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