NEUROLOGY 2 MARKS : PART 14

THE POSTERIOR HORN CELL:

  • The posterior horn contains interneurons that make connections within the spinal cord as well as neurons that enter ascending sensory pathways.
  • It receives several types of sensory information from the body, including fine touch, proprioception, and vibration.
  • The dorsal horns contain the cell bodies of sensory neurons.
  • Posterior horn also called as posterior cornu, dorsal horn, spinal dorsal horn posterior horn.

ANTERIOR AND POSTERIOR SPINAL ROOT :

  • The dorsal root ( POSTERIOR SPINAL ROOT)  is the afferent sensory root and carries sensory information to the brain.
  • The ventral root ( ANTERIOR SPINAL ROOT) is the efferent motor root and carries motor information from the brain.
  • The difference between the dorsal and ventral roots of the spinal nerves are the sensory nerve fibers enter the spinal cord through the dorsal root while the motor nerves exit through the ventral root.

NEURALGIA:

  • Pain that travels along the length of a nerve. 
  • This compression is usually caused by a nearby blood vessel pressing on part of the nerve inside the skull. In cases like, trigeminal neuralgia can occur as a result of damage to the trigeminal nerve.
  • It’s a stabbing pain in the middle of the night. Symptoms can include a chronic prickling, tingling, or burning sensation  all day.
  • Uncontrolled nerve pain can be hard to bear. 

TRACTS:

  • The spinal cord has numerous groups of nerve fibers going towards and coming from the brain.
  • These have been collectively called the ascending and descending tracts of the spinal cord, respectively.
  • The tracts are responsible for carrying sensory and motor stimuli to and from the periphery .
  • The ascending tracts refer to the neural pathways by which sensory information from the peripheral nerves is transmitted to the cerebral cortex.

DORSAL COLUMN:

  • Fasciculus Gracilis
    • Fasciculus Cuneatus

LATERAL COLUMN:

  • Lateral Spinothalamic tract
  • Dorsal Spinocerebellar tract
  • Ventral Spinocerebellar tract
  • Spinotectal tract
  • Spinoreticular fibers
  • Spino-olivary pathway
  • Spinovestibular tract

VENTRAL COLUMN:

  • Anterior Spinothalamic tract.

DESCENDING TRACTS OF THE SPINAL CORD:

  • ·        Corticospinal Tracts
  • ·        Vestibulospinal Tract
  • ·        Rubrospinal Tract
  • ·        Reticulospinal Tracts
  • ·        Tectospinal Tract

THE COUGH REFLEX:

  • The cough reflex serves to prevent the entry of harmful substances into the tracheobronchial tree and to expel excess secretions and retained material from the tracheobronchial tree.
  • Cough begins with stimulation of cough receptors, located in the upper and lower airways, and in many other sites such as the ear canal, tympanic membrane, sinuses, nose, pericardium, pleura, and diaphragm.
  • Receptors send messages via vagal, phrenic, glossopharyngeal, or trigeminal nerves to the “cough center,” which is in the medulla. 

THE SWALLOWING REFLEX:

  • The swallowing reflex is one phase of the swallow which is under reflexive or involuntary control.
  • This stage of the swallow begins after food which has been masticated has been gathered together in the mouth and formed into a bolus which is passed from the posterior tongue through the faucial arches.
  • The swallowing process was classified into oral, pharyngeal, and esophageal stages according to the location of the bolus.
  • The oral stage was later subdivided into oral preparatory and oral propulsive stages.

WHAT IS THE SALIVARY REFLEX?

  • Salivary gland secretion is a nerve-mediated reflex and the volume of saliva secreted is dependent on the intensity and type of taste and on chemosensory, masticatory or tactile stimulation.
  • Saliva is secreted in response to taste and somatosensory oral stimulation. Because salivary secretion is solely initiated in response to activation of the autonomic nerve supply to the salivary glands, sensory information from the oral cavity must form the afferent limb of this reflex.
  • Salivary glands are innervated, either directly or indirectly, by the parasympathetic and sympathetic arms of the autonomic nervous system.
  • Parasympathetic stimulation evokes a copious flow of saliva.

THE SUCKING REFLEX:

  • The sucking reflex is probably one of the most important reflexes your newborn has.
  • It is paired with the rooting reflex, in which a newborn searches for a food source.
  • When they find it, the sucking reflex allows them to suck and swallow the milk.
  • The sucking reflex is one of seven natural reflexes newborns have, including the Moro reflex, the grasping reflex, the rooting reflex, the stepping reflex, the fencing reflex, and the Babinski reflex. 

VOMITING REFLEX:

  • Vomiting is the forceful expulsion of contents of the stomach and often, the proximal small intestine.
  • There are three steps in the vomiting reflex .
  • First -Nausea develops. Second-retching occurs as a result of activation of spasmodic contractions of the diaphragm and intercostal muscles combined with closure of the glottis.
  • Third- the act of vomiting occurs.
  • Vomiting can serve the function of emptying a noxious chemical from the gut, and nausea appears to play a role in a conditioned response to avoid ingestion of offending substances.

CATHERINE SHALINI RAJA
M.P.T.,MIAP.,PGDYN
CARDIO RESPIRATORY PHYSICAL THERAPIST
FITNESS & SPORTS REHABILITATION SPECIALIST.

2 Replies to “NEUROLOGY 2 MARKS : PART 14”

  1. Excellent and valuable one for the students.very easy way to understand.Go ahead

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