University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2024
Views:

132

Pages:

26
Author:

strofamay56

Pharynx Pharynx • Muscular tube lying behind the nose, oral cavity & larynx. • Extends from the base of the skull to level of the 6th cervical vertebra, where it is continuous with the esophagus. • The anterior wall is deficient and shows (from above downward): § Posterior nasal apertures § Opening of the oral cavity § Laryngeal inlet N OC L Pharyngeal Wall • It is a musculo-membranous wall, composed of: § Mucosa & submucosa § Pharyngobasilar fascia § Muscles: circular & longitudinal § Buccopharyngeal fascia • The buccopharyngeal fascia is separated from the prevertebral fascia by the retropharyngeal space. Retropharyngeal Space • A potential space between the buccopharyngeal fascial lining of the pharynx and the prevertebral fascia. • Contains loose areolar tissue. • Closed: § Superiorly (by the base of the skull) § Laterally (by the carotid sheath) • Open inferiorly into the superior mediastinum. • Allows movement of pharynx, esophagus, larynx, and trachea during swallowing. Retropharyngeal abscess Circular (Constrictor) Muscles “External Layer” Pharyngobasilar Fascia • Three in number: Superior, Middle & Inferior • Extend around the pharynx and are inserted posteriorly into a fibrous raphe that extends from the pharyngeal tubercle on the occipital bone to the esophagus. • The three muscles overlap each other. The gap between the superior border of the superior constrictor and the occipital bone is filled by thickened pharyngobasilar fascia. • Superior constrictor § Origin: pterygoid hamulus, pterygomandibular ligament, mylohyoid line § Insertion: pharyngeal tubercle, pharyngeal raphe • Middle constrictor § Origin: lower part of stylohyoid ligament, greater & lesser horn of hyoid bone § Insertion: pharyngeal raphe • Inferior constrictor § Origin: oblique line of thyroid cartilage, cricoid cartilage § Insertion: pharyngeal raphe • Functions: • The constrictor muscles propel the bolus of food down into the esophagus. • Cricopharyngeus (lower fibers of the inferior constrictor) act as a sphincter, preventing the entry of air into the esophagus between the acts of swallowing. Longitudinal Muscles “Internal Layer” • Three in number: • Salpingopharyngeus • Palatopharyngeus • Stylopharyngeus • Function: § Elevate the larynx & pharynx during swallowing. • Salpingopharyngeus § Origin: auditory tube § Insertion: blends with palatopharyngeus. • Palatopharyngeus § Origin: palatine aponeurosis § Insertion: posterior border of thyroid cartilage, pharynx and esophagus. • Stylopharyngeus § Origin: styloid process § Insertion: posterior border of thyroid cartilage. Division • Pharynx is divided into three parts: § Nasopharynx: § Superior part, communicates with the nasal cavity through posterior nasal apertures. § Oropharynx: § Middle part, communicates with the oral cavity through the oropharyngeal isthmus. § Laryngopharynx: § Inferior part, communicates with the larynx through the laryngeal inlet. Nasopharynx Boundaries: • Roof: body of sphenoid & basal part of the occipital bone. Pharyngeal tonsils (adenoides) present in the submucosa • Floor: upper surface of soft palate & the pharyngeal isthmus (opening between the free margin of soft palate and posterior pharyngeal wall) • Anterior wall: Shows posterior nasal apertures • Posterior wall: Supported by anterior arch of atlas (C1) • Lateral wall shows: § § § § § Opening of pharyngotympanic tube Tubal elevation (torus tubarius), produced by posterior margin of tube. Pharyngeal recess Tubal tonsil Salpingopharyngeal fold (raised by salpingo-pharyngeus muscle) Oropharynx • Lies behind the mouth. • Extends from soft palate to upper border of epiglottis. Boundaries: • Roof: soft palate and pharyngeal isthmus. • Floor: posterior one third of tongue, median & lateral glossoepiglottic folds, and the valleculae. Epiglottis • Anterior wall: opening of the oral cavity • Posterior wall: supported by body of C2 and upper part of body of C3 vertebrae. • Lateral wall shows: § Palatopharyngeal folds posterior to the palatoglossal folds. § Palatine tonsil located between them in the Tonsillar fossa Laryngopharynx • Lies behind the laryngeal inlet & the posterior surface of larynx. • Extends from upper border of epiglottis to lower border of cricoid cartilage. Boundaries: • Anterior wall: has opening of the larynx in the upper part and below that is the mucosa covering the posterior surface of larynx. Epiglottis • Posterior wall: supported by bodies of C3, 4, 5, 6 vertebrae. • Lateral wall: § Supported by thyroid cartilage and thyrohyoid membrane. § On each side of laryngeal inlet, lies the piriform fossa. Piriform Fossa • A small depression situated on either side of the laryngeal inlet. • Leads obliquely backward and downward from the region of the back of the tongue to the esophagus • It is a common site for the lodging of foreign bodies. v Bounded: § Medially by the aryepiglottic fold § Laterally by the lamina of thyroid cartilage & the thyrohyoid membrane. • Branches of internal laryngeal (& recurrent laryngeal) nerve lie deep to the mucous membrane of the fossa and are vulnerable to injury during removal of a foreign body. Nerve Supply • Sensory Nerve Supply: § Nasopharynx: Maxillary nerve (V2). § Oropharynx: Glossopharyngeal nerve (IX) § Laryngopharynx: Internal laryngeal branch of the vagus nerve (X). • Motor Nerve Supply: § All the muscles of pharynx, except the stylopharyngeus, supplied by the pharyngeal plexus. § The stylopharyngeus is supplied by the glossopharyngeal nerve. Blood Supply & Lymphatics Arterial supply is derived from branches of: • Ascending pharyngeal artery • Ascending palatine artery • Facial artery • Maxillary artery • Lingual artery Blood Supply & Lymphatics Veins of the pharynx form a plexus, which drains superiorly into the pterygoid plexus in the infratemporal fossa, and inferiorly into the facial and internal jugular veins. • The lymphatics drain into the deep cervical lymph nodes either directly, or indirectly via the retropharyngeal or paratracheal lymph nodes. Clinical Notes Adenoids (enlarged pharyngeal tonsils) & adenoidectomy. • Adenoids results in obstruction to nasal breathing and make mouth breathing necessary. The patient develops a typical facial expression called the ‘adenoid facies. May also cause impaired hearing. • Otitis media (middle ear infection), secondary to infection of nasopharynx. • Tonsillitis & Tonsillectomy Adenoid facies • Peritonsillar abscess (quinsy), is a complication of tonsillitis and consists of a collection of pus beside the tonsil (peritonsillar space). • Piriform fossa: a common site for the lodging of foreign bodies • Pharyngeal pouch, posteromedial herniation of mucosal diverticulum between thyropharyngeal and cricopharyngeal parts of the inferior constrictor muscle leading to dysphagia (difficulty in swallowing). It occurs mainly in older people. • Retropharyngeal abscess, may spread to the superior mediastinum.

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