Download the palate

THE PALATE
The palate forms the upper wall of the oral cavity. It consists of two parts:
 Hard palate
 Soft palate
Anterior 2/3 is represented by the hard palate and the posterior 1/3 by the soft
palate. The hard palate is formed by the palatine process of the maxilla and
horizontal plate of the palatine bone. A seam, raphe palati is seen on the midline of
the palate and in its anterior part can be distinguished from 3 to 6 transverse ridges,
plicae palatinae transversum, that are well developed in new-born, having an
important role in sucking The palatine seam, raphe palati ends in front between the
medial incisors forming a small prominence named incisive papilla, that covers
the incisive canal.
The mucous membrane which covers the palate adheres to the periosteum by
means of dense fibrous tissue. The mucous membrane contains a lot of palatine
glands, which open by means of small orifices on the surface of the palate. The
mucous membrane of the palate is divided into 4 zones as follows:
 The adipose zone that corresponds to the anterior 1/3 of the palate.
 The glandular zone corresponds to the posterior 2/3 of the palate.
 The marginal zone corresponds to the region where the mucous membrane
of the palate continues with the mucous of the gums.
 Zone of the palatine seam corresponds to the raphe palati.
Fig. 11. Zones of the mucous coat of the
hard palate (scheme after I. V.
Gaivoronskii).
1 – the marginal zone;
2 – the incisive papilla;
3 – the adipose zone;
4 – the zone of the palatine seam;
5 – the glandular zone;
6 – the soft palate.
THE SOFT PALATE
The soft palate is a duplication of the mucous membrane in which are lodged
muscles and a fibrous plate, the palatine aponeurosis. The mucous membrane of
the soft palate contains glands.
The anterior margin of the soft palate is attached to the posterior edge of the
hard palate, but its posterior part, velum palatinum extends freely downward and to
the back, having on the midline a tongue-like projection, named uvula.
On the lateral sides of the soft palate there are two arches:
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 Palatoglossal arch – stretches from the soft palate to the lateral surface of
the tongue.
 Palatopharyngeal arch – stretches for some distance on the lateral wall of
the pharynx.
Between the two named arches forms the tonsilar fossa, in which the palatine
tonsil is placed.
The muscles of the soft palate consist of striped muscle tissue. They bound the
fauces, isthmus faucium.
Fig. 12. The muscles of the soft palate.
1 – m. tensor veli palatini;
2 – m. levator veli palatini;
3 – hamulus pterygoideus;
4 – m. palatoglossus;
5 – m. palatopharyngeus;
6 – m. uvulae;
7 – isthmus faucium.
a) Palatopharyngeus muscle – arises from the aponeurosis of the soft palate
and from the pterygoid process. It inserts on the posterior margin of the
thyroid cartilage and on the pharyngeal wall.
Under contraction this muscle depresses the velum palatinum, narrows the isthmus
faucium and dilates the auditory tube.
NB: The isthmus faucium is the orifice, which is located between the oral cavity
and oral part of the pharynx and it is bounded:
 On the both lateral sides - by the palatoglossal and palatopharyngeal
arches.
 Above - by the soft palate (velum palatinum).
 Below - by the root of the tongue.
b) Palatoglossus muscle arises on the inferior surface of the soft palate and
inserts on the lateral side of the tongue. It lowers the velum palatinum and
narrows the isthmus faucium.
c) Levator veli palatini muscle arises from the inferior surface of the base of
the skull and from the inferior surface of the cartilaginous part of the
auditory tube and inserts in the soft palate. This muscle raises the velum
palatinum.
d) Tensor veli palatini muscle arises from the spina ossis sphenoidalis and
from the lateral surface of the cartilaginous part of the auditory tube. Its
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tendon surrounds the hamulus of the pterygoid process, then turns medially
and inserts into the aponeurosis of the soft palate. It tenses the velum
palatinum in the transverse direction.
e) Musculus uvulae arises from the spina nasalis posterior and from the
aponeurosis of the soft palate and inserts within the uvula. This muscle
shortens the uvula.
THE PALATINE TONSIL
The palatine tonsil, tonsilla palatina is a lymphoid organ that accomplishes a
protection function. The palate tonsil possesses a lymphopoietic capacity and some
immunological reactions occur in the lymphopoietic centers.
The palatine tonsil is of an oval shape and it is located in the tonsilar fossa,
which is bounded by the palatoglossal and palatopharyngeal arches. The tonsil
reaches the maximal development in 5-6 years old children.
The palatine tonsil is invested in a thin capsule. The medial surface of the
palatine tonsils is covered with epithelium, having an irregular contour and
containing crypts. The lateral surface is covered by a fibrous capsule which
separates the tonsil from the pharyngeal wall. The vertical diameter of the tonsil is
from 20 to 25 mm; the transverse dimension is 12-15 mm and the anteroposterior
dimension is from 15 to 20 mm.
The facial artery passes next to the tonsil and this fact should be taken into
consideration under surgical intervention. At a distance of about 1cm from the
palatine tonsil passes the internal carotid artery.
THE PHARYNX
The pharynx is an unpaired organ, which is situated in the head and neck
regions and it is a part of the digestive and respiratory systems. It is a connecting
link between the nasal and oral cavities from one side and the oesophagus and
larynx from another one. In the pharynx the respiratory and alimentary canal
intersects with each other.
The pharynx extends from the base of the skull to the level of the VI-VIIth
cervical vertebrae. Its length is about 15 cm. In front of the pharynx are situated the
nasal and oral cavities, and the larynx. Behind the pharynx are situated the basilar
part of the occipital bone and the upper cervical vertebrae. On the both lateral sides
of the pharynx passes the neurovascular patch of the neck: the carotid artery, the
internal jugular vein and the vagus nerve.
Three parts are distinguished in the pharynx:
 The nasal part, nasopharynx, or epipharynx;
 The oral part, oropharynx, or mesopharynx;
 The laryngeal part, laryngopharynx, or hypopharynx.
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Fig. 13. The intersection of the
respiratory and alimentary ways.
1 – cavitas nasi;
2 – pars nasalis pharyngis;
3 – pars oralis pharyngis;
4 pars laryngea pharyngis;
5 – cavitas laryngis;
6 – cartilago epiglotis;
7 – lingua;
8 – cavitas oris;
9 – palatum molle.
The upper wall of the pharynx was named the fornix of the pharynx.
The nasal part accomplishes purely respiratory functions, and its walls do
not collapse. In front the pharynx is connected with the nasal cavity by means of
choanae. On the lateral wall of the nasopharynx is located the pharyngeal opening
of the auditory tube, ostium pharyngeum tubae. Above and behind the tube orifice
there is a protrusion called torus tubarius, which is formed by the prominence of
the cartilaginous part of the auditory tube. By means of the ostium pharyngeum
tubae the nasopharynx connects with the tympanic cavity (middle ear). Behind the
torus tubarius the pharyngeal recess is located. In front and below the ostium
pharyngeum tubae, between the torus tubarius and the velum palatinum is located
the tube tonsil, tonsilla tubaria.
Inferiorly, the torus tubarius continues with the salpingopharyngeal fold, and
from the anterior margin of the ostium pharyngeum tubae stretches the
salpingopalatine fold.
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The oral part of the pharynx is connected to the oral cavity by means of the
isthmus faucium. Behind the oral part of the pharynx is situated the III cervical
vertebra. This part of the pharynx accomplishes a mixed function: it serves both for
the passage of air into the respiratory ways and for passage of food into the
alimentary canal.
The laryngeal part is the lower part of the pharynx. On its anterior wall is
located the aditus laryngis, inlet into the larynx. On the lateral sides of the
laryngeal part of the pharynx, between it and the larynx are located two
depressions called piriform recesses.
At the base of the pharyngeal wall structure is a connective tissue lamina, fascia
pharyngobasilaris, which inserts on the pharyngeal tubercle of the basilar part of
the occipital bone. The inner coat of the pharynx is the mucous membrane and
outside the connective tissue plate is located the muscular coat, which consists of
striped muscle tissue. The external surface of the pharyngeal wall is covered by the
adventitia.
The mucous membrane of the pharynx in the nasal part is lined with ciliated
epithelium, while the oral and laryngeal parts are lined by stratified squamous
epithelium. The mucous membrane of the pharynx contains a lot of mucous glands,
which moisten the pharynx and the food glides into the oesophagus.
The muscular coat of the pharynx consists of striped muscle tissue and two
groups of muscles are distinguished in the pharynx: the longitudinal muscles, or
dilators and the circular muscles, or constrictors.
Constrictors muscles are:
 Superior constrictor of the pharynx consists of 4 parts according to the
anatomical formations from which it originates:
a) Pterygopharyngeal part (from the medial plate of the pterygoid process);
b) Buccopharyngeal part (from the pterygomandibular seam, or raphe);
c) Mylopharyngeal part (from the mylohyoid line);
d) Glossopharyngeal part (from the root of the tongue).
All four parts of the muscle insert to the median line and median seam of the
pharynx, raphe pharyngis.
 Middle constrictor of the pharynx originates from the hyoid bone and
from the base of the pharynx and it inserts to the greater and lesser horns of
the hyoid bone, and then the muscular fibers run towards the median line of
the pharynx. Two parts of this muscle are distinguished:
a) Ceratopharyngeal part (inserts on the greater horn of the hyoid bone).
b) Chondropharyngeal part (inserts on the lesser horn of the hyoid bone).
Then muscular fibers run toward the median line of the pharynx and to the
pharyngeal seam where they end.
 Inferior constrictor of the pharynx consists of two parts according to the
points of its origin:
a) Thyropharyngeal part (from the thyroid cartilage);
b) Cricopharyngeal part (from the cricoid cartilage).
The muscle inserts to the median line of the pharynx and to the pharyngeal seam.
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Contraction of the pharyngeal constrictors muscles assures the propulsion of the
food into the oesophagus.
Dilators are:
 Stylopharyngeus muscle originates from the styloid process and inserts in
the pharyngeal wall and on the superior edge of the thyroid cartilage.
 Palatopharyngeus muscle originates from the aponeurosis of the soft palate
and from pterygoid process and inserts on the posterior margin of the
thyroid cartilage and on the pharyngeal wall. Under contraction this muscle
depresses the velum palatinum, narrows the isthmus faucium and dilates the
auditory tube.
The longitudinal pharyngeal muscles act as elevators and they pull the pharynx
to meet the alimentary bolus.
The adventitia consists of connective tissue fibers, which invest from
outside the pharynx. Mobility of the pharynx is assured by the fact that this organ
is connected to the neighbouring organs by means of loose connective tissue.
Between the posterior surface of the pharynx and prevertebral fascia of the neck is
located the retropharyngeal space that connects with the posterior mediastinum.
THE ACT OF SWALLOWING OR DEGLUTITION
As it was mentioned above in the oral part of the pharynx the respiratory and
digestive tracts intersect and special devices exist, which separate the respiratory
ways from the alimentary tract. By contraction of the tongue muscles the bolus is
pressed against the hard palate by the dorsum of the tongue and then pushed
through the fauces. During this process the soft palate is pulled upward (tensor and
levator veli palatini muscles contract) and the bolus is brought near the posterior
pharyngeal wall (contraction of the palatopharyngeus muscle), the nasal part of the
pharynx being completely separated from the oral part. At the same time the
suprahyoid muscles pull the pharynx upward and the root of the tongue is pulled
downward by contraction of the hyoglossus muscle. The root of the tongue presses
against the epiglottis and depressing it closes the inlet into the larynx. Contraction
of the pharyngeal constrictor muscles assures the propulsion of the food into the
oesophagus. The longitudinal pharyngeal muscles act as elevators and they pull the
pharynx to meet the bolus.
THE OESOPHAGUS
The oesophagus is a tubular organ that connects the pharynx with the stomach
and assures the passage of food from the pharynx into the stomach.
The oesophagus begins at the level of the VI–VIIth cervical vertebrae and ends
at the inferior border of the XIth thoracic vertebra.
Three parts of the oesophagus are distinguished:
 The cervical part
 The thoracic part
 The abdominal part
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The length of the oesophagus is 23-25 cm, but the entire length of it from the
anterior teeth until the cardiac orifice of the stomach is about 40-42 cm.
Fig. 15. The oesophagus.
I – pars cervicalis;
II – pars thoracica;
III – pars abdominalis
1 – pharynx (pars laryngea);
2 – the cricoid constriction;
3 –the aortal constriction;
4 – the diaphragmatic constriction;
5 – the diaphragm;
6 – pars cardiaca ventriculi.
The cervical part of the oesophagus is projected between the VIth cervical and
IInd thoracic vertebrae. In front of it is located the trachea. Behind is the
prevertebral fascia of the neck. On the both lateral sides pass the recurrent
laryngeal nerves and the right and left common carotid arteries.
The thoracic part of the oesophagus topographically is subdivided into three
more parts:
The upper third of the thoracic part of the oesophagus is placed behind and to the
left of the trachea.
In front of it passes the left recurrent laryngeal nerve and the left common
carotid artery.
Behind the oesophagus is located the spinal column.
On the right side of it passes the mediastinal pleura.
Topography of the middle third of the thoracic part:
In front of the oesophagus at the level of the fourth thoracic vertebrae is
situated the aortic arch, and at the level of the fifth thoracic vertebrae is located the
bifurcation of the trachea and the left bronchus.
Behind the oesophagus passes the thoracic lymph duct.
To the left and little posteriorly the descending aorta passes.
To the right side is located the right vagus nerve
To the right and posteriorly is the azygos vein.
Topography of the lower third of the thoracic part:
Behind and to the right passes the thoracic aorta.
In front - is the pericardium and the left vagus nerve.
To the right is the right vagus nerve, and then it passes posteriorly to the
oesophagus.
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Behind – is the azygos vein.
To the left - is the left mediastinal pleura.
Abominal part of the oesophagus:
In front and bilaterally it is covered by peritoneum.
In front and to the right – is the left lobe of the liver.
To the left – is the upper pole of the spleen.
Lymph nodes are found at the junction of the oesophagus with the stomach.
Structure of the oesophageal wall and its regional peculiarities
The oesophageal walls consist of:
 Mucous coat, tunica mucosa
 Submucous layer, tela submucosa
 Muscular coat, tunica muscularis
 Adventitious coat, tunica adventitia
The mucous coat is lined with squamous epithelium and contains a lot of
mucous glands, which facilitate the gliding of alimentary bolus during swallowing.
In the lower part of the oesophagus there are small glands, which are similar in
structure to the cardial glands of the stomach. Due to the presence of the welldeveloped submucous layer the mucous membrane possesses greater mobility and
forms longitudinal folds. The lamina muscularis mucosae as well contributes to the
formation of these folds. In the submucous layer lymphatic follicles are
encountered.
The muscular coat consists of two muscular layers:
 The outer – longitudinal layer provides dilatation of the oesophagus.
 The inner – circular layer provides constriction of the oesophagus.
In the upper part of the oesophagus both layers consist of striped muscle tissue,
but distally they are gradually replaced and in the abdominal part of the
oesophagus almost all the muscular fibers are smooth.
The adventitious coat consists of loose connective tissue by means of which
the oesophagus is connected with the neighbouring organs. The abdominal part of
the oesophagus is covered by the peritoneum.
The oesophagus has three anatomical and two physiological constrictions.
Anatomical constrictions are:
 Pharyngeal constriction (at the origin of the oesophagus).
 Bronchial constriction (at the level of the tracheal bifurcation).
 Diaphragmatic constriction (at the level where the oesophagus penetrates
the diaphragm).
Physiological constrictions of the oesophagus:
 Aortal constriction, where the oesophagus is crossed by the aortal arch.
 The cardiac constriction of the oesophagus is located at the level, where
the oesophagus continues with the stomach.
The anatomical formations that contribute to the prevention of the
gastroesophageal reflux refer the following:
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 The internal sphincter of the oesophagus that is located at the
gastroesophageal boundary (as the mater of fact there is not a real sphincter
of the oesophagus, but it is a functional one, and this function is performed
by the internal layer of the muscular coat of the cardiac part of the stomach).
 The peduncles of the diaphragm.
 The angle of His, that forms at the level where the oesophagus continues
with the stomach. Under normal condition this angle varies form 20 to 90
degrees, and depends on the width of the thorax, see the fig.). The less is the
angle the better functions the sphincter's mechanism. In new-born this angle
is always opened and this fact causes gastroesophageal reflux.
 The mucous coat of the abdominal part of the oesophagus is rich in venous
blood vessels, which form a venous network that keeps the stomach in
hermetic status.
 The intraabdominal pressure.
Fig. 16. The gastroesophageal junction and the His angle (a sharp and an obtuse angle).
Development of the oesophagus and its abnormalities
Esophagus derives from the foregut. In the early stages of development the oesophagus
consists of smooth musculature, which arises from mesenchyme. After the rupture of the
pharyngeal (or buccopharyngeal) membrane, striated musculature of mesodermal origin forms a
layer above, and as a result the upper part of the oesophagus contains a striated muscle tissue, but
the middle and the lower part contain smooth muscle tissue. The tracheoesophageal septum
(located in the frontal plane) divides the foregut into the oesophagus and the trachea.
Abnormalities:
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Esophageal atresia occurs when the esophagus ends as a blind tube. Sometimes between the
oesophagus and the trachea forms a tracheoesophageal fistula.
Age peculiarities of the oesophagus
In newborn the oesophagus has about 10-12 cm in length and from 4 to 9 mm in diameter.
The anatomical constrictions of the oesophagus are slightly developed.
The pharyngeal constriction is well seen. At 11-12 years of age the oesophagus becomes
twice longer, and reaches about 20-22 cm in length.
The beginning of the oesophagus in newborn is located at the level of the III rd-IVth cervical
vertebrae. At the age of 2 years the oesophagus descends until the level of the IV-Vth cervical
vertebrae.
At 10-12 years old the oesophagus reaches the level of the V-VIth cervical vertebrae, and at
age of 15 it reaches the level of the VI-VIIth cervical vertebrae.
In old person the begging of the oesophagus is located at the level of the Ist thoracic vertebrae
(because of muscular weakness).
The muscular coat of the oesophagus in newborn is slightly developed, and it intensively
develops until the age of 15.
The mucous membrane in children until 1 year old is poor in glands. The longitudinal folds
become seen at about 2-2,5 years old.
Topography and projection of the oesophagus on alive person
In alive man the oesophagus projects in the cervical, thoracic and abdominal regions. Its
superior border is situated at the level of the VIth –VIIth cervical vertebrae. Its lower border
projects in front of the XIth thoracic vertebrae and behind to the VIIth left costal cartilage. From
the incisors until the beginning of the oesophagus are accounted 15th cm in male and 13th cm in
female.
Examination on alive person of the oesophagus
The examination of the oesophagus on alive person is performed by means of
oesophagoscopy, X-rays examination, CT. In a healthy man the mucous membrane of the
oesophagus is smooth, velvety and moist. The longitudinal folds are soft and plastic. To perform
the examination of the gastric juice the doctor needs a probe of about 40 cm in length.
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