Inductive Spinothalamic Tract

Clinical neuroanatomy

Anne Lingford-Hughes , Nicola Kalk , in Core Psychiatry (3rd Edition), 2012

Pain and temperature

The lateral spinothalamic tract carries information nearly pain and temperature. The anterior spinothalamic tract carries sensory information regarding calorie-free, poorly localized touch on. This information is carried in slow-conducting fibres (Aδ and C fibres) in contrast to the rapidly conducting fibres carrying data most pain and temperature. Later on joining the spinal cord, the fibres cross later on ascending 1–2 segments and synapse in Lissauer'southward tract. From at that place, the fibres ascend equally the lateral or anterior spinothalamic tract, and terminate in the ventral posterior nucleus of the thalamus. Fibres are too given off to the reticular formation and periaqueductal grey affair. The sensory cognitive cortex receives the final projections every bit described above.

Since the dorsal columns and spinothalamic tracts contain ipsilateral and contralateral fibres, respectively, transection of 1-half of the spinal cord leads to a feature pattern of sensory loss. This is known as Brown–Sequard syndrome or sensory dissociation. Below such a lesion, there is loss of two-bespeak discrimination and proprioception ipsilaterally and loss of pain and temperature sensation contralaterally.

Read full chapter

URL:

https://world wide web.sciencedirect.com/science/article/pii/B9780702033971000021

Spinal Tracts – Ascending/Sensory Pathways

Paul Rea , in Essential Clinical Anatomy of the Nervous Organisation, 2015

8.4.1.i.1 Anatomical Location and Function

The spinothalamic tract is comprised of two split up components that transmit dissimilar information – the ventral (or inductive) and lateral spinothalamic tracts. The ventral spinothalamic tract transmits information related to rough touch and business firm pressure level, whereas the lateral spinothalamic tract transmits data related to temperature and hurting.

Information related to hurting, temperature, crude touch and firm pressure would enter the dorsal horn from the lower and upper limbs. Those fibers related to pressure and impact will enter through the dorsal rootlets medial sectionalisation. Fibers containing data related to temperature and pain will enter through the dorsolateral tract of Lissauer (also called the dorsolateral fasciculus of Lissauer, tract of Lissaeur, or simply the dorsolateral tract).

Those fibers, which enter the dorsolateral tract, pass to the substantia gelatinosa (see Chapter 7). The sensory information arriving in the substantia gelatinosa is modified, and has many interneurons at that signal (Gurdt and Perl, 2002; Hantman et al., 2004; Yasaka et al., 2007, 2010).

From hither, the fibers and so laissez passer through the white thing through the ventral white commissure ascending to the ventral posterior nucleus of the thalamus. They then pass to the postcentral gyrus.

Read total affiliate

URL:

https://www.sciencedirect.com/science/article/pii/B978012802030200008X

Groundwork information

Lisa Harvey BAppSc, GradDipAppSc(ExSpSc), MAppSc, PhD , in Management of Spinal Cord Injuries, 2008

Sensory pathways

In that location are many sensory tracts and pathways conveying different types of sensory information from the periphery to the cerebral cortex. The central ones are the lateral and anterior spinothalamic tracts and the gracile and cuneate tracts inside the posterior columns. The spinothalamic tracts sit within the dorsal horn of the spinal string. Most of the fibres cantankerous at or near the level they enter the spinal cord. The lateral spinothalamic tract carries information almost hurting and temperature, and the anterior spinothalamic tract carries data about crude bear on. The gracile and cuneate tracts carry information nearly proprioception and calorie-free touch. The gracile tract is positioned medially and predominantly carries sensory fibres from the lower body while the cuneate tract is positioned laterally and predominantly carries fibres from the upper body. The fibres within the gracile and cuneate tracts cantankerous in the brainstem.

Read full chapter

URL:

https://www.sciencedirect.com/science/commodity/pii/B9780443068584500071

Neuroanatomy

D. Gupta , in Essentials of Neuroanesthesia, 2017

Function of Ascending Tract

1.

Gracile and cuneate tracts: Discriminative impact, vibratory sense, and conscious muscle joint sense (sense of position)

two.

Lateral spinothalamic tract: Pain—Temperature

3.

Anterior spinothalamic tract: Crude touch on—pressure

4.

Spinotectal tract: Provides afferent information for spinovisual reflexes and brings movements of the eyes and head toward the source of the stimulation.

5.

Spinoolivary tract: Carries unconscious proprioceptive and exteroceptive sensation.

6.

Spinocerebellar tract (dorsal and ventral): Carries unconscious proprioceptive sensation.

vii.

Lissuar's gelatinosa tract: Links the spinal segments.

Both the anterior and posterior spinal arteries are reinforced by the anastomotic arteries entering along the nerve roots. These anastomotic arteries are the special importance at the level of T1 and T11 vertebrae and chosen the arteries of Adamkiewicz which correspond to the enlarged spinal cord (Fig. 1.28) (Table 1.6).

Figure 1.28. Schematic diagram of spinal cord arterial supply.

Figure 1.29. Diagrammatic representation of claret supply of spinal cord at unmarried level.

Table 1.six. Arterial Supply of the Spinal Cord (Figs. i.28 and 1.29)

Arteries Origin and Site Course and Supply
Single anterior spinal artery From each vertebral avenue They unite forming single anterior spinal artery.
•

Supply anterior cavalcade and inductive horn
Two posterior spinal arteries From each vertebral artery They did non unite.
•

Posterior arteries supply posterior column and posterior horn.

•

The anterior artery shares in formation of arterial corona (supply lateral cavalcade)
Lateral spinal arteries From vertebral avenue, ascending and deep cervical, and descending aorta at interventricular foramina Each run forth the spinal nerve body to divide into anterior and posterior radicular arteries.
•

These arteries anastomos with arterial corona to supply lateral column.

Read full chapter

URL:

https://www.sciencedirect.com/scientific discipline/commodity/pii/B9780128052990000014

Central Nervous System Disorders

David Myland Kaufman Doctor , Mark J. Milstein MD , in Kaufman's Clinical Neurology for Psychiatrists (Seventh Edition), 2013

Signs of Spinal String Lesions

The spinal cord's gray matter, a broad H-shaped structure, consists largely of neurons that transmit nerve impulses in a horizontal plane. It occupies the center of the spinal string. The spinal cord's white thing, composed of myelinated tracts that convey data in a vertical direction, surrounds the central grayness matter (Fig. 2-15). This pattern – grey matter on the inside with white outside – is opposite to that of the cerebrum. Because intermission of the myelinated tracts causes about of the signs, neurologists call spinal string injury "myelopathy."

The major descending pathway, entirely motor, is the lateral corticospinal tract.

The major ascending pathways, entirely sensory, include the following:

•

Posterior columns, comprised of the fasciculi cuneatus and gracilis, behave position and vibration sensations to the thalamus.

•

Lateral spinothalamic tracts behave temperature and pain sensations to the thalamus.

•

Anterior spinothalamic tracts carry light touch on awareness to the thalamus.

•

Spinocerebellar tracts carry articulation position and motion sensations to the cerebellum.

When a spinal cord injury is detached and consummate, such every bit a complete transection, the lesion's location – cervical, thoracic, or lumbosacral – determines the nature and distribution of the motor and sensory deficits. Cervical spinal cord transection, for example, blocks all motor impulses from descending and sensory perception from arising through the neck. This lesion volition cause paralysis of the arms and legs (quadriparesis) and, after 1–ii weeks, spasticity, hyperactive DTRs, and Babinski signs. In add-on, it volition foreclose the perception of all limb, body, and bladder sensation. Similarly, a mid thoracic spinal cord transection will cause paralysis of the legs (paraparesis) with similar reflex changes, and sensory loss of the trunk below the nipples and the legs (Fig. 2-16). In general, all spinal cord injuries disrupt bladder command and sexual function, which rely on delicate, intricate systems (see Chapter 16).

In a variation of the complete spinal cord lesion, when a lesion transects only the lateral half of the spinal cord, information technology results in the Brown-Séquard syndrome (Fig. 2-17). The defining features of this archetype syndrome are ipsilateral paralysis of limb(s) from corticospinal tract damage and loss of vibration and proprioception from dorsal cavalcade harm combined with loss of temperature and hurting (hypalgesia) sensation in the opposite limb(s) from lateral spinothalamic tract damage. In the vernacular of neurology, one leg is weak and the other is numb.

Another motor impairment attributable to spinal cord damage, whether structural or nonstructural, is spasticity. The pathologically increased muscle tone often creates more disability than the accompanying paresis. For example, because information technology causes the legs to be direct, extended, and unyielding, patients tend to walk on their toes (see Fig. xiii-3). Similarly, spasticity greatly limits the usefulness of patients' hands and fingers.

Even with devastating spinal cord injury, cerebral function is preserved. In a ofttimes occurring and tragic instance, soldiers surviving a penetrating gunshot wound of the cervical spinal cord, although quadriplegic, retain intellectual, visual, and verbal facilities. Those surviving spinal string injuries oftentimes despair from isolation, lack of social support, and loss of their physical abilities. They have a loftier divorce rate, and their suicide rate is virtually five times greater than that of the full general population. In addition, several patients with quadriplegia have requested withdrawal of mechanical life support non only immediately subsequently the injury, when their decision may be attributable to depression, simply also several years later on when they are clearheaded and not overtly depressed.

Conditions that Touch the Spinal Cord

Discrete Lesions

The entire spinal string is vulnerable to penetrating wounds, such equally gunshots and stabbings; tumors of the lung, breast, and other organs that metastasize to the spinal cord (see Fig. 19-5); degenerative spine disease, such equally cervical spondylosis, that narrows the spinal culvert enough to compress the spinal cord (encounter Fig. 5-10); and MS and its variant, neuromyelitis optica (see Affiliate 15). Nonetheless, whatever its etiology, the lesion'due south location determines the deficits.

The cervical region of the spinal cord is particularly susceptible to nonpenetrating as well every bit penetrating trauma because, in many accidents, sudden and forceful hyperextension of the neck crushes the cervical spinal string against the cervical vertebrae. Approximately 50% of civilian spinal cord injuries result from motor vehicle accidents; 20% from falls; and fifteen% from diving accidents. Other unsafe sports are football, skiing, surfing, trampoline work, and horseback riding. Hanging by the neck, which dislocates or fractures cervical vertebrae, crushes the cervical spinal cord and cuts off the air supply. Survivors are likely to be quadriplegic as well as brain-damaged.

A lesion that frequently affects only the cervical spinal cord consists of an elongated cavity, syringomyelia or a syrinx (Greek, syrinx , pipe or tube + myelos marrow), next to the central canal, which is the thin tube running vertically inside the gray thing. The syrinx usually develops, for unclear reasons, in adolescents. Traumatic intraspinal bleeding may cause a variety of syrinx, a hematomyelia. The clinical findings of a syrinx or hematomyelia, which allow a diagnosis by neurologic exam, reflect its underlying neuroanatomy (Fig. 2-18). Every bit the cavity expands, its pressure rips autonomously the lateral spinothalamic tract fibers as they cross from ane to the other side of the spinal cord. It besides compresses on the inductive horn cells of the anterior gray matter. The expansion not only causes neck hurting, but a hitting loss in the arms and easily of sensation of pain and temperature, muscle bulk, and DTRs. Considering the sensory loss is restricted to patients' shoulders and artillery, neurologists frequently depict it as greatcoat-similar or suspended. Moreover, the sensory loss is characteristically restricted to loss of pain and temperature sensation because the posterior columns, merely displaced, remain functional.

Neurologic Illnesses

Several illnesses impairment only specific spinal cord tracts (Fig. 2-19). The posterior columns – fasciculus gracilis and fasciculus cuneatus – seem particularly vulnerable. For instance, tabes dorsalis (syphilis), combined system illness (B12 deficiency; see Chapter 5), Friedreich ataxia, and the SCAs each damages the posterior columns alone or in combination with other tracts. In these weather, impairment of the posterior columns leads to a loss of position sense that prevents patients from existence able to stand up with their eyes airtight (Romberg sign). When they walk, this sensory loss produces a steppage gait (Fig. 2-xx).

In another example, the human being T-lymphotropic virus type 1 (HTLV-one) infects the spinal cord's lateral columns. The infection, which is endemic in Caribbean area islands, causes HTLV-1 myelopathy in which patients develop spastic paraparesis that resembles MS. Perhaps more than in any other common myelopathy, the spasticity is disproportionately greater than the paresis.

Several toxic-metabolic disorders – some associated with substance corruption – damage the spinal cord. For example, nitrous oxide, a gaseous anesthetic, typically when inhaled continually as a drug of abuse by thrill-seeking dentists, causes a pronounced myelopathy by inactivating B12 (meet Chapter 5). Copper deficiency, often from excess consumption of zinc by food faddists or inadvertently ingested with excess denture cream, leads to myelopathy. Also, unless physicians closely monitor and supplant vitamins and nutrients following gastric bypass surgery, patients are prone to develop myelopathy for upwardly to several years after the surgery.

Most importantly, dementia accompanies myelopathy in several illnesses considering of concomitant cerebral damage. Examples of this association include tabes dorsalis, B12 deficiency, AIDS, and, when disseminated throughout the cerebrum, MS.

Read full chapter

URL:

https://world wide web.sciencedirect.com/scientific discipline/commodity/pii/B9780723437482000025

Proprioception, Touch, and Vibratory Sensation*

Julie Rowin , Matthew N. Meriggioli , in Textbook of Clinical Neurology (Tertiary Edition), 2007

Calorie-free Bear upon and Force per unit area

The mechanoreceptors associated with light affect include the RA and SA type I receptors. The sensory nerve fibers are big and myelinated. The central form of the fibers subserving tactile sensation is more diffuse than that of the other large fiber modalities with fibers coursing in both the anterior spinothalamic tract and the dorsal columns. It has long been recognized that a morbid procedure confined to the dorsal cavalcade will give no clear‐cut loss of unproblematic tactile sensibility. Conditions are similar for lesions affecting the anterolateral sensory tracts. It appears that if ane of the two systems subserving impact sensibility is damaged, the reduction is then mild that it is of no practical clinical relevance. 20

Tactile sensory nervus fibers have their beginning‐order neurons in the DRG and enter the spinal string through the medial partitioning of the dorsal root. These fibers are largely thought to traverse the medial strand of the dorsal roots and enter the dorsal columns ascending to the contralateral thalamus (see previous discussion of class of dorsal columns). Other fibers bifurcate into ascending and descending fibers that synapse within a few segments in the dorsal horn and laminae I, IV, Five, and some of Vi and Seven. Some of these 2d‐order neurons decussate in the anterior commissure and ascend in the contralateral anterior spinothalamic tract to the VPL nucleus of the thalamus. Within the thalamus, the tactile sensory fibers are placed slightly caudad to those conveying pain. These third‐social club neurons then ascend to somatosensory cortex. The organization of this modality at the cortical level is not well understood.

Pressure is related to tactile sense only involves the perception of pressure sensations other than light touch from subcutaneous structures. Information technology is closely related to proprioception and is mediated through the dorsal columns.

Read total chapter

URL:

https://www.sciencedirect.com/science/commodity/pii/B9781416036180100190

Pain

Perrine Inquimbert , ... Joachim Scholz , in Basic Neurochemistry (8th Edition), 2012

Nuclei in the brainstem and thalamus, and singled-out cortical areas are the major project targets for nociceptive data

Neurons in laminae I, Four and V of the dorsal horn, laminae VII and Viii of the intermediate zone and the medial ventral horn of the spinal string convey nociceptive input through the spinothalamic tract. Axons of lamina I neurons rise through the lateral portion of the spinothalamic tract and end in the posterior part of the ventral medial nucleus (VMpo), the ventral posterior inferior nucleus (VPI) and the ventral caudal part of the medial dorsal nucleus (MDvc), whereas axons from projection neurons in the deeper dorsal horn ascend through the inductive spinothalamic tract to the VPI, the ventral posterior lateral nucleus (VPL), and the ventral and central lateral nuclei (VL and CL). Most of the projections to the thalamus cross to the opposite side of the spinal cord earlier ascending ( Fig. 54-3).

Figure 54-iii. Nociceptive pathways in the central nervous system.

(A) The dorsal horn of the spinal cord is the starting time relay station for nociceptive input. Projections from neurons in lamina I of the dorsal horn give ascent to the main central pathway for pain, the lateral spinothalamic tract. It conveys information to the rostral ventromedial medulla (RVM), the periaqueductal gray (PAG) and thalamic nuclei. (B) Projections of dorsal horn neurons in deeper laminae (4, V) ascend through the inductive spinothalamic tract. (C) Brainstem nuclei attune the processing of afferent input through inhibition or facilitation. The PAG integrates information from the anterior insula, the anterior cingulate cortex, hypothalamus and amygdala. The RVM is the major origin of pathways descending to the spinal cord. CL, cardinal lateral nucleus; MDvc, ventral caudal part of the medial dorsal nucleus; VL, ventral lateral nucleus; VMpo, ventral medial nucleus; VPI, ventral posterior junior nucleus; VPL, ventral posterior lateral nucleus.

The interest of the thalamus in pain perception was discovered at the beginning of the 20th century when Henry Caput and Gordon Holmes examined brain lesions in patients with central pain. With the arrival of modern imaging techniques, noninvasive in vivo studies of forebrain connections involved in nociception became available. Magnetic resonance imaging (MRI) and positron emission tomography (PET) studies have demonstrated a functional association among the somatosensory cortex (SI and SII), inductive insula, inductive cingulate cortex, hypothalamus, amygdala, hippocampus and cerebellum (Fig. 54-3). This "pain matrix" serves the perception of pain and its contextual interpretation. Activation of the anterior cingulate cortex, for case, relates to the affective evaluation of painful events. Functional imaging further allows investigating complex pathophysiological processes that would exist hard to study in animal models. MRI, for example, has been used to demonstrate that placebo analgesia is non a "psychological trick"; instead information technology is associated with increased spinal inhibition and distinct changes in brain activity in regions that are involved in the processing of nociceptive input (Eippert et al., 2009 ). Functional MRI studies have also highlighted the dynamic changes in cortical nociceptive fields that follow deafferentation, including cortical plasticity associated with the development of phantom hurting after amputation (Flor et al., 2001). Techniques with loftier temporal resolution such as magnetoencephalography (MEG) are currently employed to determine the sequence in which components of pain pathways are activated.

Read total chapter

URL:

https://www.sciencedirect.com/science/commodity/pii/B9780123749475000547

The Somatosensory Organisation

Stewart Hendry , Steven Hsiao , in Fundamental Neuroscience (Fourth Edition), 2013

Ascending Paths to the Thalamus

Axons from both lamina I neurons and laminae Four/V neurons decussate and enter fiber tracts in the anterolateral quadrant of spinal cord, but the tracts they enter differ from i another in location and termination (Fig. 24.eleven ). Neurons of laminae IV and 5 enter the inductive spinothalamic tract and terminate in lateral parts of the thalamus, including the VPL and VPI, and an intralaminar nucleus, the central lateral nucleus. The innervation of ventral posterior thalamus does not mean both nociceptive and mechanosensory data converge in the thalamus. The two remain segregated equally medial lemniscal axons terminate on groups of large neurons, whereas spinothalamic axons innervate clusters of smaller neurons. Response properties of the smaller neurons in the VPL are much like those of the wide dynamic range neurons that innervate them, both in the type of stimuli to which they respond and the size of their receptive fields.

Nociceptive specific neurons of lamina I enter the lateral spinothalamic tract and terminate in several nuclei of the thalamus, including two that receive few deep lamina inputs (Fig. 24.xi). Targets in which convergence of lamina I and lamina Five inputs are strongly suspected or known to occur include the nucleus of the ventral posterior complex. Although the most compelling information in support of convergence has been reported for VPI, several careful studies have documented termination of lamina I inputs in the clusters of small neurons in VPL and VPM. This represents what has become a traditional view of the nociceptive pathway, that discriminative pain is driven past nociceptive inputs to both lamina I and lamina V, through a relay in the ventral posterior nuclei, and that nociceptive data reaches SI and SII (Perl and Kruger, 1996).

Outside the ventral posterior complex are two sites of spinothalamic terminations predominantly from lamina I (Fig. 24.11). Ane of these is a subnucleus of the mediodorsal nucleus (Mdvc) in which spinothalamic terminations are surprisingly rich. The other is posterior to the classically fatigued borders of VP and includes the medial nucleus of the posterior grouping (POm). Neurons in this region are innervated past spinothalamic axons and brandish the same chemical signature (immunoreactivity for the calcium-binding protein, calbindin) equally spinothalamic-recipient neurons of VPL and VPM (Craig and Dostrovsky, 1999).

Considerable disagreement exists nearly the spinothalamic innervation in posterolateral thalamus of monkeys and humans. One part of the disagreement deals with the proportion of lamina I afferents that finish within the bounds of the VPL and VPM and those that end caudal and medial to it. A conservative reading of the literature leads u.s. to recognize spinothalamic innervation of iv regions, each with its own cortical target. Spinothalamic terminations in the VPL and VPM are relayed to SI and those in VPI to SII. Together, they tin can be seen as a lateral path to first or discriminative pain. A second medial path to anterior cingulate by way of MDvc and to the insula by neurons of VMpo appears to be the central route for second or punishing pain.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B978012385870200024X

Signs of Key Nervous System Disorders

David Myland Kaufman Dr. , ... Mark J. Milstein MD , in Kaufman'southward Clinical Neurology for Psychiatrists (Eighth Edition), 2017

Signs of Spinal Cord Lesions

The spinal cord's grayness affair, which when viewed in the axial plane appears as a broad H-shaped structure in the centre of the spinal string, consists largely of neurons that transmit nerve impulses at i horizontal level. The spinal cord'due south white matter, composed of myelinated tracts that convey information in a vertical direction, surrounds the central greyness affair (Fig. 2.15). This pattern – grey affair on the inside with white exterior – is contrary that of the cerebrum. Pause of the myelinated tracts causes most of the signs of spinal cord injury, which neurologists telephone call "myelopathy."

The major descending pathway, entirely motor, is the lateral corticospinal tract.

The major ascending pathways, entirely sensory, include the post-obit:

•

Posterior columns (or dorsal columns), comprised of the fasciculi cuneatus and gracilis, deport position and vibration sensations to the thalamus.

•

Lateral spinothalamic tracts carry temperature and hurting sensations to the thalamus.

•

Inductive spinothalamic tracts bear light bear upon sensation to the thalamus.

•

Spinocerebellar tracts carry articulation position and move sensations to the cerebellum.

Spinal Cord Transection

If an injury severs the spinal cord, the transection's location – cervical, thoracic, or lumbosacral – determines the pattern of the ensuing motor and sensory deficits. Cervical spinal cord transection, for instance, blocks all motor impulses from descending and sensory information from arising through the neck. This lesion causes paralysis of the arms and legs (quadriparesis) and, after one–two weeks, hyperactive DTRs, and Babinski signs. In add-on, it prevents the perception of all limb, trunk, and bladder and bowel sensation. Similarly, a midthoracic spinal cord transection causes paralysis of the legs (paraparesis) with like reflex changes, and sensory loss in the trunk and beneath (Fig. two.16). In general, all spinal cord injuries disrupt bladder control and sexual function, which rely on frail, intricate systems (run into Chapter 16).

Some other motor impairment owing to spinal cord damage, whether from a specific lesion or a neurodegenerative illness, is pathologically increased muscle tone, which neurologists characterization hypertonicity or spasticity. It often creates more inability than the accompanying paresis. For instance, because spasticity causes the legs to be straight, extended, and unyielding, patients tend to walk on their toes (see Fig. 13.3). Similarly, spasticity greatly limits the usefulness of patients' hands and fingers.

In a variation of the complete spinal string lesion, when a penetrating injury severs only the lateral half of the spinal cord, neurologists refer to the injury every bit a spinal cord hemitransection. The lesion causes the classic Chocolate-brown–Séquard syndrome, which consists of ipsilateral paralysis of limb(s) from corticospinal tract impairment and loss of vibration and proprioception from dorsal cavalcade damage combined with loss of temperature and pain (hypalgesia) sensation in the opposite limb(s) from lateral spinothalamic tract impairment (Fig. 2.17). In the vernacular of neurology, one leg is weak and the other is numb.

Fifty-fifty with devastating spinal cord injury, cerebral function is preserved. In a often occurring and tragic example, soldiers surviving a penetrating gunshot wound of the cervical spinal cord, although quadriplegic, retain intellectual, visual, and verbal facilities. Nevertheless, veterans and other individuals with spinal cord injuries oft despair from isolation, lack of social support, and loss of their physical abilities.

Syringomyelia

A lesion that ofttimes affects simply the cervical spinal cord consists of an elongated crenel, syringomyelia or simply a syrinx (Greek, syrinx, pipe or tube + myelos marrow). The syrinx occurs in the substance of the spinal string, adjacent to its central canal, which is the sparse tube running vertically within the gray matter. It usually develops, for unclear reasons, during adolescence. Traumatic intraspinal haemorrhage may cause a diversity of syrinx, a hematomyelia. These weather condition produce clinical findings that reflect their neuroanatomy (Fig. 2.18). In both cases, as the crenel expands, its pressure rips apart the lateral spinothalamic tract fibers as they cross from one to the other side of the spinal cord. It also presses on the anterior horn cells of the anterior grayness matter. The expansion not only causes neck pain, only a hit loss in the artillery and hands of pain and temperature sensation, muscle majority, and DTRs. Because the sensory loss is restricted to patients' shoulders and artillery, neurologists often describe information technology as cape- or shawl-like. Moreover, the sensory loss is characteristically restricted to loss of hurting and temperature awareness because the posterior columns, merely displaced, remain functional.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780323415590000022

Medulla Oblongata

A.J.M. Verberne , in Encyclopedia of the Neurological Sciences (Second Edition), 2014

Ascending Pathways

Dorsal cavalcade tracts

The dorsal column tracts or medial lemniscal organisation (Figure 2) 'conveys' sensory information pertinent to fine affect, vibration, point discrimination, and positioning (proprioception) associated with the peel and joints. Ascending axons in the gracile and cuneate fasciculi convey data from the upper and lower halves of the body, respectively, to finish in the gracile and cuneate nuclei of the dorsal medulla oblongata. In turn, the axons of neurons of the gracile and cuneate nuclei arise, crossing in the midline at the lemniscal decussation of the medial lemniscus, relaying in the thalamus en route to the somatosensory cortex.

Spinothalamic tracts

The lateral spinothalamic tract (Figure 2 ) conveys pain and temperature information, whereas the inductive spinothalamic tract carries information nearly light bear on. These tracts arise from spinal dorsal column neurons, which receive input from afferent fibers entering the dorsolateral fasciculus or Lissauer's tract of the spinal cord.

Spinoreticular tract

This less clearly defined tract consists of axons carrying information about deep pain and originates from ventrolateral spinal string neurons and terminates onto neurons of the midline medullary raphe and rostral ventrolateral medulla.

Spinocerebellar tracts

Dorsal and ventral spinocerebellar pathways (Figure ii) ascend through the lateral medulla oblongata to the cerebellum via the cerebellar peduncle. Both pathways are involved in move control, conveying sensory information from muscle spindles, tendon organs, and touch and force per unit area receptors.

Cranial nerves and cranial nerve nuclei

Apart from the major ascending and descending pathways traversing its length, somatic motor, somatic sensory, visceral motor, and visceral sensory neurons are major features of the medulla oblongata. Cranial nerves, which comprise fibers arising from, or projecting to, medullary structures, include the facial nerve (cranial nervus Vii), glossopharyngeal nervus (cranial nerve IX), vagus nerve (cranial nervus X), accompaniment nerve (cranial nervus XI), and hypoglossal nerve (cranial nerve XII) (Figure 3).

Effigy 3. Motor and sensory neuronal cell groups of the medulla oblongata and caudal pons. The somatic motor (hypoglossal nucleus and the abducens nucleus), visceral motor (dorsal motor nucleus of the vagus, and superior and inferior salivatory nuclei), and branchial motor (nucleus ambiguus, facial nucleus, and trigeminal motor nucleus) columns are depicted on the left. The somatic sensory (trigeminal sensory nucleus), special somatic sensory (vestibular nucleus and cochlear nucleus), and visceral sensory (nucleus of the lone tract) columns are depicted on the correct.

 Reproduced with permission from Nauta W and Feirtag M (1986) Fundamental Neuroanatomy. New York: Freeman.
•

Facial nerve (cranial nerve VII): The facial nerve arises from neurons in the facial motor nucleus in the rostral medulla/caudal pons (Figure 3). It contains predominantly somatic motor axons supplying muscles of the face and scalp, ear, posterior abdomen of the digastric muscle, and stylohyoid musculus. In particular, motor neurons of the facial nucleus control the muscles of the forehead, lips, and cheeks, which together are chosen muscles of facial expression. Neurons of the superior salivatory nucleus give rise to parasympathetic preganglionic neurons that project in the facial nerve via the submandibular and sphenopalatine ganglia, to the submandibular and sublingual glands.

•

Glossopharyngeal nerve (cranial nerve Nine): The glossopharyngeal nervus contains somatic and visceral sensory besides equally somatic and visceral motor components (Effigy 3). Somatic motor fibers originate from neurons of the ambiguus nucleus to innervate the stylopharyngeus muscle. Parasympathetic neurons of the inferior salivatory nucleus exit the medulla in the glossopharyngeal nerve and, via the tympanic nerve, project to the otic ganglion to innervate the parotid gland. Visceral sensory afferent fibers arising from the carotid sinus baroreceptors and chemoreceptors travel in the glossopharyngeal nerve. The cell bodies of these afferents are found in the jugular and petrosal ganglia, and they end in the nucleus of the solitary tract onto second-guild neurons of the baroreflex and chemoreflex.

•

Vagus nerve (cranial nerve X): Three visceral motor cell groups consisting of parasympathetic preganglionic neurons are establish in the medulla oblongata. These include the dorsal motor nucleus of the vagus, ambiguus nucleus, and rostral medullary salivatory nuclei (Figure iii). The vagus, or 'wanderer', so named considering of its diverse array of peripheral projection targets, contains afferent fibers, which ascend from intestinal visceral and thoracic structures besides as parasympathetic preganglionic motor nervus fibers. Parasympathetic motor neurons coursing in the vagus nervus innervate parasympathetic ganglia located close to, or within, a various range of cervical, thoracic, and intestinal visceral structures. The nearly caudal grouping of parasympathetic neurons that contributes efferent fibers to the vagus, the dorsal motor nucleus of the vagus, lies ventral to, and at approximately the same level every bit, the hypoglossal nucleus. It supplies preganglionic parasympathetic vagal outflow to the smooth muscle and glands of the gastrointestinal tract also as to the middle and respiratory tract via the vagus and glossopharyngeal nerves. Vagal stimulation activates gastrointestinal peristalsis and gastric, hepatic, and pancreatic secretory activity and reduces middle rate. An additional group of neurons contributing preganglionic parasympathetic fibers to the vagus nervus are found in the vicinity of the ambiguus nucleus. The ambiguus nucleus has two major components: (1) the compact germination that consists of motor neurons projecting to the esophagus and upper airways, and (ii) the external formation, which contains a loose drove of parasympathetic preganglionic neurons that project to the heart, lungs, and airways.

Vagal preganglionic neurons of the dorsal motor nucleus of the vagus receive input from a broad range of medullary and supramedullary sources. These include cerebral cortical regions, the amygdala, lateral hypothalamic area, paraventricular hypothalamic nucleus, midbrain cardinal gray area, pontine A5, and parabrachial nuclei, besides as intramedullary neuronal groups. Similarly, the neurons within the ambiguus nucleus and its surroundings receive input from hypothalamic, midbrain, and pontine structures.

Vagal afferent fibers arise from a diverse array of structures of the abdominal viscera and cardiopulmonary region. These convey data from chemoreceptors and mechanoreceptors of the gastrointestinal tract, heart, and lungs, and hepatic glucoreceptors to neurons of the nucleus of the solitary tract. Vagal afferent projections to the nucleus of the solitary tract are regarded as pseudo-bipolar and their jail cell bodies are amassed within the nodose ganglion. Destruction of the nucleus of the solitary tract in anesthetized experimental animals interrupts a number of reflexes, including the baroreceptor reflex and chemoreflex. In animals that are allowed to recover, this handling produces fulminating hypertension and pulmonary edema reminiscent of neurogenic pulmonary edema that may occur secondary to head trauma in humans. Neurogenic pulmonary edema caused by trauma to intramedullary structures may involve interruption of pathways involved in cardiovascular and respiratory command.

•

Accessory nervus (cranial nerve Xi): The accessory nerve includes medullary and spinal branches. The erstwhile contains axons arising from motor neurons of the ambiguus nucleus that project to the larynx, whereas the latter contains motor fibers arising from the anterior horns of the beginning 5 to six cervical spinal cord segments. These supply the trapezius and sternocleidomastoid muscles.

•

Hypoglossal nerve (cranial nerve XII): The caudally located hypoglossal nucleus lies bilaterally on either side of the dorsal medulla and innervates the striated muscles of the natural language via the hypoglossal nervus (Figure iii). Motor fibers emerge from the medulla betwixt the inferior olive and pyramids. Neurons in the hypoglossal nucleus receive input from the cognitive cortex and other supramedullary sources, also as sensory input from the trigeminal nerve and from the nucleus of the alone tract, an elongated structure located bilaterally in the dorsal medulla oblongata.

Spinal trigeminal tract

Sensory data from the face up, mouth, and olfactory organ is conveyed to the nervous system by the trigeminal nervus. Many trigeminal (cranial nervus 5) main afferent cell bodies are found within the trigeminal ganglion (also known every bit the Gasserian or semilunar ganglion), although a pocket-sized number are also found in the trigeminal mesencephalic nucleus. The latter group represents the simply case of primary afferent neuronal cell bodies located within the central nervous system.

Trigeminal ganglion neurons enter the brainstem at the level of the pons and synapse inside the trigeminal nuclear complex, which consists of: (1) a principal sensory nucleus and (2) a spinal trigeminal nucleus located in the lateral medulla oblongata (Figure 3). The caudal one-third of the spinal trigeminal nucleus is establish inside the medulla oblongata in the subnucleus caudalis. Primary afferent fibers conveying pain and temperature signals project caudally in the spinal trigeminal tract to the subnucleus caudalis. These neurons, in turn, send crossed projections to the thalamus via the ventral trigeminothalamic tract.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B978012385157401160X