Anatomy and relations of the pharynx Flashcards
Where is the location of the pharynx
The pharynx is a mixed soft
tissue space of the upper
airways and the digestive tract
It has a valve (soft palate) to
direct air and food flows
Located behind the nose, the
mouth and the larynx and above
the oesophagus
What are the functions of the pharynx
- Passes food safely across the
airway / food-way crossing (soft
palate acting as a flap-valve) during
swallowing - Helps direct air flow via oral
cavity for maximum air flow and
e.g. during expectoration of
mucus from respiratory system - Closes the upper airway (nasal
cavity) from the oral cavity during
chewing and swallowing
Describe the topographic anatomy of the pharynx
Muscular tube, fastened to the pharyngeal tubercle
of the basi-occipital bone, with anterior attachments
to:
* The occipital bone (pharyngeal tubercle)
* The sphenoid (medial pterygoid plates)
* The mandibular body and ramus (mandibular raphe)
* The greater horn of the hyoid and the thyroid and
cricoid cartilages
* Posterior attachments to the pharyngeal raphe
* Three anterior openings
* Positioned between the trachea and vertebral
column
..and continuous with the oesophagus
Explain the 3 regions of the pharynx (oropharynx, laryngopharynx and nasopharynx)
Nasopharynx:
Located above the palate, behind the nasal cavity, covered by the
sphenoid body and rostrum, contains the adenoids (tonsils) and
the opening of the auditory tube
Oropharynx:
Lies behind the oral cavity, its floor is formed by the posterior part
of the tongue and the space between the tongue and epiglottis.
The roof is formed by the soft palate. Contains the palatine tonsils
and the valleculae
Laryngopharynx:
The lateral wall is formed by thyroid cartilage and the thyrohyoid
membranes. It contains the piriform fossae
Describe the auditory (pharyngotympanic) tube
- Connects the anterior wall of the
tympanic cavity to the nasopharynx - Its posterior 1/3rd is bony, the
anterior 2/3rd are cartilaginous - The opening of the cartilaginous
part into the nasopharynx is in close
proximity to tonsillar tissue around
its entrance (tubal tonsils) - Closely associated with soft palate
muscles and tensor tympani muscle
which help close it (Vagus (X) and
trigeminal nerve, mandibular
division (Viii) innervation)
What is the piriform fossae
These are depressions in
the mucous membrane
on each side of the
laryngeal inlet
- Together with the
valleculae at the base of
the tongue, they
“channel” food and
water around the
laryngeal inlet (choking
prevention)
What are the muscles of the pharynx
The pharynx muscles enable the
pharynx to:
- Assist the movements of the soft
palate: superior constrictor,
palatopharyngeus - Constrict the diameter of the pharynx
and push food boli along their way:
superior, middle & inferior pharyngeal
constrictors - Lift the pharynx as a whole:
palatopharyngeus, stylopharyngeus
and superior constrictor
What are the muscles of the soft palate
1.Tensor veli palatini
2. Levator veli palatini
3. Palatoglossus
4. Palatopharyngeus
5. Superior pharyngeal
constrictor
Relate each muscle of the soft palate to its movement
Tensor veli palatini – stretch/lifts the soft
palate
2) Palatoglossus – lowers the soft palate
anteriorly
3) Levator veli palatini – lifts the soft palate up
4) Superior constrictor – lifts and sphinctercloses the soft palate
5) Palatopharyngeus – lowers the soft palate
posteriorly
What is the blood supply to the pharynx
The pharynx is a deep and posterior located
structure, its blood supply will therefore be
from branches of the external carotid artery.
Branches differ according to pharynx region:
- Ascending pharyngeal artery
- Maxillary artery
- Facial artery (ascending palatine arteries,
tonsillar arteries) - Lingual artery
Venous drainage is via the pharyngeal venous
plexus which drains to the internal jugular
veins
What are the lymphatics in the pharynx
The tonsils are a collection of lymphoid tissues, covered by
mucous membrane at the junction between oral cavity and
the pharynx and the nasal cavity and the pharynx
There are adenoids, tubular tonsils, palatine tonsils and lingual tonsils
What is the nerve supply to the pharynx
Pharyngeal branch of the vagus nerve (X), glossopharyngeal nerve
(IX) and sympathetic fibres from the superior cervical ganglion
Motor supply:
Mostly vagus nerve (X), with contributions from the accessory nerve
(cranial branch) (XI) and the glossopharyngeal nerve (IX), to the
stylopharyngeus on its way from the jugular foramen to the tongue
Sensory supply (mucosa):
Nasopharynx: Maxillary nerve, trigeminal nerve (Vii)
Oropharynx: Glossopharyngeal nerve (IX), gagreflex
Laryngopharynx: sensory laryngeal branches of the vagus nerve (X)
What is the swallowing cycle for
Swallowing transports a mass of chewed food (bolus) or small volume of liquid from the oral
cavity to the stomach. The swallowing cycle can be divided into a series of muscular actions:
* 1. Trap the bolus in the anterior part of the oral cavity
* 2. Move the bolus from the mouth to the entrance of the pharynx
* 3. Allow the bolus to enter the oesophagus while closing off the entrance to the
larynx (vocal and vestibular folds) and nasal cavity (soft palate)
* 4. Transport the bolus through the oesophagus to the stomach
During swallowing there is also a brief interruption of breathing
What are the 3 phases of the swallowing cycle (oral, pharyngeal and oesophageal)
Oral phase:
Tongue is raised against hard palate to push the bolus backward
* Assisted by elevating mandible and raising the hyoid bone
* Soft palate is elevated to close off the nasopharynx and to direct the bolus into
the oropharynx
Pharyngeal phase
- Food contacts the posterior wall of the pharynx (mucosa, glossopharyngeal neve (IX) innervated)
- This contact initiates a sequential contraction of pharyngeal constrictors (involuntary, vagus
nerve (X) innervated). The contraction travels superior to inferior along the pharynx - On the way down, the bolus now contacts the epiglottis and folds it backwards over the
laryngeal inlet (vagus nerve (X) innervated) - Respiration stops, and vestibular and vocal folds are both strongly adducted by interarytenoid muscles to prevent inhalation of food (vagus nerve (X) innervated)
oesophageal phase:
- Contractions of the
cricopharyngeus (lowest part of
inferior pharyngeal constrictor)
initiates passage of the bolus
through the oesophagus - A wave of contractions of the
circular muscles passes down
the oesophagus, coordinated
by the vagal nuclei in the
brainstem
