Pharynx and Esophagus – Digestive System Organs (Nursing)

00:01 The next major organ of the digestive system is the pharynx.

00:05 Recall that the pharynx is divided into three parts.

00:09 The nasopharynx, the oropharynx, and the laryngopharynx.

00:14 Food is going to pass from the mouth into the oropharynx and then into the laryngopharynx.

00:22 This is going to allow the passage of both food fluids and also air.

00:29 The pharynx is made up of a stratified squamous epithelium that is lined with mucus producing glands.

00:38 The external muscle layer of the pharynx consists of two skeletal muscle layers.

00:45 You have an inner layer of muscles that are going to run longitudinally and as well, we have outer pharyngeal constrictors that are going to encircle the wall of the pharynx.

00:58 After the pharynx, the next major organ of the digestive tract is the esophagus.

01:05 The esophagus is a flat muscular tube that runs from the laryngeal pharynx to the stomach.

01:12 It is collapsed until food is actually inside of the esophagus.

01:20 This esophagus begins at the laryngopharynx posterior to the trachea and anterior to the vertebral column.

01:29 It then pierces the diaphragm at a structure known as the esophageal hiatus.

01:37 From there it joins the stomach at the cardial orifice.

01:42 A sphincter known as the gastro esophageal sphincter or cardiac sphincter surrounds the cardial orifice.

01:51 This sphincter keeps the orifice closed when food is not being swallowed.

01:58 Also mucous cells on both sides of the sphincter help to protect the esophagus from acid reflux from the acids of the stomach.

02:10 So next we have swallowing.

02:13 The pharynx and the esophagus are conduits to pass food from the mouth to the stomach.

02:21 The major function of both of these organs is propulsion and propulsion is going to begin with a process of deglutition or swallowing.

02:32 Recall that there is no mechanical or chemical digestion that actually takes place in the pharynx and esophagus.

02:40 Their main function is propulsion.

02:45 When we look at the process of deglutition, we see that it involves the coordination of 22 muscle groups and two major phases.

02:54 The first phase the buckle phase.

02:57 It's going to involve the voluntary contraction of the tongue.

03:01 From there, we had the pharyngel-esophageal phase and which is going to be the involuntary phase.

03:09 This is going to primarily involve the work or stimulation by the vagus nerve.

03:16 This is going to control swallowing by way of the swallowing center in the medulla oblongata and the lower pons.