Head & Neck Anatomy (Session 8) PDF

Anatomy of the Pharynx By Assistant Professor Dr. Shilan Hussein Pharynx The pharynx is a fibromuscular tube, attached above to the base of the skull and continuous below with the oesophagus. It is about 12 cm in length unbite 6 is largely deficient and it thereby communicates with the nose, mou...

Anatomy of the Pharynx By Assistant Professor Dr. Shilan Hussein Pharynx The pharynx is a fibromuscular tube, attached above to the base of the skull and continuous below with the oesophagus. It is about 12 cm in length unbite 6 is largely deficient and it thereby communicates with the nose, mouth and larynx. it is descriptively divided into three parts: nasopharynx, oropharynx laryngopharynx. Muscles and fascia The muscular wall is thin. It consists of three curved sheets of muscle, the superior, middle and inferior constrictors supplemented by three smaller muscles: stylopharyngeus, palatopharyngeus salpingopharyngeus. my They overlap posteriorly, being telescoped into each other like three stacked cups. But the muscle does not extend up to the base of the skull; here the immobile wall of the nasopharynx consists of a rigid membrane, the pharyngobasilar fascia. Fifth largest pharyngobasilar fascia. This is a fibrous thickening of the submucosa that fills in the gap between the skull and the upper border of the superior constrictor, making. Superior constrictor The superior constrictor fibres arise from the lower part the medial pterygoid plate down to the tip of the hamulus. The superior constrictor passes backwards from the pterygomandibular raphe; buccinator passes forwards from it. minor gap There is a gap laterally between the superior and middle constrictors, through which stylopharyngeus passes down into the pharynx, styloglossus and the glossopharyngeal and lingual nerves pass forwards to the tongue. Middle constrictor The middle constrictor arises from the lower part of the stylohyoid ligament, the lesser horn of the hyoid bone and the greater horn, Its fibres diverge upwards and downwards and end in the median raphe. The anterior gap between the middle and inferior constrictors is closed by the thyrohyoid membrane , which thereby contributes to the wall of the laryngeal part of the pharynx . Passing through this gap by piercing the membrane are: the internal laryngeal 2Tsuperior laryngeal vessels. nerve and e e Inferior constrictor This has two parts, named from their origins. 1. The thyropharyngeus part arises from the oblique line of the thyroid the Cartilage. f 2. The cricopharyngeus, rounded and thicker than the flat sheets of the other constrictors, extends uninterruptedly from one side of the cricoid arch to the other around the pharynx. There is no raphe here. The muscle acts as a sphincter at the lower extent of the pharynx. Thyrohighbran Is cricophorangen Palatopharyngeus the muscle fibres pass down from the palate they lie internal to the superior constrictor . Salpingopharyngeus Salpingopharyngeus is a very slender muscle that arises from the lower part of the cartilage of the auditory tube and runs downwards to blend with palatopharyngeus. a Stylopharyngeus Stylopharyngeus arises from the deep aspect of the styloid process high up. It slopes down across the internal carotid artery , in front of which it crosses the lower border of the superior constrictor and passes down inside the middle constrictor, to be inserted with palatopharyngeus into the posterior border of the thyroid lamina Blood supply Branches of many arteries supply the pharynx: Ascending pharyngeal, ascending palatine and I tonsillar (from facial), greater palatine and pharyngeal (from maxillary), lingual and the superior and inferior laryngeal arteries. Venous blood is largely collected into the pharyngeal venous plexus ; it drains into the internal jugular vein and has connections with the pterygoid plexus. __ Nerve supply The main motor nerve supply of the muscles of the pharynx is from the pharyngeal plexus. However, 0 Stylopharyngeus is supplied by the glossopharyngeal nerve and cricopharyngeus is also supplied by the recurrent and external laryngeal nerves. Sensory Nerve Supply of the Pharyngeal Mucous Membrane Nasal pharynx: The maxillary nerve (V2) Oral pharynx: The glossopharyngeal nerve Laryngeal pharynx (around the entrance into the larynx): The internal laryngeal branch of the vagus nerve f The nasopharynx The nasopharynx extends from the base of the skull to the upper surface of the soft palate, at the level of C1 vertebra. The opening of the auditory tube lies in the lateral wall . The opening is guarded above, behind and in front by a prominent rounded ridge, the tubal elevation. it underlies the mucous membrane, which here contains lymphatic tissue, the tubal tonsil. If geno Fannie 8 The tubal elevation is continued downwards as the salpingopharyngeal fold, produced by the underlying salpingopharyngeus muscle. In the mucous membrane high on the posterior wall is a collection of lymphoid nodules, prominent only in children and forming the pharyngeal tonsil. When enlarged the nodules are commonly known as the adenoids. The oropharynx a extends from the lower surface of the soft palate to the upper border of the epiglottis. At the sides there are projecting ridges, the palatopharyngeal and palatoglossal arches , formed by the underlying corresponding muscles, with the palatine tonsils between them. The palatine, lingual, pharyngeal and tubal tonsils collectively form an interrupted circle of lymphoid tissue Eg (Waldeyer’s ring) at the upper end of the respiratory and alimentary tracts. The laryngopharynx extends from the upper border of the epiglottis to the level of the lower border of the cricoid cartilage (C6 vertebra) where it becomes continuous with the oesophagus. In the upper part of the anterior aspect is the opening into the larynx (aditus or laryngeal inlet). The piriform recesses, broad above and narrow below, lie beside the aperture of the larynx. At each side of the epiglottis the lateral glossoepiglottic fold separates the oropharynx from the laryngeal part. Below the fold is the piriform recess (piriform fossa) This mucosa-lined space is bounded medially by the quadrangular membrane of the larynx,, and laterally by the thyrohyoid membrane above and the lamina of the thyroid cartilage below. The recesses are danger sites for perforation by an endoscope and lodging of foreign bodies.