Pharynx and Larynx Flashcards
What is the Pharynx?
A muscular tube that connects the oral and nasal cavity to the larynx and oesophagus. It begins at the base of the skull and and ends at the inferior border of the cricoid cartilage (C6). The Pharynx is made up of three parts:
Nasopharynx - lying behind the nasal cavity
Oropharynx - lying behind the oral cavity
Larngopharynx (hypopharynx) - lying behind the larynx
What does the Nasopharynx do?
The nasopharynx is found between the base of the skull and the soft palate. It is continuous with the nasal cavity, and performs a respiratory function by conditioning inspired air and propagating it into the larynx.
Lined with respiratory epithelium; ciliated pseudostratified columnar epithelium with goblet cells. Contains the adenoid tonsils.
What is the adenoid?
The adenoid, also known as a pharyngeal tonsil or nasopharyngeal tonsil, is the superior-most of the tonsils. It is a mass of lymphatic tissue located behind the nasal cavity, in the roof of the nasopharynx, where the nose blends into the throat.
What is the oropharynx?
The oropharynx is the middle part of the pharynx, located between the soft palate and the superior border of the epiglottis. It contains the posterior third of the tongue, lingual tonsils, palatine tonsils and the superior constrictor muscle. It’s involved in the voluntary and involuntary phases of swallowing.
What is the laryngopharynx?
The laryngopharynx is located between the superior border of the epiglottis and inferior border of the cricoid cartilage (C6). It contains the middle and inferior pharyngeal constrictors. Communicates with the larynx via the laryngeal inlet.
What is Waldeyer’s ring?
Waldeyer’s ring is the ring of lymphoid tissue in the naso- and oropharynx formed by the paired palatine tonsils, the adenoid tonsils and lingual tonsil.
What is the superior pharyngeal constrictor?
Uppermost constrictor located in the oropharynx. Originates from the medial pterygoid plate and the pterygomandibular raphe (extends from the medial pterygoid plate to the mandible). Inserts posteriorly into to the pharyngeal tubercle of the occiput and the median pharyngeal raphe.
What is middle pharyngeal constrictor?
Located in the laryngopharynx. Originates from the stylohyoid ligament and the horns of the hyoid bone. Inserts posteriorly into the pharyngeal raphe.
What is the inferior pharyngeal constrictor?
Located in the laryngopharynx. It has two components: Superior component (thyropharyngeus) has oblique fibres that attach to the thyroid cartilage. Inferior component (cricopharyngeus) has horizontal fibres that attach to the cricoid cartilage.
What innervates the pharyngeal constrictors?
Vagus nerve
What are the pharyngeal constrictors?
Three circular constrictor muscles that constrict the lumen and propel the bolus of food inferiorly into the oesophagus.
The inner aspect of the constrictors are lined by the thick pharyngobasilar fascia which is attached to the pharyngeal tubercle, the Eustachian tube and the medial pterygoid plate. The fascia bridges the gap between the superior constrictor and the base of the skull.
What is Killian’s dehiscence?
The weakest part of the pharyngeal wall is the lower part of the pharynx in the midline. This weakness between the diverging fibres of the thyro-pharyngeal part of the inferior constrictor is known as Killian’s dehiscence.
What makes up the pharyngeal plexus?
It mainly overlies the middle pharyngeal constrictor and is formed by:
Pharyngeal branches from the glossopharyngeal nerve (CN IX).
Pharyngeal branch of the vagus nerve (CN X).
Branches from the external laryngeal nerve.
Sympathetic fibres from the superior cervical ganglion.
How is the pharynx sensory innervated?
Receives sensory innervation from the glossopharyngeal nerve, except the anterior and superior aspect of the nasopharynx (maxillary nerve (CN V2)) and the inferior aspect of the laryngopharynx (the internal branch of the vagus nerve).
How is the pharynx motor innervated?
All the muscles of the pharynx are innervated by the vagus nerve (CN X), except for the stylopharyngeus, which is innervated by the glossopharyngeal nerve (CN IX).
What is the blood supply of the pharynx?
Arterial supply to the pharynx is via branches of the external carotid artery:
Ascending pharyngeal artery
Branches of the facial artery
Branches of the lingual and maxillary arteries.
What is the venous drainage of the pharynx?
Venous drainage is achieved by the pharyngeal venous plexus, which drains into the internal jugular vein.
What is the cervical sympathetic chain made up of?
Posterior to the carotid sheath is the cervical sympathetic chain. It has three ganglia in the neck.
- Superior cervical ganglion just below the skull
- Smaller middle cervical ganglion (may be absent)
- Larger inferior cervical ganglion which is often fused to the first thoracic ganglion to form the stellate ganglion.
The stellate ganglion is situated at a level between the neck of the first rib and the transverse process of the seventh cervical vertebrae.
What is the superior laryngeal nerve?
A branch of the vagus nerve. In its course receives a branch from the superior cervical ganglion of the sympathetic nervous system.
The superior laryngeal nerve passes over the carotid arteries and disappears in the gap between the middle and inferior constrictors. It gives two branches.
The internal laryngeal nerve is a sensory nerve to the larynx above the vocal cords.
The external laryngeal nerve supplies the crico-thyroid muscle and the crico-pharyngeal part of the interior constrictor.
What is the carotid sinus?
A dilated area at the base of the internal carotid artery just superior to the bifurcation of the internal carotid and external carotid at the level of the superior border of thyroid cartilage.
Innervated by the glossopharyngeal nerve.
What does the glossopharyngeal nerve supply?
Cranial Nerve IX. Gives sensory fibres to the posterior third of the tongue (both general sensation and taste) and the oropharynx (general sensation). It also has a tympanic branch which supplies the middle ear and the Eustachian tube. It also supplies the stylopharyngeus muscle, running along its surface.
What is the pharyngeal pouch?
During swallowing the high pressure in the pharynx can cause the mucosa to bulge out through Killian’s dehiscence causing a pharyngeal pouch. Food entering this pouch can cause swelling, difficulty swallowing and bad breath.
How can the carotid sinus be manipulated to treat patients with a fast heart rate?
Pressure on the carotid sinus fools the sensory receptors into thinking the blood pressure is too high. This message is sent to the brain via the glossopharyngeal and then back through the vagus to slow the HR.
Why are patients who have had a stroke prone to infection?
Patients who have had a stroke lose sensation from the glossopharyngeal nerve. When they swallow they can’t detect fluid passing down, meaning fluid enters the lungs and causes infection.
