Amongst the many contributions to surgery which we owe to the late Sir William Fergusson, not the least is that interesting account given of the anatomy of cleft palate, derived from a minute dissection of a case which came under his observation in the dissecting room. The specimen was obtained from the mouth of an aged female.[63] The fissure in this case was one of medium severity, implicating the velum and the posterior portion of the hard palate. The upper horizontal fibres of the superior constrictor were more fully developed than under ordinary circumstances, and would appear to have assisted in shutting off the posterior nares during deglutition and speech. The tensor and levator palati muscles were normally situated and developed, and it appeared from this dissection that the latter muscle was the main factor in drawing the velum upwards and outwards. Consequently the division of this muscle in some way or other is absolutely essential where any plastic operation is undertaken for the closure of the cleft. The palato-glossi and palato-pharyngei evidently possess the power of drawing the posterior part of the velum outwards and downwards, but they are by no means so powerful as the levator. During muscular repose the edges of the cleft are considerably approximated to one another; indeed, the posterior halves of the velum may even touch, and the same condition to a limited degree obtains during deglutition. Fergusson rightly ascribed the latter effect to the contraction of the upper portion of the superior constrictor, which we have already mentioned is hypertrophied, the levator and tensor muscles being at the same time presumably relaxed. If the edges of the cleft be irritated, the lateral segment is instantly drawn upwards and outwards, and disappears as it were, an observation which emphasizes the necessity for the complete division of the levatores at some period of the operation. Where the cleft extends into the bony palate, it is not uncommon to find the pitch of the palatal segments vary considerably. If the cleft be incomplete, the sides will be regularly sloped, although the vault may be higher than usual; whilst in cases of complete cleft, it is not uncommon to see an excessive upward slope of the bones like a Gothic arch, but not always symmetrical. Pollock states that “the more complete the cleft, the nearer the perpendicular are the sides of the palate;” and consequently when the soft tissues are detached from the bone in uranoplasty the flaps will fall into position more readily, and in many cases meet without difficulty in the median line. The following diagrams (Figs. 42 and 43) indicate how much more advantageous such a condition is than when the palatal segments approach more nearly the horizontal. [Illustration: FIGS. 42 AND 43.—Diagrams representing the greater facility for bringing the muco-periosteal flaps together when the palatal segments are vertical rather than horizontal. (_Mason._)