21 & 22 Overview of the organization of the nervous system Flashcards
Which of the following about PNS is incorrect?
A. It has 2 groups of peripheral nerve: 12 pairs of cranial nerves and 31 pairs of spinal nerves
B. Optic nerve is included
C. it includes the sensory and autonomic ganglia
B: Optic nerve is an extension from the CNS due to its embryological origin
Dorsal horn harbours neurons processing incoming sensory signals while ventral horn harbours motor neurons for controlling skeletal muscles.
How about the lateral horn?
At what locations the lateral horn is present?
Preganglionic sympathetic neurons;
only present in thoracic and upper lumbar segment of spinal cord
What is a communicating rami?
Communicating rami is between spinal nerve and sympathetic ganglion, which allows sympathetic nerves to exit the route to join the sympathetic ganglion of the sympathetic trunk, giving postganglionic fibers
What kinds of sensory receptors are for pain and temperature?
- free nerve endings
2. thinly myelinated/ unmyelinated axons
What kinds of sensory receptors are for
- touch sensation
- vibration sensation ?
Encapsulated (thick) nerve endings
- Meissner’s corpuscle
- Pacinian corpuscle
Give example of sensory receptor that detects proprioception, and therefore control muscle tone and joints movement.
Muscle spindle - located parallel to skeletal fibers (detect tensional signals and inform CNS)
Give the 3 types of receptors for special sense associated with the head.
- Taste buds of tongue
- Hair cells in inner ear (hearing and equilibrium)
- Olfactory epithelium in nasal cavity (smell)
What is myasthenia gravis?
Autoimmune disease with antibodies against acetylcholine receptors
Sympathetic system:
- ____________ is the NT in preganglionic fibers
- ___________ is the NT in postganglionic fibers
Acetylcholine;
Noradrenaline
Parasympathetic system:
- ____________ is the NT in preganglionic fibers
- ___________ is the NT in postganglionic fibers
Acetylcholine;
acetylcholine
Where are the preganglionic neurons and postganglionic neurons located in sympathetic nervous system?
- Preganglionic neurons: in T1 to L2/3 segments of spinal cord (lateral horn)
- Postganglionic neurons:
1. sympathetic ganglia forming a chain (sympathetic trunk)
2. Dispersed cell clusters around abdominal aorta (prevertebral ganglia)
State all the routes of sympathetic pathways to trunk and limbs.
- Preganglionic neurons project to postganglionic neurons in sympathetic trunk, via white communicating ramus, postganglionic fibers then join spinal nerve via gray ramus > skin and limbs
- Preganglionic neurons project to postganglionic neurons in sympathetic trunk (paravertebral ganglion) via white communicating ramus, then via sympathetic nerves (e.g. cardiac nerves) to internal organs
- Preganglionic neurons project to prevertebral ganglion via thoracic and lumbar splanchnic nerves (to gut)
Where are the preganglionic fibers located in parasympathetic system?
- Brainstem
2. Sacral segments (S2-4) of spinal cord
Give the routes of the parasympathetic pathways.
- Preganglionic fibers of the brainstem project to postganglionic ganglia of the head region via CN3,7, 11
- Preganglionic fibers of cranial nerve X innervate postganglionic neurons close to thoracic and abdominal viscera
- Sacral preganglionic fibers project to dispersed cell clusters (postganglionic neurons adjacent to various pelvic viscera)
Vagus nerve contains sensory fibers to monitor activities of the viscera: relayed to _______________________ (nucleus in medulla).
Nucleus of solitary tract
Brainstem = medulla + pons + midbrain; Diencephalon = ?
thalamus + hypothalamus
Give the names of the fiber tracts that can be seen in the mid-sagittal plane.
- corpus callosum
2. fornix
What are the functions of the superior colliculus and inferior colliculus respectively?
Superior colliculus: Visual function;
Inferior colliculus: Auditory function
What fibers does cerebral peduncle contain?
Contains fibers running to and from the cerebrum, white matter of midbrain
Most cranial nerves are associated with the brainstem except?
Instead, what structures are they related to?
- CN1 from nasal mucosa
- CN2 from diencephalon
- CN 11 associated with the spinal cord although it later goes up to the brainstem and exit via the jugular foramen
Major functions of the brainstem:
A. Extensive connections with the cerebellum
B. Contains motor neurons for controlling muscles in head and neck
C. Pons contains regulatory centers for respiratory and cardiovascular system
D. Substantia nigra in midbrain connects with other basal ganglia neurons in cerebral hemisphere, degeneration causes Parkinson’s disease
E. Pain modulatory centers
All except C
Should be medulla
____________ in the diencephalon is a relay station for processing sensory information before being distributed to the cerebral cortex. It contains nuclei that regulate motor activities together with ____________ and _____________.
Thalamus;
Basal ganglia and cerebellum
Which part of the diencephalon is a central station for regulating body activities to as to achieve homeostasis?
Hypothalamus
Which of the following about the diencephalon is correct?
A. Hypothalamus links with the pituitary gland
B. Hypothalamus is a major component of the limbic system
C. Hypothalamus controls ANS
D. Epithalamus contains the limbic structures only
E. Epithalamus secretes melatonin (regulate day-night)
All except D
Epithalamus: Pineal gland and some limbic structures
