Download The pharynx: Is a musculomemebranous sac which belongs to the

The pharynx: Is a musculomemebranous sac which belongs to the digestive system and respiratory
tract in common, it is funnel in shape which has:
1-large opening of the funnel face anteriorly and opens to the mouth and nasal cavity.
2-the small opening caudally and continuous by esophagus and larynx. The long axis of it, is directly
oblique, it is about 15cm. in length.
The pharynx bounded by:
1-dorsally by the base of cranium (vomer and the bodies of sphenoid).
2-venterally by the larynx and esophagus.
3-laterally: A-pterygoid muscle. B-palatine muscle. C-hyoid bone muscle. D-in horse related to
the guttural pouch.
The pharyngeal cavity has seven (7) openings which are:
1-The paired posterior nose –rostrodorsally which connect nasopharynx with nasal cavity.
2-The paired eustachian tube –dorsolaterally, opening of the auditory tubes, connect the
nasopharyngeal with auditory tubes and then middle ear.
3-The oral opening (aditus pharynges)-slit like leading from oral cavity into oropharynx.
It is bounded laterally by the palatoglossal arch, dorsally by the soft palate and ventrally by the root
of the tongue.
4-The laryngeal opening –caudoventerally (aditus larynges) it is closed by epiglottis through the
swallowing. It is surrounded by the rostral laryngeal cartilage.
5-The esophagus opening is the entrance to the esophagus closed except when swallowing. Found at
the caudal end of the laryngopharynx.
The pharyngeal cavity consists of two parts:
1-The rostral part: This divided by soft palate into:
A-dorsal channel (dorsally) called nasopharynx which is the part of respiratory system.
B-the ventral part (ventrally) called oropharynx or isthmus. It is extend from the pharyngeal
entrance at the level of the palatoglossal arch to the base of the epiglottis.
This roof is formed by soft palate and the floor is the root of tongue.
2-The caudal part is narrow which is known as the laryngopharynx and common to the respiratory
and digestive system. It is caudal continuation of the oropharynx and extends from the base of
epiglottis to the level of the cricoids cartilage.
Muscle of the pharynx
1-constrictor muscles:
A-anterior group
include:
1-palatopharyngeus muscle
Origin: palatine bone
2-pterygopharyngeus muscle
Origin: pterygoid bone
Both are inserted in the raphe of the pharynx.
B-middle group:
1-cranial (oral) stylopharyngeus muscle
Origin: styloid process. Insertion: lateral wall of pharynx.
2-hyopharyngeal muscle
Origin: thyroid bone.
Insertion: lateral wall of the pharynx.
C-posterior group:
1-thyropharyngeus muscle
Origin: thyroid cartilage.
Insertion: pharyngeal raphe.
2-cricopharyngeus muscle
Origin: cricoid cartilage
Insertion: pharyngeal raphe
2-Dilated muscle of the pharynx: This is include only caudal stylopharyngeal muscle
Origin: styloid process
Insertion: lateral wall of the pharynx.
Structure of the pharyngeal wall: consist from inside to outside:
1-mucous membrane
2-fascia (thin)
4-fascia (thick)
5-tunica adventitia
3-large of pharyngeal muscle
The mucous membranous of the nasopharynx is similar to that of respiratory region of nasal cavity
(ciliated pseudo stratified columnar epithelium), while the mucous membrane of oropharynx is
similar to that of oral cavity, it has stratified sqaumous epithelium.
Lymphatic organs of the pharynx (tonsils):
Tonsil: lymphatic organs consist of combination of the large number of lymph nodules with diffuse
lymphatic tissue. there are two types (follicular tonsils and non follicular tonsil) and the both are
surrounded by connective tissue capsule and well supplied blood vessels .they have efferent
lymphatic, but not have afferent lymphatic.
The tonsils are named according to their position in the pharynx:
1-lingual tonsil: found in the mucosa of the root of the tongue and in the area around the glossoepiglotic fold.
2-palato-tonsil: located either on or in lateral wall of the oropharynx. it is found in the tonsil sinus.
3-tonsil of soft palate: found on ventral surface of the soft palate.
4-paraepiglottis tonsil: found on the base of the epiglottis ,it is absent in dog.
5-pharyngeal tonsil: found in the root of the nasopharynx.
6-tubal tonsil: found in the lateral wall of the pharyngeal opening of the auditory tube (absent in
carnivores).