Muscles of mastication MUDr. Anna Rábová MUSCULI MASTICATORII § Lat. masticare = to chew § § Embryologically, the muscles of mastication develop from the first (mandibular) pharyngeal arch (branchial origin) § § Movements of the mandible in the temporomandibular joint, while the rest of the skull remains stable § § origin - from the bones of the neurocranium (non-movable bones), insertion - on the mandible (freely movable bone) § Pinnate structure § § Blood supply: maxillary artery (end branch of ACE) § § Nerve supply: mandibular branch of trigeminal nerve § § 4 pairs of muscles § Masseter muscle - Thick, quadrilateral muscle, superficially located – on the side of the face, anterior to the parotid salivary gland - Divided into Superficial, middle and deep portion - inervation: n. massetericus (V3) lamina spf. lamina prof. pars ventralis pars dorsalis: l. spf. l. intermedia l. prof. Functional organization of the human masseter muscle. J.F. Gaudy et al. (2000) Surg Radiol Anat 22:181-190. Pars superficialis Pars intermedia Pars profunda Origo the lower edge of the os zygomaticum up to the zygomaticotempor suture Fibers pass downward and backward – fibers with oblique course Insertio lower ½ of outer surface of the ramus mandibulae up to tuberositas masseterica Pars spf. Pars media Origo lower edge of anterior 2/3 arcus zygomaticus Insertio middle 1/3 of ramus mandibulae Smaller and more muscular in texture Origo inner side of arcus zygomat. deep lamina of temporal fascia Fibers pass downward – vertically running fibers Insertio the upper ½ of the lateral (outher) surface of the ramus mandible Pars prof. Functional organization of the human masseter muscle www.springerlink.com/index/U007G453650W2163.pdf Frontal section p. superficialis p. intermedia p. profunda Bilateral contraction: The superficial part: Elevation – closes the mouth propulsion § The deep portion: elevation Unilateral contraction: lateropulsion Function Pars media et profunda works together as one unit § The typical pinnate structure § Zones of muscular and aponeurotic attachments § § The structure allows spreading the infection (submasseteric abscess) § The Architecture § Firmly connected with the muscle § § From arcus zygomaticus to basis mandibulae § § Dorsally merge with fascia parotis (fascia parotideomasseterica) § § Caudally connected with basis mandibulae -> fascia colli spf. § §Ventrally attached to the ramus mandibulae The Masseteric Fascia Palpation Palpation of the masseter muscle by having patient clench the teeth The Superficial Portion The Deep Portion Palpace: lékař stojí za pacientem a 4 prsty palpuje sval – pacient stiskne čelisti k sobě několikrát po sobě. Muscle palpation is a very important step in the diagnosis of TMD and myofascial pain syndromes. By means of mechanical stimuli caused by digital pressure, nociceptive neurons located in the muscular and myofascial structures are stimulated to detect and transmit pain messages to the central nerve system. The graduation of patient's response to palpation allows evaluating the severity of pain and is used to measure the efficacy of a given treatment modality in follow-up visits. Palpation should be performed with a pressure of 1.5 Kg, which is strong enough to elicit pain message in symptomatic patients, and mild enough to not cause pain in asymptomatic control subjects2,15,40. Palpation should be done bilaterally, in a relaxed position, with the tip of the finger or by pincer palpation, when no underline bone support is present. Yet, during the examination, the patient should be seated facing the orthodontist in such a way that the clinician can observe the patient's reactions. Obr. dole: vpravo: extraorální bilaterální palpace. Vlevo: extra a intraorální unilaterální palpace. Temporalis muscle M. TEMPORALIS - -Lies in fossa temporalis - -Flat muscle - -Broad, fan-shaped, pinnate structure - - Covered by fascia temporalis - Blood supply.: a. tempor. media (a.tempor.superfic.) a. tempor. prof. (a.maxillaris) - inervation: nn. tempor. prof. (V3) In the long axis of the muscle, a caudally strengthening central tendon (double pinched muscle) is formed. Therefore, some authors divide muscle into : - part ventrally from the tendon – pars anterior - part dorsally from the tendon – pars posterior Origo - fossa temporalis – planum temporale ANTERIOR PART: linea temporalis inf. ossis pariet., facies temporalis alae majoris ossis sphen., adjacent part of os frontale and os parietale + inner surface of the deep lamina of the fascia temporalis POSTERIOR PART: squama ossis temporalis Insertio - muscle fibers converge caudally into a strong tendon - tendon on the processus coronoideus - further converges along the linea obliqua and crista temporalis (up to the trig. retromolare) - also attached to the lig. pterygomandibulare mandibula 029 Někdo dělí na 2 části, někdo ne 2 - pars post. (temp.) 2/3, light color, connection with fascia looser 1 - pars ant. (orbitalis) 1/3, width approx. 3 cm, dark color, adheres to fascia temporalis Detailed description The temporalis muscle consists of three parts: superficial zygomatic deep portion The human temporalis muscle: Superficial, deep, and zygomatic ... onlinelibrary.wiley.com › ... › Journal Home › Vol 22 Issue 6 Origo: temporal aponeurosis, temporal line Insertion: the coronoid process of the mandible The Superficial Portion Origo: superior and medial zygoma and zygomatic arch Insertion: coronoid process Fuse with tendon of the superficial part of the temporalis muscle and with the deep masseter portion. Rostrally interdigitated with the portion of the deep temporalis part The Zygomatic Portion Origo: bony surface of the frontal, sphenoid, parietal and temporal bones Insertion: coronoid process and the ramus of the mandible, just caudal to the last molar (retromolar triangle) Fibers from deep part interdigitated with the buccinator and the superior pharyngeal constrictor The Deep Portion Function Contraction bilateral: - ant. and middle fibers = elevation (propulsion) - Posterior fibers = retropulsion (horizontaly running fibres pull the mandible dorsally) Contraction unilateral:: kontralateral lateropulsion Maintains the middle position of TMJ Covers the temporal muscle Origo: superior temporal line Insertion: zygomatic arch Has two layers: 1. superficial inserted into the lateral border of the arch 2. deep inserted into the medial border of the arch Between these layers is a small quantity of fat and attachment of the superficial fibres of the temporal muscle The Temporal Fascia Skull Palpation The Anterior Part The Posterior Part Palpace: lékař stojí za pacientem a 4 prsty palpuje sval – pacient stiskne čelisti k sobě několikrát po sobě. Muscle palpation is a very important step in the diagnosis of TMD and myofascial pain syndromes. By means of mechanical stimuli caused by digital pressure, nociceptive neurons located in the muscular and myofascial structures are stimulated to detect and transmit pain messages to the central nerve system. The graduation of patient's response to palpation allows evaluating the severity of pain and is used to measure the efficacy of a given treatment modality in follow-up visits. Palpation should be performed with a pressure of 1.5 Kg, which is strong enough to elicit pain message in symptomatic patients, and mild enough to not cause pain in asymptomatic control subjects2,15,40. Palpation should be done bilaterally, in a relaxed position, with the tip of the finger or by pincer palpation, when no underline bone support is present. Yet, during the examination, the patient should be seated facing the orthodontist in such a way that the clinician can observe the patient's reactions. Obr. dole: vpravo: extraorální bilaterální palpace. Vlevo: extra a intraorální unilaterální palpace. Medial (Internal) Pterygoid Muscle M. pterygoideus med. -Internal wing muscle -Strong flattened muscle - quadrilateral - Located in the infratemporal fossa -Two parts (medial and lateral) -Innervation: n.pteryg. med. (V3) - Some muscle fibres in area of angulus mandibulae could be connected with m. masseter – then create a loop around angulus mandibulae obr It is similar to the masseter on the inside of the ramus mandibulae Caput lat. smaller Origo: tuber maxillae Caput med. bigger Origo: fossa pterygoidea, from the med. surface of lamina later. proc. pteryg., proc. pyramidalis ossis palatini Course of fibers: caudally, dorsally, later. Insertio: tuberositas pterygoidea on med. side of angulus mandib., part of ramus mandib. above tuberosity 1 - lateral part 2 - medial part Inner surface of the ramus mandibulae Funktion Bilateral contraction: elevation propulsion Unilateral contraction: kontralateral lateropulsion The beginning of the muscle is closer to the midline than the attachment, so in a one-sided contraction it pulls the mandible to the opposite side; plays a major role in frictional chewing movements 7 musculo-aponeurotic layers are making up a penniform structure 7 5 6 4 3 2 1 The Architecture Palpation Difficult It is performed simultaneously intra and extraorally: Intraorally: at the site of application of seductive anesthesia and laterally Extraorally: med. From lower edge of ramus mandibulae Lateral (External) Pterygoid Muscle - Short, thick muscle, conical in form - Located in upper part of infratemporal fossa, deep to the temporalis muscle - Innervation: n. pteryg. lat. (V3) - Two separate heads of origin, they fuse posteriorly Origo: caput sup. crista infratempor. alae maj. ossis sphenoidalis caput inf. lower ¾ of lat. surface lamina lat. pr. pterygoidei Fibres pass horizontally backward and laterally Insertion: - fovea pterygoidea (depression in front of the neck of the condyle) - joint capsule and articular disc of the TMJ (front margin) Bilateral contraction: protraction, brings the lower jaw forward Depression, opening of the jaw - tightens the disc and the front part of the joint capsule - prevents it from closing! Unilateral contraction: lateropulsion, it pulls the jaw to the contralateral side Function Palpation This muscle is inaccessible to intraoral palpation Between the medial and lateral pterygoid muscles Origo: the base of the skull Insertion: inner surface of the mandible The border is reinforced by sphenomandibular ligament Contain nerves and vessels Allow spread of infection The Interpterygoid Fascia From the functional viewpoint, some of suprahyoid muscles pull the mandible caudally and cause the mandibular depression (mouth opening) – m.mylohyoideus, venter ant. m. digastrici – and form the masticatory muscles. They both start on corpus mandibulae and are innervated by n.mylohyoideus (V3) ØReferences: Ø •Čihák, R.: Anatomie 1,2,3, Praha, Grada, 2001 •Netter, F.: Atlas of HumanAnatomy, 4th ed., Elseviesr, USA, 2006 •Naňka, Elišková: Přehled anatomie. Galén, Praha 2009 •Seidl et al.: Radiologie pro studium i praxi, Grada publishing, 2013 •Mrázková, Doskočil: Klinická anatomie pro stomatology, Alberta, Praha, 1994 •Brand, Isselhard: Anatomy of orofacial structures, 8th edition, Elsevier, USA, 2019 •Fehrenbach, Herring: Illustrated anatomy of the head and neck, 5th edition, Elsevier, USA, 2017 •Moore, Dalley: Clinically oriented anatomy, 5th edition, USA, 2006 Ø