When the head has rotated, and presents at the external opening, or vulva, and begins to distend it, the greatest care is required. This is a critical period, during which the accoucheur can render more real assistance than at almost any other. There is danger at this time, as formerly explained, of the head passing through too quickly, before the parts are sufficiently relaxed, and so causing them to rupture. This is particularly the case with the perineum, against which the head presses with great force. It is necessary therefore to _support the perineum_, as it is termed, to prevent this accident. This is done by passing the right arm under the patient's right thigh, and placing the palm of the hand flat against the perineum, with the thumb encircling one side of the vulva, and the forefinger the other. The hand is then gently, but firmly, pressed against the part during every pain, so as to prevent the head passing too quickly, and also to _elevate it_, and thus relieve the perineum of part of the strain, and throw the occiput under the pubes. Some practitioners also pass the left hand over the thigh, at the same time, and grasp the back of the head with it, thus holding the head as it were between the two hands, so as to direct it at pleasure. The manner of doing this is represented in plate XXXIX. PLATE XXXIX. The manner of supporting the perineum, during the passage of the head. The right hand is placed underneath, so as to push the head gently back, when it presses on the perineum too forcibly, before it is dilated; and also to elevate it towards the pubes. The left hand is seen above, grasping the top of the head, to assist. This may be done or not, according to the necessities of the case, or the custom of the assistant. [Illustration: Plate XXXIX. The manner of supporting the perineum, during the passage of the head.] It is also necessary to request the female at this time to moderate her efforts, and not bear down too strongly. If however she be too excited, and eager to do so, more care must be used, and the head pressed back still more forcibly, till the parts are fully relaxed. For want of these precautions there is often serious lacerations of the perineum and vulva, particularly in first labors, and when the parts are unusually rigid. If proper care be bestowed however, these accidents ought to occur but seldom, even in the worst cases, and nothing can be more hurtful to the reputation of an accoucheur than for them to happen. Sometimes it is necessary to support the perineum for hours, and to bestow constant attention the whole time. It is often useful to keep applying a little simple ointment, or lard, in the intervals of the pains, mixed with the extract of Belladonna, which will soften and relax the parts. Dr. Lee also advises the application of a sponge, dipped in warm water, and which would probably do much good in many cases.