The spinal cord extends from the brainstem down the back and is protected by the vertebrae. It has gray matter in an H-shape surrounded by white matter. The spinal cord conducts sensory signals to the brain and motor signals from the brain. It also mediates spinal reflexes through circuits in the gray matter without brain involvement. These reflexes provide quick responses to stimuli for protective functions. The internal organization allows sensory input to travel to the brain or mediate reflexes, and motor output from the brain or spinal cord to control muscles and organs.
BRAINSTEM
The Brainstem lies at the base of the brain and the top of the spinal cord.
The brainstem is located in the posterior cranial fossa.
The brainstem is the structure that connects the cerebrum of the brain to the spinal cord and cerebellum.
Provides a pathway for tracts running between higher and lower neural centers.
Divided into 3 major divisions:
midbrain,
pons, and
medulla oblongata.
It is responsible for many vital functions of life, such as breathing, consciousness, blood pressure, heart rate, and sleep.
It contains many critical collections of white and grey matter.
The grey matter within the brainstem consists of nerve cell bodies and form many important brainstem nuclei. Ten of the twelve cranial nerves arise from their cranial nerve nuclei in the brainstem.
The white matter tracts of the brainstem include axons of nerves traversing their course to different structures. These tracts travel both to the brain (afferent) and from the brain (efferent) such as the somatosensory pathways and the corticospinal tracts, respectively.
Mid Brain
The midbrain is continuous with the cerebral hemisphere.
The upper posterior (i.e. rear) portion of the midbrain is called the tectum, which means "roof."
The surface of the tectum is covered with four bumps representing two paired structures: the superior and inferior colliculi.
The superior colliculi are involved in eye movements and visual processing, while the inferior colliculi are involved in auditory processing.
Another important nucleus, the substantia nigra, is located here.
The substantia nigra is rich in dopamine neurons and is considered part of the basal ganglia.
Pons
An important pathway for tracts that run from the cerebrum down to the medulla and spinal cord, as well as for tracts that travel up into the brain.
It also forms important connections with the cerebellum via fibre bundles known as the cerebellar peduncles.
Posteriorly, the pons and medulla are separated from the cerebellum by the fourth ventricle.
Home to several nuclei for cranial nerves.
Medulla
The point where the brainstem connects to the spinal cord.
Contains a nucleus called the nucleus of the solitary tract that is crucial for our survival (receives information about blood flow, along with information about levels of oxygen and carbon dioxide in the blood, from the heart and major blood vessels).
When this information suggests a discordance with bodily needs (e.g. blood pressure is too low), there are reflexive actions initiated in the nucleus of the solitary tract to bring things back to within the desired range.
Blood Supply
The brain stem receives its blood supply exclusively from the posterior circulation, including the vertebrae and basilar artery.
The medulla receives its blood supply from the vertebral via medial and lateral perforating arteries.
The pons and midbrain receive their blood from the basilar via the medial and lateral perforating arteries.
CERVICAL PART OF SYMPATHETIC TRUNK
https://www.slideshare.net/DRCAPRICORN/slideshelf
VESSICO-BULLOUS DISORDER LECTURE : https://youtu.be/lgizglcWJ9I
HOOVER SIGN for leg paresis/ copd=
https://youtu.be/v-rT80AksZw
BEEVOR SIGN = https://youtu.be/QTBqQ31KqUA
ALL PERIPHERAL SIGN'S OF AORTIC REGURGITATION=
https://youtu.be/JZBQGsmK4dY
SUBSCRIBE US ON YOUTUBE : www.youtube.com/c/DrCapricorn
1.Anatomy of the Medulla
2. Introduction to Brainstem Anatomy of the brainstem includes ( midbrain-pons-medulla ) is very complicated !! •It connects spinal cord to the cerebrum. • The mid brain pons, and medulla are connected to cerebellum posteriorly. •1 - ascending an descending tracts that connect brain to spinal cord. •2 - cranial nerves nuclei and their connections •3 - Reticular formation •4 - others e.g (olivarynucleus in MO tapizusbody in pons and red nucleus in MB )
3. Medulla oblongata •The medulla oblongata is the part of the brainstem between the pons and spinal cord •It extends through the foramen magnum to the level of the atlas. •Medulla is vital for our function, without medulla we die. •Above the foramen magnum it is embraced dorsally by the cerebellar hemispheres. 1.The lower end which contains the upward continuation of the central canal of the spinal cord is the ‘closed part of the medulla’, 2.The upper end, where the canal comes to the surface as the lower part of the floor of the fourth ventricle, is the ‘open part’.
4. Medulla contd….. MO is lowest 3 cm of the brainstem •it extend from the ponto- medullary junction until plane below foramina magnum for about 0.5 cm. •Medulla spinalis have a central canal which prolonged into its lower half to open in the fourth ventricle at its upper half. •CSF is encircle the MO from outside ( subarachnoid space ) and inside ( central canal ). •MO is between the two lobes of cerebellum ( anterior cerebellar notch )
5. EXTERNAL FEATURES AND RELATIONS • 3Cm long. • Located at the caudal portion of brainstem • Upper limit is cerebello-pontine angle • Transverse plane that above C1 (suboccipital) intersects upper border of atlas dorsally and centre of dens ventrally marks lower limit
6. VENTRAL SURFACE • Ventral median fissure extends from foramen coecum to caudal end of pyramid decussation • Lateral to median fissure is pyramid • Lat to pyramid is the ventrolateral sulcus (VLS) • Hypoglossal nerve rootlets emerge from VLS • Lat to VLS is olive which contains inf olivary nucleus • Inferior cerebellar peduncle connects medulla with cerebellum and forms side wall of caudal half of fourth ventricle
7. Ventral Surface Pyramid: Swelling on each side of anterior median fissure. • Composed of bundles of nerve fibers, (corticospinal fibers) originate from the precentral gyrus of the cerebral cortex. • The pyramids taper inferiorly and majority of the descending fibers decussate to the opposite side. Olive: • Olives are the anterolateral oval elevations produced by the underlying inferior olivary nuclei. • From the groove between the pyramid and the olive, the rootlets of the hypoglossal nerve emerge
8. LATERAL ASPECT • Roots of glossopharyngeal , vagus and cranial division of accessory nerves are attached to the medulla dorsal to olive.
9. Dorsal surface At dorsal surface of closed part of medulla, gracile and cuneate fasciculi continue from the spinal
BRAINSTEM
The Brainstem lies at the base of the brain and the top of the spinal cord.
The brainstem is located in the posterior cranial fossa.
The brainstem is the structure that connects the cerebrum of the brain to the spinal cord and cerebellum.
Provides a pathway for tracts running between higher and lower neural centers.
Divided into 3 major divisions:
midbrain,
pons, and
medulla oblongata.
It is responsible for many vital functions of life, such as breathing, consciousness, blood pressure, heart rate, and sleep.
It contains many critical collections of white and grey matter.
The grey matter within the brainstem consists of nerve cell bodies and form many important brainstem nuclei. Ten of the twelve cranial nerves arise from their cranial nerve nuclei in the brainstem.
The white matter tracts of the brainstem include axons of nerves traversing their course to different structures. These tracts travel both to the brain (afferent) and from the brain (efferent) such as the somatosensory pathways and the corticospinal tracts, respectively.
Mid Brain
The midbrain is continuous with the cerebral hemisphere.
The upper posterior (i.e. rear) portion of the midbrain is called the tectum, which means "roof."
The surface of the tectum is covered with four bumps representing two paired structures: the superior and inferior colliculi.
The superior colliculi are involved in eye movements and visual processing, while the inferior colliculi are involved in auditory processing.
Another important nucleus, the substantia nigra, is located here.
The substantia nigra is rich in dopamine neurons and is considered part of the basal ganglia.
Pons
An important pathway for tracts that run from the cerebrum down to the medulla and spinal cord, as well as for tracts that travel up into the brain.
It also forms important connections with the cerebellum via fibre bundles known as the cerebellar peduncles.
Posteriorly, the pons and medulla are separated from the cerebellum by the fourth ventricle.
Home to several nuclei for cranial nerves.
Medulla
The point where the brainstem connects to the spinal cord.
Contains a nucleus called the nucleus of the solitary tract that is crucial for our survival (receives information about blood flow, along with information about levels of oxygen and carbon dioxide in the blood, from the heart and major blood vessels).
When this information suggests a discordance with bodily needs (e.g. blood pressure is too low), there are reflexive actions initiated in the nucleus of the solitary tract to bring things back to within the desired range.
Blood Supply
The brain stem receives its blood supply exclusively from the posterior circulation, including the vertebrae and basilar artery.
The medulla receives its blood supply from the vertebral via medial and lateral perforating arteries.
The pons and midbrain receive their blood from the basilar via the medial and lateral perforating arteries.
CERVICAL PART OF SYMPATHETIC TRUNK
https://www.slideshare.net/DRCAPRICORN/slideshelf
VESSICO-BULLOUS DISORDER LECTURE : https://youtu.be/lgizglcWJ9I
HOOVER SIGN for leg paresis/ copd=
https://youtu.be/v-rT80AksZw
BEEVOR SIGN = https://youtu.be/QTBqQ31KqUA
ALL PERIPHERAL SIGN'S OF AORTIC REGURGITATION=
https://youtu.be/JZBQGsmK4dY
SUBSCRIBE US ON YOUTUBE : www.youtube.com/c/DrCapricorn
1.Anatomy of the Medulla
2. Introduction to Brainstem Anatomy of the brainstem includes ( midbrain-pons-medulla ) is very complicated !! •It connects spinal cord to the cerebrum. • The mid brain pons, and medulla are connected to cerebellum posteriorly. •1 - ascending an descending tracts that connect brain to spinal cord. •2 - cranial nerves nuclei and their connections •3 - Reticular formation •4 - others e.g (olivarynucleus in MO tapizusbody in pons and red nucleus in MB )
3. Medulla oblongata •The medulla oblongata is the part of the brainstem between the pons and spinal cord •It extends through the foramen magnum to the level of the atlas. •Medulla is vital for our function, without medulla we die. •Above the foramen magnum it is embraced dorsally by the cerebellar hemispheres. 1.The lower end which contains the upward continuation of the central canal of the spinal cord is the ‘closed part of the medulla’, 2.The upper end, where the canal comes to the surface as the lower part of the floor of the fourth ventricle, is the ‘open part’.
4. Medulla contd….. MO is lowest 3 cm of the brainstem •it extend from the ponto- medullary junction until plane below foramina magnum for about 0.5 cm. •Medulla spinalis have a central canal which prolonged into its lower half to open in the fourth ventricle at its upper half. •CSF is encircle the MO from outside ( subarachnoid space ) and inside ( central canal ). •MO is between the two lobes of cerebellum ( anterior cerebellar notch )
5. EXTERNAL FEATURES AND RELATIONS • 3Cm long. • Located at the caudal portion of brainstem • Upper limit is cerebello-pontine angle • Transverse plane that above C1 (suboccipital) intersects upper border of atlas dorsally and centre of dens ventrally marks lower limit
6. VENTRAL SURFACE • Ventral median fissure extends from foramen coecum to caudal end of pyramid decussation • Lateral to median fissure is pyramid • Lat to pyramid is the ventrolateral sulcus (VLS) • Hypoglossal nerve rootlets emerge from VLS • Lat to VLS is olive which contains inf olivary nucleus • Inferior cerebellar peduncle connects medulla with cerebellum and forms side wall of caudal half of fourth ventricle
7. Ventral Surface Pyramid: Swelling on each side of anterior median fissure. • Composed of bundles of nerve fibers, (corticospinal fibers) originate from the precentral gyrus of the cerebral cortex. • The pyramids taper inferiorly and majority of the descending fibers decussate to the opposite side. Olive: • Olives are the anterolateral oval elevations produced by the underlying inferior olivary nuclei. • From the groove between the pyramid and the olive, the rootlets of the hypoglossal nerve emerge
8. LATERAL ASPECT • Roots of glossopharyngeal , vagus and cranial division of accessory nerves are attached to the medulla dorsal to olive.
9. Dorsal surface At dorsal surface of closed part of medulla, gracile and cuneate fasciculi continue from the spinal
Functions and ascending tract of spinal cordFatima Mangrio
As the name suggests, the ascending tracts of the spinal cord ascend from the spinal cord and connect it to the brain. These tracts are named based on their origin and termination. They are found running along the dorsal, lateral, and ventral columns of the white matter.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
2. Introduction
The spinal cord and spinal nerves contribute to homeostasis
by providing quick, reflexive responses to many stimuli.
The spinal cord is the pathway for sensory input to the brain
and motor output from the brain.
4. External
Anatomy of
SpinalCord
The spinal cord, although roughly cylindrical, is flattened
slightly anteriorly and posteriorly.
In adults, it extends from the medulla oblongata, the
inferior part of the brain, to the superior border of the
second lumbar vertebra.
In newborn infants, it extends to the third or fourth lumbar
vertebra.
During early childhood, both the spinal cord and the
vertebral column grow longer as part of overall body
growth.
5. Contd……….
Elongation of the spinal cord stops around age 4 or 5, but
growth of the vertebral column continues. Thus, the spinal
cord does not extend the entire length of the adult vertebral
column.
Thus, the spinal cord does not extend the entire length of the
adult vertebral column.The length of the adult spinal cord
ranges from 42 to 45 cm (16–18 in.).
Its diameter is about 2 cm (0.75 in.) in the mid thoracic region,
somewhat larger in the lower cervical and mid lumbar
regions, and smallest at the inferior tip.
6. When the spinal cord is viewed externally, two conspicuous
enlargements can be seen. The superior enlargement, the
cervical enlargement, extends from the fourth cervical
vertebra to the first thoracic vertebra.
Nerves to and from the upper limbs arise from the cervical
enlargement. The inferior enlargement, called the lumbar
enlargement, extends from the ninth to the twelfth
thoracic vertebra.
Nerves to and from the lower limbs arise from the lumbar
enlargement.
7. Inferior to the lumbar enlargement, the spinal cord
terminates as a tapering, conical structure called the conus
medullaris, which ends at the level of the intervertebral disc
between the first and second lumbar vertebrae in adults.
Arising from the conus medullaris is the filum terminale, an
extension of the pia mater that extends inferiorly and blends
with the arachnoid mater and dura mater and anchors the
spinal cord to the coccyx.
9. Internal
Anatomy of
theSpinal
Cord
A freshly dissected section of the spinal cord reveals regions
of white matter that surround an inner core of gray matter.
The white matter of the spinal cord consists primarily of
bundles of myelinated axons of neurons.
Two grooves penetrate the white matter of the spinal cord
and divide it into right and left sides. The anterior median
fissure is a wide groove on the anterior (ventral) side. The
posterior median sulcus is a narrow furrow on the posterior
(dorsal) side.
The gray matter of the spinal cord is shaped like the letter H
or a butterfly; it consists of dendrites and cell bodies of
neurons, unmyelinated axons, and neuroglia.
10. The gray commissure forms the crossbar of the H. In the
center of the gray commissure is a small space called the
central canal; it extends the entire length of the spinal
cord and is filled with cerebrospinal fluid.
At its superior end, the central canal is continuous with the
fourth ventricle (a space that contains cerebrospinal fluid) in
the medulla oblongata of the brain.
Anterior to the gray commissure is the anterior (ventral)
white commissure, which connects the white matter of the
right and left sides of the spinal cord.
13. A reflex action is an immediate motor response to a sensory stimulus.
Many connector and motor neurones may be stimulated by afferent impulses from
a small area of skin, e.g. the pain impulses initiated by touching a very hot surface
with the finger are transmitted to the spinal cord by sensory nerves.
These stimulate many connector and lower motor neurones in the cord
which results in the contraction of many skeletal muscles of the hand, arm and
shoulder, and the removal of the finger.
14. Contd….
❖ Reflex action takes place very quickly, in fact, the motor
response may have occurred simultaneously with the
perception of the pain in the cerebrum.
❖ Reflexes of this type are invariably protective but they
can on occasion be inhibited. For example, if it is a
precious plate that is very hot when lifted every effort
will be made to overcome the pain to prevent dropping
it!
15. The internal organization of the spinal cord allows sensory
input and motor output to be processed by the spinal cord in
the following way:
Sensory receptors detect a sensory stimulus.
Sensory neurons convey this sensory input in the form of
nerve impulses along their axons, which extend from sensory
receptors into the spinal nerve and then into the posterior
root.
From the posterior root, axons of sensory neurons may
proceed along three possible paths. [see next 3 steps]
Axons of sensory neurons may extend into the white
matter of the spinal cord and ascend to the brain as part of a
sensorytract.
16. Contd….
Axons of sensory neurons may enter the posterior gray
horn and synapse with interneurons whose axons extend
into the white matter of the spinal cord and then ascend
to the brain as part of a sensory tract.
Axons of sensory neurons may enter the posterior
gray horn and synapse with interneurons that in turn
synapse with somatic motor neurons that are involved in
spinal reflex pathways.
17. Contd…
Motor output from the spinal cord to skeletal muscles
involves somatic motor neurons of the anterior gray horn.
Many somatic motor neurons are regulated by the brain.
Axons from higher brain centers form motor tracts that
descend from the brain into the white matter of the spinal
cord.
There they synapse with somatic motor neurons either
directly or indirectly by first synapsing with interneurons
that in turn synapse with somatic motor neurons.
18. When activated, somatic motor neurons convey motor output
in the form of nerve impulses along their axons, which
sequentially pass through the anterior gray horn and anterior
root to enter the spinal nerve. From the spinal nerve, axons of
somatic motor neurons extend to skeletal muscles of the
body.
Motor output from the spinal cord to cardiac muscle, smooth
muscle, and glands involves autonomic motor neurons of the
lateral gray horn. When activated, autonomic motor neurons
convey motor output in the form of nerve impulses along their
axons, which sequentially pass through the lateral gray horn,
anterior gray horn, and anterior root to enter the spinal nerve.
19. From the spinal nerve, axons of autonomic motor neurons
from the spinal cord synapse with another group of
autonomic motor neurons located in the peripheral nervous
system (PNS). The axons of this second group of autonomic
motor neurons in turn synapse with cardiac muscle, smooth
muscle, and glands.