Session 4: The Infratemporal Fossa and Oral Cavity; The Mandible and Temporomandibular Joint Flashcards
What are the 2 separate bundles of the trigeminal that leave the brainstem?
The large sensory root
The small, medial motor root
What is the route of the trigeminal bundles after they leave the brain?
The two roots pass forwards below the tentorium cerebelli through an oval opening in the dura mater, on the apex of the petrous temporal bone, at the trigeminal impression.
What are the 3 divisions of the sensory root of the trigeminal?
Va - Opthalmic
Vb - Maxillary
Vc - Mandibular
Which of the sensory divisions does the motor root join?
Vc
Which foramen does Va pass through to exit the skull?
Supraorbital fissure via the cavernous sinus
Which foramen does Vb pass through to exit the skull?
Foramen rotundum
Which foramen does Vc pass through to exit the skull?
Foramen ovale
What are the branches of the opthalmic (Va) division of the trigeminal? (5)
Supraorbital (from frontal) Supratrochlear (from frontal) Lacrimal Long ciliary (from nasociliary) Short ciliary (from nasociliary)
What does the frontal nerve (Va) supply?
Skin of the forehead and anterior half of the scalp
What does the lacrimal nerve (Va) supply? What does it carry?
Skin of the upper eyelid
Carries parasympathetic from the pterygopalatine ganglion to the lacrimal gland.
What does the nasociliary nerve (Va) supply?
Ethmoidal and sphenoidal sinuses, and the root of the nose.
Describe the 2 main functions of the long ciliary nerve (Va).
1) sensory fibres from cornea
2) sympathetic fibres to dilator pupillae
What does the short ciliary nerve (Va) do?
Carries parasympathetic from the ciliary ganglion to the sphincter pupillae, the ciliary muscle and the ciliary body (for accommodation and constriction).
What are the branches of the maxillary (Vb) division of the trigeminal? (4)
Zygomaticotemporal
Zygomaticofacial
Infraoribital
Ganglionic
What does the zygomatic nerve (Vb) supply?
Skin of the lateral part of the forehead and over the cheek
What does the ganglionic nerve (Vb) supply?
Branches to the pterygopalatine ganglion.
What is a specific function of the zygomaticotemporal nerve (Vb)?
Carries parasympathetics from the ptergopalatine ganglion destined for the lacrimal gland (transfers them onto the lacrimal nerve (Va))
What does the infraorbital nerve (Vb) supply?
The maxillary teeth
What are the motor branches of the mandibular nerve (Vc)?
Nerve to medial pterygoid
Deep temporal
Lateral pterygoid
Nerve to masseter
What does the nerve to medial pterygoid (Vc) supply? (3)
Medial pterygoid
Tensor palati
Tensor tympani
What does the deep temporal nerve (Vc) supply? (1)
Temporalis
What are the sensory branches of the mandibular nerve (Vc)? (5)
Buccal Auriculotemporal Inferior alveolar Lingual Mental (from inferior alveolar)
What does the buccal nerve (Vc) supply?
Mucous membrane and skin of the cheek
What does the auriculotemporal nerve (Vc) supply?
TMJ, skin of upper half of ear and EAM, scalp above the meatus
What does the inferior alveolar nerve (Vc) supply? What else does this nerve contain?
Mandibular teeth
Also contains motor fibres which are given off in the nerve to mylohyoid.
What does nerve to mylohyoid (Vc) supply? Where does it come from?
Mylohyoid and anterior belly of digastric.
Comes off inferior alveolar nerve.
What does the mental nerve (Vc) supply?
Skin of lower lip
What is the lingual nerve joined by? What does it supply?
Chorda tympani (VII) Anterior 2/3 tongue, floor of mouth, sensory branches to submandibular ganglion.
Where is the temporal fossa?
The space occupied by temporalis muscle.
Where is the infratemporal fossa?
The space deep to the superior half of the mandibular ramus.
What are the contents of the infratemporal fossa? (6)
Pterygoid muscles Maxillary artery Pterygoid plexus of veins Branches of mandibular nerve (Vc) Otic ganglion Distal part of chorda tympani (VII)
Describe the pterygopalatine fossa.
A small pyramidal-shaped space that lies between the back of the orbit, the maxilla, and the sphenoid.
What is the position of the pterygopalatine fossa ideal for?
Connecting the eyes, nose and face as well as the infratemporal fossa and brain.
What are the main structures that run through the pterygopalatine fossa?
Maxillary nerve (Vb)
Terminal branches of maxillary artery
Pterygopalatine ganglion
Describe the boundaries of the pterygopalatine fossa.
Anterior wall - posterior surface maxilla
Posterior wall - pterygoid process of spenoid
Medial wall - perpendicular plate of palatine bone
Which foramen are connected with the pterygopalatine fossa?
Inferior orbital fissure Foramen rotundum (where Vb enters) Pterygoid canal (where nerve of pterygoid canal enters and carries autonomic fibres to ptergopalatine ganglion)
Which muscle forms the lateral walls of the oral cavity?
Buccinator
What is buccinator continuous with and from which point?
Continuous with the superior constrictor from the pterygomandibular raphe.
What does the pterygomandibular raphe run between?
Medial pterygoid plate of sphenoid and the mandible posterior to the mylohyoid ridge.
Which muscles lie medial to the pterygomandibular raphe and dominate the posterior border of the oral cavity? Discuss these muscles.
Palatoglossus and palatopharyngeus. They connect the tongue and the pharynx to the palate and are covered by mucous membrane.
What lies between palatoglossus and palatopharyngeus? What is an alternative name for them?
Palatine tonsils. They are also known as the tonsillar pillars.
What occupies the floor of the oral cavity?
The tongue.
How is the tongue divided and what are the 2 parts called?
It is divided into the anterior 2/3 (oral part) and the posterior 1/3 (pharyngeal part) by the sulcus terminalis.
What is the appearance of the anterior 2/3 of the tongue? What is covering it?
Velvety appearance, covered by small papillae. Mostly pointed filiform papillae, with mushroom shaped fungiform papillae among them.
Which papillae contain taste buds? Where are these located?
Fungiform papillae in the ant 2/3 tongue and circumvallate papillae lying in a row anterior to the sulcus terminalis.
What is the appearance of the posterior 1/3 of the tongue? Why?
Nodular from underlying masses of lymphoid tissue, the lingual tonsils.
How are the intrinsic muscles of the tongue arranged? What is their action?
Arranged as longitudinal, transverse and vertical fibres. Change the shape of the tongue.
Where does genioglossus attach?
Anterior part of mandible
What is the action of genioglossus?
Protrusion of the tongue
Where does hyoglossus attach?
Hyoid bone
What is the action of hyoglossus?
Retraction and depression of the tongue
Where does styloglossus attach?
Styloid process
What is the action of styloglossus?
Retraction and elevation of the tongue
Where does palatoglossus attach?
The palate
What is the action of palatopharyngeus?
It has a stronger action in depressing the palate than its effect on the tongue
What is the nerve supply of the muscles of the tongue? What is the exception?
Hypoglossal nerve (XII) except palatoglossus which is supplied by the pharnygeal plexus.
What is taste to the anterior 2/2 of the tongue supplied by?
Chorda tympani (VII)
What is general sensation to the anterior 2/3 of the tongue supplied by?
Lingual nerve (Vc)
What is the posterior 1/3 of the tongue supplied by?
Glossopharyngeal (IX)
What is the small part of the tongue above the epiglottis supplied by?
Internal laryngeal branch of the vagus (X).
What are the attachments of the mylohyoid muscles? What do they form?
Inner surfaces of the mandible and hyoid bone, connected together at a midline raphe. Form a muscular sling which marks the floor of the oral cavity.
Which border of the mylohyoid muscles is free?
Posterior
What are the mylohyoid muscles supplied by? What else does this nerve supply?
Nerve to mylohyoid (Vc) from inferior alveolar nerve. Also supplies anterior belly of digastric.
Where do the sublingual glands lie? Where do they open into the sublingual region?
On the superior surface of mylohyoid along the inner surface of the mandible. They open via several small, short ducts.
Where does the submandibular gland lie?
In the submandibular fossa under cover of the body of the mandible.
Describe the lobes of the submandibular gland.
The superficial lobe is separated from the parotid gland by the stylomandibular ligament and is grooved by the facial artery.
The deep lobe passes with its duct around the posterior free bored or mylohyoid.
Where do the submandibular ducts enter into the mouth?
Papilla beside the lingual frenulum.
Where does parasympathetic secretomotor supply for the submandibular and sublingual glands come from?
Facial nerve via chorda tympani and submandibular ganglion and the lingual nerve (Vc).
Which is the largest salivary gland
Parotid gland
Where does the parotid gland lie?
Retromandibular region. It also extends onto the lateral surface of the mandibular ramus and masseter.
Where does the parotid duct pass?
It crosses masseter and pierces buccinator to enter the mouth opposite the upper second molar tooth.
Where does parasympathetic supply to the parotid gland come from?
Lesser petrosal nerve (from tympanic branch of IX) –> otic ganglion –> Auriculotemporal nerve (Vc).
What attaches to the mastoid process?
Medial wall - posterior belly digastric
Lateral wall - SCM
What attaches the the ramus of the mandible?
Medial wall - medial pterygoid
Lateral wall - masseter
What forms the hard palate?
Palatine process of the maxilla and the horizontal plate of the palatine bone
What are the five muscles of the soft palate?
Palatoglossus Palatopharyngeus Tensor palati Levator palati Musculus uvulae
What is the action of palatoglossus and palatopharyngeus?
Raise the tongue and oropharynx to control opening of the oropharynx
What does the tensor palati attach to?
Medial pterygoid plate, around hamulus to attach to sides of soft palate.
What is the action of tensor palati?
Tenses the soft palate
What is the innervation of tensor palati?
Mandibular nerve Vc
Where does levator palati attach?
Superior surface of soft palate
What is the action of levator palati?
Elevates the soft palate to close the nasopharynx
What is the action of the musculus uvulae?
Stiffens the uvula.
What type of joint is the TMJ?
Synovial condyloid joint
What does the TMJ articulate between?
Head of the mandible and the articular tubercle on the inferior surface of the temporal bone
What divides the joint into upper and lower cavities?
Intra-articular fibrocartilagenous disc
Why is the TMJ atypical?
Because its articular surface are covered by fibrocartilage instead of hyaline cartilage
What are the muscles of mastication?
Masseter Temporalis Medial pterygoid Lateral pterygoid (Buccinator)
Where does masseter arise?
Zygomatic process of the maxilla and the zygomatic arch
Where does masseter insert?
Lateral aspect of the ramus and angle of the mandible
What is the action of masseter?
Elevates the mandible
Where does temporalis arise?
Inferior temporal line and temporal fossa
Where does temporalis insert?
Coronoid process and anterior border of the mandibular ramus
What is the action of temporalis?
Primarily elevates the mandible but posterior fibres can also retract
Where does medial pterygoid arise?
Pterygoid fossa and medial surface of lateral pterygoid plate of sphenoid
Where does medial pterygoid insert?
Medial surface of mandibular ramus
What is the action of medial pterygoid?
Elevates the mandible and produce lateral movement as with chewing with the mouth closed
Where does lateral pterygoid arise?
Superior head - infratemporal fossa of sphenoid
Inferior head - lateral surface of the lateral pterygoid plate
Where does lateral pterygoid attach?
Superior fibres - articular capsule and disc of TMJ
Inferior fibres - pterygoid fovea or pit on the neck of the mandible
What is the action of lateral pterygoid?
ONLY muscle of mastication to open the mouth (protrudes and depresses the mandible)
Superior fibres also assist in stabilising the joint.
Where does gliding of the TMJ occur?
In the upper compartment. The mandibular condyle and the intrarticular fibrocartilagenous disc move together over the articular surface
Where do hinge movements of the TMJ occur?
In the lower compartment, where the condyle of the mandible articulates with the inferior surface of the fibrocartilagenous disc.
How is depression of the mandible produced?
Condyles pulled forwards by lateral pterygoid
Body of the mandible pulled downwards by digastric and infrahyoid muscles
How is passive depression of the mandible produced?
Assisted by gravity
How is elevation of the mandible produced?
Masseter, temporalis and medial pterygoid
How is protrusion of the mandible produced
Lateral and medial pterygoids
How is retraction of the mandible produced?
Posterior fibres of temporalis
What muscles are involved in chewing?
Mandible moved from side to side by medial pterygoid, also elevated by masseter and temporalis to keep the mouth closed.
What is the vestibule of the oral cavity?
The cleft between the lips and cheeks externally and the gums internally.
What is the oral cavity proper bounded by?
The alveolar arches, teeth and gums, palate and tongue.
What is the posterior communication of the oral cavity?
The oropharynx
What is the lymphatic drainage of the tongue?
Anterior - submental lymph nodes
Lateral - submandibular lymph nodes
Posterior - superior deep cervical lymph nodes
Medial - inferior deep cervical lymph nodes
What attaches to the styloid process? What are the nerve supplies of these muscles?
Stylohyoid (VII)
Styloglossus (XII)
Stylopharyngeus (IX)
