Pharyngeal plexus cricopharyngeus part can also receive innervation from the recurrent laryngeal nerve and/or the external laryngeal nerve.Īs soon as the bolus of food is received in the pharynx, the elevator muscles relax, the pharynx descends, and the constrictors contract upon the bolus and convey it down into the esophagus. The thickest of the three constrictors arises from the sides of the cricoid and thyroid cartilage.Īscending pharyngeal artery, branch of the external carotid artery. The Inferior pharyngeal constrictor, the thickest of all three constrictors, arises from the sides of the cricoid and thyroid cartilage. Similar to the superior and middle pharyngeal constrictor muscles, This Muscle Nerve supply is the vagus nerve (cranial nerve X), specifically, by branches from the pharyngeal plexus and by neuronal branches from the recurrent laryngeal nerve. The cricopharyngeus also receives innervation from the external and recurrent laryngeal nerves. Pharyngeal muscles play an integral role in vital processes such as breathing, swallowing, and speaking. The pharynx can be divided into the oropharynx, nasopharynx, and laryngopharynx. The constrictor muscles are innervated by the pharyngeal plexus - with the vagus nerve carrying fibers that emerged from the brainstem as CN XI. The pharynx is a component of the digestive system that lies posterior to the nasal cavity, oral cavity, and larynx. SLN impairment greatly affects deglutition specially related to aspiration risk.The Inferior pharyngeal constrictor, the thickest of all three constrictors, arises from the sides of the cricoid and thyroid cartilage. An image showing the pharyngeal constrictors (superior, middle, and inferior). 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. 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.
#Innervations inferior pharyngeal constrictor generator
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. That means a unilateral lesion can result in bilateral pharyngeal motor and sensory dysfunction. Brainstem representation is both sided and they are interconnected. Both parts of the muscle are innervated by branches of vagus nerve (CN X) via the pharyngeal plexus of nerves. The primary function of the UES is to prevent aspiration of.
This band of striated muscle, innervated by the pharyngeal branch of the vagus nerve, is contracted at rest, creating a high-pressure zone about 12 cm in length. The brainstem is responsible for the involuntary phases. Pharynx is 1214 cm in its vertical length and extends from the base of skull to the upper border of upper esophageal sphincter (UES) 14. It is created by the convergence of the inferior pharyngeal constrictor muscle and the cricopharyngeus muscle (Fig. 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. The three major muscles which constrict the pharynx are the superior pharyngeal constrictor (SC), the middle pharyngeal constrictor (MC), and the inferior.
Cognitive awareness, drive for food and nutrition plays an important role. Dose was 65 Gy to primary and nodal tumour and 54 Gy to remaining pharyngeal subsite and nodal areas at risk of microscopic disease.
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