Mastication & TMJ Student Notes PDF

Happy Halloween!! Temporal Fossa Infratemporal Fossa TMJ C H R I S T I W I L L I A M S , P T, D P T, O C S , C E R T. M D T Big Picture 3 Regions:  Temporal Region  TMJ  Infratemporal Region Big Picture ▪ Muscles of Mastication - CN V3 – ▪ Blood supply Mandibular n....

Happy Halloween!! Temporal Fossa Infratemporal Fossa TMJ C H R I S T I W I L L I A M S , P T, D P T, O C S , C E R T. M D T Big Picture 3 Regions:  Temporal Region  TMJ  Infratemporal Region Big Picture ▪ Muscles of Mastication - CN V3 – ▪ Blood supply Mandibular n. ▪ Maxillary artery (from ECA) ▪ 4 muscles ▪ Inferior alveolar a. ▪ Masseter ▪ Middle meningeal a. ▪ Temporalis ▪ Sphenopalatine a. ▪ Lateral Pterygoid ▪ Medial Pterygoid ▪ Nerves ▪ V3 – Mandibular n. ▪ 5 motor branches ▪ TMJ ▪ 4 sensory branches ▪ Articular disc – divides joint into 2 ▪ CN VII, IX, X, XII compartments (superior & Inferior) ▪ 3 ligaments ▪ Muscles of the tongue & palate  Temporal Fossa Temporal Lines Superior Frontal ▪Floor Inferior ▪4 bones: frontal, parietal, temporal & sphenoid ▪*Pterion* ▪Temporalis muscle F P ▪Borders ▪Superior & Posterior Borders: temporal lines S T ▪Anterior border: frontal & zygomatic bones ▪Lateral border: zygomatic arch ▪Inferior border: inferior border Zygomatic arch of sphenoid bone ▪ Roof: Sphenoid ▪Temporal fascia Zygomatic Netter 8th ed. S125  Pterion ▪ Junction of the sphenoid bone, frontal bone, parietal bone and temporal bone ▪ Approx 3 cm behind and slightly above the zygomatic process of the frontal bone ▪ Clinical significance: ▪ Fracture – weakest point in the skull ▪ Middle meningeal artery ▪ Epidural hematoma Netter 8th ed. S125 Temporal Fossa - Contents Temporalis Temporal fascia Netter 8th ed. S186 Parotid Region ▪ Between mastoid process and neck/ramus of mandible ▪ Contains: ▪ Parotid gland ▪ Facial n ▪ Lymph nodes ▪ ECA & branches Netter 8th ed. S125  CN VII (Facial nerve) within Parotid Gland ? Temporal ? Zygomatic Facial n. emerges from the stylomastoid foramen & innervates the muscles of facial ? Buccal expression ? Marginal Mand Ten Zebras Bit My Cheek ? Cervical Netter 8th ed. S-64 Salivary Glands ▪ Parotid Gland ▪ Submandibular Gland ▪ Sublingual Gland ▪Function: ▪ Produce saliva ▪ Keeps mouth moist ▪ Lubricates food ▪ Begins digestion of starches Netter 8th ed. S-64 Parotid Gland ▪ Largest of the salivary glands ▪ Overlaps the posterior part of the masseter ▪ lobular appearance ▪ Branches of facial nerve pass through the parotid gland ▪ Parasympathetic control ▪ Produces thin, watery saliva ▪ CN IX -> otic ganglion -> auriculotemporal n. to parotid gland ▪Sympathetic ▪ Produce thick, mucus type saliva Netter 8th ed. S-64 Infratemporal Fossa Netter 8th ed. S125  Infratemporal Fossa - Borders Superior border: Inferior surface greater wing sphenoid Ramus of the mandible (lateral border) Anterior border: Posterior border: Posterior aspect Mastoid process & of maxilla Styloid process of temporal bone Medial border: Lateral pterygoid plate Netter 8th ed. S125 Infratemporal fossa - contents ▪Inferior part of temporalis muscle ▪Lateral and medial pterygoid muscle ▪Maxillary artery ▪Pterygoid venous plexus ▪Nerves ▪ Mandibular- V3 ▪ Inferior alveolar – supplies mandibular teeth ▪ Lingual – sits anterior to the inferior alveolar, sensory ant. 2/3 tongue ▪ Buccal - Br of V3 sensory to buccal region ▪ Chorda tympani (CN VII) - taste ant. 2/3 of tongue, secretomotor for submandibular and sublingual glands ▪ Otic ganglion – (CN IX) hanging off V3 below foramen ovale  Infratemporal Fossa - Contents Muscles: Nerves: Mandibular n (V3) Temporalis via foramen ovale Otic ganglion Auriculotemporal n. buccal n Lateral Chorda pterygoid tympani inf alveolar n Medial Maxillary artery pterygoid (from ECA) lingual n Netter 8th ed. S189  Nerves of the Infratemporal Fossa COA 9th ed. Figure 8.77 COA 9th ed. Figure 8.77 Temporomandibular Joint (TMJ) Trail Guide to the Body  Temporomandibular Joint (TMJ) ▪ The joint is divided into two ▪ Articular disc of TMJ compartments by an articular disc ▪ Fibrocartilage ▪ Superior compartment – gliding ▪ Is fused with the articular capsule movements of protrusion and ▪ When the mouth is opened, the disc retrusion (translation) slides anteriorly on the articular surface ▪ Inferior compartment – hinge movements of depression and elevation  Temporomandibular Joint Type of Joint - Synovial Articular Capsule Modified Hinge superior synovial membrane inferior synovial membrane Articular disc Closed Mandibular fossa of temporal bone Mandibular condyle Open Open Inferior compartment Superior compartment depression protrusion Netter 8th ed. S136 elevation retrusion TMJ Movements https://www.youtube.com/watch?v=Nmg3xl13TY0 TMJ ligaments ◦ Lateral ligament of the TMJ ◦ Intrinsic ligament (thickened part of the capsule) ◦ Strengthens the TMJ laterally ◦ Stylomandibular ligament ◦ Extends from the styloid process of the temporal bone to the angle of the mandible ◦ Does not contribute significantly to the strength of the joint ◦ Sphenomandibular ligament ◦ Runs from the spine of the sphenoid to mandible ◦ Primary passive support of the mandible ◦ Serves as a “swinging hinge” for the mandible serving as both a fulcrum and as a check ligament for the movements of the mandible at the TMJ  TMJ - Ligaments Joint capsule Intrinsic ligament Lateral TMJ lig Extrinsic ligaments Stylomandibular Sphenomandibular Netter 8th ed. S136  TMJ Movements ▪ Mandibular Depression (opening mouth) ▪ Prime mover: Gravity ▪ Suprahyoid & infrahyoid muscles assist mainly against resistance (and platysma) ▪ Lateral pterygoid ▪Protrusion ▪ Primer mover: Lateral Pterygoid To fully open mouth: ▪ Medial Pterygoid Mandibular depression must be ▪ Masseter accompanied by mandibular protrusion Trail Guide to the Body TMJ Movements ▪ Mandibular Elevation (closing) ▪Retrusion (retraction) ▪ Temporalis ▪ Prime mover: Temporalis ▪ Masseter ▪ Digastric ▪ Medial Pterygoid Trail Guide to the Body  TMJ Movements CN V3 (mandibular) Foramen Ovale & Otic ganglion Mandibular Lateral Deviation ▪ Contraction of lateral & medial pterygoid unilaterally, will deviate the mandible to the opposite side Insert lateral deviation from flash cards Netter 8th ed. S-187 What do you call a skeleton who went out in the snow? Muscles of Temporalis Masseter Mastication Medial Pterygoid Lateral Pterygoid MUSCLES OF MASTICATION ARE ALL INNERVATED BY CN V3 (TRIGEMINAL N.) MANDIBULAR BRANCH Temporalis O: Temporal fossa / fascia I: Coronoid Process & ramus of mandible N: CN V3 (trigeminal nerve – mandibular division) A: Elevate mandible Retract mandible Trail Guide to the Body Temporalis Seated Trail Guide to the Body Masseter O: Zygomatic arch I: Angle of ramus of mandible N: CN V3 (trigeminal nerve – mandibular division) A: Elevate mandible Protract mandible Trail Guide to the Body Masseter Seated Medial Pterygoid O: Medial surface of lateral pterygoid plate of sphenoid bone I: Medial surface of ramus of mandible N: CN V3 (trigeminal nerve – mandibular division) A: Unilaterally: deviate mandible to opposite side Bilaterally: elevate mandible, protract mandible Trail Guide to the Body Lateral Pterygoid O: Infratemporal surface & crest of greater wing of sphenoid bone Lateral surface of lateral pterygoid plate I: Articular disc and capsule of TMJ, neck of mandible N: CN V3 (trigeminal nerve – mandibular division) A: Unilaterally: Lateral deviation of mandible to opposite side Bilaterally: Protract mandible Trail Guide to the Body  Lateral Pterygoid ▪ Lateral pterygoid has attachment to articular disc and capsule of the TMJ ▪Approximately 30% of the superior belly of the lateral pterygoid muscle attaches to the anteromedial portion of the articular disc. ▪This superior belly is active during mandibular elevation, especially in the last phase of forceful chewing between molars. ▪It helps to stabilize the disc and the condyle in a functional position. ▪Spasm of the superior belly of the lateral pterygoid muscle can result in anterior displacement of the disc because of its anteromedial pull on the disc during contraction. Trail Guide to the Body  Lateral Pterygoid & Articular disc https://www.youtube.com/watch?v=mB468Jh9aAY Action of Pterygoid muscles https://www.youtube.com/watch?v=af-SxNj4MRg Muscles of Mastication Temporalis Lateral Pterygoid Articular Disc Masseter Medial Pterygoid Netter 8th ed. S186-187  Masseter & Medial pterygoid have similar functions MASSETER MEDIAL PTERYGOID Elevate and Protract Mandible Muscles run in same orientation Trail Guide to the Body Blood Supply Maxillary Artery ▪Maxillary artery: ▪ Branch of External Carotid a. ▪ Supplies structures in infratemporal fossa Maxillary a. ECA Netter 8th ed. S-189  Sphenopalatine a. Middle Maxillary Artery Meningeal a. branches Key Branches: ▪ Middle meningeal a. ▪ Passes through foramen spinosum ▪ Supplies periosteum, dura mater of lateral wall, calvaria ▪ Encircled by auriculotemporal n. ▪ *Clinical Significance: epidural hematoma ▪ Inferior alveolar a. ▪ Supplies mandible, mandibular teeth ▪ Travels with inferior alveolar n. into inferior alveolar foramen/mandibular foramen ▪ Sphenopalatine a. ▪ Terminal branch ▪ Clinical significance: nose bleeds Inferior Alveolar a. Netter 8th ed. S-189 Nerves (Think: Trigeminal CN V) MUSCLES OF MASTICATION: V3  Trigeminal Nerve COA 9th ed. Fig 10.10 Trigeminal n. - CN V1 (Ophthalmic) V1 (Ophthalmic) Superior orbital fissure Sensation to upper 1/3 of face via supraorbital nerve which exits the supraorbital foramen COA 9th ed. Table 10.4 Trigeminal n. - CN V2 (Maxillary) V2 (maxillary) Foramen rotundum Sensation to the middle face via the infraorbital n. which passes through the maxillary sinus and exits the infraorbital foramen COA 9th ed. Table 10.4  Trigeminal n. - CN V3 (Mandibular) V3 (mandibular) Foramen ovale Sensation to the lower part of the face via the mental nerve exiting the mental foramen Sensory to ant. 2/3 of tongue Motor to muscles of Mastication, Mylohyoid, Anterior belly of digastric, tensor veli palatini & tensor COA 9th ed. Table 10.4 tympani Mandibular nerve (V3) ▪ Branch of the Trigeminal nerve (CN V) ▪ Descends through foramen ovale to enter the infratemporal fossa ▪Divides into 4 sensory and 5 motor branches ▪ Motor branches – muscles of mastication, mylohyoid and tensor tympani & tensor veli palatini ▪ Sensory branches ▪ Auriculotemporal ▪ Inferior alveolar ▪ Lingual ▪ Buccal  Mandibular Nerve (V3) – 5 Motor branches Temporal br Masseteric br Pterygoid br Lateral Medial N to mylohyoid To mylohyoid & anterior belly digastric (not shown) N to tensor tympani & tensor veli palatini Netter 8th ed. S-62  V3 – Motor Branches Tensor veli palatini & Tensor tympani Tensor tympani (V3) Tensor veli Eustachian palatini (V3) tube Tensor veli palatini (V3) Muscle of the soft palate Muscle of the inner ear - Tenses the soft palate which opens - Tenses the tympanic membrane, reducing the the pharyngeal opening of the auditory amplitude of oscillations of the inner ear tube (eustachian tube) during bones, which prevents damage to the internal swallowing & yawning ear when exposed to loud sounds  Mandibular nerve V3 - 4 Sensory branches ▪Sensory ▪ Auriculotemporal- sensation to auricle and temporal region, sends articular fibers to the TMJ ▪ Inferior alveolar nerve – supplies sensation to mandibular teeth, mental branch supplies lip and chin ▪ Lingual nerve- sensory to anterior 2/3 of tongue ▪ Buccal nerve – sensation to cheek  Mandibular nerve (V3) - Sensory Mandibular Nerve V3 – from Foramen Ovale Auriculotemporal N Inferior Alveolar N. Buccal N. Lingual N. Netter 8th ed. S-62  Innervation of Salivary Glands ▪ Parotid gland ▪ Presynaptic parasympathetic via the glossopharyngeal n. (CN IX) -> Synapse in Otic ganglion -> post synaptic fibers to parotid gland via the auriculotemporal n. ▪ Otic ganglion ◦ Hangs off V3 ◦ Located just inferior to foramen ovale ▪ Submandibular & Sublingual glands ▪ Presynaptic parasympathetic via the facial nerve (CN VII) -> Chorda Tympani -> Lingual n. ▪ Synapse in Submandibular ganglion  Auriculotemporal n & Chorda Tympani ▪ Auriculotemporal – Sensory branch of V3 Chorda tympani ▪ Sensory to TMJ ▪ Encircles middle meningeal artery ▪ Also carries secretomotor fibers from CN IX to the parotid gland via the otic ganglion ▪ Chorda tympani – branch from CNVII that travels with lingual n. ▪ Sensory: Carries taste from anterior 2/3 of tongue (SVA) ▪ Also supplies secretomotor fibers to submandibular and sublingual salivary glands Auriculotemporal  Chorda Tympani Nerve Branch of CN VII Lingual Nerve V3 Facial n Lingual n Chorda Lingual n Tympani n Submandibular Ganglion ▪ Taste– ant 2/3 tongue ▪ Secretomotor fibers for submandibular & ▪ General Sensory sublingual glands (synapse in submandibular (pain & temperature) – ant 2/3 tongue ganglion) Netter 8th ed. S-62  Key structures in area of TMJ Mandibular Nerve V3 – from Foramen Ovale Middle Menigeal A Auriculotemporal N Chorda Tympani Inferior Alveolar N. Buccal N. Lingual N. N. To Mylohyoid Netter 8th ed. S-62 Key structures in region of TMJ Middle Meningeal A. Chorda Tympani off Lingual N. CN VII – taste ant. 2/3 tongue Maxillary A. Sphenomandibular Ligament External Carotid A. Inferior Alveolar A. & N. V3 – mandibular teeth Lingual N. V3 – sensation ant. 2/3 tongue Netter 8th ed. S-189 Nasal Cavity Nasal Cavity ▪ Olfaction (CN I) ▪ Includes a septum with nasal ▪ Superior 1/3 conchae (turbinates) ▪ Superior, Middle and Inferior ▪ Respiration ▪ Convolutions increases surface area ▪ Conditions and warms air for heat exchange ▪ Inferior 2/3 ▪ Receives secretions (lacrimal ▪ Sinuses glands) ▪ Decrease weight of the face/skull ▪ Resonance to voice ▪ Resonating chambers for voice ▪ Warms & humidifies air ▪ Adds contours to face Nasal Cavity Nasal Conchae Nasal conchae superior middle inferior Nasal meatus superior middle inferior Pharyngotympanic tube (auditory or Eustachean) Netter 8th ed. S-361 Paranasal Sinuses Frontal Sinus Sphenoid Sinus F Ethmoidal Sinus Maxillary Sinus E S Netter 8th ed. S-369  Paranasal Sinuses Function - Resonating chambers for voice - Warms & humifies air - Decrease weight of F skull E - Add contours to face Note location to upper teeth Sinus infection can cause a M toothache. Tooth extractions can fracture into the maxillary sinus & cause infection Netter 8th ed. S-368  Pterygopalatine Fossa Maxillary n Pterygopalatine Ganglia V2 ▪ Hangs off V2 in pterygopalatine fossa ▪ Parasympathetic fibers Pterygopalatine (CN VII) to lacrimal Ganglion gland (tear production) (more on lacrimal glad) COA 9th ed. p. 911 Netter 8th ed. S-364 Pterygopalatine Ganglia Ciliary Ganglion Lacrimal gland - CN III Oculomotor -> pupillary constriction V1 Ophthalmic Trigeminal V2 Maxillary Ganglion Infraorbital n. in V3 Mandibular Infraorbital canal (travels through maxillary sinus) Pterygopalatine Ganglion - CN VII Facial -> Lacrimal Gland Netter 8th ed. S-61 Clinical Notes Rhinitis Sinusitis ◦ Inflammation and swelling of ◦ Inflammation and swelling of the nasal mucosa during the mucosa of the paranasal upper respiratory infections sinuses often due to and allergic reactions infection reaching the sinuses via the nasal cavity Rhinorrhea ◦ Note poor drainage of maxillary sinus ◦ Runny nose Sinuses Note the questionable design of the maxillary sinus (high opening) – thus, hard to drain In the roof of the maxillary sinus, runs the infraorbital nerve (V2) Oral Cavity Oral Cavity Palate hard soft Orbicularis oris Netter 8th ed. S-360  Soft Palate Muscles Pharyngotympanic tube (cartilage) Tensor veli Levator veli palatini (V3) palatini (CNX) Tensor veli palatini Tenses the soft palate which opens Palatopharyngeus the pharyngeal opening of the auditory tube (eustachian tube) (CN X) during swallowing & yawning Levator veli palatini & Uvula Palatopharyngeus Elevate & tense soft palate for swallowing Netter 8th ed. S-398  Nerves of the Tongue Nerves General Sensation Sensation Taste ▪ Motor ◦ Hypoglossal (XII) ◦ Motor to muscles of the tongue except palatoglossus ◦ Vagus (X) ◦ Palatoglossus Posterior 1/3 ▪ Sensory Glossopharyngeal Glossopharyngeal IX IX ◦ General Sensation ◦ CN V3 - Lingual n (anterior 2/3) ◦ CN IX - Glossopharyngeal (posterior 1/3) ◦ Taste Anterior 2/3 Lingual n (V3) Facial n (VII) ◦ CN VII - Facial (anterior 2/3) Chorda tympani ◦ CN IX - Glossopharyngeal (posterior 1/3) Netter 8th ed. S-402  Nerves of the Tongue Glossopharyngeal n. (CN IX) – Lingual N. – from V3 – sensation to sensation & taste posterior 1/3 anterior 2/3 of tongue & chorda tympani from CN VII is taste to ant. 2/3 tongue Submandibular Ganglion (Facial CN VII) – Submandibular & sublingual glands Hypoglossal n (CN XII) – Intrinsic & extrinsic muscles of tongue (except palatoglossus – CN X) Netter 8th ed. S-401 Muscles of the tongue ▪ Palatoglossus (CN X) ▪ Styloglossus ▪ Genioglossus CN XII – Hypoglossal n. ▪ Hyoglossus  Muscles of the Tongue Palatoglossus (CN X) Syloglossus (CN XII) Genioglossus (CN XII) All muscles of the tongue (intrinsic & extrinsic) are innervated by CN XII - Hypoglossal n. Hyoglossus (CN XII) (except palatoglossus which is CN X) Geniohyoid (C1) Netter 8th ed. S-401 Lab Today ▪ On one side: dissect muscles of mastication & TMJ joint ▪ Review CN’s & facial muscles ▪ C1-2 dissection ▪ Review Circle of Willis