Organs - Pharynx

Question 1

What are the divisions of the pharynx?

Where does it start and end?

Answer 1

Nasopharynx

Oropharynx

Laryngopharynx

Starts at the base of the skull and ends at the cricoid (C6).

Question 2

Nasopharynx

Epithelium?

Tonsils?

Answer 2

Between the base of skull and the soft palate - continuous with the nasal cavity.

Respiratory epithelium (ciliated pseudostratified epithelium with goblet cells).

Posterosuperior nasopharynx contains adenoid tonsils.

Question 3

Clinical relevance: enlarged adenoid tonsils

Answer 3

Can become pathologically large due to viral infection of the upper respiratory tract.

These tonsils can obstruct the Eustachian tube.

Chronic obstruction causes Eustachian tube dysfunction, which can lead to otitis media with effusion - increases chances of infection due to negative pressure and static fluid.

Question 4

Oropharynx

Borders?

Contents?

Function?

Answer 4

Located between the soft palate and superior border of the epiglottis.

Contents:

• Posterior 1/3 of tongue
• Lingual and palatine tonsils
• Superior constrictor muscle

Involved in voluntary and involuntary parts of swallowing.

Question 5

Laryngopharynx

Answer 5

Located between the superior border of the epiglottis and the inferior border of the cricoid cartilage (C6).

Continuously inferior with the oesophagus. Posterior to the larynx. Communicates with it via the laryngeal inlet. Laterally to this inlet is the piriform fossae.

Contains the inferior and middle pharyngeal constrictors.

Question 6

Clinical relevance - pharyngeal diverticulum (pouch)

Answer 6

The inferior constrictor muscles is made up of the cricopharyngeus and the thyropharyngeus. The area between the two is the weak area in the mucosa.

Normally in swallowing - thyrophayngeus contracts while the cricopharyngeus relaxes.

Incoordination of these muscles leads to an increase in intrapharyngeal pressure, leading to a midline diverticulum betwee the two muscles. Food can accumulate here - dysphagia can occur.

Question 7

What are the muscles of the pharynx?

Answer 7

1) Three circular constrictors

(superior, middle and inferior pharyngeal constrictor)

2) Three longitudinal muscles

(stylopharyngeus, palatopharyngeus and salpingopharyngeus)

Question 8

What nerve innervates the circular pharyngeus muscles?

Answer 8

Vagus nerve (CN X)

Question 9

Superior pharyngeal constrictor

Answer 9

Oropharynx

Origin - pterygomandibular ligament, medial pterygoid plate

Insertion - pharyngeal tubercle of the occiput and median pharyngeal raphe

Question 10

Middle pharyngeal constrictor

Answer 10

Laryngopharynx

Origin - stylohyoid ligament

Insertion - posteriorly into the pharyngeal raphe

Question 11

Inferior pharyngeal constrictor

Answer 11

Laryngopharynx

Thyropharyngeus (from thyroid)

Cricopharyngeus (from cricoid)

Question 12

Action of the longitudinal muscles?

Answer 12

Shorten and widen the pharynx.

Elevate the larynx when swallowing.

Question 13

Stylopharyngeus

Answer 13

Origin - styloid process

Insertion - pharynx

Innervation - glossopharyngeal (CN IX)

Question 14

Palatopharyngeus

Answer 14

Origin - hard palate of the oral cavity

Insertion - pharynx

Innervation - vagus (CN X)

Question 15

Salpingopharyngeus

Answer 15

Origin - eustachian tube

Insertion - pharynx

Actions - swallowing + opens Eustachian tube

Innervation - vagus (CN X)

Question 16

Innervation of pharynx

Answer 16

Motor and sensory - pharyngeal plexus - mainly overlies the middle pharyngeal constrictor

Formed by:
- pharyngeal branches of the CN IX

• pharyngeal branches of CN X
• branches of external laryngeal
• sympathic fibres of superior cervical ganglion

Sensory innervation - CN IX - superior nasopharynx is by maxillary - inferior laryngopharynx is by vagus (internal branch).

Motor - vagus (CN X) except stylopharyngeus (CN IX)

Question 17

Vasculature

Answer 17

Branches of external carotid:

• Ascending pharyngeal
• branches of facial artery
• branches of lingual and maxillary arteries

Venous drainage - pharyngeal venous plexus