Neural Control of Swallowing

CNS: Functional Organization

Cortical planning and execution of voluntary movements associated with voice and swallowing...lateral primary motor cortex, lateral primary somatosensory cortex, premotor cortex, inferior frontal operculum, laterality and the swallowing and voice.

Reticular Formation

Descending reticular nuclei mediate reflexive behaviors including chewing and swallowing also apart of brain stem structures.

Higher Level Cortical and Subcortical input involved in neural control of swallowing

Implicated during swallowing are: inferior precentral gyrus, insula cerebellum (involved in the coordination required to chew and swallow), internal capsule, subthalamus, amygdala, hypothalamus, substantia nigra

What are the subcortical regions

Insula, Basal Ganglia, and thalamus

Dorsal Motor Nuclei of CN 10

Involved in the coordinated motor response, particularly mm of larynx. Also think output of gag reflex.

Thalamus

Major sensory relay center for incoming sensory information; relays information to the parietal cortex.

Nucleus Tractus Solitarius (NTS)

Medullary center for sensory input. Receives information from CN 7, 9, 10, 11. Connects via interneurons to motor output and higher centers

Medulla

Nuclei generate from here. Integral for reflexive pharyngeal phase of swallowing Areas are referred to as the central pattern generator, or regulatory center for swallowing, laryngeal control and respiration. These regions are responsible for the integrated sequential pattern functions of respiration, voicing, and swallowing.

Nuclei of the Medulla

Nucleus Tractus Solitarius (NTS), Nucleus Ambiguus (NA), Dorsal Motor Nuclei of CN x (10), and Hypoglossal nucleus

Cerebellum

Second major influence on motor impulses that work to refine and balance smooth skilled movement. Damage to this area results in: Loss of coordinated, refined skilled motor movements, and symptoms ipsilateral to side of damage: double cross over.

CNS

Skilled, voluntary motor functions that occur within the pharynx/larynx are located in the lateral motor strip of the cortex and travel by way of the UMN.

Nucleus Ambiguus (NA)

Surrounding reticular formation, generates coordinated motor response from CN 9 and 10 to pharynx and larynx.

Nucleus Tractus Solitaris (NTS)

The SENSORY nucleus for swallowing, including: CN VII (7), CN IX (9), and CN X (10). This is the principle sensory nucleus for pharynx and esophagus. It's located in the (DORSAL) back of the medulla.

Medulla 2

There is bilateral representation (within medulla) as well as many interconnections to mediate the integrated functions of the pharyngeal and esophageal phases. Either side may mediate these regulatory functions

Hypoglossal Nucleus

This is active during the oropharyngeal swallow (given the crucial role of the tongue.) Also located in the back (DORSAL) of the medulla.

Cortical input think as

Voluntary component: such as mastication and chewing

Pyramidal tract:

____________ ____________: is the direct corticobulbar and corticospinal pathways for information traveling between cortex and lower motor neurons

Insula

____________: is (inferior to temporal lobe-still cortical) Connections with cortical and subcortical sites involved in voice and swallowing, gustatory pathway, and the anterior portions activate during singing

Interneurons are

______________ are neurons in the CNS that connect with multiple brainstem areas that comprise a swallowing central pattern generator (CPG). These are located in the dorsal medulla and ventrolateral medulla.

Nucleus Ambiguus

a MOTOR nucleus for CN IX (9) and CN X (10) Located in the (VENTRAL) front part of the medulla.

Motor Nuclei of CN 10

is located in the Nucleus Ambiguus and Dorsal Motor Nucleus of CN 10 within the medulla.

Cortical damage results in

loss of motor planning and coordination, contralateral sensory/motor deficits: bilateral representation

Subcortical regions think as

more autonomic process such as the role of cerebellum responsible for motor coordination.

Hypoglossal nucleus

motor output to the tongue.

basal ganglia

series of parallel circuits that inhibit/excite motor activity: must work in balance for skilled motor movements