Part 169

(5) The =superior labial artery= (A. labialis superior) arises from the facial in front of the facial crest (Fig. 435). It passes forward under the dilatator naris lateralis and levator nasolabialis to the upper lip, gives twigs to the upper part of the cheek and the lateral nasal region, and ramifies in the upper lip, anastomosing with the opposite artery and the palato-labial.

(6) The =lateral nasal artery= (A. lateralis nasi) arises usually a little above the preceding one, and runs forward parallel with it and under the levator nasolabialis to the nostril (Fig. 435). It supplies branches to the lateral nasal region and the nostril.

The vessel is often double. It may arise from the superior labial at the point of bifurcation of the facial or with the dorsal nasal from the infraorbital artery (as in the ox). In some cases it gives off a dorsal nasal branch.

(7) The =dorsal nasal artery= (A. dorsalis nasi) arises on the levator labii superioris proprius and passes forward under the levator nasolabialis to the dorsum nasi (Fig. 435).

(8) The =angular artery of the eye= (A. angularis oculi) runs toward the internal canthus of the eye, where it anastomoses with the orbital branch (Ramus malaris) of the infraorbital artery (Fig. 435).

In addition to the preceding, unnamed branches are supplied to the submaxillary salivary gland and the submaxillary lymph glands.

3. The =posterior auricular artery= (A. auricularis posterior) arises at an acute angle from the external carotid just above the origin of the masseteric. It passes upward under cover of the parotid gland, to which it gives branches, and divides into several branches which supply the skin and muscles of the external ear (Fig. 435). The =posterior branch= passes to the posterior part of the base of the ear, where it divides into two branches; of these, one (Ramus intermedius) passes up the convex surface of the external ear to the apex, while the other (Ramus medialis) winds around to the anterior (inner) border, and forms an arch with the intermediate branch. The =external branch= (Ramus lateralis) passes up the posterior (external) border of the ear and forms an arch with the intermediate branch. The =deep branch= (A. auricularis profunda) enters the interval between the external auditory canal and mastoid process, and passes through an opening into the interior of the external ear and ramifies in the skin which lines it. It gives off the =stylo-mastoid artery=, which passes through the stylo-mastoid foramen into the tympanum, forms an arch around the membrana tympani, and supplies the middle ear and its muscles.

THE SUPERFICIAL TEMPORAL ARTERY

This artery (A. temporalis superficialis) is much the smaller of the two terminal branches of the external carotid. It passes upward behind the posterior border of the ramus of the mandible under cover of the parotid gland, and divides below the level of the condyle into the anterior auricular and transverse facial arteries. It is crossed superficially by the facial nerve.

The =anterior auricular artery= (A. auricularis anterior) passes upward behind the temporo-mandibular articulation under cover of the parotid gland, crosses the zygomatic arch, and reaches the temporalis muscle. It is crossed deeply at its origin by the superficial temporal nerve and is accompanied by a satellite vein and the auriculo-palpebral branch of the facial nerve. It is distributed to the skin and the temporal and anterior auricular muscles, and sends a branch through the conchal cartilage to the skin which lines it. Collateral twigs are detached to the parotid gland, and an anterior branch anastomoses with the supraorbital artery. A branch sometimes passes into the parieto-temporal canal and anastomoses with the posterior meningeal (mastoid) artery.

The =transverse facial artery= (A. transversa faciei) is larger than the preceding. It turns around the neck below the condyle of the mandible and emerges from beneath the parotid gland (Fig. 435). It then passes forward a short distance on the masseter about half an inch below the zygomatic arch and plunges into the muscle, in which it commonly divides into two chief branches. It is accompanied by a vein and a branch of the superficial temporal nerve. It supplies the masseter and the skin of this region, and anastomoses with the external maxillary and posterior deep temporal arteries.

FIG. 437.—DEEP DISSECTION OF HEAD OF HORSE.

The left ramus of the mandible and structures connected with it have been removed. a, a, Stumps of stylo-glossus; b, genio-glossus; c, genio-hyoideus; d, omo-hyoideus; e, kerato-hyoideus; f, thyro-hyoideus; g, thyro-pharyngeus; h, crico-thyroideus; i, sterno-thyroideus; k, thyroid gland; m, crico-pharyngeus; n, palatinus and palato-pharyngeus; o, pterygoideus externus; p, tensor palati; q, levator palati; r, temporalis; s, rectus cap. ant. major; t, obliquus cap. ant.; u, guttural pouch; v, great cornu of hyoid bone, posterior extremity of which is removed and indicated by dotted line; w, position of small cornu, dotted line; x, thyroid cornu; y, tongue; z, anterior pillar of soft palate; 1, superficial temporal nerve; 2, chorda tympani; 3, stump of inferior alveolar nerve; 4, 4, lingual nerve, intermediate part removed; 5, deep temporal nerve; 6, masseteric nerve; 7, buccinator nerve; 8, great palatine nerve; 9, infraorbital nerve; 10, sphenopalatine and posterior nasal nerves; 11, spinal accessory nerve; 12, vagus; 13, pharyngeal branch of vagus; 14, superior laryngeal nerve; 15, vago-sympathetic trunk; 16, sympathetic, with superior cervical ganglion a little further back; 17, glosso-pharyngeal nerve; 18, pharyngeal and 19, lingual branches of glosso-pharyngeal; 20, hypoglossal nerve; 21, left recurrent nerve; 22, common carotid artery; 23, parotid branch; 24, thyro-laryngeal artery; 24′, laryngeal artery; 25, occipital artery; 26, internal carotid artery; 27, external carotid artery; 28, 30, external maxillary artery; 29, pharyngeal artery; 31, lingual artery; 32, internal maxillary artery; 33, stump of inferior alveolar artery; 34, middle meningeal artery; 35, deep temporal artery; 36, buccinator artery; 37, palatine artery; 38, end of internal maxillary artery; 39, right external maxillary artery; 40, satellite vein of 39; 41, right parotid duct; 42, submaxillary lymph glands; 43, pharyngeal lymph glands; 44, trachea; 45, wing of atlas; 46, dotted line indicating outline of submaxillary gland; 47, lacrimal gland. (After Ellenberger-Baum, Top. Anat. d. Pferdes.) ]

The pulse may usually be felt in this artery as it passes below the articulation of the jaw.

THE INTERNAL MAXILLARY ARTERY (Figs. 437, 438, 439)

This artery (A. maxillaris interna) is much the larger of the two terminal branches of the external carotid. It begins at the inner side of the posterior border of the mandible about two inches (ca. 5 cm.) below the articulation of the jaw and ends in the anterior part of the pterygo-palatine fossa. On account of its complex course and the large number of branches given off it is convenient to divide it into three parts.

The =first part= is much the longest, forms an =S=-shaped curve, and is in great part in contact with the guttural pouch. It passes upward and forward on the inner surface of the mandible a distance of about an inch (ca. 2 to 3 cm.) and is related here to the vein, which is ventral. It then turns inward below the external pterygoid muscle and the inferior maxillary nerve, passes between that muscle and the tensor palati, and runs forward to enter the alar (pterygoid) foramen. This part gives off the following branches:

1. The =inferior alveolar= or =dental artery= (A. alveolaris mandibulæ s. inferior) passes downward and forward with the homonymous vein and nerve, being at first between the external and internal pterygoid muscles, then between the latter and the ramus of the mandible. It enters the mandibular foramen, passes downward and forward in the mandibular canal, and terminates at the mental foramen by dividing into mental and incisor branches. The =mental branch= (A. mentalis) emerges through the mental foramen and anastomoses in the lower lip with the opposite artery and the inferior labial. The =incisor branch= continues forward in the bone, supplies twigs to the canine and incisor teeth, and anastomoses with its fellow of the opposite side. Collateral branches are detached to the pterygoid and mylo-hyoid muscles, and within the bone to the teeth, alveolar periosteum, the gums, and the spongy substance of the mandible.

2. The =pterygoid arteries=, two or three in number, are distributed to the pterygoid and tensor and levator palati muscles.

3. The =tympanic artery= is a very small vessel which passes along the Eustachian tube to the petro-tympanic fissure (of Glaser) and enters the middle ear.

FIG. 438.—RIGHT EYE OF HORSE.

a, Remnants of periorbita; b, levator palpebræ superioris; c, obliquus oculi inferior; d, rectus oculi inferior; e, rectus oculi externus; f, rectus oculi superior; g, sclera; g′, cornea; h, lacrimal gland; i, frontal nerve; k, frontal artery; l, branch of lacrimal nerve to gland; m, lacrimal artery; n, zygomatic nerve; o, branch of ophthalmic artery; p, branch of oculomotor nerve to obliquus oculi inferior; q, maxillary nerve; r, infraorbital nerve; s, posterior nasal nerve; t, great palatine nerve; u, small palatine nerve; v, internal maxillary artery; w, buccinator artery (cut); x, infraorbital artery; x′, malar artery; y, sphenopalatine artery; z, great palatine artery; z′, small palatine (or staphyline) artery; 1, posterior deep temporal artery; 2, 3, stumps of orbital margin; 4, facial crest; 5, temporal fossa; 6, foramen lacerum orbitale; 7, anterior end of alar canal; 8, posterior opening of same. (After Ellenberger, in Leisering’s Atlas.) ]

4. The =middle meningeal artery= (A. meningea media) arises beneath the buccinator nerve where the internal maxillary turns forward. It passes backward across the temporal wing of the sphenoid to the antero-external part (foramen spinosum) of the foramen lacerum. Entering the cranium, it divides into branches which course in the grooves on the temporal and parietal bones and supply the dura mater. It anastomoses with the posterior meningeal.

The size of this artery is variable, and is in inverse ratio to that of the posterior meningeal.

5. The =posterior deep temporal artery= (A. temporalis profunda aboralis) arises from the internal maxillary just before the latter enters the canal of the pterygoid process. It passes upward and backward in the temporal fossa on the deep face of the temporalis muscle, in which it ramifies. It sends a branch outward to the masseter, and anastomoses with the superficial temporal and middle meningeal arteries.

In some cases the tympanic and middle meningeal arise from this artery.

The =second part= lies in the alar canal and is about an inch (ca. 2 to 3 cm.) in length. It gives off two branches—the anterior deep temporal and the ophthalmic.

1. The =anterior deep temporal artery= (A. temporalis profunda oralis) emerges from the canal through the temporal or small alar foramen, and passes upward in the anterior part of the temporal fossa on the deep face of the temporalis muscle, in which it is chiefly distributed. It gives twigs to the orbital fat and the skin of the frontal region.