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On account of the very slender anastomosis between the vessels of the two halves f the tongue, scarcely any bleeding occurs when the organ is split in the median lane.
According to Poirier, the collecting trunks which arise from the lymph networks in the mucous membrane and muscular substance of the tongue may be ivided into four groups: (1) Apical trunks which open partly into the submental lands and partly into a gland of the medial deep cervical group lying immediately bove the anterior belly of the omo-hyoid muscle. (2) Marginal trunks which pass, come lateral to the sublingual gland and through the mylo-hyoid muscle, to join the most anterior of the submaxillary lymph glands; others pass medial to the subingual gland, in front of and behind the hyoglossus muscle, to join the glands of the medial deep cervical group. The more anterior their lingual origin the lower in the chain is the gland to which they pass. (3) The basal trunks, from the posterior third of the tongue, pass from before backwards towards the inferior extremity of the tonsils, where they pierce the superior and middle constrictors of the pharynx, and, after surrounding the lingual artery, open into a gland placed on the internal jugular vein immediately below the posterior belly of the digastric. (4) The central trunks, which descend in the middle line between the genio-glossi, pass beneath the hyoglossus and mylo-hyoid muscles into the submaxillary space, and thence in front of the hyoid bone (having embraced the tendon of the digastric) to join the glands of the medial deep cervical group.
Between the tongue and the lingual surface of the gums is the alveolo-glossal sulcus, crossed in the median plane by the frenulum linguæ, which passes upwards to the inferior surface of the tongue (Fig. 1084). Immediately on either side of the lower part of the frenulum is the orifice of the submaxillary duct. A little external to the frenulum the profunda veins are seen lying immediately under the thin mucous membrane; to the lateral side of the veins are the profunda arteries and the lingual nerves, both of which lie deeper than the veins, and are therefore not visible.
The mucous membrane at the anterior part of the floor of each alveolo-glossal sulcus is thrown into a slight elevation, which overlies, and is caused by, the corresponding sublingual salivary gland. The duct of the submaxillary gland and the lingual nerve lie beneath and to the medial side of the sublingual gland.
In dividing a shortened frenulum for "tongue-tie" the deep lingual vessels and the orifices of the submaxillary ducts must be avoided. Behind the frenulum linguæ are the anterior borders of the genio-glossi, which descend to the superior genial tubercles. In operations necessitating the removal of the region of the symphysis of the mandible, or the separation of the origins of the genio-glossi, the tongue must be kept forward, otherwise the patient will be suffocated by the organ falling backwards over the entrance to the larynx. In removing a small salivary calculus from the floor of the mouth the calculus should be fixed with the finger against the lingual surface of the mandible before cutting down upon it.
When the teeth are clenched the vestibule of the mouth communicates behind the last molars with the oral cavity proper through an opening which barely admits a medium-sized catheter. Hence, when the jaws cannot be separated it is generally necessary to feed the patient through a tube passed along the floor of the nose.
When the mouth is opened widely and a deep inspiration is taken, the soft palate is elevated, and the glosso-palatine and pharyngo-palatine arches are rendered prominent. The glosso palatine arches spring from the anterior surface of the soft palate, close to the base of the uvula, and arch downwards and laterally, in front of the palatine tonsils, to end at the posterior end of the side of the tongue. The pharyngo-palatine arches are really the continuation of the lower free border of the soft palate downwards behind the palatine tonsils to become attached to, and lost upon, the side wall of the pharynx. Together with the lower edge of the soft palate and the base of the tongue they bound a hemispherical opening (pharyngo-nasal isthmus), through which the mucous membrane covering the posterior wall of the nasal portion of the pharynx is visible. The palatine tonsils (Fig. 1085) lie one on each side of the isthmus, between the palatine arches; they are situated opposite the angle of the mandible, but they cannot
be felt from the outside. Each tonsil is covered, on its free surface, by mucous vi membrane upon which are seen the orifices of the tonsillar crypts; the lateral or alte deep surface is covered by a layer of fibrous tissue which forms an imperfect capsule to the organ. According to Merkel, the internal carotid artery is situated 1.5 cm. behind the lateral margin of the tonsil, which is separated from the superior constrictor by a quantity of loose cellular tissue and fat, so that the gland can be grasped with a volsellum and pulled forwards without dragging the vessel with it. The tonsil receives its blood-supply mainly from a small vessel derived from the anterior palatine artery; when this branch is larger than usual and adherent to
FIG. 1085.-HORIZONTAL SECTION THROUGH MOUTH AND PHARYNX AT THE LEVEL OF THE TONSILS. The stylopharyngeus, which is shown immediately to the inner side of the external carotid artery, and the prevertebral muscles, are not indicated by reference lines. (From Birmingham).
the capsule of the tonsil the bleeding which attends the operation of removal of the tonsils may be considerable. The hæmorrhage can be arrested by pressing the bleeding point outwards against the internal pterygoid and the ramusof the mandible. If the bleeding be from a spurting vessel of larger size, its source, according to Merkel, is probably the external maxillary artery, which has been wounded as it arches upwards beneath the digastric and stylo-hyoid muscles to within a short distance from the lateral surface of the tonsil. In children and adolescents the tonsils are frequently hypertrophied; the enlargement may be either general, more towards the median line, downwards along the pharynx, or upwards behind the soft palate; to expose and thoroughly remove the last-mentioned variety of enlarge ment the upper part of the glosso-palatine arch must be divided.
The mucous membrane and the periosteum of the hard palate are so closely united as to form practically one membrane. The greater palatine arteries, after
leaving the greater palatine foramina, run forwards in shallow grooves in the hard palate, close to its alveolar margin. In the operation for cleft palate (staphylorraphy), in order to secure nourishment for the muco-periosteal flaps, the lateral incisions should be made lateral to those vessels.
Secondary hæmorrhage after the operation for cleft palate is treated by plugging the greater palatine foramen, which lies a little medial to the last molar tooth about in. in front of the hamular process, which can be felt at the superior extremity of the fold of mucous membrane containing the pterygo-maxillary ligament. In the closure of a wide cleft of the soft palate the tension of the tensor veli palatini muscle is got rid of by chipping off the hamulus with a small chisel introduced at the posterior extremity of the lateral relief incisions.
Nasal Part of the Pharynx.-To explore the superior or nasal part of the pharynx the finger should be hooked upwards behind the soft palate. Anteriorly, the finger readily detects the sharp posterior border of the vomer, the choanae, and the posterior extremity of the middle and inferior concha. The roof of the space is formed by the basilar part of the occipital bone, while upon the posterior wall is a transverse bony ridge caused by the projection of the anterior arch of the atlas. Upon the side walls of the nasal part of the pharynx are the openings of the auditory tubes, situated in. behind the posterior extremities of the inferior concha. The orifices, bounded superiorly and posteriorly by a prominent margin, are directed downwards and forwards, and, therefore, in a direction favourable to the passage of the Eustachian catheter. Behind the prominent posterior margin of the orifice is the recess of the pharynx (O.T. fossa of Rosenmüller), in which the point of the Eustachian catheter is apt to become engaged. Upon the roof and posterior wall of the pharynx, down to the level of the anterior arch of the atlas, and extending laterally as far as the orifices of the auditory tubes, is a collection of adenoid tissue, the pharyngeal tonsil. Hypertrophy of this tissue constitutes the condition known as " adenoids," the harmful effects of which are due to their interference with nasal respiration. Upon the centre of the pharyngeal tonsil is an orifice leading into a small recess into which numerous mucous glands open. The structures felt in the post-nasal space may be rendered visible by reflecting the light upon a small mirror placed immediately behind and below the soft palate (posterior rhinoscopy). The inferior part of the inferior concha is obscured from view by the bulging of the superior surface of the soft palate.
In plugging the posterior nares, it is important to remember that those openings measure nearly one inch in the vertical and half an inch in the transverse direction. In the child, owing to the small size of the face, the vertical diameter of the nasopharynx is relatively much smaller than in the adult.
The lymph vessels from the nasal cavities and pharynx, including the palatine and pharyngeal tonsils, join the sub-parotid and superior deep cervical glands, one of which lies medial to the carotid vessels between the recess of the pharynx and the prevertebral fascia. In children suppuration originating in this gland is the commonest cause of a retro-pharyngeal abscess.
In the adult the four upper cervical vertebræ can be explored from the mouth, while in the child the finger can also reach as far down as the sixth vertebra and the back of the cricoid cartilage.
The general envelope of deep cervical fascia, along with the processes and partitions which proceed from its deep surface, subdivides the neck into compartments which limit and determine the spread of pus. The most important compartment is the central or visceral compartment, bounded anteriorly by the pretracheal fascia, posteriorly by the prevertebral fascia, and laterally by the fascia forming the vascular compartment. Posteriorly, this compartment extends from the base of the skull downwards into the posterior mediastinum; anteriorly, it extends from the hyoid bone into the anterior part of the superior mediastinum. Abscesses in the visceral compartment are either secondary to disease of the lymph glands or organs it
contains, or the result of a primary suppurative cellulitis. A tubercular abscess th originating in one of the retropharyngeal lymph glands (Fig. 1085) lies in front the of the prevertebral fascia, and points towards the posterior wall of the pharynx;d abscesses secondary to disease of the cervical vertebræ lie behind the prevertebral erval fascia, and spread laterally behind the vascular compartment; they point behind and the sterno-mastoid, and should be opened through an incision at the posterior border of the muscle, the surgeon keeping to the anterior aspect of the transverse sthesio processes in order to avoid the structures in the vascular compartment (Chiene).
In front of the visceral compartment is a small muscular compartment containing this the infra-hyoid muscles; anterior to it again, in the region of the supra-sternal her notch, is the small supra-sternal compartment, containing the lower part of the
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anterior jugular veins, along with their transverse communicating branch, a little fat, and one or two lymph glands.
The vascular compartment contains the carotid vessels, and the internal jugular vein, and the following nerves, viz.: the vagus, the first part of the hypoglossal, the descendens hypoglossi, and the superior part of the accessory. These structures are enveloped in a thin fascial tube, the carotid sheath. The sheath is surrounded by cellular tissue in which are embedded the carotid chain of lymph glands; normally they may be readily separated from the sheath of the internal jugular vein, to which, however, they become adherent when inflamed. A few small lymph glands lie within the sheath. The cervical sympathetic trunk and the inferior thyreoid artery lie in the cellular space between the posterior wall of the carotid sheath and the prevertebral fascia; they can be reached through an incision along the posterior border of the sterno-mastoid muscle, this muscle, along
with the carotid sheath and its contents, being pulled well forwards. In approachng the trunk of the inferior thyreoid artery from the front the sterno-mastoid and arotid sheath are retracted and the dissection is continued through the cellular nterval between the carotid sheath and the sheath (outer capsule) of the thyreoid gland, which is formed by the splitting of the pretracheal fascia.
A glandular abscess in this compartment usually points upon the surface, adhesions being formed, first, between the gland and the fascia, and, subsequently, between the latter and the cutaneous structures. In diffuse suppurative cellulitis of this compartment the pus burrows towards the root of the neck, and may reach either the mediastinum or the axilla.
Median Line of the Neck.-The body of the hyoid bone divides the median plane of the neck into supra- and infra-hyoid portions. Above the hyoid bone is the submental triangle, with its apex at the inferior border of the symphysis menti and its
FIG. 1087.-DISSECTION OF THE FRONT OF THE NECK. The lower portions of the sterno-mastoid muscles have been removed, and the lower part of the right common carotid artery cut away to show the deeper parts. (From Cunningham.)
sides formed by the anterior bellies of the digastrics. In the floor of the triangle are the anterior portions of the mylo-hyoid muscles, separated by the median raphe (Fig. 1087). The most important structures in the triangle are the submental lymph glands, which can usually be felt a little above the body of the hyoid bone. In children they are a frequent seat of abscess secondary to impetigo of the lower lip and chin. About 1 in. below the hyoid bone is the pomum Adami, more prominent in the male than in the female. On either side of the pomum Adami are the laminæ of the thyreoid cartilage, while between the latter and the hyoid bone is the thyreo-hyoid membrane. In the operation of sub-hyoid pharyngotomy the epiglottis and the superior opening of the larynx are reached by passing through the anterior wall of the pharynx at the level of the thyreo-hyoid membrane. The structures divided from without inwards are: the integuments, the sternohyoid, omo-hyoid, and thyreo-hyoid muscles, the median portion of the thyreo-hyoid membrane, along with a layer of fat between it and the lower part of the epiglottis, and, finally, the glosso - epiglottic ligament and fold of mucous membrane. The incision must not be extended too far on either side of the