2.2 Biting, Chewing and Swallowing Flashcards
What are the structures in the temporal fossa?
- temporalis muscle (covered by the temporalis fascia [tight fascia])
- superficial temporal artery (terminal branch of the ECA)
- Auriculotemporal nerve (V3): supplies the skin over the temporal region
What are the structures of the infratemporal fossa?
- medial & lateral pterygoid muscles (muscles of mastication, innervated by different parts of the mandibular nerve [V3])
- mandibular nerve (V3)
- maxillary artery
What are the branches of the Mandibular Nerve (one of the sensory divisions of CNV)
- From main trunk: muscular branches (motor to medial pterygoid, tensor tympani, tensor veli palatini), meningeal branch (sensory)
- Anterior division: masseteric nerve (motor), deep temporal nerves (motor), lateral pterygoid nerve (motor), buccal nerve (sensory)
- Posterior division: auriculotemporal nerve (sensory), lingual nerve (sensory), inferior alveolar nerve (mixed; gives off mylohyoid nerve)
What are the branches of the maxillary artery (terminal branch of the ECA?
- 1st part: anterior tympanic, deep auricular, middle meningeal, superior tympanic, accessory meningeal, inferior alveolar
- 2nd part: anterior & posterior deep temporal, pterygoid branches, masseteric, buccinator
- 3rd part: posterior superior alveolar, infraorbital, descending palatine, artery of pterygoid canal, sphenopalatine
What are the boundaries of the infratemporal fossa
- anterior: maxilla
- posterior: carotid sheath
- medial: lateral pterygoid plate, wall of pharynx
- lateral: ramus of mandible
- roof: greater wing of sphenoid bone
Which part of the mandible is the attachment of the later pterygoid muscle?
pterygoid fovea
which part of the mandible leads to the mandibular canal; transmits the inferior alveolar (inferior dental) nerve (branch of V3) and vessels
Mandibular foramen
which part of the mandible lies superior to the mandibular foramen; attachment of the sphenomandibular ligament
Lingula
which part of the mandible contains sockets for teeth
Upper border
which part of the mandible transmits mental nerve and vessels
Mental foramen
which part of the mandible attaches the mylohyoid muscle
Mylohyoid groove
which part of the mandible lies inferior to the mandibular foramen; attachment of the medial pterygoid muscle
Roughening
The TMJ is a synovial joint between the ________________ with the mandibular fossa and articular tubercle of the temporal bone:
• Joint cavity separated by the fibrocartilaginous articular disc into two compartments
- innervation: ______________
condylar process of the mandible;
Auriculotemporal nerve (branch of V3)
What is the movement of the upper compartment of the TMJ?
Gliding (protrusion/ retraction of mandible)
what is the movement of the lower compartment of the TMJ?
Rotation (opening/closing of mouth)
The stability of the temporomandibular joint is contributed by the following structures:
- Capsule: Surrounds the joint and synovial cavity
- lateral ligament: Strengthens the capsule; attached superiorly to the ___________ and inferiorly to the ________________
- Stylomandibular ligament: Thickening of the _______________ (part of the capsule of the submandibular gland),runs from the styloid process to the ________________
- sphenomandibular ligament: Runs from the spine of the sphenoid bone to the _______________
zygomatic arch;
posterior aspect of the neck of mandible;
investing layer of the deep cervical fascia;
mandibular arch;
lingula of the mandible
Anterior dislocation of mandibular condyle: common condition where mandibular condyles are dislocated anterior to the respective mandibular fossae
• __________________ prevents mandibular condyle from relocating in mandibular fossa
• Dislocations can be reduced easily by pressing down the molar teeth → directs mandibular condyles back into the mandibular fossae (done with/without general anaesthesia)
Articular eminence/tubercle, masseter and temporalis
Masseter
- origin
- insertion
- function
- innervation
- zygomatic arch
- ramus & angle of mandible
- elevation
- Sensory: auriculotemporal branch of V3; Motor: branches of V3 (anterior division)
Temporalis
- origin
- insertion
- function
- innervation
- temporal fossa & fascia
- coronoid process (tendon)
- elevation, retraction
- Sensory: auriculotemporal branch of V3; Motor: branches of V3 (anterior division)
Medial pterygoid
- origin
- insertion
- function
- innervation
- Deep head: lateral pterygoid plate, superficial head: tuberosity of maxilla
- ramus & angle of mandible
- protrusion, elevation
- Sensory: auriculotemporal branch of V3; Motor: main trunk of V3
Lateral pterygoid
- origin
- insertion
- function
- innervation
- Upper head: roof of infratemporal fossa (sphenoid bone), Lower head: maxilla
- neck of mandible & articular disc of TMJ
- Sensory: auriculotemporal branch of V3; Motor: branches of V3 (anterior division)
What does grinding/ chewing require?
alternate retraction and protrusion of the mandible (alternating contraction of the pterygoids and masseter muscles)
What does opening the mouth require?
pterygoids, digastric, geniohyoid, and mylohyoid
What does closing the mouth involve?
Temporalis, masseter, medial pterygoid, geniohyoid and digastric
What are the main branches of the trigeminal nerve and what is it’s course?
The trigeminal nerve (CN V) has three main sensory divisions (branches from trigeminal ganglion) – ophthalmic (V1), maxillary (V2), mandibular (V3):
• Course: exits the skull via the foramen ovale (in the sphenoid bone) → infratemporal fossa → splits into the anterior and posterior divisions
The anterior division of V3 is a mixed nerve (predominantly motor to muscles of mastication). What are it’s branches?
Sensory:
- Buccal nerve: skin over buccinator muscle (over chin and mucosa covering buccinators)
Motor nerve
- Deep temporal nerves (temporalis)
- nerve to lateral pterygoid
- nerve to masseter
The posterior division of V3 is also a mixed nerve (predominantly sensory). What are its branches and what do they supply??
Sensory
- inferior alveolar nerve: supplies the gums and teeth of mandible (incisive nerve), skin of chin and lower lip (mental nerve)
- auriculotemporal nerve: supplies the skin of external ear, temporal fossa, part of the scalp
- lingual nerve: supplies the general sensation from anterior two-thirds of the tongue
Mylohyoid nerve:
- supplies the mylohyoid and anterior belly of the digastric muscle
What is the course of the inferior alveolar nerve
travels deep to the lateral pterygoid → mandibular foramen → mandibular canal → exits at mental foramen → branches into the mental nerve and incisive nerve
what is the course of the auriculotemporal nerve
arises from 2 roots enclosing the middle meningeal artery → runs backwards (winding around neck of mandible) → runs close/passes through parotid gland → temporal region
What is the course of lingual nerve?
Course: joined by the chorda tympani nerve → runs anterior to inferior alveolar nerve → lies just below/behind the last molar tooth → submandibular region → oral cavity
Mylohyoid nerve is a branch of?
inferior alveolar nerve
Lingual neuropathy: lingual nerve (sensory branch of V 3 ) potentially damaged during dental procedures (especially last molar tooth extraction)
- May result in damage to the chorda tympani nerve (CN VII) which runs with it
- Causes loss of __________________
taste sensation , loss of general sensation from the anterior two thirds of the tongue and dry mouth (loss of secretomotor innervation to salivary glands)
What is the course of the maxillary artery?
ECA → parotid gland → maxillary artery (main terminal branch) and superficial temporal artery → behind neck of mandible → infratemporal fossa (superficial/deep to lateral pterygoid) → gives off branches
What does the Middle Meningeal artery supply?
• Trauma to the lateral aspect of the skull results in injury to the MMA → epidural haematoma → compression of motor areas of the brain
Enters the cranial cavity via the foramen spinosum to supply the dura mater (lies deep to the pterion):
What does the inferior alveolar artery supply?
Follows the inferior alveolar nerve to supply the gums and teeth of the mandible:
• Continues as the mental artery which supplies the chin and lower lip
What does the Posterior/middle/anterior superior alveolar artery supply?
Supplies the gum and the teeth of the maxilla
What does the sphenopalatine artery supply?
Runs in the pterygopalatine fossa to supply the palate
What does the infraorbital artery supply?
Supplies the orbital roof
The pterygoid plexus is located around the pterygoid muscles and provides the venous drainage of the infratemporal fossa:
• Drains areas supplied by the maxillary artery and converge to drain into the ___________ → joins with the ____________ in the parotid gland to form the retromandibular vein
• Retromandibular vein exits the parotid gland and splits into anterior and posterior divisions
- Anterior: Joins with the _________ to form the common facial vein → empties into IJV
- Posterior: Joins with the ______________ → forms the EJV
• Communicates anteriorly with the facial vein via the __________
• Emissary veins communicate with the __________ through foramina in the base of the skull → clinical importance
Infections of maxillary tooth/danger triangle (upper lip to nose): may spread to the pterygoid plexus then to the cavernous sinus in the brain via the emissary veins forming thrombus etc.)
maxillary vein;
superficial temporal vein;
facial vein;
posterior auricular vein;
deep facial vein;
cavernous sinus
The parotid glands are cone-shaped salivary glands which are located inferior to the ________________ and lies between the _____________ (anterior) and ______________ (posterior):
• Invested in dense inextensible fibrous capsule (from investing layer of deep cervical fascia)
o Enlargements/inflammation in the parotid gland (e.g. parotid gland stones) are painful as their growth is resisted by the capsule
• Parotid (Stensen’s) duct (5cm long): emerges from the anterior border of the gland → crosses the _______ → pierces the ___________ → opens into the oral
cavity (oral vestibule) opposite the second upper molar tooth
P arotid gland stones: may develop within the parotid duct –> blocks the passage of saliva into the oral cavity –> eating/producing saliva causes pain
external acoustic meatus;
ramus of mandible;
mastoid process and SCM;
masseter;
buccinator muscle
What is the course of the facial nerve and what are its branches ?
Exits the cranial cavity via the stylomastoid foramen and enters the parotid gland (splits into 2 divisions):
• Splits into the 5 motor branches (temporal, zygomatic, buccal, marginal mandibular, cervical) at the anterior border of the parotid gland
Parotid gland tumours: masses within the parenchyma of the parotid gland may potentially compress the ______________________
facial nerve facial palsy ), retromandibular vein and ECA
Frey’s syndrome: ___________________ of auriculotemporal nerve, causing the parasympathetic fibres to switch course
- Causes gustatory sweating (sweating in anticipation of eating) instead of the normal salivatory response
severance and inappropriate regeneration
[Innervation of Parotid gland]
The parotid glands receive parasympathetic secretomotor fibres from the_________________ arising from the inferior salivatory nucleus:
• Preganglionic fibres run in CN IX and its ___________ to the tympanic plexus in the middle ear → ___________ nerve
• Synapse in the otic ganglion (below foramen ovale in relation to CN V3) → postganglionic fibres travels with the ________________ to the gland
glossopharyngeal nerve (CN IX);
tympanic branch;
lesser petrosal
auriculotemporal nerve
SUBMANDIBULAR GLANDS
The submandibular glands are hook-shaped (with superficial and deep parts), continuous around the posterior border of the mylohyoid muscle:
- Superficial: Beneath the _______________ (outside oral cavity)
- Deep: Between the _____________ muscles medially/laterally (lies within the floor of the oral cavity)
• Submandibular (Wharton’s) duct: arises from the deep part of the gland and runs forward beneath the mucous membrane of the mouth → opens at the _____________ (on each side of frenulum of tongue)
inferior border of the ramus of mandible;
hyoglossus and mylohyoid;
sublingual papilla
Marginal mandibular branch of facial nerve
- function
- pathology
- Uplifting of the corners of lips
- Facial nerve palsy (drooping of lower lip, salivary drooling)
hypoglossal nerve (CNXII)
- innervation
- pathology
- Innervates the muscles of the tongue (except the palatoglossus)
- Paralysis of ipsilateral side of tongue
Lingual nerve
- course
- pathology
- Loops under the submandibular duct (crosses from lateral to medial side of the duct) → ascends into the tongue;
- Loss of general sensation and taste in anterior two-thirds of tongue. Dry mouth (minor; most saliva produced from parotid glands)
The sublingual glands lie beneath the mucous membrane (sublingual fold) of the floor of the oral cavity:
• Each gland lies directly against the _______________
• Sublingual ducts (8 – 20 in number) opens into the oral cavity along sublingual fold
medial surface of the body of mandible
Both the submandibular and sublingual glands receive parasympathetic secretomotor fibres from the ________________ arising from the superior salivary nucleus (pons):
• Preganglionic fibres travel in CN VII → lingual nerve (CNV3) joins ______________ (CNVII) → synapse at the submandibular ganglion
• Submandibular glands: direct postganglionic innervation
• Sublingual glands: postganglionic fibres enter _______________ then separate
facial nerve (CN VII);
chorda tempeni nerve;
lingual nerve (V3)
The oral cavity (mouth) opens into the face via the oral fissure (horizontal opening between the lips) and lies inferior to the nasal cavities:
• Continuous posteriorly with the pharynx at the oropharyngeal isthmus
• Divided into the ___________________ (cheek pouch; area between teeth, lips, and cheeks) and inner ________________ by the upper and lower dental arches
- Roof: ___________________ (separate from nasal cavities)
- Floor: ___________ (mainly occupied by the tongue), geniohyoid, salivary glands and ducts, tongue (connected to floor by frenulum of the tongue)
- Lateral: Cheeks (formed by buccinator muscles; lined by oral mucous membrane) and retromolar trigones (mucosa posterior to last mandibular molar)
The oral cavity is the inlet to the alimentary canal, and serves three major functions:
- Digestion: receives food (prepares it for digestion in stomach and small intestines)
- Communication: modifies sound produced in larynx (creates a range of sounds)
- Breathing: air inlet (in addition to the nasal cavity)
outer oral vestibules;
oral cavity proper;
Hard (anterior) and soft (posterior) palates ;
Mylohyoid muscles
Decidious teeth
- Begin erupting about 6 months after birth; all erupted by the end of 2 years
- Each half of each jaw contains ____________________
Permanent teeth
- Begin erupting around 6 years; last tooth (M3/wisdom tooth) erupts by 17 – 30 years (sometimes do not form/erupt at all)
- Each half of each jaw contains _______________________
5 deciduous teeth (2I, 1C, 2M) → 2 incisors (medial/lateral), 1 canine, 2 molars;
8 permanent teeth (2I, 1C, 2PM, 3M) → 2 incisors (medial/lateral), 1 canine, 2 premolars, 3 molars
Each tooth has a different shape and structure, but possess the same basic parts:
- Crown: Part of the teeth above the gum (covered by ______________)
- Root: Part fixed into the surface of the ___________ (root canal transmits nerves and vessels)
- Neck: Area between the root and crown
enamel;
mandible/maxilla
The tongue is composed chiefly of skeletal muscles (covered by mucous membrane):
• Anterior two-thirds (presulcal) lies in the mouth; posterior third (postsulcal) lies in the pharynx (divided by the _____________)
• Outline of the tongue is formed by the tip (apex) and the margin (lateral borders)
• Divided into the body and the root
sulcus terminalis
What does the anterior dorsum of the tongue contain?
Contains lingual papillae (house the taste buds and taste receptors): • Papillae are classified by structure: filiform (most numerous; fine, small cone-shaped → no taste buds), fungiform (club-shaped), foliate (short vertical folds), circumvallate (dome-shaped)
What does the posterior dorsum of the tongue contain?
Contains lingual tonsils (lymphatic nodules) and are devoid of papillae
What does the underside of the tongue contain?
Underside of the tongue: Smooth and devoid of papillae; connected to the floor of the mouth by the frenulum of tongue (fold of mucous membrane)
- Deep lingual vein: seen beside frenulum (deep to mucous membrane)
- Submandibular duct: opens into the sublingual papillae (on each side of the base of the lingual frenulum)
- Sublingual folds: sublingual glands lie beneath these folds
Tongue-tie (ankyloglossia): congenital condition which restricts the tongue’s range of motion
• Due to an ________________ frenulum which tethers the bottom of the apex to the floor of the mouth
• May affect breastfeeding, development of speech and eating behaviours
• Correction: surgical incision of frenulum (frenotomy; frenuloplasty if additional repair required)
unusually short/tight/thick
Genioglossus
- origin
- function
- genial tubercle of mandible
- protrudes apex of the tongue
hypoglossus (quadrangular muscle)
- origin
- function
- hyoid bone
- depresses tongue
styloglossus
- origin
- function
- styloid process of base of skull
- draws tongue upwards and backwards
patoglossus
- origin
- functions
- soft palate
- elevates posterior tongue and constricts oropharyngeal isthmus
function of superior longitudinal muscle of tongue?
curls tip and sides of tongue upwards
function of inferior longitudinal muscle of tongue?
Curls tip and sides of tongue downwards
function of transverse muscle of tongue?
Narrows and elongates the tongue
function of vertical muscle of tongue?
Flattens and broadens the tongue
what artery supplies the tongue and what are its branches ?
Lingual artery (branch of the ECA; identified in the neck by its characteristic loop) → runs deep to the hyoglossus towards the tongue:
• Gives off branches to the submandibular and sublingual glands
• Dorsal lingual arteries: supplies the back of the tongue
• Deep lingual artery: supplies deeper portions of the tongue
What is the venous drainage of the tongue?
Deep lingual veins (adjacent to frenulum), sublingual vein and dorsal lingual veins all drain into the lingual vein (which then drains into the IJV)
lymphatic drainage of tongue?
The lymph nodes of the tongue drain into the deep cervical nodes, which then drain into the jugular venous trunks and the venous angles
- Lymph from the root of the tongue drains bilaterally into the superior deep cervical lymph nodes.
- Lymph from the medial part of the body drains bilaterally and directly to the inferior deep cervical lymph nodes.
- Lymph from the right and left lateral parts of body drains to the submandibular lymph nodes on the ipsilateral side.
- The apex and frenulum drain to the submental lymph nodes, the medial portion draining bilaterally.
general sensation of anterior 2/3 of tongue
lingual nerve (branch of CN V3)
taste of anterior 2/3 of tongue
chorda tympani nerve (branch of CN VII)
general sensation and taste of posterior 1/3 of tongue
CN IX & internal laryngeal branch of CN X
nerve in charge of gag reflex
CN IX (afferent) & CN X (efferent)
motor innervation to the tongue?
Hypoglossal nerve (CN XII) except palatoglossus (supplied by cranial part of accessory nerve (CN XI) or vagus nerve (CN X))
what is the route of the hypoglossal nerve?
The hypoglossal nerve (CN XII) arises from the medulla oblongata and leaves the skull via the hypoglossal canal in the occipital bone:
• Runs between the ICA and IJV in the neck and crosses the ECA → passes deep to the mandible between the mylohyoid and hyoglossus muscles to enter the tongue
• Supplies all the muscles of the tongue (except the palatoglossus muscle)
Injury to CN XII:
may occur due to trauma from tonsillectomy, mandible fracture etc.
- Leads to paralysis and atrophy of ipsilateral side of the tongue
- tongue deviation to paralysed side during protrusion (due to action of the _________________)
unaffected genioglossus muscle on the other side
location of nasopharynx
Behind nasal cavity (base of skull to soft palate)
location of oropharynx
Behind oral cavity (uvula to level of hyoid bone)
location of laryngopharynx (hypopharynx)
Behind larynx (oropharynx to oesophagus)
The nasopharynx communicates anteriorly with the nasal cavity via the 2 choanae (posterior nasal apertures):
- Anterior: Hard palate (made of bone) and soft palate (made of skeletal muscle) → separates the nasal cavity from the oral cavity
- Roof + posterior :Pharyngeal tonsils (adenoid when enlarged) are found in the roof and posterior wall (under the ________________):
• Prominent in children and atrophies with age
• Blocks posterior nasal aperture if too big → difficulty breathing - Lateral
• Auditory (Eustachian) tube opening: connects nasopharynx with middle ear and helps equalise pressure on either side of ______________
• Tubal elevation: contains tubal tonsils (lymphoid tissue)
• Salpingopharyngeal fold: continuous with tubal elevation (formed by the salpingopharyngeal muscle)
• Pharyngeal recess: behind the tubal elevation
sphenoid bone in the mucous membrane;
tympanic membrane
what are important relations to the oropharynx?
CN IX, tonsillar branch of facial artery, palatine veins
o During tonsillectomies, must be careful not to cut CN IX and the highly vascular tonsils (results in severe bleeding → tie off ECA to stop if too severe)
The pharyngeal wall is made of skeletal muscles (constrictor or longitudinal), fibrous tissue, and lined by mucous membrane:
The constrictor muscles include the superior, middle, inferior constrictors which overlap each other to support the pharynx:
• Inferior constrictor is divided into the _________________ and ____________________
• Cricopharyngeus forms a constriction around the junction between the pharynx and oesophagus (almost always closed; except during swallowing) → narrowest part
• Gaps between muscles are filled with fibrous tissue and allow for the passage of nerves, blood vessels through pharyngeal wall
thyropharyngeus (arises from thyroid cartilage) and cricopharyngeus (arises from cricoid cartilage);
Zenker’s diverticulum: protrusion of the mucous membrane through the weak area (gap between __________________) due to increased pressure in distal pharynx
- Pseudodiverticulum not involving all layers of the oesophageal wall
- Presents with dysphagia , trapping of food (causing regurgitation, cough, halitosis, infection ), but rarely causes pain
thyropharyngeus and cricopharyngeus
what is the pharynx supplied by?
The pharynx is supplied by the pharyngeal plexus (formed by branches from CN X (motor) and CN IX (sensory + motor for stylopharyngeus)):
• All pharyngeal muscles are innervated by CN X (except stylopharyngeus)
• Sensory innervation: CN V2 (nasopharynx), CN IX (oropharynx), CN X (laryngopharynx)
what are the 3 longitudinal muscles of the pharynx?
what are their insertion and function?
salpingopharyngeus, palatopharyngeus, stylopharyngeus;
Posterior border of thyroid cartilage (run downwards and join the pharyngeal wall);
Elevation of pharyngeal wall (pulls wall up and over the bolus during swallowing)
what are the 5 muscles of soft palate?
tensor veli palatini, levator veli palatini, palatopharyngeus, palatoglossus, musculus uvulae
tensor veli palatini
- function
- innervation
- tenses the soft palate
- Medial pterygoid nerve (a branch of mandibular nerve, CN V3) via otic ganglion
levator veli palatini
- function
- innervation
- Elevation of soft palate and closes the nasopharynx (prevents food from entering from the oropharynx during swallowing)
- Pharyngeal branch of vagus nerve (CN X) via pharyngeal plexus
Palatopharyngeus
- function
- innervation
- Closes nasopharynx (posterior wall of pharynx pulled forward) along with soft palate
- Pharyngeal branch of vagus nerve (CN X) via pharyngeal plexus
Palatoglossus
- function
- innervation
- Narrows oropharyngeal isthmus (squeezes food from oral cavity into oropharynx during swallowing)
- Pharyngeal branch of vagus nerve (CN X) via pharyngeal plexus
Musculus uvulae
- function
- innervation
- Moves uvula
- Pharyngeal branch of vagus nerve (CN X) via pharyngeal plexus
The process of swallowing is divided into the voluntary and involuntary parts:
Voluntary portion of swallowing:
- __________ contracts: pulls root of tongue upwards and backwards → pushes bolus voluntarily against the hard palate
- ______________ contracts: squeezes bolus into the oropharynx
- Simultaneous soft palate elevation, superior constrictor and palatopharyngeus muscles: posterior wall of pharynx pulled forward → closure of nasopharynx (prevents food from entering the nose) Involuntary portion of swallowing (once bolus enters oropharynx):
- Larynx and laryngopharynx pulled upwards by the longitudinal muscles of pharynx → laryngeal inlet closed by the epiglottis (food enters the laryngopharynx)
- Successive contraction of constrictors: pushes the bolus down towards oesophagus
- Cricopharyngeus relaxes: bolus enters the oesophagus
Stylopharyngeus;
Palatoglossus
