[X]
01
Click on the structure to specify the target of your label
01
  • labels

Pharynx


General Information

The pharynx is the part of the digestive tube that is place behind the nasal and oral cavities and the larynx. It is a musculomembranous tube. Its base faces superiorly and its apex inferiorly. It extends from the under surface of the skull to the level of the cricoid cartilage anterior and that of the sixth cervical vertebra. The cavity of the pharynx is about 12.5 centimeters long. Its greatest breadth is immediately below the base of the skull. Here, it projects on either side behind the pharyngeal ostium of the auditory tube as the pharyngeal recess. Its narrowest point is at its termination in the esophagus.

Relations and Parts

The pharynx is limited superiorly by the body of the sphenoid and basilar part of the occipital bone. It is continuous with the esophagus. Posteriorly, it is connected by loose connective tissue with the cervical portion of the vertebral column and the prevertebral fascia covering the longus colli and longus capitis muscles. Anteriorly, it is incomplete and is attached in succession to the medial pterygoid plate pterygomandibular raphe, mandible, tongue, hyoid bone, and thyroid and cricoid cartilages. Laterally, it is connected to the styloid processes and their muscles. It is in contact with the common and internal carotid arteries, internal jugular veins, glossopharyngeal, vagus, and hypoglossal nerves, and the sympathetic trunks. It communicates with the nasal cavities, tympanic cavities, oral cavities, the larynx, and the esophagus. The cavity of the pharynx may be divided into three portions: nasopharynx, oropharynx, and laryngopharynx. The nasopharynx lies behind the nose and above the level of the soft palate. It differs from the oropharynx and the laryngopharynx because its cavity always remains open. Anterior it communicates through the choanae with the nasal cavities. On its lateral wall is the pharyngeal ostium of the auditory tube. This ostium is triangular and bound behind by a firm prominence that is caused by the medial end of the cartilage of the tube which elevates the mucous membrane. The salpingopharyngeal fold stretches from the lower part of the torus. The salpingopalatine fold stretches from the upper part of the torus to the palate. Posterior to the ostium of the auditory tube is the pharyngeal recess. Superior to the pharyngeal tonsil, the pharyngeal bursa extends up as far as the basilar process of the occipital bone. The oropharynx reaches from the soft palate to the level of the hyoid bone. It opens anteriorly into the mouth. The palatine tonsil is on its lateral wall. The laryngopharynx reaches from the hyoid bone to the lower border of the cricoid cartilage. Here, it is continuous with the esophagus. Anterior it presents the triangular entrance of the larynx. The base of the larynx is directed forward and is formed by the epiglottis and its lateral borders are formed by the aryepiglottic folds.

Relations and Parts

The pharynx is limited superiorly by the body of the sphenoid and basilar part of the occipital bone. It is continuous with the esophagus. Posteriorly, it is connected by loose connective tissue with the cervical portion of the vertebral column and the prevertebral fascia covering the longus colli and longus capitis muscles. Anteriorly, it is incomplete and is attached in succession to the medial pterygoid plate pterygomandibular raphe, mandible, tongue, hyoid bone, and thyroid and cricoid cartilages. Laterally, it is connected to the styloid processes and their muscles. It is in contact with the common and internal carotid arteries, internal jugular veins, glossopharyngeal, vagus, and hypoglossal nerves, and the sympathetic trunks. It communicates with the nasal cavities, tympanic cavities, oral cavities, the larynx, and the esophagus. The cavity of the pharynx may be divided into three portions: nasopharynx, oropharynx, and laryngopharynx. The nasopharynx lies behind the nose and above the level of the soft palate. It differs from the oropharynx and the laryngopharynx because its cavity always remains open. Anterior it communicates through the choanae with the nasal cavities. On its lateral wall is the pharyngeal ostium of the auditory tube. This ostium is triangular and bound behind by a firm prominence that is caused by the medial end of the cartilage of the tube which elevates the mucous membrane. The salpingopharyngeal fold stretches from the lower part of the torus. The salpingopalatine fold stretches from the upper part of the torus to the palate. Posterior to the ostium of the auditory tube is the pharyngeal recess. Superior to the pharyngeal tonsil, the pharyngeal bursa extends up as far as the basilar process of the occipital bone. The oropharynx reaches from the soft palate to the level of the hyoid bone. It opens anteriorly into the mouth. The palatine tonsil is on its lateral wall. The laryngopharynx reaches from the hyoid bone to the lower border of the cricoid cartilage. Here, it is continuous with the esophagus. Anterior it presents the triangular entrance of the larynx. The base of the larynx is directed forward and is formed by the epiglottis and its lateral borders are formed by the aryepiglottic folds.

Muscles of the Pharynx

The inferior pharyngeal constrictor is the thickest of the constrictors. It arises from the sides of the cricoid and thyroid cartilage. From the cricoid cartilage it arises in the interval between the cricothyroideus anterior and the articular facet for the inferior cornu of the thyroid cartilage posterior. On the thyroid cartilage it arises from the oblique line on the side of the lamina, from the surface behind this nearly as far as the posterior border and from the inferior cornu. From these origins the fibers spread posterior and medial to be inserted with the muscle of the opposite side into the fibrous raphe in the posterior median line of the pharynx. The inferior fibers are horizontal and continuous with the circular fibers of the esophagus. The rest of the fibers ascend, increasing in obliquity, and overlap with the middle pharyngeal constrictor. The middle pharyngeal constrictor is a fan shaped muscle. It arises from the whole length of the upper border of the greater cornu of the hyoid bone, from the lesser cornu, and also from the stylohyoid ligament. The fibers diverge from their origin: The lower ones descend beneath the inferior constrictor, the middle fibers pass transversely, and the upper fibers ascend and overlap the superior constrictor. It inserts into the posterior median fibrous raphe, blending in the midline with the muscle of the opposite side. The superior pharyngeal constrictor is a quadrilateral muscle; this is the thinnest of the three constrictors. It arises from the lower third of the posterior margin of the medial pterygoid plate and its hamulus, from the pterygomandibular raphe, from the alveolar process of the mandible above the posterior end of the mylohyoid line, and by a few fibers from the side of the tongue. The fibers curve backward to be inserted into the median raphe; it is also attached by means of an aponeurosis to the pharyngeal spine on the basilar part of the occipital bone. The superior fibers arch beneath the levator veli palatine and the auditory tube. The interval between the upper border of the muscle and the base of the skull is closed by the pharyngeal aponeurosis. The stylopharyngeus is a long slender muscle, cylindrical above, flattened below. It arises from the medial side of the base of the styloid process. It then passes downward along the side of the pharynx between the superior and middle constrictor, and spreads out beneath the mucous membrane. The glossopharyngeal nerve runs on the lateral side of this muscle and crosses over it to reach the tongue. The salpinopharyngeus muscle arises from the inferior part of the auditory tube near its orifice. It passes downward and blends with the posterior fasciculus of the pharyngopalatinus.

Innervation

The muscles of the pharynx are supplied by branches from the pharyngeal plexus, branches from the external laryngeal and recurrent nerve, and by the glossopharyngeal nerve.

Comments

Related Images

View All