Part 67

First, the =hyoid artery= (Fig. 72, No. 12) which supplies the inner portion of the depressor mandibular and also the cornua of the os hyoideum, and extends to the tip of the tongue.

Second, the =superior laryngeal artery= (Fig. 72, No. 16) which supplies the sterno-brachialis and gives off branches which extend downward to the trachea and to the esophagus. The main artery passes along the left side of the esophagus and anastomoses with branches of the inferior esophageal, forming collateral circulation in that region.

FIG. 62.

A. Blood-vessels of the head. 1, The cerebellum. 2. The cerebrum. 3, The semicircular canals. 4, Sinus occipitalis superior. 5, Sinus temporalis sphenoideus. 6, Sinus transversus dexter. 7, Superior esophageal artery. 8, Carotis externus. 9, Lingual artery. 10, Sinus longitudinalis.

B. Veins of the antero-inferior part of the head and neck. 1, The right carotid artery. 2, The left carotid artery. 3, Vena jugularis dexter. 4, Vena vertebralis dexter. 5, Transverse vein. 6, Vena cephalica dexter anterior. 7, Vena lingualis. 8, Vena cephalica posterior. 9, Vena facialis externa dexter. 10, Vena infrapalatina. 11, Posterior nares. 12, Vena facialis interna. 13, Vena facialis externa sinister.

C. The brain. 1, Medulla oblongata. 2, Cerebellum. 3, Optic lobe. 4, Cerebrum. 5, Longitudinal fissure. 6, Transverse fissure. 7, Olfactory nerve. 8, Optic nerve. 9, Optic commissure. 10, Motor oculi. 11, Patheticus. 12, Trigeminal, or trifacialis. 13, Abducens. 14, Facialis. 15, Auditory, or acousticus. 16, Glosso-pharyngeus. 17, Pneumogastric. 18, Spinal accessory. 19, Hypoglossus. 20, Hypophysis. 21, Crus cerebri. 22, Ganglion on superior nerve trunk. 23, Spinal cord. 24, A pair of spinal nerves. ]

Third, the =lingualis artery= (Fig. 62, No. A, 9) which lies between the mylo-hyoideus and the posterior part of the hyoid bone. It supplies the tongue muscles. It passes to the median surface of the lower jaw bone, where are given off small branches which enter the jaw and anastomose with the inferior alveolar artery.

Fourth, the =Facial Artery=.—The facial artery divides into the following branches:

The auricular artery is given off near the articulation of the os quadratum with the os zygomaticum. It is located at the outer auditory canal, and its branches are distributed to the parotid region and to the depressor mandibular, or digastricus, muscle.

The external facial artery is located between the os quadratum and the masseter muscle. It gives off a branch to the lower jaw bone and to the skin of that region, and then passes to the lacrimal bone and supplies branches to the commissure of the mouth, the auditory canal, the masseter muscle, the three eyelids (upper and lower eyelids and the membrana nictitans), the nose cavity, and the skin in the frontal region. It communicates on the other side with the ethmoidal artery.

The internal facial artery passes over and through the os pterygoideum, supplies all the jaw muscles, and is continued as the inferior alveolar artery.

The inferior alveolar artery enters the canal of the lower jaw bone along with the mandibular nerve. It is finally continued as the mental artery, leaving the canal, and passing to the outer jaw surface.

The facialis continues as the internal maxillary artery.

The internal maxillary artery (Fig. 72, No. 15) supplies the pterygoid muscle, the upper part of the pharynx, the commissure of the mouth, the salivary gland region, the gums, and finally anastomoses with branches of the spheno-maxillaris artery.

BRANCHES OF THE VERTEBRAL ARTERY

The vertebral artery is given off, dorsally near the thyroid gland, from the carotis communis or from the carotid trunk. The vertebral artery passes horizontally and dorsally into the canals formed in the transverse processes of the cervical vertebræ. After it leaves the carotid, it is divided into anterior and posterior branches.

The =posterior vertebral artery= passes in the canals of the transverse processes of the fifth or sixth dorsal vertebra. It sends branches into the vertebræ, into the spinal canal, and into the intercostal muscles between the ribs and anastomoses with the intercostal arteries.

The =anterior vertebral artery= is larger than the posterior. It extends laterally along the side of the neck in the foramen of the transverse processes of the cervical vertebræ, and lies along the course of the inferior vertebral vein and the deep imbedded trunk of the sympathetic nerve. It continues to the head. In its passage it gives off to each vertebral segment a dorsal and a ventral branch. Twigs from these branches pass into the bodies of the vertebræ and the spinal canal, giving nutriment to the bony structure and to the spinal cord and its coverings. Other twigs are distributed to the muscles of the neck and some finally anastomose with branches of the carotis communis. This artery, reaching the head, gives off a long anastomosing branch which passes between the atlas and posterior part of the occipital bone and joins the ramus profundus and the occipital artery, thus again communicating with the carotid artery. The remainder of the vertebral artery is small and passes through the foramen magnum into the cranial cavity where it anastomoses with terminal branches of the cerebral artery. At the base of the neck and before the vertebral artery enters the canal of the cervical vertebræ, it gives off the arteria cervicalis ascendens, superior artery of the crop (Fig. 73, No. 18) which branches out on the upper surface of the crop is also distributed to the neck muscles, and later subdivides into the transverse cervical arteries which supply the skin and the muscles of the base of the neck, and the shoulder region.

On the ventral side of the neck there are given off two subvertebral carotid arterial branches. They lie in a shallow furrow on the ventral side of the cervical vertebræ and close to the median line.

BRANCHES OF THE SUBCLAVIAN ARTERY

The subclavian artery (Fig. 20, No. 13; Fig. 73, No. 11) gives off the following branches:

1. =Sterno-clavicularis= (Fig. 73, No. 9) which originates on the upper part of the subclavia, between the carotid artery and external thoracic (Fig. 73, No. 3), divides into many branches. The sterno-clavicularis gives off the sternal artery, which enters by the side of the supra-coracoid muscle and the anterior rim of the sternum. It is distributed to the inner surface and over the air-sac. Another outside branch passes the posterior end of the crista sterna and supplies the large breast muscles.

The clavicular artery (Fig. 73, No. 8) accompanies the clavicle to the shoulder-joint.

The acromial artery is given off from the sterno-clavicularis on the ligament near the shoulder-joint.

2. The =thoracic artery= branches from the subclavian artery (Fig. 70, No. 4). The thoracic artery gives off the following branches:

The internal mammary, or internal thoracic artery (Fig. 73, No. 16) arises on the inner side of the sternum and extends downward and backward, giving nutrient branches to the anterior vena cava and to the diaphragm. At the point of the costo-sternal muscle it divides into an inner and an outer branch.

The inner branch supplies the costo-sternal muscle and extends along the ribs and along their juncture with the breast-bone. It finally extends posteriorly, giving numerous branches to the abdominal muscles. The outer branch is distributed in a similar manner, giving off branches to the diaphragm and to the abdominal muscles, and anastomoses, on the surface of the abdominal muscles, with the epigastric artery.

The external thoracic artery (Fig. 73, No. 3), ramus superior, supplies principally the large breast muscles.