8 Techniques of Temporal Muscle Dissection Temporal muscle preservation is a key point in planning surgical approaches to the fronto-temporal convexity as well as to the anterior and middle cranial fossa. Adopting adequate dissection techniques aims to improve surgical exposure, preserve anatomical and functional integrity of superficial temporal neurovascular structures, optimizing further reconstruction and cosmetic results. • Optimize the surgical exposure. • Preserve functionality. • Avoid injuries to the superficial temporal artery. • Avoid injuries to the frontotemporal branch of the facial nerve. • Prevent cerebrospinal fluid (CSF) leak. • Preserve craniofacial symmetry. To better understand the general principles underlining surgical techniques of muscle dissection the temporal muscle anatomy must be analyzed. • Temporal muscle is formed by four structures (Fig. 8.1) ◦ Main portion. ◦ Anterior medial bundle. ◦ Anterior lateral bundle. ◦ Middle lateral bundle. • Blood supply to muscle fibers (Fig. 8.2) ◦ Middle temporal artery: branch of the superficial temporal artery. Fig. 8.1 The four portions of the temporal muscle. Fig. 8.2 Blood supply and innervation of the temporal muscle. (Reproduced with permission from Kadri PAS, Al-Mefty O. The anatomical basis for surgical preservation of temporal muscle. J Neurosurg 2004; 100 (3): 517–522.) ◦ Anterior and posterior deep temporal arteries: branches of the internal maxillary artery. • Innervation (Fig. 8.3) The innervation to the temporal muscle is provided by the anterior division of the mandibular nerve (V3), through 3 branches: ◦ Masseteric nerve (most posterior). ◦ Middle deep temporal nerve. ◦ Buccal nerve (most anterior). • Superficial temporal artery preservation, surgical steps: ◦ Superficial temporal artery identification. ◦ The artery is dissected from the subcutaneous tissue, downward, preserving its attachment to the muscle. ◦ The skin incision has to be continued upward until the desired ending point. ◦ It is advisable not to reflect the artery together with the skin flap. ◦ The anterior branch of the artery can be cut and elevated with the skin flap. • Frontotemporal branch of the facial nerve preservation. (Fig. 8.4) • Sub-fascial dissection, surgical steps: ◦ Straight incision 1 cm posteriorly and parallel to the frontotemporal branch of the facial nerve, along the zygomatic arch. ◦ The incision has to run through the superficial fascia, fat pad and deep fascia, until muscle fibers are identified. ◦ The deep fascia, fat pad and the superficial fascia (containing the nerve fibers) are then reflected with the skin flap. • Muscle releasing, surgical steps (Fig. 8.5): Subperiosteal retrograde dissection is mandatory to preserve the neurovascular structures. ◦ Section of the muscle, if needed, should be performed at its posterior aspect.
8.1 Introduction
8.2 Objectives of Temporal Muscle Preservation
8.3 Temporal Muscle Anatomy
Abbreviations: ALB = anterior lateral bundle; AMB = anterior medial bundle; MA = mandible; MLB = middle lateral bundle; MP = main portion.
Abbreviations: A-DTA = anterior deep temporal artery; A-DTN = anterior deep temporal nerve; AD-MN = anterior division of mandibular nerve; BN = buccal nerve; ECA = external carotid artery; IMA = internal maxillary artery; M-DTN = middle deep temporal nerve; MMA = middle meningeal artery; MN = mandibular nerve; P-AA = posterior auricular artery; P-DTA = posterior deep temporal artery; P-DTN = posterior deep temporal nerve; STA = superficial temporal artery; TFA = transverse facial artery.
8.4 Muscle Preservation in Temporal Approaches
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