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Head and Neck Muscles
Published in Eve K. Boyle, Vondel S. E. Mahon, Rui Diogo, Handbook of Muscle Variations and Anomalies in Humans, 2022
Eve K. Boyle, Vondel S. E. Mahon, Rui Diogo, Warrenkevin Henderson, Hannah Jacobson, Noelle Purcell, Kylar Wiltz
Senoo et al. (2001) describe a case of congenital unilateral soft palate aplasia in which palatoglossus and levator veli palatini were absent on the right side. In a fetus with craniorachischisis, palatoglossus was the only soft palate/pharyngeal muscle that was present (Alghamdi et al. 2017). Bersu et al. (1976) describe a male infant with Hanhart syndrome. On the right side of this infant, the muscles of the soft palate were underdeveloped and displaced. A muscle descended from the cartilage of the auditory tube and split into two portions at the level of the soft palate. The anterior portion of this muscle inserted onto the side of the tongue forming the right palatoglossal arch. The posterior portion blended with the superior pharyngeal constrictor and the stylopharyngeus muscles forming the palatopharyngeal arch. In an otocephalic fetus examined by Lawrence and Bersu (1984), muscle fibers were present in the soft palate, but most individual palatal muscles could not be identified. In a male neonate with Meckel syndrome, Pettersen (1984) found that palatoglossus and palatopharyngeus originated from the medial aspect of the medial pterygoid plate on each side, instead of originating from the soft palate.
Baroreflex Failure
Published in David Robertson, Italo Biaggioni, Disorders of the Autonomic Nervous System, 2019
The glossopharyngeal nerve is of mixed function; it has both visceral and somatic sensory function. The sensory nerves supply the mucous membranes of the pharynx, the fauces, the palatine tonsils, and the sensation and taste buds of the posterior part of the tongue. The somatic afferents convey pain and temperature sensation from the external auditory meatus and skin of the ear (these central processes ultimately terminate in the nucleus of the spinal tract of the trigeminal (V) nerve). Parasympathetic fibers innervate the parotid gland and small glands in the posterior tongue and neighbouring pharynx. There are also efferent fibers that innervate the stylopharyngeus muscles and perhaps some other striated muscle of the pharynx (Brodal, 1957).
Neural Control of Respiratory Muscle Activation During Vomiting
Published in Alan D. Miller, Armand L. Bianchi, Beverly P. Bishop, Neural Control of the Respiratory Muscles, 2019
Laurent Grélot, Alan D. Miller
In the cephalic region, the patencies of both the oropharyngeal cavity and the larynx, which depend on the degree of contraction of numerous muscles, also fluctuate rhythmically during vomiting12 (Figure 1). The relaxation of the inspiratory intrinsic and extrinsic laryngeal muscles and concomitant potent activation of the expiratory intrinsic laryngeal muscles lead to closure of the glottis during both retching and expulsion. The contraction of the diaphragm, in conjunction with a closed glottis, is responsible for the negative intrathoracic pressure that develops during each retch. The rhythmic contractions of the stylopharyngeus muscle, which dilates the pharynx, and the genioglossus muscle, which protrudes the tongue, increase the oropharyngeal patency, allowing an easier expulsion of GI contents. The constrictors of the pharynx also contract rhythmically during retching, but out of phase with abdominal and diaphragmatic cocontraction, and then relax during expulsion to facilitate transit of the bolus. The digastricus muscle contracts tonically throughout vomiting, thereby depressing the jaw and opening the mouth. Following expulsion, several episodes of deglutition occur to clean the oropharyngeal cavity. This swallow-related activity can be observed in paralyzed animals in the absence of actual expulsion.
Transcervical endoscopic approach for parapharyngeal space: a cadaver study and clinical practice
Published in Acta Oto-Laryngologica, 2020
Yi Fang, Haitao Wu, Andrew D. Tan, Lei Cheng
A transcervical approach incision was made about two fingers’ width (2 cm) beneath the mandible, then elevating the subplatysmal skin flaps to the submandibular fascia and body of the mandible (Figure 1(A)). The greater auricular nerve was located and preserved. The posterior belly of the digastric muscle was divided below the submandibular gland and dissected posteriorly to the parotid gland and mastoid tip (Figure 1(B)). Then the stylohyoid, styloglossus muscles were dissected to expose the fatty tissue, part of the deep lobe of the parotid gland in the prestyloid compartment. Further dissection was performed along the medial border of the sternocleidomastoid muscle. When the later was pulled outward, the internal jugular vein appeared and the carotid artery was found medially, while the vagus nerve was divided in the middle of the internal jugular vein and the carotid artery, as shown in Figure 2(A). The spinal accessory nerve was identified laterally of the internal jugular vein and run posteriorly into sternocleidomastoid muscle. The carotid artery was followed superiorly to the hypoglossal nerve which looped across the internal and external carotid arteries. The internal maxillary artery and ascending palatine artery in the prestyloid were divided along external carotid artery (Figure 2(B)). The parapharyngeal segment began at the level of the common carotid bifurcation and ended in the external orifice of the carotid canal of the petrous bone. Only the inferior part of parapharyngeal ICA beneath the level of the digastric muscle could be seen directly via cervical incision. The superior part was covered by styloid muscles, mandible, maxilla, and zygoma (Figure 3(A)). The posterior bellies of digastric and stylohyoid muscle were performed to allow maximal space for exposure. With the aid of endoscope, the superior segment of the parapharyngeal vessels and cranial nerves could be located clearly. The ICA traveled inside the carotid sheath medial upward to the carotid canal posterior to the root of styloid. The sympathetic nerve was ascending posterior alongside the ICA, which carried the postsynaptic fibers from the superior cervical ganglion. Internal jugular vein (IJV) lied external of carotid sheath ascending to the jugular foramen (JF) (Figure 3(B)). The vagus nerve was located between the accessory and glossopharyngeal nerves descending vertically from the jugular forum. The vagus and accessory nerves ran together in the JF and were encased in the same fibrous sheath. After leaving from JF, the glossopharyngeal nerve descended beneath the stylopharyngeus muscle, then passed downward in the carotid sheath with vagus accessory nerves and was joined by the hypoglossal nerve, which emerged at the hypoglossal canal. The glossopharyngeal nerve descended vertically and then made a curve with angle of 90°–100° and ran in an anteromedial direction (Figure 3(C,D)).