Pharynx & Oesophagus

Head & Neck Unit – Lecture 13األعسم. جليل حيدر د

The PharynxPharynx is funnel shaped musculo-membranous tube which is deficient anteriorly and situated behind nasal cavities, mouth and larynx. Thus, it is divided into nasal, oral & laryngeal parts. Its upper end is wider lying under the skull and its lower end is narrow and continuous with esophagus opposite 6th cervical vertebra. It is also continuous with mucous membrane of tympanic cavity by the auditory tube.

Muscles of the PharynxSuperior, Middle & Inferior constrictor muscles: Their fibers run in a circular direction. They extend around pharyngeal wall to be inserted into a fibrous band or raphe that extends from pharyngeal tubercle on basilar part of occipital bone of skull down to esophagus. They overlap each other so that middle constrictor lies on outside of lower part of superior constrictor and inferior constrictor lies outside lower part of middle constrictor. Cricopharyngeus is the lower part of inferior constrictor arising from cricoid cartilage. Its fibers pass horizontally around lowest and narrowest part of pharynx and act as a sphincter. Killian's dehiscence is area on posterior pharyngeal wall between upper propulsive part of inferior constrictor and lower sphincteric part (cricopharyngeus).

Stylopharyngeus, Palatopharyngeus and Salpingopharyngeus : Their fibers run in a longitudinal direction.

Interior of the PharynxNasal Pharynx (Nasopharynx):It lies above soft palate & behind nasal cavities. It has submucosal collection of lymphoid tissue called Pharyngeal Tonsil. Pharyngeal Isthmus is the opening in floor between soft palate and posterior pharyngeal wall.Tubal Elevation is elevated ridge of the opening of Auditory Tube on lateral pharyngeal wall. Pharyngeal recess is a depression in pharyngeal wall behind tubal elevation. Salpingopharyngeal fold is a vertical fold of mucous membrane covering Salpingopharyngeus.

Interior of the PharynxOral Pharynx (Oropharynx): It lies behind oral cavity. Its floor is formed by posterior 1/3 of tongue and interval between tongue and epiglottis. Median Glossoepiglottic Fold is a midline foldLateral Glossoepiglottic Fold lies on each side of it . Vallecula is a depression on each side of median glossoepiglottic fold. Palatoglossal and Palatopharyngeal arches are folds on lateral wall of oropharynx covering Palatoglossus & Palatopharyngeal respectively and palatine tonsils lies in between them in Tonsillar fossa. Oropharyngeal isthmus is the interval between the two Palatoglossal arches and marks the boundary between mouth & pharynx.

Interior of the PharynxLaryngeal Pharynx: It lies behind the opening into the larynx. The lateral wall is formed by Thyroid cartilage and Thyrohyoid membrane. Piriform fossa is a depression in the mucous membrane on each side of the laryngeal inlet.

Ascending pharyngeal ArteryTonsillar branches of facial arteriesBranches of maxillary and lingual arteries

Blood Supply of the Pharynx

Lymph Drainage of the Pharynx:

Directly into Deep Cervical Lymph nodes

OR

Indirectly via Retropharyngeal or Paratracheal nodes into deep cervical nodes

Nerve Supply of the Pharynx

Mucous membrane of the pharynx is supplied as follows:

Nasal pharynx: Maxillary nerve. Oral pharynx: Glossopharyngeal nerve Laryngeal pharynx: Internal laryngeal branch of vagus nerve.

Palatine TonsilsThey are two masses of lymphoid tissue located in tonsillar fossa between palatoglossal and palatopharyngeal arches. Each tonsil is covered by mucous membrane on its free medial surface that projects into the pharynx. The tonsil is covered on its lateral surface by a fibrous capsule that is separated from superior constrictor muscle by loose areolar tissue containing External palatine vein descends from soft palate.Lateral to superior constrictor muscle lie Styloglossus muscle, loop of facial artery, & internal carotid artery.Blood Supply: Tonsillar branch of facial artery.Veins pierce superior constrictor to join External palatine, pharyngeal or facial veinsLymph Drainage: by Upper deep cervical lymph nodes.

Waldeyer's Ring of Lymphoid TissueThe lymphoid tissue surrounding opening into respiratory and digestive systems forms a ring. The lateral part of this ring is formed by Palatine tonsils & tubal tonsils (lymphoid tissue around auditory tube opening). Pharyngeal tonsil in roof of nasopharynx forms upper part of the ring, and Lingual tonsil on posterior 1/3 of tongue forms the lower part.

The Esophagus It is a muscular tube about (25 cm) long, extending from pharynx to stomach. It begins at the level of cricoid cartilage, opposite the body of 6th cervical vertebra. It commences in midline, but as it descends through neck, it inclines to the left side.

Relations in the Neck:Anteriorly: Trachea and Recurrent laryngeal nerves (ascend in between trachea&esophagusPosteriorly: Prevertebral layer of deep cervical fascia, longus colli, and vertebral column.Laterally: lobes of thyroid gland and carotid sheath.

Blood Supply in the Neck: Arteries: Inferior thyroid arteries.Veins: Inferior thyroid veins.

Lymph Drainage in the Neck: Deep cervical lymph nodes.

Nerve Supply in the Neck: Recurrent laryngeal nerves & Sympathetic trunks.

End of the Lecture

GOOD LUCK