Major sensory and motor pathways within the central nervous system in relation to nervous connections of the pelvic organs Flashcards
T/F: ‘nerve sparing’ surgical procedure preserveS the normal functions of pelvic organs
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6 treatment options for chronic pelvic pain which include:
- sympathectomy
- nerve blocks
- neurolysis
- presacral neurectomy
- laparoscopic uterine nerve ablation (LUNA)
- pelvic neuromodulation
Sensory impulses ascend through the spinal cord to the brain via –
the sensory pathways
Motor impulses from the brain and spinal cord descend to the pelvic viscera via
Motor pathways
The pelvic sympathetic system derives from what column and region of the spinal cord
Intermediolateral grey column of the thoracolumbar region of the spinal cord
The presynaptic sympathetic fibres synapse in two ways:
Paravertebral sympathetic trunks
Prevertebral autonomic plexuses
Post-synaptic fibres from the sympathetic trunk run with –, – and –
somatic nerves, vessels or enter autonomic plexuses
The lumbar and sacral part of the sympathetic trunks are responsible for the innervation of
the pelvic and lower limb structures
Series of nerve plexuses and ganglia located anterior to the vertebra are known as
Prevertebral autonomic plexuses
The prevertebral autonomic plexuses include –, – and –
- Inferior hypogastric plexus (IHP)
- Hypogastric nerve (HN)
- Superior hypogastric plexus (SHP)
The prevertebral autonomic plexuses receive sympathetic fibres in 2 ways – and –
presynaptic fibres from the sympathetic trunks
post synaptic fibres from the trunks
T/F: The sympathetic nervous system relaxes the internal urethral sphincter
F. Constricts
T/F: The sympathetic nervous system constricts the internal anal sphincter
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The sympathetic system mediates proprioception and pain from the upper pelvis via – and – to the sympathetic trunk
Hypogastric nerve and superior hypogastric plexus
Parasympathetic supply of the pelvis comes from – and –
Primarily from the pelvic splanchnic nerves (PSN), but with some contribution from the Vagus nerve
the sacral component of the parasympathetic system is constituted by –
Pelvic splanchnic nerves
PSN fibers arise from
the sacral spinal nerves S2–S4
Fibres from the pelvic splanchnic nerves pass to the —- plexus without synapsing
inferior hypogastric plexus
T/F: Fibres from the pelvic splanchnic nerves pass to the inferior hypogastric plexus (IHP) without synapsing
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T/F: Fibres from the pelvic splanchnic nerves pass to the inferior hypogastric plexus without synapsing and pass from there to synapse at ganglia close to the target organs
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T/F: The bladder muscles contract under the influence of the parasympathetic system
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T/F: The sympathetic system has some proerectile function
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T/F: contraction of smooth muscle of the rectum is mediated by the parasympathetic system
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T/F: The sensation of the bladder and rectum is carried by the sympathetic system
F. Parasympathetic
Pain impulses from the vagina, cervix and bladder is carried by which arm of the autonomic nervous system
Parasympathetic
The parasympathetic system carries pain impulses from the –, – and –
Vagina, cervix and bladder
Where is the pelvic pain line for the genitourinary viscera
corresponds to the inferior limit of the peritoneum
Where is the pelvic pain line for the large intestine
middle of the sigmoid colon
Which arm of the autonomic system conducts pain impulses from abdominopelvic viscera above the pelvic pain line
Sympathetic
Which arm of the autonomic system conducts pain impulses from abdominopelvic viscera below the pelvic pain line
Parasympathetic
The somatic nerve system of the pelvis is supplied by the – plexus
Lumbosacral plexus
The chief nerve from the lumbosacral plexus is
the pudendal nerve (S2-S4)
The chief nerve from the lumbosacral plexus is
the pudendal nerve (S2-S4)
T/F: All somatic nerves are accompanied by postsynaptic parasympathetic fibers
F. All somatic nerves are accompanied by postsynaptic sympathetic fibers to supply the smooth muscles of the blood vessels, sweat glands, apocrine glands, arrector pili muscle of hair follicle of the skin, and also the bone marrow
T/F: During sexual activity the somatic system stimulates the pelvic floor muscles (ischiocavernosus, bulbospongiosus, superficial and deep transverse perineal muscles, external anal sphincter, and the pelvic diaphragm) to maintain rigidity
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T/F: Rhythmic contractions of the bulbospongiosus cause semen to release into the spongy urethra causing ejaculation
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T/F: Sensory or ascending pathways
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T/F: Only the afferent impulses that reach the cerebral cortex are consciously perceived
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T/F: Afferent impulses ending in the cerebellum or in the brainstem are consciously perceived
F.
Afferent impulses ending in the cerebellum or in the brainstem influence the activities of cerebellum and brainstem respectively
The 3 tracts in the sensory pathways of the CNS are
Spinoreticular Tracts
Spino-olivary tract
Spinomesencephalic tracts
The 3 pathways in the sensory pathways of the CNS are
- The Posterior Column −Medial Lemniscus Pathway
- Spinothalamic Pathways
- Spino-cervico-thalamic pathway
The posterior column-medial lemniscus pathway carries –, – and –
1.Some components of the sense of touch
2. Proprioceptive impulses
3. The sense of vibration
The 4 components of the sense of touch carried by the posterior column-medial lemniscus pathway are
*deep touch and pressure
*tactile localisation
*tactile discrimination
*stereognosis
The first order neuron of the posterior column pathway lies where
in the dorsal root ganglion (DRG)
The tracts in the posterior column occupy and run up in what part of the spinal cord
in the posterior funiculus of the spinal cord
Which fibres of the posterior column are situated most medially
The fibres derived from the lowest ganglia
Which fibres of the posterior column are situated most laterally
Fibres derived from the highest ganglia
The fibres of the posterior column ascend upwards to the – and synapse in the – and – nuclei
Medulla
Gracile and cuneate nuclei
The second order of neurons of the posterior column are
the neurons of the gracile and cuneate nuclei of the medulla
The axons of the second order neurons of the posterior column run forwards and medially decussating in the midline to form –
The medial lemniscus
The medial lemniscus runs upwards through the medulla, pons and midbrain to end in the –
Thalamus (ventral posterolateral nucleus)
The medial lemniscus ends in which nuclei of the thalamus
ventral posterolateral nucleus
The third order neurons of the posterior column are located in –
Thalamus
The axons of the third order neurons of the posterior column run from the thalamus through the – and – to reach the somatosensory areas of the cerebral cortex
Internal capsule and corona radiata
Spinothalamic tract carries sensations of –, –, – and –
crude touch, pressure, pain and temperature
The first order neurons of the spinothalamic tract is
the central process of the dorsal root ganglion
The central processes of the first order neurons of the spinothalamic tract enter the spinal cord and synapse in the – column of the spinal cord
Dorsal column
The second order neurons of the spinothalamic tract are located in the
dorsal grey column
T/F: The axons of the second order neurons of the spinothalamic tract cross to the opposite side of the spinal cord in the white matter
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What are the anterior spinothalamic tracts
Fibres of the second order neurons of the spinothalamic tract that run in the anterior funiculus of the white matter
What are the lateral spinothalamic tracts
Fibres of the second order neurons of the spinothalamic tract that run in the lateral funiculus of the white matter
T/F: The anterior and lateral spinothalamic tract form one continuous band that runs up the spinal cord
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Where does the band of the anterior and lateral spinothalamic tracts separate
Medulla
From the medulla the anterior spinothalamic tract joins the –and travels through it to the thalamus
Medial lemniscus
To which nucleus in the thalamus does the anterior spinothalamic tract run
The ventral posterolateral nuclei
The lateral spinothalamic tract runs through the brainstem as a separate bundle called — which also ends in the thalamus
the spinal lemniscus
The third order of neuron of the spinothalamic tract arise from –
The thalamus
Passing through the – and – , the third order neurons of the spinothalamic tract project to the — of the cerebral cortex
posterior limb of the internal capsule and the corona radiata
post central gyrus
T/F: Motor pathways/tracts convey motor impulses (command) from the higher centers to the brainstem and the spinal cord, for onward relay to the peripheral structures
T
The 8 motor pathways of the CNS
- Corticonuclear tracts
- Cortico-ponto-cerebellar
pathway - corticospinal tract
- Rubrospinal tract
- Tectospinal tract
- Vestibulospinal tracts
- Reticulospinal tracts
- Hypothalamospinal fibres
Tracts of the motor pathway that terminate in the brainstem are – and –
Corticonuclear tracts and Cortico-ponto-cerebellar pathway
The 6 tracts of the motor pathway that terminate in the spinal cord:
corticospinal tract
Rubrospinal tract
Tectospinal tract
Vestibulospinal tracts
Reticulospinal tracts
Hypothalamospinal fibres
T/F: All the tracts of the motor pathway are collectively referred to as extrapyramidal tracts
F.
except corticospinal tract
The corticospinal tract is also known as
The pyramidal tract
The corticospinal tract is composed of axons lying in these 4 areas
It is made of axons of neurons lying mainly in the motor area of the cerebral cortex (area 4), but also with minor contributions from the premotor area (area 6), the somatosensory area (areas 3, 2, 1) and the parietal cortex (area 5)
Area 4 or
Motor area
Area 6 or
Premotor area
Somatosensory area
Areas 3, 2 and 1
Area 5 or
Parietal cortex
Fibres of the pyramidal tract pass through the – to enter the – limb of internal capsule
corona radiata
posterior limb
The fibres of the pyramidal tract pass through the – (of the midbrain), through the ventral part of the pons to enter the pyramids in the upper part of the medulla (thus the name pyramidal track)
crus cerebri
% of pyramidal tract fibres that decussate at the lower part of the medulla
80%
% of the pyramidal tract fibres that do not decussate
20%
The decussating fibres of the corticospinal tract enter the lateral funiculus of the spinal cord and descend as the —
lateral corticospinal tract
The lateral corticospinal tract terminate in the — at various levels of the spinal cord either directly or through —
anterior horn cells
internuncial neurons
The non decussating fibres of the corticospinal tract enter the anterior funiculus of the spinal cord to form —
the anterior corticospinal tract
On reaching the appropriate level of the spinal cord the anterior corticospinal fibres cross the midline through —- to terminate in a similar way with that of the lateral corticospinal tract
the anterior white commissure
Voluntary control of movement of the skeletal muscles is conveyed by the — tract
Corticospinal tract
T/F: Both the anterior and lateral corticospinal tracts extend to the lowest segments of the spinal cord
F.
The lateral corticospinal tract extends to the lowest segments of the spinal cord, but the anterior tract extends only to the midthoracic level
The part of the corticospinal tract that extend to the lowest segment of the spinal cord
Lateral corticospinal tract
The part of the corticospinal tract that extends only to the midthoracic level
Anterior corticospinal tract
T/F: The longest fibres of the corticospinal tract lie most superficially within the tract
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T/F: the shortest fibres of the corticospinal lie most medially within the tract
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T/F: Fibres of the corticospinal tracts are arranged somatotropically
T.
(ie the fibres for control of muscles in different parts of the body are arranged in a definite sequence)
The descending autonomic tracts are also known as
Hypothalamospinal tract
The hypothalamospinal tract begin in the
Mainly in the paraventricular nucleus of the hypothalamus
locus coeruleus and
some contribution from the medulla
T/F: The hypothalamospinal tract descend uncrossed in the dorsolateral funiculus
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The axons of the hypothalamospinal tract end in relation to sympathetic and parasympathetic preganglionic neurons located in the
intermediolateral grey column of the spinal grey matter, and in some other diverse areas of the spinal grey matter
