![]() SLN impairment greatly affects deglutition specially related to aspiration risk. demonstrated that electric stimulation of SLN elicits swallowing more readily than stimulation of the IX cranial nerve alone. The CPG is activated by either peripheral afferent input such as the ones conducted by the superior laryngeal nerve (SNL) or by supramedullary inputs, conducted by the cerebral cortex in the case of a voluntary swallow. In this article, we shall look at the anatomy of the vagus nerve its anatomical course, functions and clinical correlations. It is associated with the derivatives of the fourth and sixth pharyngeal arches. It is a functionally diverse nerve, offering many different modalities of innervation. The interneurons in the DSG are involved in the triggering, shaping, and timing of swallowing, and modulate the VSG premotor neurons which distribute the swallowing drive to the motorneurons of the different cranial nerves involved in swallowing. The recurrent laryngeal nerve functionally contributes to the motor innervation of the cricopharyngeal muscle in all patients and contributes to the motor innervation of the inferior pharyngeal constrictor muscle in most patients. The vagus nerve is the 10 th cranial nerve (CN X). The brainstem swallowing center, called the central pattern generator (CPG), is formed by two groups of interneurons: one located in the nucleus tractus solitarius (NTS), called the dorsal swallowing group (DSG), which is a primary sensory nucleus from the afferent stimuli and the other one located in the ventrolateral medulla (VLM), called ventral swallowing group (VSG), adjacent to the nucleus ambiguus (Fig. It originates as separate bellies on the cricoid and. That means a unilateral lesion can result in bilateral pharyngeal motor and sensory dysfunction. The inferior constrictor muscle, as expected by its name is the most inferior of the three constrictors. Brainstem representation is both sided and they are interconnected. The brainstem is responsible for the involuntary phases. ![]() The sensory motor cortex receives afferent information of the oral, pharyngeal, and laryngeal areas modulating the brain stem response according to the type of information received. Suppression of cortical input makes oral time longer, uncoordinated and with a prolonged triggering time of the reflexive swallow. The cerebral cortex has an important role in swallowing initiation and strong involvement in the coordination of the normal swallow. The clinical implication is that impairment of swallowing will be more prominent if the hemisphere affected is the dominant one and that there will be a possibility of rehabilitation reorganizing the swallowing areas in the non-dominant hemisphere. The muscle groups involved in swallowing are represented bilaterally but asymmetrically in the premotor cortex, in a somatotopic fashion, with a dominant hemisphere independent of handedness. The coordination with apnea is essential. Insertions: Blends with pharyngeal constrictors, lateral glossoepiglottic fold, posterior border of thyroid cartilage: Innervation: They are all innervated by the pharyngeal plexus and pharyngeal branch of the vagus nerve, except the stylopharyngeus which is innervated by the glossopharyngeal nerve. Conclusions: The innervations pattern suggests that the pharyngeal muscles comprise four groups: the first innervated by the glossopharyngeal nerve, the second and third by the pharyngeal plexus, and the fourth by the plexus and the laryngeal nerves. The pharyngeal branch of the glossopharyngeal nerve arises prior to the. It is formed by the pharyngeal branches from the vagus and glossopharyngeal nerves and the cervical sympathetic 3-7. They are innervated by the pharyngeal branch of the vagus nerve (CN X) with the exception of the stylopharyngeus muscle which is innervated by the glossopharyngeal nerve (CN IX).Cognitive awareness, drive for food and nutrition plays an important role. The inferior constrictor received additional innervations from the laryngeal nerves. The pharyngeal plexus sends some branches between the middle and inferior constrictors and other branches between the superior and middle constrictors 4,6. There are two muscular layers of the pharynx: the outer circular layer and the inner longitudinal layer.ĭuring swallowing, these muscles constrict to propel a bolus downwards (an involuntary process).ĭuring swallowing, these muscles act to shorten and widen the pharynx. The pharyngeal muscles (involuntary skeletal) push food into the esophagus. ![]() Cricopharyngeus had its origin from the cricoid cartilage. The pharyngeal muscles are a group of muscles that form the pharynx, which is posterior to the oral cavity, determining the shape of its lumen, and affecting its sound properties as the primary resonating cavity. Inferior pharyngeal constrictor This muscle is split into two distinct muscle groups.
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