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Nerve fibers that form medial lemniscus include axons from?
Nucleus gracilis, nucleus cuneatus
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Second order neuron of dorsal column tract – medial lemniscus pathway lies in?
Tubercle gracilis, tubercle cuneatus
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Decussation of dorsal column tracts is called?
great sensory decussation / internal arcuate fibers
-
Dorsal column tracts decussate at the level of
upper medulla
-
Continuity of dorsal grey column of the spinal cord is interrupted in the medulla oblongata by
Internal arcuate fibers
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Pain and temperature are most closely associated with
Lateral spinothalamic tract
-
Crude touch (light touch) and pressure are closely associated with ---
ventral spinothalamic tract
-
Anterior spinothalamic tract carries sensations of crude touch (light touch) and pressure
lateral spinothalamic tract carries sensation of pain and temperature
-
Spinotectal tract connects the spinal grey matter to the
superior colliculus. It is a crossed tract.
-
carries impulses that regulate reflex movements of the head and eye in response to stimulation of some parts of the body.
spinotectal tract
-
Unconscious muscle joint sense is carried by
Anterior and posterior spinocerebellar tracts
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Deep touch and pressure, tactile localization, tactile discrimination, Stereognosis, sense of position, sense of vibration sensations are closely associated with
dorsal column column tracs, fasciculus gracilis, fasciculus cuneatus, medial lemniscus, internal arcuate fibers
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Stereognosis would be most closely associated with
Fasciculus cuneatus, fasciculus gracilis / dorsal column tracts / medial lemniscus, internal arcuate fibers, sensory decussation (decussation of medial lemniscus, lemniscal decussation)
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The medial lemniscus (and lateral and ventral spinothalamic tracts) runs upwards through the medulla, pons and midbrain to end in the
thalamus (ventral posterolateral nucleus).
-
First order sensory neurons for dorsal column tracts is
(central processes of) pseudounipolar neuron in dorsal root ganglion of spinal nerves
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Which of the following is most closely associated with nucleus dorsalis?
Muscle spindle and tendon organ; dorsal and ventral spinocerebellar tracts; cerebellum
-
Spinocerebelar tracts would most closely associated with
Nucleus dorsalis (Clarke’s column)
-
Spinal nucleus of trigeminal nerve would be most closely associated with
Substantia gelatinosa
-
Nerve fibers that form anterior spinocerebellar tract; dorsal spinocerebellar tract include axons from
Nucleus dorsalis / Clark’s column (2nd order neurons)
-
Continuity of anterior grey horns of the spinal cord is interrupted in the medulla oblongata by
Pyramidal decussation
-
Pyramidal decussation is at the level of
lower medulla
-
Rapid skilled voluntary movement is performed (controlled) by
Lateral corticospinal tract
-
The tract that is facilitatory to flexor muscles include
Corticospinal tract, rubrospinal tract
-
The tract that is facilitatory to extensor muscle include
Vestibulospinal tract
-
The tract that is inhibitory to flexor muscle include
Vestibulospinal tract
-
The tract that is inhibitory to extensor muscle include
Corticospinal tract
-
Most corticospinal neurons synapse with internuncial neurons, which in turn synapse with
alpha motor neurons and some gamma motor neurons
-
The corticospinal tract confers speed alertness to voluntary movements. Thus this helps in performing
rapid skilled movements. This tract is said to be facilitatory for flexors and inhibitory for extensors
-
Uncrossed pyramidal tract fibers descend
In the ventral funiculus of the spinal cord
-
Ventral part of the central grey matter of the midbrain at the level of superior colliculus is closely related to
Oculomotor nucleus, Parasympathetic Edinger Westphal nucleus
-
Ventral part of the central grey matter of the midbrain at the level of inferior colliculus is closely related to
Trochlear nucleus
-
Middle two-thirds of the crus cerebri in the midbrain is related to
Corticospinal fibers, corticobulbar fibers
-
Lateral one-sixth of the crus cerebri in the midbrain is related to
parieto-pontine, temporopontine and occipito-pontine fibers
-
Medial one-sixth of the crus cerebri in the midbrain is related to
fronto-pontine fibers
-
Red nucleus Is located in the tegmentum of the midbrain at the level of
superior colliculus
-
Rubrospinal tract is given off from
red nucleus
-
The decussatuion of the rubrospinal tract is called
ventral tegmental decussation
-
Pretectal nucleus is located
cranial and lateral to the superior colliculus
-
Third order sensory neurons located in the thalamus give off axons that pass to reach the somatosensory areas of the cerebral cortex through
Internal capsule and Corona radiata
-
Tectospinal tract arises from the
superior colliculus (midbrain).
-
The crossing fibers form the dorsal tegmental decussation at the level of
superior colliculus
- Vestibulospinal Tract originates from the lateral vestibular nucleus,
- uncrossed; This tract is an important efferent path for equilibrium
-
Labrynthine artery is a branch of
Basilar artery
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Which is most closely associated with sympathetic trunk?
Postganglionic sympathetic neuron; lateral horn neurons in the spinal cord at T 1 to L2
-
Which of the following is most closely associated with sympathetic trunk?
Postganglionic sympathetic neuron
-
Which of the following is most closely associated with nucleus dorsalis?
Muscle spindle and tendon organ
-
Spinocerebelar tract would most closely associated with
Nucleus dorsalis (Clarke’s column)
-
Spinal nucleus of trigeminal nerve would be most closely associated with
Substantia gelatinosa
-
Stereognosis would be most closely associated with
Fasciculus cuneatus
-
Which of the following contains preganglionic sympathetic neurons?
Thoracic spinal cord
-
The dorsal spinocerebellar tract is most closely associated with
inferior cerebellar peduncle , nucleus dorsalis, pseudounipolar neurons in Dorsal root ganglion
-
Sensory nucleus of trigeminal nerve is
the longest occupying almost the whole length of the brain stem
-
The superior cervical sympathetic ganglion supply
post ganglionic sympathetic fibers to the eye, all salivary glands and also heart.
-
If superior cervical sympathetic ganglion is damaged the normal functions of these organs will be interrupted
Proper eye movements, and eye functions, salivary secretion will be interrupted.
-
Autonomic N system has:
2-neuron path to target (pre- and postganglionic neurons)
-
Somatic N system has :
1-neuron path to target (lower motor neurons)
-
The parasympathetic part aims at conserving and storing energy, for example,
in the promotion of digestion
-
Parasympathetic: the absorption of food by
increasing the secretions of the glands of the gastrointestinal tract and stimulating peristalsis.
-
The sympathetic part of the system has a widespread action on the body as the result of the preganglionic fibers synapsing on many postganglionic neurons and the suprarenal medulla releasing the sympathetic transmitters epinephrine and norepinephrine, (Into the blood) which are distributed throughout the body through the
bloodstream
-
The visceral receptors include
chemoreceptors, baroreceptors, and osmoreceptors.
-
Pain receptors are not present in viscera, and certain types of stimuli, such as lack of oxygen or stretch,
can cause extreme pain.
-
the sympathetic nerves
dilate the pupils, inhibit smooth muscle of the bronchi, intestine, and bladder wall; and close the sphincters
-
Many of the preganglionic fibers entering the lower part of the sympathetic trunk from the lower thoracic and upper two lumbar segments of the spinal cord travel caudal to synapse in
ganglia in the lower lumbar and sacral regions.
-
the postganglionic nerve fibers pass via
gray rami communicantes to join the lumbar, sacral, and coccygeal spinal nerves.
-
Postganglionic nerve fibers may pass through
the ganglia of the sympathetic trunk without synapsing.
-
These myelinated fibers leave the sympathetic trunk as the
greater splanchnic, lesser splanchnic, and lowest or least splanchnic nerves.
-
The greater splanchnic nerve is formed from branches from the
fifth to the ninth (5 to 9) thoracic ganglia.
-
It descends obliquely on the sides of the bodies of the thoracic vertebrae and pierces the crus of the diaphragm to synapse with excitor cells in the
ganglia of the celiac plexus, the renal plexus, and the suprarenal medulla.
-
The lesser splanchnic nerve is formed from branches of the
tenth and eleventh (10 , 11) thoracic ganglia.
-
The lesser splanchnic nerve descends with the greater splanchnic nerve and pierces the diaphragm to join excitor cells in ganglia in the
lower part of the celiac plexus.
-
The lowest splanchnic nerve when present) arises from the twelfth (12) thoracic ganglion, pierces the diaphragm, and synapses with excitor neurons in the
ganglia of the renal plexus.
-
The splanchnic nerves, therefore, are formed of
preganglionic fibers.
-
The postganglionic fibers arise from the excitor cells in the peripheral plexuses and are distributed to the
smooth muscle and glands of the viscera.
-
These medullary cells of adrena medulla , which may be regarded as modified Sympathetic excitor neurons, are responsible for the secretion of
epinephrine and norepinephrine.
-
The afferent myelinated nerve fibers travel from the viscera through
the sympathetic ganglia without synapsing.
-
The afferent myelinated nerve fibers pass to the spinal nerve via
white rami communicantes
-
The afferent myelinated nerve fibers reach their cell bodies in the
posterior root ganglion of the corresponding spinal nerve.
-
The central axons enter the spinal cord and may form the afferent component of a local reflex arc or ascend to higher centers,
such as the hypothalamus.
-
Below, the two sympathetic trunks end by joining together to form a single ganglion,
the ganglion Impar.
-
The activities of the parasympathetic part of the autonomic system are directed toward
conserving and restoring energy.
-
The heart rate is slowed, pupils are constricted, peristalsis and glandular activity is increased, sphincters are opened, and the bladder wall is
contracted.
-
The connector nerve cells of the parasympathetic part of the autonomic nervous system are located in the brainstem and the sacral segments of the
spinal cord.
-
Those nerve cells located in the brainstem form nuclei in the following cranial nerves: oculomotor (parasympathetic or Edinger-Westphal nucleus),
facial (superior salivatory nucleus and lacrimatory nucleus), the glossopharyngeal (inferior salivatory nucleus), and the vagus nerves (dorsal nucleus of the vagus).
-
The axons of these connector nerve cells are myelinated and emerge from the brain within
the cranial nerves.
-
The sacral connector nerve cells are found in
the gray matter of the second (2), third (3), and fourth (4) sacral segments of the spinal cord.
-
These cells are not sufficiently numerous to form a lateral gray horn, as do the sympathetic connector neurons in
the thoracolumbar region.
-
The myelinated axons leave the spinal cord in the anterior nerve roots of
the corresponding spinal nerves.
-
They then leave the sacral nerves and form
the pelvic splanchnic nerves.
-
The myelinated efferent fibers of the craniosacral outflow are preganglionic and synapse in peripheral ganglia located close to
the viscera they innervate.
-
What is the neurotransmitter in peripheral ganglia?
acetylcholine
-
The cranial parasympathetic ganglia are the
clilary, pterygopalatine, submandibular, and otic.
-
In certain locations, the ganglion cells are placed in nerve plexuses, such as
the cardiac plexus, pulmonary plexus, myenteric plexus (Auerbach’s plexus, and mucosal plexus (Meissner’s plexus); the last two plexuses are associated with the gastrointestinal tract
-
The pelvic splanchnic nerves synapse in ganglia in
the hypogastric plexuses.
-
Sympathetic ganglia form part of
the sympathetic trunk or are prevertebral in position (e.g.. celiac and superior mesenteric ganglia).
-
Parasympathetic ganglia, on the other hand, are situated
close to or within the walls of the viscera.
-
The synaptic transmitter that excites the postganglionic neurons in both sympathetic and parasympathetic ganglia is
acetylcholine (ACh).
-
The action of acetylcholine in autonomic ganglia is quickly terminated by hydrolysis with
acetylcholinesterase.
-
The hypothalamus has a controlling influence on the autonomic nervous system and appears to integrate the autonomic and neuroendocrine systems, thus
preserving body homeostasis
-
Essentially, the hypothalamus should be regarded as a higher nervous center for the control of lower autonomic centers in
the brainstem and spinal cord
-
It should also be noted that the higher centers of the brain can abnormally influence the activities of the autonomic nervous system and induce disease such as
cardiac palpitations (arrhythmias) and even myocardial infarction
-
It has been shown that contractions of the smooth muscle in the gut wall can occur in the absence of the myenteric plexus, but the coordinated purposeful contractions, as seen with peristalsis and segmental movements, require the presence of a
nerve plexus, even though this may be isolated from the central nervous system.
-
The sympathetic part of the system has a widespread action on the body as the result of the preganglionic fibers synapsing on many postganglionic neurons and the suprarenal medulla releasing the sympathetic transmitters
epinephrine and norepinephrine, which are distributed throughout the body through the bloodstream.
-
The parasympathetic part of the autonomic system has a more discrete control, since the preganglionic fibers synapse on only a few postganglionic neurons and there is no comparable organ to the
suprarenal medulla
-
The sympathetic postganglionic endings liberate norepinephrine at most endings and acetylcholine at a few endings (e.g., sweat glands). The parasympathetic postganglionic endings liberate
acetylcholine.
-
The sympathetic part of the autonomic system prepares the body for emergencies and severe muscular activity, whereas the parasympathetic part
conserves and stores energy.
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