts airways, slows heartbeat).
• Sympathetic: Fight or flight (e.g., dilates pupils, increases heartbeat).
What are the differences between motor and sensory fibers?
Motor fibers (GVEs): General visceral efferents.
• Sensory fibers (GVAs): General visceral afferents.
What are the anatomical terms for direction?
Dorsal (posterior): Top end.
• Ventral: Belly end.
• Anterior (rostral): Head.
• Posterior (caudal): Feet.
What are the three planes used in brain imaging?
Coronal: Cuts facing the front.
• Sagittal: Cuts from the front, midline.
• Horizontal: Flat sideways cut.
What are the functions of the different brain lobes?
Temporal lobe: Memory, language.
• Occipital lobe: Vision.
• Parietal lobe: Sensory processing, arithmetic, spelling.
• Frontal lobe: Executive functions, emotion, behavior, personality, planning, thinking.
How is the spinal cord organized?
• The spinal cord is housed in the vertebral canal.
• 31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal).
• The spinal cord is shorter than the vertebral column (ends between L1/2).
• The first spinal nerve emerges between the skull and the first cranial vertebra
What is the difference between grey and white matter in the spinal cord?
• Grey matter: Neuronal cell bodies.
• White matter: Myelinated axons
What is the surface anatomy of the cerebrum?
Gyri: Ridges on the brain surface.
• Sulci: Shallow grooves.
• Fissures: Deep grooves.
What are the regions of the brain?
Forebrain: Cerebrum, hypothalamus.
• Midbrain: Top bit just over hindbrain.
• Hindbrain: Pons, cerebellum, medulla oblongata.
• Brainstem: Midbrain + Pons + Medulla oblongata.
Why is the risk of injury lower when performing a lumbar puncture at L3/4?
L3/4 lumbar puncture: The spinal cord ends between L1/2, so a puncture at L3/4 avoids the spinal cord and the risk of injury is reduced.
What is the cauda equina?
Cauda equina: A bundle of spinal nerves and nerve rootlets at the end of the spinal cord, resembling a horse’s tail.
What is the composition of spinal nerves?
Spinal nerves are mixed: They contain both motor and sensory fibers.
Describe the pathway of a sensory signal through the spinal cord.
Sensory signal pathway:
- Sensory neuron.
- Dorsal root.
- Interneuron.
- Motor neuron.
- Muscle (response).
How do spinal nerves connect to the spinal cord?
• Spinal nerves: Enter and exit the spinal cord as a collection of nerve rootlets.
• Spinal cord segmentation: The spinal cord is segmented, and nerves are associated with these segments.
What is the function of the filum terminale?
Filum terminale: A structure that anchors the spinal cord to the coccyx, preventing movement.
What is the structure and function of the ventricular system in the brain and spinal cord?
Ventricular system: Includes four ventricles and the central canal.
• Function: Filled with cerebrospinal fluid (CSF), which cushions and nourishes the brain and spinal cord.
What is the pathway of cerebrospinal fluid (CSF) in the brain and spinal cord?
Central canal: CSF flows down through the central canal of the spinal cord.
• Interventricular foramen: CSF flows into the cerebral aqueduct.
What is the role of the choroid plexus in CSF production?
Choroid plexus: Muscle-like tissue in all ventricles that produces CSF.
• Production: CSF is continuously produced by the choroid plexus epithelium (ependymal cells), which is highly vascularized.
What are the main functions of cerebrospinal fluid (CSF)?
Buoyancy (supports the brain).
- Protection (cushions the brain and spinal cord).
- Removal of waste products.
- Provides growth and signaling factors.
What is hydrocephalus and how does it occur?
Hydrocephalus: Condition where the CSF pathway is blocked, preventing its reabsorption into the venous bloodstream.
• Result: Fluid builds up, causing expansion of the head.
Where is CSF released into after production?
Subarachnoid space: CSF is released into the space between the first and second meninges (the subarachnoid space).
What are the three layers of meninges surrounding the CNS?
mater (inner layer):
• Protects the CNS.
• Allows blood vessels to enter the CNS.
• Impermeable to contain CSF.
- Arachnoid mater:
• Cobweb-like membrane forming the upper limits of the subarachnoid space.
• Protects the CNS and is associated with the dura mater.
- Dura mater (outer layer):
• Toughest layer protecting the brain and spinal cord.
• In the skull, it forms a double layer that separates to create sinuses carrying venous blood.
• Firmly attached to the brain but loosely attached to the spinal cord.
What is the difference between CNS and PNS neurons?
CNS neuron: Entirely within the brain or spinal cord.
• PNS neuron: Projects outside the CNS.
Flow of CSF direction
Choroid plexus epithelium
Ventricles
Foramina
Sub-arachnoid space
Arachnoid granulations
Superior sagittal sinus