Part 16

148. =Furrow in palm.=--The only furrow in the palm useful as a surgical landmark is that which runs transversely across its lower third, and is well seen when the fingers are slightly bent. This transverse furrow corresponds pretty nearly with the metacarpal joints of the fingers, with the upper limit of the synovial sheaths of the flexor tendons of the fingers (that of the little finger excepted (143)); also with the splitting of the palmar fascia into its four slips. The transverse metacarpal ligament lies in the same line with it. Again, a little below this furrow, the digital arteries bifurcate to run along the opposite sides of the fingers.

149. =Interdigital folds.=--By pressing upon the interdigital folds of skin, we can feel the transverse ligament of the fingers, which prevents their too wide separation. The skin of these folds is much thinner on the dorsal than the palmar aspect; hence deep-seated abscesses in the palm very frequently burst on the back of the hand.

150. =Digital furrows.=--Concerning the transverse furrows on the palmar surface of the fingers, notice that the first furrows, close to the palm, do not correspond with the metacarpal joints. The second and third furrows do correspond with their respective joints.

The slight depression observable between the ball of the thumb and that of the little finger corresponds with the middle of the anterior annular ligament.

151. =Palmar arterial arches.=--In opening abscesses in the palm, it is important to bear in mind the position of the large arterial arches which lie beneath the palmar fascia. The line of the superficial palmar arch crosses the palm about the junction of the upper with the lower two-thirds--that is, in the line of the thumb separated widely from the fingers. From this, the digital arteries run straight between the shafts of the metacarpal bones towards the clefts of the fingers. Incisions, therefore, to let out pus beneath the palmar fascia may safely be made in the lower two-thirds of the palm, provided they run in the direction of the middle line of the fingers. The deep palmar arch lies half an inch nearer the wrist than the superficial.

152. =Digital arteries.=--As the digital arteries run along the sides of the fingers, the incision to open a thecal abscess should be made strictly in the middle line. It should be made not over but between the joints, since the sheath is strongest and thickest over the shafts of the phalanges, and therefore more likely to produce strangulation of the enclosed tendons.

153. =Metacarpal joint of thumb.=--The joint of the metacarpal bone of the thumb with the trapezium can be distinctly felt by tracing the dorsal surface of the bone upwards till we come to the prominence which indicates the joint at the bottom of the ‘tabatière anatomique’ (144). Supposing, however, there be much swelling, the knife introduced at the angle between the first and second metacarpal bones readily finds the joint if the blade be directed outwards.

154. =Sesamoid bones.=--The sesamoid bones of the thumb can be distinctly felt. Just above them--that is, nearer to the wrist--lies the joint between the metacarpal bone and the first phalanx. We should remember the position of these bones in amputation at this joint. Mutatis mutandis the same observations apply to the sesamoid bones of the great toe.

The extensor tendon of the last joint of the thumb crosses the apex of the first interosseous space. Under the tendon, and in the angle between the bones, we feel the radial artery just before it sinks into the palm.

155. =Subcutaneous veins.=--The veins on the back of the hand, and their arrangement in the form of arches which receive the digital veins, is sufficiently obvious. The number and arrangement of the arches may vary, but in all hands it is interesting to notice that the veins from the fingers run up between the knuckles and are out of harm’s way.

156. =Interosseous arteries.=--Since the dorsal interosseous arteries, like the palmar, run along the interosseous spaces, incisions to let out pus should always be made along the lines of the metacarpal bones.

157. =Digital bursæ.=--Small subcutaneous bursæ are sometimes developed over the knuckles and the backs of the joints of the fingers. They often become enlarged and unseemly in persons of a rheumatic or gouty tendency.

158. =Knuckles and digital joints.=--The three rows of projections called ‘the knuckles’ are formed by the proximal bones of the several joints: thus the first row is formed by the ends of the metacarpals; the second by the ends of the first phalanges, and so forth. In amputations of the fingers it is well to remember that in all cases the line of the joints is a little in advance of the knuckles, that is, nearer the end of the fingers.

Long and graceful fingers, coupled with thickness and breadth of the sentient pulp at their ends, and too great arching of the nails, have been regarded, ever since the days of Hippocrates, as not unlikely indications of a tendency to pulmonary disease.

PALPATION BY THE RECTUM.

The following report is from Mr. Walsham, of St. Bartholomew’s Hospital, who, having a small hand (somewhat less than seven and a half inches round), has had opportunities of introducing it up the rectum, in the living subject, for the purpose of diagnosis:--

‘It is possible to introduce the hand (if small) into the rectum; in many cases into the sigmoid flexure, and in rare instances into the descending colon.

‘Once beyond the sphincter, the hand enters a capacious sac, and the following important parts can be felt through its walls:--

‘Through the anterior wall the hand first recognises the prostate, which feels like a moderately large chestnut. Immediately behind the prostate, the vesiculæ seminales may be distinguished as two softish masses situated one on either side of the middle line. Internal to them, the whipcord-like feel of the vasa deferentia can be readily traced over the bladder to the sides of the pelvis.

‘The bladder is easily recognised, when moderately distended, as a soft fluctuating tumour behind the prostate; when empty it cannot be distinguished from the intestines, which then descend between the rectum and the pubes. The arch of the pubes can well be defined when the bladder is empty.

‘Through the posterior wall of the bowel the coccyx and sacrum can be felt, the curve of the sacrum being readily followed by the hand.

‘The projecting spine of the ischium on each side of the pelvis is a valuable landmark. From this point the outlines of the greater and lesser sacro-ischiatic foramina can be traced by the fingers; and any new growth, encroaching on the pelvic cavity through these apertures, could be easily detected.

‘If the hand be now pushed farther up the gut, the promontory of the sacrum is reached; the pulsation of the iliac vessels becomes manifest, and the course of the external iliac can be traced along the brim of the pelvis to the crural arch, the loose attachments of the rectum permitting very free movement in this direction. The internal iliac artery can also be followed to the upper part of the great sacro-ischiatic foramen.

‘By semi-rotatory movement, and alternately flexing and extending the fingers, the hand can gradually be insinuated into the commencement of the sigmoid flexure. In the sigmoid flexure the fingers can explore the whole of the lower part of the abdomen, the loose attachment of this portion of the gut permitting the hand to travel freely over the iliac and hypogastric regions.

‘The parts that can here be felt are the bifurcation of the aorta, the division of the common iliac arteries, the iliac fossa, and the crest of the ilium.

‘In the female, the uterus in the middle line, and the ovaries on either side, can be readily distinguished.

‘In the introduction of the hand into the rectum, in a patient under chloroform, the dilatation of the sphincter ani should be very gradual: first two fingers, then four, and finally the thumb should be passed. It is necessary to use considerable force, and unless care be taken, not only the integumentary edge of the anus, but the sphincter itself, may be lacerated. The introduction is facilitated by the application of the other hand upon the abdomen.

‘When the dilatation has been gradual and the hand not too large, no incontinence of fæces and no very considerable amount of pain has resulted.