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Home , Parotid gland, Sublingual gland

THE TOPOGRAPHICAL ANATOMY OF THE SALIVARY GLANDS. By J. SYMINGTON, M.D., F.R.S., Professor of Anatomy, Queen's University, Belfast. (Read at a meeting of the Anatomical Society held on. 2nd June 1911.) THE ordinary method of dissecting the head and neck is not well adapted for the demonstration of the shape and deep relations of the salivary glands. Thus, after the superficial surface of the parotid has been exposed, the gland is usually removed piecemeal in order to display the facial and the blood-vessels embedded in it; and the submandibular and sublingual glands are not fully exposed until some of the principal relations such as the , the mylo-hyoid muscle, and the have been considerably displaced. The usual text-book description of these glands, based mainly on this method of examination, is on various points inaccurate and misleading. At a meeting of this Society in January 1910 Mr Parsons exhibited some parotid glands which he had removed entire from subjects hardened in formol; and he has recently described' the form and relations of the as displayed by this method. This is the only paper I have seen in which the topography of any of the salivary glands has been revised with the aid of formol for fixation and hardening in situ. I have recently had occasion to study the macroscopic anatomy of the salivary glands, and I propose in this communication to describe the method I have found best adapted for this purpose, and to indicate some of the results of my observations. My plan consisted in the preparation of series of frozen sections of heads previously hardened in formol. Each head was fixed in a square wooden box, made without nails, and just large enough to admit the specimen. A thick solution of gum was added until the box was filled. The lid was then secured in position and the box wrapped in oilcloth and placed in a freezing mixture of ice and salt. After the specimen was well frozen by being kept in this mixture for about a week, the box, previously divested of its covering, was firmly fixed to a strong, heavy table. This is most conveniently done by having the box made with its base projecting at each end, as such projections can easily be screwed to the table. The I " On the Form of the Parotid Gland," Jour. of Anat. and Phys., April 191 h 174 Professor J. Symington box and its contents were cut with a saw into a series of slabs of the desired thickness and direction. The sections, after being well washed, were allowed to thaw in a solution of 5- p.c. formol. Most of my sections were made at distances of about half an inch apart. One cut surface of each slab was photographed or traced, so as to obtain an accurate record of the shape and relations of the glands as they appeared in the plane of the various sections. The glands in each slab were then removed, and by placing the pieces belonging to each gland in contact with one another in their proper order the shape of the whole gland was easily demonstrated. The structures forming the boundaries of each space from which a piece of gland had been removed were defined. The pieces of gland removed can easily be replaced and preserved in their original position in the slabs. In some cases it may be found advantageous to remove part of a slab in order to demonstrate some special relation, but, as far as possible, the structures should be removed so that they can be readily replaced (see figs. 7 and 8). The method is really an examination of sections combined with dissec- tions and reconstructions; and by this means any given organ can be removed from the slabs in which it is situated, and the pieces into which it has been divided placed in contact so as to reconstruct the whole organ, and its relations determined by a study of the sections and of the walls of the cavities from which it has been removed. I have made four coronal, one sagittal, and two horizontal sets of frozen sections of heads by the plan already described. Figs. 1 to 5 are a series of coronal sections of a female aged 55 years; and fig. 6 is a reconstruction of the salivary glands of this subject, with some of their important relations, viewed from the lateral aspect. Figs. 7 and 8 are coronal sections from another adult female, and figs. 9, 10, and 11 are horizontal sections of an adult male. According to my experience, the variations in the shape and relations of the salivary glands are generally slight and unimportant. The parotid gland is shown in figs. 4 to 10 inclusive. Shape.-Mr Parsons describes the gland as having the form of an in- verted pyramid with a base directed upwards, an apex near the angle of the jaw, and four surfaces called anterior, posterior, external, and internal. It is difficult to give a satisfactory definition of the shape of such an irregular mass as the parotid, but I prefer to adhere to the usual plan, and describe it as having a superficial or subcutaneous surface forming the base of the organ, and an internal or deep aspect divided by an inner border into an anterior and a posterior surface. The upper part of the gland terminates in a thin curved border placed external to and behind the condyle of the jaw; and when the gland is viewed from above, the surfaces in front of and behind this border slope so abruptly downwards that they The Topographical Anatomy of the Salivary Glands 175

Bucecinator muscle.

Wharton's . Subling glands mandible.

FIG. 1.-Coronal section, female 55 years old, anterior surface of slab 3. For position of section see vertical line between 2 and 3 in fig. 6. (* natural size.)

Hard . . Socia parotidis. Stenson's duct. Tongue. . Hypoglossal nerrs. - Genlo-gloss mucle. Wharton's duct. . FEW-, w s~hbGenlo-hyoid muscle. iylo-hyold muscle. Ant. belly of digatric muscle. FIG. 2.-Coronal section, female 55 years old. Anterior surface of slab 4. For position of section see vertical line between 3 and 4 in fig. 6. (* natural size.)

Soft palate. Stenson's duct. Ruceinator muscle. Xasseter muscle.' Tongue.

Llngual nerve. A_iB~~~~~~anine3 _ yrpoglosalartery.nerve. duct. | 1 _ ~~~Wharton'sSublingual gland. Genlo-hyoid muscle. Mylo-hyold muscle. Ant. belly of digastric musle.

FIG. 3.-Coronal section, female 55 years old. Anterior surface of slab 5. For position of section see vertical line between 4 and 5 in fig. 6. (j natural size.) VOL. XLVI. (THIRD SER. VOL. VII.)-JAN. 1912. 12 176 Professor J. Symington are more appropriately described as parts of the anterior and posterior surfaces than as forming a basal surface. Relation8.-The external or subcutaneous surface of the parotid is so well known and so easily displayed that nothing needs to be added to the

Mandibular nerve. j _ / -_ Eustachian tube. Ext. pterygoid muscle. Elevator palati. oaso-. Int. pterygoid muscle. Sup. constrictor muscle. . Cavity of . Stylo-glossus. . Hypoglossal nervc. Lingual . Digastric muscle. Hypo-glossus mvi1e. Hyoid bone.

FIG. 4.-Coronal section, female 55 years old. Anterior surface of slab 6. For position of section see vertical line between 5 and 6 in fig. 6. (J natural size.)

Ext. aud. meatus.

Styloid process. . Parotid gland. Accessory nerve. mnt. Jug. vein. Digastric muscle. Int. carotid artery.

Lymphatic gland. Ext. carotid artery.

FIG. 5.-Coronal section, female 55 years old. Anterior surface of slab 7. For position of section see vertical line between 6 and 7 in fig. 6 (J natural size.) usual description, and it is the deep surface that we shall specially consider. When well hardened, this surface exhibits a number of depressions and prominences which are due to its being moulded against the structures immediately related to it. Thus, on the posterior aspect there is a distinct depression for the lodgment of the anterior border of the sterno-mastoid muscle, and above this a smaller concavity for the front of the mastoid process, and above this again is a flattened area which is attached to the floor and The Topographical Anatomy of the Salivary Glands 177 anterior wall of the external auditory meatus. Internal to the mastoid areas is a rather broad and shallow depression passing downwards and forwards, which lies in contact with the posterior belly of the digastric muscle. Internal to the upper part of the digastric impression there is an, area in close relation with the internal jugular vein (see fig. 5), and behind this the facial nerve enters the gland soon after its exit from the stylo- mastoid foramen. Still further inwards is a styloid groove lodging the upper part of the styloid process and styloid muscles. This groove is bounded in front by the inner border, which occasionally dips inwards in

Ext. and. meatus. Lieb ji @ --gC4 ~~~Parotidgland.~t Roll nerve. da parotidis. SotStenson's duct. Tongue.

Wharton duct. Sublingual gland. Mylohyold muscle. Ant. belly of digastric.

Submandibular gland. Post. of digastri. StrnomastolbellYmuscle FIG. 6.-Lateral view of the salivary glands, etc., reconstructed from a series of coronal sections of female 65 years old. Numbers 2 to 7 indicate the slabs into which the head was divided opposite the sali- vary glands, and the vertical lines between them show the position of the cuts. (J natural size.) front of the stylo-glossus-muscle, and comes into relation with the , separated, however, by some fat. This is sometimes called the pharyngeal process. Below the digastric muscle, and between the sterno-mastoid and the angle of the jaw, the pointed lower part of the gland' lies superficial to the internal jugular vein, carotid vessels, and hypoglossal nerve, but it is separated from these structures by fat and lymphatic glands. A considerable part of the anterior surface rests on the masseter muscle. If this masseteric area be traced backwards it will be found to turn inwards round the posterior border of the masseter, the mandible, and the internal 178 Professor J. Symington pterygoid, and then forwards for a short distance on the median aspect of the internal pterygoid, as the pterygoid process of the gland. Three deep processes of the parotid gland are usually described, viz. the glenoid, pterygoid, and pharyngeal. As Mr Parsons has shown, the glenoid process does not really lie in the glenoid fossa, and in fig. 8 it is seen to leave the anterior surface of the tympanic plate almost entirely uncovered. The pterygoid process only extends a short distance on the deep surface of the internal pterygoid muscle, and less than 1 cm. in front of the posterior border of the mandible. The extent and approximation to the pharynx of the so-called pharyngeal process have been greatly exaggerated. Testut

Mandible. Ext. pterygoid muscle. Facial nerve. Naso-pharynx. xPterygoid process of parotid. Parotid gland. Xit. pterygoid muscle. Masseter muscle. Sup. constrictor muscle. Stylo-glossus muscle. Palatine tonsil. Digastric and stylo-byold muscles.

FIG. 7.-Coronal section of the head of an adult female passing through the temporo-mandibular articulation. Viewed from-the front. (* natural size.) gives a diagram of a horizontal section showing the compartment occupied by the parotid gland, in which this space extends between the internal pterygoid, muscle in front and the styloid muscles behind, and then comes into close relation with the pharyngeal wall, opposite to which the capsule of the parotid is represented as deficient. Testut's diagram has been adopted by Woolsey2 without any change except the insertion of the facial nerve, , and temporo-maxillary vein in thelparotid com- partment, and Woolsey's figure has been introduced into Morris's Anatomy.3 The object of the diagram is to show the intimate relation between the I Traite'd'Anatomie, tome 3, p. 587. 2 Applied Subrgical Anatomy, 1902, plate vi. fig. 22. 3 Treatise on Anatomy, 4th ed., 1907, fig. 777. The Topographical Anatomy of the Salivary Glands 179 parotid gland and the pharynx, and the facility with which an abscess of the parotid might extend to the pharynx, or even, according to Woolsey, a postpharyngeal abscess might burst externally, via the parotid gland. Testut's description is as follows: " Du bord interne de la parotide se d6tache ordinairement un prolongement, prolongement interne ou pharyngien, qui sort de la loge parotidienne par un orifice decrit plus haut et se porte ensuite en dedans du c6t6 du pharynx. Ce prolongement, dont l'importance est grande en chirurgie est a peu pres constant (7 ou 8 fois sur 10) mais son developpement est tries variable: tant6t c'est une saillie en forme de mamelon qui est rattachee a la masse glandulaire par une large base:

Tympanic plate. Temporal artery. Spheno-mandibular 11g. Internal carotid artery. Internal . Pterygoid process of parotid. Inner border of parotid. Stylo-pharyngeus muscle. Stylo-glossus muscle. Ext. carotid artery.

Palatine tonsil. Digastrieand stylo hyold uscle.

FIG, 8.-Same section as fig. 7 with posterior part of mandible and attachments to it of the ext. and int. pterygoid and masseter muscles removed. ( natural size.) tant6t c'est un volumineux lobule A peu pres isol6, qui n'est reli6 a la parotide que par un 6troit pedicule. Quoi qu'il en soit de sa forme, qu'il soit sessile ou pedicule, il passe toujours en avant du paquet vasculaire et s'6tend jusqu'a la paroi laterale du pharynx" (p. 591). Testut does not state what part of the lateral wall of the pharynx comes into such intimate relation with the parotid gland. Charpy1 also refers to this pharyngeal process, and mentions that Richet found it in 7 cases out of 12. He says that the gland usually stops at a plane corre- sponding to the interval between the stylo-maxillary and spheno-maxillary ligaments, but may pass through this interval and come into close relation with the pharyngeal wall. He gives drawings of two horizontal sections; 1 Poirier's Traee' d'Anatomie humaine, tome 4. 180 Professor J. Symington one, fig. 342, through the superior part of the parotid gland opposite the naso-pharynx, and the other, fig. 341, lower down, at the level of the palatine tonsil. In the upper section the inner border of the parotid gland is separated from the lateral recess of the pharynx by the internal pterygoid and the tensor and levator muscles of the palate, and in the lower by the stylo-glossus and stylo-pharyngeus from the superior constrictor, where this muscle covers the tonsil. The figures are less than the natural size and the amount of reduction is not given, so that the actual distance of the gland from the pharynx cannot be estimated, but in both of these planes

| Temporal| muscle. Coronold process. Masseter muscle. Int. pterygold. Eustaclijan tube. . Neck of condyle. Auricislo-temporal nerve. Styloid process. alterna jugular vein. F2acialnerve. 2Mastoid process. Digastric muscle.

FIG. 9.-Horizontal section of the bead of a man 40 years old, at the level of the neck of the condyle of the mandible. The parotid gland is seen external to the neck of the condyle, and turning back- wards and inwards between the neck of the condyle and the mastoid process. The fibres passing backwards and outwards from the outer surface of the external pterygoid plate to the neck of the condyle belong to the external pterygoid muscle. Section viewed from above. (j natural size.) there is a considerable interval between the gland and the pharyngeal wall. In the lower section this space is equal to the thickness of the parotid gland measured from its lateral surface to its inner border. I have not been able to find any work on anatomy which contains drawings of sections showing the inner part of the parotid in close relation to the pharyngeal wall. A series of sections, however, unless close to one another, might not happen to cut the pharyngeal process of the parotid, but the point could easily be determined by combining the examination of such sections with the dissection of the gland and of its compartment in each slab. The great mass of the parotid gland lies either external to the lower jaw and masseter muscle or above and behind the level of the side wall of The Topographical Anatomy of the Salivary Glands 181 the pharynx, and the only part of the gland which tends to approach the pharyngeal wall is its inner border in front of the stylo-glossus and stylo- pharyngeus muscles. When well developed, as in the specimen shown in fig. 8, it projects inwards in front of these muscles, and comes into relation with the internal carotid artery. Even in this case, however, it terminates 14 mm. from the outer surface of the superior constrictor. The usual condition is that represented in fig. 10, where the internal border ends at the outer side of the stylo-glossus, and the interval between this muscle and the internal pterygoid is occupied by fat. Here the distance between the gland and the superior constrictor muscle was 2-0 cm. Although the

Lingual nerve. Int. pterygoid muscle. Sup. constrictor muscle. Inferior dental nerve. Namo-pharyni.

Temnporo-mand. vein. Ext. carotid artery. Sterno-mastoid muscle.

g 1 wii 11 | | Di~~gastric muscle. S ||111rlnt~~~~~ijgular vein. Styloid process. FIG. IQ. -Horizontal section of head of same subject as shown in fig. 9, but 16 mm. lower. Viewed from above. (I natural size.) parotid gland cannot be properly described as coming into close relation with the side of the pharynx, still the continuity in this situation of loose fatty tissue between the deep part of the gland and the side wall of the pharynx and the space in front of the carotid vessels is of interest. The usually described as being embedded in the substance of the parotid are the external carotid and its two terminal branches, temporal and internal maxillary. This, however, is only the case to a slight extent. Thus the external carotid, which enters the gland near its inner border, only lies in the gland for about an inch and keeps close to the anterior surface, being covered merely by a thin layer of glandular tissue. Just as it emerges from the gland it divides into its terminal branches, neither of which is usually surrounded by glandular tissue. The internal maxillary passes forwards between the neck of the condyle and the spheno-mandibular ligament, and the temporal ascends between the jaw and the gland, and 182 Professor J. Symington appears at the upper border of the gland in front of the . The gland lies close to the outer side of the internal jugular vein in the interval between the digastric muscle .and the styloid process (see fig. 5). The facial nerve enters the gland near the stylo-mastoid foramen, and passes forwards and outwards towards the posterior border of the mandible and, near the neck of the condyle, divides into two main divisions. The main trunk lies near the deep surface of the gland, and its various branches traverse the gland much nearer the deep than the superficial surface. The glosso-pharyngeal and vagus do not come into contact with it, and this is usually the case also with the accessory nerve. The auriculo-

Wharton's duct. Sublingual gland. Gento-glossus.

Hypoglosual nerve. Mylo-hyoid muscle. Lingual nerve. Wharton's duct.

Submandibular gland. Digfastric and stylo-hyold muscles.

FIG. 11.-Horizontal section of head, same subject as figs. 9 and 10, but 3'5 cm. below the section shown in fig. 10. Viewed from above. (Q natural size.) temporal nerve is not embedded in the gland, and only lies close to it near its upper border (see fig. 9). The gland seldom extends sufficiently far forwards to come in contact with the lingual or inferior dental nerves.- Indeed, the gland can be entirely removed without much danger of injuring any cerebral nerve except the facial. The is firmly attached to the mastoid process, the carti- laginous part of the auditory meatus, and the zygomatic arch just in front of the pinna; in most other situations it can easily be shelled out with the gland. The subrnadi bwlar gland is shown in figs. 4, 6, and 11. It is often figured and described as though it were bounded below by the digastric muscle. It is so represented in a drawing by Allen Thomson which has appeared in several editions of Quain's Ancatomry. Birmingham, in The Topographical Anatomy of the Salivary Glands 183 Cunningham's Text-book of Anatomy, second edition, 1906, when defining the position of this gland, said that " It is placed partly in the submaxillary triangle and partly under cover of the posterior border of the mandible" (p. 1011). Instead of being limited to this area, the greater portion of the gland lies below a line drawn parallel with the upper border of the posterior belly of the digastric and of the intermediate tendon of this muscle (see fig. 6). The gland has a somewhat flattened oval form, with the long axis nearly vertical, and its surfaces may be described as external and internal. The external surface is convex, and its upper and smaller portion lies against the inner surface of the lower part of the internal pterygoid muscle, and in front of the insertion of this muscle against the inner surface of the mandible. The lower and larger portion extends downwards into the neck, is subcutaneous, and has an area of about 3 cm. by 2 cm. It lies below the mandible, opposite the insertion of the masseter, reaching backwards to the sterno-mastoid, but not extending forwards to occupy the part of. the bounded internally by the anterior belly of the digastric. The deep surface of the gland lies on the lateral aspect of the posterior belly of the digastric and the stylo-hyoid, below and in front of where these muscles groove the parotid gland (see fig. 6). It also extends above these muscles to lie on the stylo-glossus and hyo-glossus muscles and the hypoglossal nerve, while below it reaches into the carotid triangle and overlaps the great cornu of the hyoid bone, the hypoglossal nerve, and the . From the upper and anterior part of the gland two thin processes pass forwards, separated by a groove lodging the free posterior border of the mylo-hyoid muscle. The external of these processes extends a short distance on the cervical aspect of the mylo-hyoid, and the internal into the narrow interval between the mylo-hyoid and hyo-glossus. This process is accompanied by Wharton's duct and the lingual nerve, and it usually ends below the posterior extremity of the sublingual gland. The s&blingual gland is shown in figs. 1, 2, 3, 6, and 11. The two glands come into close relation with one another behind the symphysis and above the genio-glossi muscles. The anterior and larger portion of each gland follows the curve of the inner surface of the mandible and lies in close contact with the bone as far back as the molar teeth. Here the ascent of the line of origin of the mylo-hyoid muscle separates the gland from the bone. and the posterior end of the gland is some distance from the jaw (see fig. 3).