GROSS ANATOMY
OF THE PHARYNXDOSUMU O.O
Introduction
The pharynx, (throat),
extends behind the nasal
and oral cavities until the
voice box (larynx) and the
esophagus.
It begins at the base of the
skull, and ends at the
inferior border of the
cricoid cartilage (C6).
Measures 12–14 cm in length
Widest above, where it
measures 3.5 cm but narrows
below where it is 1.5 cm wide (pharyngo-esophageal
junction)
Is invested externally by the
bucopharyngeal fascia
Structure of the Pharynx
Consists of 4 layers, from internal to
external these layers are:
Mucous membrane- (lined by
ciliated pseudostratified columnar
epithelium in the nasopharynx,
and non-keratinized stratified
squamous epithelium in the
oropharynx and laryngopharynx).
Fibrous layer- which is thickened above as pharyngobasilarfascia
Muscular layer-which consists of skeletal muscle fibres, and
Bucopharyngealfascia- which is a layer of connective tissue
• It is comprised
of three parts (superior to
inferior):• Nasopharynx
• Oropharynx
• Laryngopharynx
Nasopharynx
Is the part of the pharynx
located above the soft
palate, and behind the
nasal cavities (Fig. 160)
Is respiratory in function
and; lined by respiratory
epithelium (ciliated
pseudostratified
columnar)
Communicates anteriorly with the nasal cavities via the choanae
Is linked to the tympanic cavities by the pharyngotympanic (auditory) tubes. These open onto the lateral walls of the pharynx (one on each side)
Is continuous below with the oropharynx, thru the pharyngeal isthmus. The latter is closed during swallowing by the soft palate
The pharyngeal opening of each auditory tube is bounded above and behind by a mucosal elevation – tubal elevation.
Descending from the tubal elevation is a vertical fold of mucosa- the salpingopharyngeal fold; contains salpingopharyngeus
Behind the tubal elevation, the pharyngeal wall has a lateral depression-pharyngeal recess
In the roof and posterior wall of the nasopharynx are the pharyngeal tonsils (adenoids)
These are aggregations of lymphoid tissue (and are more prominent in children).
Their inflammation (tonsillitis may necessitate tonsillectomy [surgical removal]).
Oropharynx
Extends from the soft
palate above to the upper
border of the epiglottis
below
Communicates anteriorly
with the buccal cavity thru
the oropharyngeal isthmus
below which is the
pharyngeal part of tongue
Is bounded laterally by the palatoglossal and palatopharyngeal arches; Between these is a triangular tonsillar fossa that lodges the palatine tonsil
Related posteriorly to the C2 and C3 vertebrae
Has a lining of non-keratinized stratified squamous epithelium
Laryngopharynx
Extends from the upper
border of epiglottis
above to the lower
border of cricoid
cartilage below
Narrows markedly at its
lower end where it is
continuous with the
oesophagus
Is related anteriorly to
the larynx, with which it is
continuous (via the
laryngeal inlet) and
posteriorly to c3-c6
Has, on each side of the
laryngeal inlet, a small
fossa- the piriform recess.
Pharyngeal muscles
There are two main groups
of pharyngeal muscles-
Circular (constrictors) and
longitudinal muscles
As a rule all muscles of the
pharynx are innervated by
Vagus except
stylopharyngeus
(Glossopharyngeal)
Constrictors
They form an incomplete
circle and contract
sequentially (sup-inf) to
move food down to
esophagus. They are:
Superior constrictor
Middle constrictor
Inferior constrictor
Superior constrictor
Origin:
Pterygomandibular ligament,
alveolar process of mandible
and medial pterygoid plate and
pterygoid hamulus of the
sphenoid bone.
Insertion:
Pharyngeal tubercle of occiput;
the median pharyngeal raphe.
Middle constrictor
Origin: Stylohyoid ligament and the horns
of the hyoid bone.
Insertion: Pharyngeal
raphe.
All pharyngeal constrictors are
innervated by Vagus
Inferior constrictor
Has 2 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.
Insertion: Pharyngeal raphe
Longitudinal muscles
The longitudinal muscles
are:
Stylopharyngeus,
Palatopharyngeus
Salpingopharyngeus.
They act to shorten and
widen the pharynx, and
elevate the larynx during
swallowing.
Stylopharyngeus – from the styloid process of the
temporal bone, inserts into the pharynx.
Palatopharyngeus – arises from hard palate of the oral
cavity, inserts into the pharynx.
Salpingopharyngeus – arises from the Eustachian tube,
inserts into the pharynx.
All supplied by vagus except stylopharyngeus
InnervationMotor and sensory innervation of the majority of the
pharynx (except nasopharynx) is thru the pharyngeal
plexus.
The pharyngeal plexus 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.
Vascular supply
Arterial- via branches of the external carotid artery:
Ascending pharyngeal artery
Branches of the facial artery
Branches of the lingual and maxillary arteries.
Venous drainage- by the pharyngeal venous
plexus, which drains into the internal jugular vein.
Lymph vessels of the pharynx end in the
following nodes:
Upper deep cervical nodes (these drain the
nasopharynx)
Retropharyngeal nodes, located in the
retropharyngeal space
Lower deep cervical nodes
“Clinical titbit”
The inferior pharyngeal
constrictor is split into two
parts; thyropharyngeus and
cricopharyngeus.
This area btw the two is a
weak area in the mucosa.
If their activities are
uncoordinated, it can lead to
a midline diverticulum in the
pharynx