Spinoreticular tract

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Spinoreticular tract
Details
Identifiers
Latin tractus spinoreticularis
TA98 A14.1.02.231
TA2 6105
FMA 75693
Anatomical terminology

The spinoreticular tract (also paleospinothalamic pathway, or indirect pathway of the anterolateral system ) is a partially decussating (crossed-over) four-neuron sensory pathway of the central nervous system. The tract transmits slow nociceptive/pain information (but thermal, and crude touch information as well) from the spinal cord to reticular formation which in turn relays the information to the thalamus via reticulothalamic fibers as well as to other parts of the brain (as opposed to the spinothalamic tract - the direct pathway of the anterolateral system - which projects from the spinal cord to the thalamus directly without such "layovers"). Most (85%) second-order axons arising from sensory C first-order fibers ascend in the spinoreticular tract - it is consequently responsible for transmiting "slow", dull, poorly-localised pain. By projecting to the reticular activating system (RAS), the tract also mediates arousal/alertness (including wakefulness) in response to noxious (potentially dangerous) stimuli. The tract is phylogenetically older than the spinothalamic ("neospinothalamic") tract. [1] [ page needed ]

Contents

Anatomy

Origin

Sensory group C first-order axons first synapse with interneurons in the lamina II (substantia gelatinosa) and lamina III of the posterior grey column of the spinal cord. These interneurons then synapse with second-order neurons in laminae V-VIII [1] whose axons then ascend in the spinal cord near the lateral spinothalamic tract. [2]

A minority of second-order axons of the spinoreticular tract however bypass the reticular formation, projecting to the intralaminar thalamic nuclei directly. [1] [ page needed ]

Pathway

The tract is bilateral: its fibers ascend predominately ipsilaterally, but a minority decussate in the anterior white commissure to ascend contralaterally. Second-order axons of this tract terminate by forming multiple synapses in the nuclei of the medullary, pontine, and mesencephalic reticular formation. The nuclei of the reticular formation lack somatotopic organisation (consequently, sensory stimuli conveyed via this pathway are indistinctly localised). [1] [ page needed ]

The reticular formation in turn conveys the tract to: [1] [ page needed ]

Related Research Articles

In physiology, nociception, also nocioception; from Latin nocere 'to harm/hurt') is the sensory nervous system's process of encoding noxious stimuli. It deals with a series of events and processes required for an organism to receive a painful stimulus, convert it to a molecular signal, and recognize and characterize the signal to trigger an appropriate defensive response.

<span class="mw-page-title-main">Brainstem</span> Posterior part of the brain, adjoining and structurally continuous

The brainstem is the stalk-like part of the brain that interconnects the cerebrum and diencephalon with the spinal cord. In the human brain, the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is continuous with the thalamus of the diencephalon through the tentorial notch.

<span class="mw-page-title-main">Trigeminal nerve</span> Cranial nerve responsible for the faces senses and motor functions

In neuroanatomy, the trigeminal nerve (lit. triplet nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewing; it is the most complex of the cranial nerves. Its name (trigeminal, from Latin tri- 'three', and -geminus 'twin') derives from each of the two nerves (one on each side of the pons) having three major branches: the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3). The ophthalmic and maxillary nerves are purely sensory, whereas the mandibular nerve supplies motor as well as sensory (or "cutaneous") functions. Adding to the complexity of this nerve is that autonomic nerve fibers as well as special sensory fibers (taste) are contained within it.

<span class="mw-page-title-main">Grey column</span>

The grey column refers to a somewhat ridge-shaped mass of grey matter in the spinal cord. This presents as three columns: the anterior grey column, the posterior grey column, and the lateral grey column, all of which are visible in cross-section of the spinal cord.

<span class="mw-page-title-main">Nociceptor</span> Sensory neuron that detects pain

A nociceptor is a sensory neuron that responds to damaging or potentially damaging stimuli by sending "possible threat" signals to the spinal cord and the brain. The brain creates the sensation of pain to direct attention to the body part, so the threat can be mitigated; this process is called nociception.

<span class="mw-page-title-main">Spinothalamic tract</span> Sensory pathway from the skin to the thalamus

The spinothalamic tract is a part of the anterolateral system or the ventrolateral system, a sensory pathway to the thalamus. From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory cortex of the postcentral gyrus.

<span class="mw-page-title-main">Dorsal column–medial lemniscus pathway</span> Sensory spinal pathway

The dorsal column–medial lemniscus pathway (DCML) is a sensory pathway of the central nervous system that conveys sensations of fine touch, vibration, two-point discrimination, and proprioception from the skin and joints. It transmits information from the body to the primary somatosensory cortex in the postcentral gyrus of the parietal lobe of the brain. The pathway receives information from sensory receptors throughout the body, and carries this in nerve tracts in the white matter of the dorsal column of the spinal cord to the medulla, where it is continued in the medial lemniscus, on to the thalamus and relayed from there through the internal capsule and transmitted to the somatosensory cortex. The name dorsal-column medial lemniscus comes from the two structures that carry the sensory information: the dorsal columns of the spinal cord, and the medial lemniscus in the brainstem.

<span class="mw-page-title-main">Periaqueductal gray</span> Nucleus surrounding the cerebral aqueduct

The periaqueductal gray is a brain region that plays a critical role in autonomic function, motivated behavior and behavioural responses to threatening stimuli. PAG is also the primary control center for descending pain modulation. It has enkephalin-producing cells that suppress pain.

<span class="mw-page-title-main">Reticular formation</span> Spinal trigeminal nucleus

The reticular formation is a set of interconnected nuclei that are located in the brainstem, hypothalamus, and other regions. It is not anatomically well defined, because it includes neurons located in different parts of the brain. The neurons of the reticular formation make up a complex set of networks in the core of the brainstem that extend from the upper part of the midbrain to the lower part of the medulla oblongata. The reticular formation includes ascending pathways to the cortex in the ascending reticular activating system (ARAS) and descending pathways to the spinal cord via the reticulospinal tracts.

<span class="mw-page-title-main">Thalamocortical radiations</span> Neural pathways between the thalamus and cerebral cortex

In neuroanatomy, thalamocortical radiations, also known as thalamocortical fibres, are the efferent fibres that project from the thalamus to distinct areas of the cerebral cortex. They form fibre bundles that emerge from the lateral surface of the thalamus.

The dorsal longitudinal fasciculus (DLF) is a longitudinal tract interconnecting the posterior hypothalamus, and the inferior medulla oblongata. It contains both ascending tracts and descending tracts, and serves to link the forebrain, and the visceral autonomic centres of the lower brainstem. It conveys both visceral motor signals, and sensory signals.

<span class="mw-page-title-main">Nucleus raphe magnus</span> Cluster of nuclei in the brain stem

The nucleus raphe magnus is one of the seven raphe nuclei. It is situated in the pons in the brainstem, just rostral to the nucleus raphe obscurus.

<span class="mw-page-title-main">Posterolateral tract</span>

The posterolateral tract is a small strand situated in relation to the tip of the posterior column close to the entrance of the posterior nerve roots. It is present throughout the spinal cord, and is most developed in the upper cervical regions.

<span class="mw-page-title-main">Spinotectal tract</span>

The spinotectal tract and/or spinomesencephalic tract is a component of the ascending reticular activating system that is involved in processing of pain and visceral sensations. The tract is involved in the processing of pain sensation, and reflex turning of the head and trunk in the direction of painful stimuli. It arises in the spinal cord, and projects contralaterally to various structures of the midbrain.

Cutaneous innervation refers to an area of the skin which is supplied by a specific cutaneous nerve.

<span class="mw-page-title-main">Central tegmental tract</span> Structure in the midbrain and pons

The central tegmental tract is a structure in the midbrain and pons.

<span class="mw-page-title-main">Spinal cord</span> Long, tubular central nervous system structure in the vertebral column

The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal cord is hollow and contains a structure called the central canal, which contains cerebrospinal fluid. The spinal cord is also covered by meninges and enclosed by the neural arches. Together, the brain and spinal cord make up the central nervous system.

The hypothalamospinal tract is an unmyelinated non-decussated descending nerve tract that arises in the hypothalamus and projects to the brainstem and spinal cord to synapse with pre-ganglionic autonomic neurons.

The raphespinal tract is an unmyelinated descending serotonergic tract involved in pain modulation. It is a descending pain-inhibiting pathway; it is a component of the reticulospinal tract.

References

  1. 1 2 3 4 5 Patestas, Maria A.; Gartner, Leslie P. (2016). A Textbook of Neuroanatomy (2nd ed.). Hoboken, New Jersey: Wiley-Blackwell. pp. 202–203, 205, 307, 310–311, 313. ISBN   978-1-118-67746-9.
  2. "Chapter 25:Neural Mechanisms of Cardiac Pain: The Anterolateral System" . Retrieved 2009-11-26.[ dead link ]

Further reading