Pharyngeal constrictors (outer circular layer of muscles): contract sequentially to move the bolus of food through the pharynx into the esophagus.The muscles of the pharynx can be divided into two groups:.Middle and inferior pharyngeal constrictors.Squamous cell carcinoma of the hypopharynx most commonly develops in this region.Food particles can become trapped in these spaces.Piriform recess: a set of depressions in the hypopharynx located posterolaterally to both sides of the laryngeal opening.Inferiorly: esophagus at the level of the cricoid cartilage.Superiorly: upper margin of the epiglottis.Extends from the epiglottis to the beginning of the esophagus.Part of the conducting zone of the respiratory system.Inferiorly: upper margin of the epiglottis.Extends from the inferior border of the soft palate to the superior aspect of the epiglottis.Formed by the cartilaginous portion of the medial end of the eustachian tube.A mucosal prominence in the lateral aspect of the nasopharynx that protects the opening of the eustachian tube.Laterally: pharyngeal openings of the eustachian tube (connecting with the tympanic cavities), fossa of Rosenmueller, medial pterygoid plates, and superior pharyngeal constrictor muscles.
Posteriorly: clivus, prevertebral musculature covering C1–C2.Extends from the base of the skull to the soft palate.Diseases that may affect the pharynx include infections ( pharyngitis, tonsillitis, diphtheria, infectious mononucleosis), sleep apnea, dysphagia, and pharyngeal cancer. The pharyngeal mucosa is lined by both stratified squamous epithelium and ciliated pseudostratified epithelium with goblet cells. Motor and sensory innervation are mainly via branches of the vagus and glossopharyngeal nerves. The lymphatics drain directly into the deep cervical nodes, either directly or through the retropharyngeal or paratracheal nodes. The pharyngeal veins drain into the internal jugular vein. The arterial supply is derived from branches of the external carotid artery, the ascending palatine and tonsillar branches of the facial artery, the maxillary artery, and the dorsal lingual branches of the lingual artery. The pharynx plays a role in deglutition, vocalization, and air conduction. from the uvula to the level of the hyoid bone), and the laryngopharynx (extending approx. from the base of the skull to the soft palate), the oropharynx (extending approx. It is divided into the nasopharynx (extending approx. If the eye is adducted by the medial rectus, the orbital axis runs almost perpendicular to the optical axis, so the inferior rectus no longer produces effective ocular depression, and instead produces external rotation and adduction.The pharynx is a musculomembranous cavity that connects the oral and nasal cavities to the larynx and esophagus. Thus, when the physician testing eye movements first asks the patient to follow their finger laterally then inferiorly in the familiar H-shape, the inferior rectus muscle (and the oculomotor nerve that supplies it) are being directly tested. If the eye is abducted by the lateral rectus such that the optical axis lines up with the orbital axis, the inferior rectus produces ocular depression only, and is solely responsible for this movement. This means that the inferior rectus has secondary actions of adduction and external rotation (see figures 2 and 3).
However, because the apex of the orbit is placed medially in the skull, the orbital axis that the inferior rectus runs in does not correspond with the optical axis of the eye in its neutral position. The primary action of the inferior rectus is to depress the eye (see figure 1) 1. Innervated by the oculomotor nerve, which also supplies medial rectus, superior rectus, and inferior oblique muscles. Inferior rectus is crossed by the inferior oblique muscle, which runs inferior to it as it crosses the floor of the orbit.īranches of the ophthalmic artery, itself a branch of the internal carotid artery.
Inferior rectus runs anteriorly on the inferior surface of the eye and inserts into the inferior surface of the sclera just posterior to the junction of cornea and sclera 2. Inferior rectus, along with the other rectus muscles, arises from the annulus of Zinn, the common tendinous ring at the apex of the orbit that surrounds the optic canal 1.
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