cial artery is divided between ligatures, as it crosses the bone in a line with the anterior edge of the masseter muscle. Separate the flap thus marked out from the bone, by means of the scalpel and elevator, and reflect it upward.

Divide with a narrow saw the bone downward and outward from the space formed by the extraction of the middle incisor tooth to a point external to the genial tubercles.

Catch the divided end of the bone with the lion forceps and draw it upward and outward, while the tissues from the inner surface and inferior border of the body are separated by means of the scalpel and elevator. Guard against the division of the lingual nerve, by keeping the edge of the knife directed toward the bone while separating the tis sues below the molar teeth. Turn the bone outward, and cut the muscular insertions from the internal surface, and the anterior edge of the coronoid process, also the insertion of the internal pterygoid. Cut the inferior dental vessels and nerve as they enter their canal. Grasp the bone and depress it. Cut the muscular attachment and the capsular ligament on the anterior surface of the neck of the bone. Dislocate the condyle and twist it loose, cutting any attachments not torn or peeled off. Keep the edge of the knife against the bone, as the internal maxillary artery is just behind and internal to the neck. Tie the inferior dental artery.

If it is necessary to prolong the external incision upward to the condyle, to effect the disarticulation, Stenson's duct, the transverse facial artery, and branches of the facial nerve will be divided.

Before beginning the removal of the other half of the bone, pass a ligature through the anterior part of the tongue and draw it forward.

Separate the attachments of the muscles arising from the genial tubercles, and proceed as in the removal of the first half. Stitch the mucous membrane together, and provide for drainage externally. Use stitches of relaxation to secure the coaptation of the incision through the lip.

Resections of different portions of the bone are best performed through external incisions following the course of that for excision. It is never necessary in these partial excisions to divide the lip.

Before the muscular attachments to the genial tubercles are severed, always secure the tongue by means of a ligature passed through its anterior part. After the operation, suture these muscles to the tissues removed anteriorly from the symphysis menti.

RESECTION OF RIB.

Place the subject in such a position that the portion of bone to be removed is uppermost.

Make an incision along the middle of the body of the rib, extending a little beyond each end of the portion to be removed. Join to each end of this incision a vertical incision, extending from the upper to the lower border of the rib. These incisions must divide the periosteum. Raise all the tissues from the bone by means of a periosteum elevator until the external surface and upper and lower borders are bare. Proceed with care to separate the periosteum, covered by the pleura, from the internal surface. The intercostal vessels run in the groove near the lower border,

from which they must be dislodged by means of the elevator and scalpel.

When the portion of bone is separated from all · of its attachments, carry a chain-saw under it and saw through one end. Protect the pleura with a spatula while sawing. Seize the divided end of the portion of bone to be removed with lion forceps to steady it while the resection is completed. for drainage, and stitch the flaps together.

Provide

RESECTION OF THE ARTICULATING ENDS OF BONES.

*

Shoulder-Joint.-Place the subject on the back, with the shoulders raised on a block. Draw the shoulder near the edge of the table, and stand on the side of the operation facing the subject. Rotate the joint inward, so that the external condyle of the humerus is directed forward.

Begin an incision just below the acromio-clavicular articulation, and extend it four or five inches downward in the middle of the anterior surface of the limb. Divide the integument and fascia, and the inner fibers of the deltoid muscle. Retract the sides of the wound, and feel the bicipital groove of the humerus. Open the sheath of the tendon of the long head of the biceps, and the capsule of the joint up to the acromion process, by cutting along the external edge of the tendon from below upward. Raise the tendon from the bicipital groove and retract it outward.

Incise the periosteum along the inner margin of the bicipital groove, and separate it from the bone

*These operations should be modified in young subjects to preserve the epiphyseal cartilages.

as far internally as possible, by means of an elevator rotating the joint outward. The elevator should not be pointed, nor have a sharp edge. The attachment of the subscapularis muscle to the lesser tuberosity is separated by means of a scalpel. The edge of the scalpel must always be directed toward the bone.

Rotate the joint inward and retract inward the tendon of the long head of the biceps muscle. Incise the periosteum along the external margin of the bicipital groove. Separate the periosteum as far outward as possible, rotating the joint inward. The attachments of the supra-spinatus, infra-spinatus, and teres minor muscles to the greater tuberosity of the humerus must be separated by means of the scalpel. The anterior and posterior circumflex vessels, and the posterior circumflex nerve, are not in danger if the edge of the elevator and scalpel are directed toward the bone during their use.

Care must be exercised that the periosteum is not lacerated during its separation from the surgical neck of the bone.

Pass a chain-saw over the head, behind the surgical neck of the bone. Protect the sides of the wound by means of spatulas to prevent the friction of the chainsaw against them. Saw the bone through and remove it from its cavity. The glenoid cavity is to be examined.

If the separation of the tissues posteriorly is impracticable, the upper extremity of the bone may be sawn off and removed. The divided upper end may now be directed to the wound and the tissues separated, when the saw can be carried over the end to the surgi cal neck. Provide for drainage, and close the wound.

Elbow-Joint (Park).-Extend the joint and raise the limb so that the posterior surface is accessible. Stand on the outside of the limb.

Make an incision five inches long in the middle of the posterior surface of the limb, having its middle point over the olecranon process near to its internal border. Divide all the tissues to the bone.

Internally to the wound, separate the tissues from the posterior surface of the humerus and the olecranon process by means of a scalpel and periosteum elevator. Carefully separate the tissues in the groove between the olecranon and the internal condyle. The ulnar nerve is not to be exposed. Separate the mus cular attachments from the internal condyle, flexing the joint when convenient. The ulnar nerve is protected by the left thumb-nail, and the edge of the scalpel is to be directed toward the bone. Retract the tissues and divide the internal lateral ligament of the joint.

Externally to the wound separate the tissues from the bones by means of the scalpel and periosteum elevator. Detach the muscles from the external condyle, preserving as before their attachment to the periosteum. Retract the tissues and divide the external lateral ligament along the lower border of the external condyle of the humerus.

Separate from the ulna the olecranon process, by means of bone-cutting forceps or the saw. In using bone-cutting forceps, the flat surface should be placed toward the shaft of the bone to prevent splintering.

Flex the joint and force the lower end of the humerus out of the wound. Separate the tissues attached to the anterior surface, no special care being