Henry Gray (18251861). Anatomy of the Human Body. 1918.
The subclavian artery is indicated on the surface by a curved line, convex upward, from the sternoclavicular articulation to the middle of the clavicle. The highest point of the convexity is from 1 to 3 cm. above the clavicle.
Veins.The surface marking for the internal jugular vein is slightly lateral and parallel to that for the common carotid artery. The position of the external jugular vein is marked out by a line from the angle of the mandible to the middle of the clavicle. A point on this line about 4 cm. above the clavicle indicates the spot where the vein pierces the deep fascia. The line of the anterior jugular vein begins close to the symphysis menti, runs downward parallel with and a little to one side of the middle line and, at a variable distance above the jugular notch, turns lateralward to the external jugular.
Nerves.The facial nerve at its exit from the stylomastoid foramen is situated about 2.5 cm. from the surface, opposite the middle of the anterior border of the mastoid process; a horizontal line from this point to the ramus of the mandible overlies the stem of the nerve. To mark the site of the accessory nerve a line is drawn from the angle of the mandible to a point on the anterior border of Sternocleidomastoideus about 3 to 4 cm. below the apex of the mastoid process, or to the midpoint of the posterior border of the muscle; the line is continued across the posterior triangle to Trapezius.
The cutaneous branches of the cervical plexus as they emerge from the posterior border of Sternocleidomastoideus may be indicated as follows: the lesser occipital begins immediately above the midpoint of the border and runs along the border to the scalp; the great auricular and cervical cutaneous both start from the middle of the border, the former running upward toward the lobule of the auricula, the latter crossing Sternocleidomastoideus at right angles to its long axis; the supraclavicular nerves emerge from immediately below the middle of the posterior border and run down over the clavicle. The phrenic nerve begins at the level of the middle of the thyroid cartilage and runs behind the clavicle about midway between the anterior and posterior borders of Sternocleidomastoideus.
The upper border of the brachial plexus is indicated by a line from the side of the cricoid cartilage to the middle of the clavicle.
Submaxillary Gland.On either side of the neck the superficial portion of the submaxillary gland, as it lies partly under cover of the mandible, can be palpated.
3. Surface Anatomy of the Back
Bones.The only subcutaneous parts of the vertebral column are the apices of the spinous processes. These are distinguishable at the bottom of a furrow which runs down the middle line of the back from the external occipital protuberance to the middle of the sacrum. In the cervical region the furrow is broad and ends below in a conspicuous projection caused by the spinous processes of the seventh cervical and first thoracic vertebræ. Above this, the spinous process of the sixth cervical vertebra sometimes forms a projection; the other cervical spinous processes are sunken, but that of the axis can be felt. In the thoracic region the furrow is shallow and during stooping disappears, and then the spinous processes become more or less visible; the markings produced by them are small and close together. In the lumbar region the furrow is deep and the situations of the spinous processes are frequently indicated by little pits or depressions, especially when the muscles in the loins are well-developed. In the sacral region the furrow is shallower, presenting a flattened area which ends below at the most prominent part of the dorsal surface of the sacrum, i. e., the spinous process of the third sacral vertebra. At the bottom of the sacral furrow the irregular dorsal surface of the bone may be felt, and below this, in the deep groove running to the anus, the coccyx.
The only other portions of the vertebral column which can be felt from the surface are the transverse processes of the first, sixth, and seventh cervical vertebræ.