Blood Supply of Mouth
and Pharynx
Five of the branches of the external
carotid artery are involved in the supply of the mouth and pharynx. The superior
thyroid artery leaves the anterior aspect of the external carotid near its
beginning and courses inferiorly and anteriorly on the external surface of the
inferior pharyngeal constrictor muscle, passing deep to the sternohyoid and
omohyoid muscles to ramify on the anterolateral surface of the thyroid gland.
Near its origin, the superior laryngeal artery pierces the thyrohyoid
membrane to supply the tissues of the larynx. The lingual artery arises
from the anterior surface of the external carotid, a short distance superior to
the superior thyroid artery, opposite the tip of the greater horn of the hyoid
bone. It courses anteriorly and slightly superiorly deep to the stylohyoid
muscle, the posterior belly of the digastric muscle, and the hypoglossal nerve,
and then passes medial to the hyoglossus muscle along the superior border of
the greater horn of the hyoid. The facial artery, coming from the
anterior aspect of the external carotid slightly superior to the lingual, is
tortuous throughout its length to allow for movements of the head and of the
lower jaw. It courses anteriorly and superiorly deep to the digastric and
stylohyoid muscles sheltered by the mandible, lies in a groove on the submandibular
gland, and then curves superiorly around the inferior border of the mandible
near the anterior margin of the masseter muscle. From here it runs anteriorly
and superiorly across the cheek and along the side of the nose, to end as the angular
artery at the medial angle of the eye. The maxillary artery, the
larger of the two terminal branches of the external carotid, passes anteriorly
between the ramus of the mandible and the sphenomandibular ligament (first
part), and continues anteriorly either deep or superficial to the lateral
pterygoid muscle (second part), between the two heads of which it dips to reach
the pterygopalatine fossa (third part). The infraorbital artery, which
is a continuation of the maxillary, courses through the infraorbital canal of
the maxilla to end in terminal branches on the face as it leaves the
infraorbital foramen. The ascending pharyngeal artery arises from the
posteromedial aspect of the external carotid very near its beginning. From here
it ascends vertically between the internal carotid artery and the
posterolateral aspect of the pharynx, to go as high as the undersurface of the
base of the skull.
The lips, which are very vascular, are
supplied chiefly by the superior and inferior labial branches of
the facial artery, each of which courses from near the angle of the mouth,
where they arise, toward the midline of each respective lip to meet the one on
the opposite side. For the most part, they lie between the orbicularis oris
muscle and the mucous membrane related to its inner surface. The mental
branch of the inferior alveolar artery, a branch of the first part of the
maxillary artery, anastomoses with the inferior labial artery, and the labial
branch of the infraorbital artery anastomoses with the superior labial
artery.
The cheek receives much of its
arterial supply by way of the buccal artery, which springs from the
second part of the maxillary artery and runs anteroinferiorly on the external
surface of the buccinator muscle.
The arterial supply of the superior
arcade of teeth, their alveolar processes, and gums is furnished in the artery,
which arises from the second part of the maxillary artery. It courses
inferiorly in the pterygopalatine fossa to divide into several small branches,
most of which enter small foramina on the posterior aspect of the maxilla. The anterior
and less constant middle superior alveolar branches of the
infraorbital artery pass along the wall of the maxillary sinus to supply the
rest of the upper jaw.
The inferior arcade of the teeth with
the related bone and gums are supplied by the inferior alveolar artery. It
enters the mandibular foramen to course in the alveolar canal and ends as the mental
artery, which gives off an incisive branch before exiting through the
mental foramen to supply the chin.
The arterial supply of the tongue is,
for the most part, by way of the lingual artery. The anastomoses between the
branches of the right and left lingual arteries are of a small enough caliber
so that ligation of one artery makes that side of the tongue sufficiently
bloodless for an operative procedure. Under cover of the posterior border of
the hyoglossus muscle, the lingual artery gives off dorsal lingual branches,
which travel superiorly and medial to the styloglossus muscle to supply the
mucous membrane of the dorsum as far back as the epiglottis, anastomosing with
other vessels supplying the tonsil. The portion of the artery from the anterior
border of the hyoglossus forward to the tip of the tongue is the deep
lingual artery, which lies deep to the genioglossus muscle and is under
cover of the mucous membrane on the inferior surface of the tongue.
The mucous membrane of the floor of
the mouth and the sublingual gland receive blood through the sublingual artery,
which branches from the lingual near the anterior border of the hyoglossus
muscle and courses anterior and superior to the mylohyoid muscle and lateral to
the genioglossus. The muscles of the floor of the mouth are supplied by the
submental branch of the facial artery and the mylohyoid branch coming off from
the inferior alveolar just before it enters the mandibular foramen. These two
arteries contribute some blood to the submandibular gland, which gets most of
its supply from the nearby facial artery.
The arterial supply of the palate is
chiefly from the descending palatine branch of the third part of the
maxillary artery, which travels interiorly through the pterygopalatine canal
to emerge from the greater palatine foramen and then courses anterior, medial
to the alveolar process, to anastomose at the incisive foramen with a septal
branch of the sphenopalatine artery. The lesser palatine artery, which
runs posteriorly from the descending palatine at the greater palatine foramen,
supplies the soft palate and anastomoses with other arteries that supply the
tonsil. Anastomoses exist also with a palatine branch of the ascending
pharyngeal artery, the dorsal lingual arteries, and the ascending palatine from
the facial artery.
The pharynx receives blood from many
sources, the amount from each source varying a great deal individually. One of
the chief sources is the ascending pharyngeal artery, usually from the
external carotid artery. Other arteries that run to the pharynx and can thus
contribute to its supply are the ascending palatine and tonsillar branches of
the facial artery, the superior thyroid artery and its superior laryngeal
branch, and the inferior laryngeal and ascending cervical branches of the
thyrocervical trunk from the subclavian artery. The pharyngeal branch of the
third part of the facial artery passes through a bony canal to reach the roof
of the pharynx, and the descending palatine artery, also from the third part of
the facial, contributes to the supply in the region of the tonsil by its lesser
palatine branches.
