8 Techniques of Temporal Muscle Dissection
Marcio S. Rassi, Paulo A. S. Kadri, Claudio V. Sorrilha, and Luis A. B. Borba
8.1 Introduction
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 superfcial temporal neurovascular structures, optimizing further reconstruction and cosmetic results.
8.2 Objectives of Temporal
Muscle Preservation
•Optimize the surgical exposure.
•Preserve functionality.
•Avoid injuries to the superfcial temporal artery.
•Avoid injuries to the frontotemporal branch of the facial nerve.
•Prevent cerebrospinal fuid (CSF) leak.
•Preserve craniofacial symmetry.
8.3 Temporal Muscle Anatomy
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 fbers (Fig. 8.2)
○Middle temporal artery: branch of the superfcial temporal artery.
Fig. 8.1 The four portions of the temporal muscle. Abbreviations: ALB = anterior lateral bundle; AMB = anterior medial bundle; MA = mandible; MLB = middle lateral bundle; MP = main portion.
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.)
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; ST al temporal artery; TFA = transverse facial artery.
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8 Techniques of Temporal Muscle Dissection
○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).
8.4 Muscle Preservation in
Temporal Approaches
•Superfcial temporal artery preservation, surgical steps:
○Superfcial temporal artery identifcation.
○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 refect the artery together with the skin fap.
○The anterior branch of the artery can be cut and elevated with the skin fap.
•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 superfcial fascia, fat pad and deep fascia, until muscle fbers are identifed.
Fig. 8.3 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.) Abbreviations: A-DTA = anterior deep temporal artery; BN = buccal nerve;
FO = foramen ovale; LPM = lateral pterygoid muscle; M-DTN = middle deep temporal nerve; MN = mandibular nerve; P-DTA = posterior deep temporal artery; P-TN = posterior temporal nerve; TM =temporal muscle.
Fig. 8.4 Preserving frontal branch of the facial nerve through a subfascial dissection.
Abbreviations: E = ear; FB = frontal bone; SF = sk
STL = superior temporal line; TMF = temporal musc s; TMDF = temporal muscle deep fascia; TMSF = temporal muscle
al fascia.
○The deep fascia, fat pad and the superfcial fascia (containing the nerve fbers) are then refected with the skin fap.
•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.
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II Planning, Patient Positioning, and Basic Techniques
Fig. 8.5 Releasing the muscle through a subperiosteal dissection. Abbreviations: E = ear; FB = frontal bone; FP = fat pad; PO = periorbit; TM = temporal muscle; TS = temporal squama;
Z = zygoma. Black arrows = periosteum; Curved arrow = proper movement of the periosteum elevator against the calvaria.
○Periosteal elevator has to be driven from inferior to superior and from posterior to anterior, beginning at the posterior root of the zygoma.
○Muscle insertion detachment is made at the superior temporal line.
○The muscle is then defected inferiorly.
•Improving the exposure through a zygomatic osteotomy, surgical steps (Fig. 8.6, 8.7):
The zygomatic osteotomy provides a better access to the temporal fossa, avoiding excessive muscle retraction.
○Anterior cut is made oblique, through the malar eminence.
○Posterior cut is made oblique, through the root of the zygoma.
○The arch is displaced downward, kept attached to the masseter muscle.
○The muscle is displaced downward through the zygomatic osteotomy.
•Reattaching the muscle, surgical steps (Fig. 8.8):
The muscle must be repositioned in anatomical position, to preserve fbers function and craniofacial symmetry.
○At the beginning the superior aspect of the muscle is fxed to multiple holes made along the superior temporal line with simple suture.
○The anterior portion, dissected to protect the frontal branch of the facial nerve (FFN), is then reattached to the main portion.
○The posterior aspect, if incised, is sutured with the same technique.
Fig. 8.6 Zygomatic osteotomy.
Abbreviations: Ant = anterior cut; F = fat; FP = fat pad; Post = posterior cut; ST al temporal artery; TF = temporal fascia; Z = zygoma.
Fig. 8.7 Temporal muscle displacement.
Abbreviations: ST al temporal artery; STL = superior temporal line; TM = temporal muscle; TS = temporal squama; Z = zygoma. Curved arrow = proper displacement of the temporal muscle to allow maximum exposure to the temporal fossa.
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8 Techniques of Temporal Muscle Dissection
•Use of temporal muscle to avoid CSF leak, surgical steps:
Temporal muscle is mostly used for surgical reconstruction following opening of the frontal sinus, sphenoid sinus and infratemporal fossa.
○The temporal muscle is sectioned according to current needs.
○The selected portion is laid in the middle fossa to cover the faw.
○The bone fap is fxed above that portion and the remaining part of the muscle.
8.5 Frontal Approaches
•Unilateral or bilateral approaches
○The pericranium should be detached from the calvaria just above the superior temporal line.
○The muscle is then released according to the need, in a subperiosteal fashion as previously described.
○The pericranium is then mobilized and refected anteriorly.
•Use of temporal muscle to avoid CSF leak
The use of temporal muscle in surgical reconstruction is particularly indicated following resection of lesions involving the anterior fossa foor and craniofacial sinuses.
○The pericranium is kept pedicled to the temporal muscles and used for packing air sinuses and the anterior fossa foor (see Chapter 6).
○In large exposures, the muscle can be directly plugged to those areas in order to promote proper sealing.
Fig. 8.8 Reconstruction 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.) Abbreviations: E = ear; FB = frontal bone;
FP = fat pad; TM = temporal muscle; Z = zygoma.
8.6 Posterior Approaches (Figs. 8.9–8.11)
•Posterolateral approaches
○The superfcial fascia of the posterior portion of the temporal muscle is dissected, preserving its attachment to the sternocleidomastoid muscle.
○The sternocleidomastoid muscle is detached from the mastoid process and displaced inferiorly and posteriorly.
○The posterior aspect of the temporal muscle is dissected from the calvaria in a subperiosteal fashion and refected anteriorly.
•Use of temporal muscle to avoid CSF leak
Temporal muscle is used for surgical reconstruction following approaches to the petrous portion of the temporal bone and the craniocervical junction.
○The part of muscle fascia attached to the sternocleidomastoid muscle is placed over the dural faw together with the temporal muscle, which lays above it.
○The bone fap is fxed over the muscle.
8.7 Complications
•Muscular atrophy.
•Ischemia and necrosis.
•Infection.
•Pain.
•Functional impairment.
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II Planning, Patient Positioning, and Basic Techniques
•Craniofacial asymmetry.
•Palsy of the frontotemporal branch of the facial nerve.
8.8 Pearls
•The muscle should be protected from retractors and other fxed rigid instruments to avoid ischemia (a gauze or sponge can be used to protect the muscle).
Fig. 8.9 Temporal muscle dissection in a posterior lateral approach. Abbreviations: EAC = external auditory
canal (divided); EJV = external jugular vein; MAN = major auricular nerve; PTM = posterior aspect of the temporal muscle; STM = sternocleidomastoid muscle; TMF = temporal muscle fascia. Dotted line = approximate location of the mastoid process.
Fig. 8.10 Temporal muscle fascia dissection (posterior lateral approach).
Abbreviations: EAC = external auditory canal (divided); EJV = external jugular vein; PB = parietal bone; PTM = posterior aspect of the temporal muscle; STM = sternocleidomastoid muscle; TMF = temporal muscle fascia.
•Keeping the muscle and fascia moisturized during surgical procedure helps maintaining their elasticity.
•Bleeding from the muscle should be controlled by simple compression when possible; the electrocautery, as bipolar and bovie, should be used with caution to avoid burning damage.
•If miniplates are used for cranioplasty at the level of the superior temporal line, the temporal muscle can be fxed by suturing it to them.
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8 Techniques of Temporal Muscle Dissection
References
1. Al-Mefty O, Ayoubi S, Gaber E. Trigeminal schwannomas: removal of dumbbell-shaped tumors through the expanded Meckel cave and outcomes of cranial nerve function.
J Neurosurg 2002;96(3):453–463
2. Borba LAB, Ale-Bark S, London C. Surgical treatment of glomus jugulare tumors without rerouting of the facial nerve: an infralabyrinthine approach. Neurosurg Focus 2004; 17(2):E8
3. Kadri PAS, Al-Mefty O. The anatomical basis for surgical preservation of temporal muscle. J Neurosurg 2004; 100(3):517–522
4. Obeid F, Al-Mefty O. Recurrence of olfactory groove meningiomas. Neurosurgery 2003;53(3):534–542, discussion 542–543
Fig. 8.11 Temporal and sternocleidomastoid muscles displacement (posterior lateral approach).
Abbreviations: DM = digastric muscle; EAC = external auditory canal (divided); EJV = external jugular vein; M = mastoid;
PB = parietal bone; PTM = posterior aspect of the temporal muscle; STM = sternocleidomastoid muscle; TMF = temporal muscle fascia. Curved arrow = proper direction of musc s displacement.
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