(3) The exposure of the meningeal territory and the ease of determining the presence of an extra-dural hæmorrhage.
(4) The possibility of draining through a split muscle rather than directly through the scalp.
(5) The subsequent protective action of the muscle in case a hernia tends to form in consequence of traumatic œdema.
(6) The subsequent absence of any deformities, the skin incision being carried out for the most part through the hairy portion of the scalp.
The operation.
The hair is shaved over the temporal region, with a wide margin to the field of operation. In other respects, those preliminary details should be adopted which are enumerated in [Chapter II]. The skin incision commences well above and behind the external angular frontal process, is directed along the line of, but below the temporal crest, and curves downwards to terminate just anterior to the tragus of the ear. Pressure is applied during the formation of the incision so as to control bleeding from temporal arteries. The flap, comprising skin, subcutaneous tissue, and superficial temporal artery, is turned down to a zygomatic base, care being taken to avoid injury to the temporal vessels at the base of the flap. The temporal fascia is then incised, parallel to but immediately below the line of the skin incision, and the fascia also turned down towards the zygoma. The temporal muscle is split in the direction of its fibres, from the temporal crest above to the zygoma below, stripped away from the bone and well retracted in both forward and backward directions. In this procedure care must be taken to avoid detachment of the muscle-fibres from the temporal crest. The area of bone exposed, however, should be as extensive as circumstances permit.
Fig. 45. Intermusculo-temporal Cerebral Decompression. First stage. The scalp and temporal fascia have been turned down as separate flaps. The temporal muscle is divided in the direction of its fibres, and the exposed bone trephined.
Fig. 46. Intermusculo-temporal Cerebral Decompression. Second Stage. The temporal muscle is retracted on either side, the bone has been freely cut away, and the bulging dura mater crucially incised.