Infratemporal fossa Flashcards
What does fossa mean ?
Depression
What is the superior boundary of the temporal fossa ?
the superior temporal line
What is the inferior boundary of the temporal fossa ?
the zygomatic arch and greater wing of the sphenoid bone
What is the posterior boundary of the temporal fossa ?
the superior and inferior temporal lines
What is the anterior boundary of the temporal fossa ?
the zygomatic bone and frontal bone
What is the medial boundary of the temporal fossa ?
- frontal bone
- parietal bone
- sphenoid bone
- temporal bone
What is the lateral boundary of the temporal fossa ?
the skin and temporal fascia
Which muscle occupies the temporal fossa ?
the temporalis muscle
What is found on the roof of the infratemporal fossa ?
the greater wing of the sphenoid bone
What is found on the medial wall of the infratemporal fossa ?
the lateral pterygoid plate and pharynx
What is found on the lateral wall of the infratemporal fossa ?
the medial surface of the ramus of the mandible
What is found on the posterior wall of the infratemporal fossa ?
the styloid process and stylomandibular ligament
What is found on the anterior wall of the infratemporal fossa ?
the maxillary tuberosity
What is found on the floor of the infratemporal fossa ?
it is imaginary - nothing there
What is protraction or protrusion of the mandible ?
the anterior movement of the mandible
What is retraction or retrusion of the mandible ?
the posterior movement of the mandible
What is elevation of the mandible ?
the upwards movement of the mandible
What is depression of the mandible ?
the downwards movement of the mandible
What is lateral excursion of the mandible ?
side to side movement of the mandible
How is lateral excursion of the mandible brought about ?
- unilateral movement of the pterygoid muscles
- the contraction of the pterygoid muscles on one side will cause contralateral movement of the mandible
Which joint is responsible for allowing the movement of the mandible ?
the temporomandibular joint
What are the muscles of mastication ?
- temporalis
- masseter
- medial and pterygoid muscles
What is the origin of the temporalis muscle ?
the temporal lines of the temporal fossa
What is the insertion of the temporalis muscle ?
the inner aspect of the coronoid process of the mandible
What is the action of the temporalis muscle ?
- the vertical anterior fibres allow the mandible to elevate
- the horizontal posterior fibres allow the mandible to retract
Summarise the temporalis muscle
- origin : the temporal lines of the temporal fossa
- insertion : the inner aspect of the coronoid process of the mandible
- action :
- the vertical anterior fibres allow the mandible to elevate
- the horizontal posterior fibres allow the mandible to retract
What is the origin of the masseter muscle ?
the zygomatic arch going to the zygomatic process of the maxilla
What is the insertion of the masseter muscle ?
the angle of the mandible
What is the action of the masseter muscle ?
- the larger superficial head is involved in the protraction and elevation of the mandible
- the smaller deep head is involved in the retraction of the mandible
Summarise the masseter muscle
- origin : the zygomatic arch going to the zygomatic process of the maxilla
- insertion : the angle of the mandible
- action :
- the larger superficial head is involved in the protraction and elevation of the mandible
- the smaller deep head is involved in the retraction of the mandible
What is the origin of the medial pterygoid muscle ?
- the smaller superficial head originates at the maxillary tuberosity
- the larger deep head attaches at the medial aspect of the lateral pterygoid plate
What is the insertion of the medial pterygoid muscle ?
the angle of the mandible
What is the action of the medial pterygoid muscle ?
- protraction
- elevation
- retraction
Summarise the medial pterygoid muscle
- origin :
- the smaller superficial head originates at the maxillary tuberosity
- the larger deep head attaches at the medial aspect of the lateral pterygoid plate
- insertion : the angle of the mandible
- action : protraction, elevation and retraction
What is the origin of the lateral pterygoid muscle ?
- the smaller superior head originates at the infratemporal surface of the sphenoid bone
- the larger inferior head originates at the lateral aspect of the lateral pterygoid plate
What is the insertion of the lateral pterygoid muscle ?
- the smaller superior head inserts at the anterior attachment of the mandibular condyle
- the larger inferior head inserts at the pterygoid fovea
What is the action of the lateral pterygoid muscle ?
its involved in the protraction of the mandible at the TMJ
Summarise the lateral pterygoid muscle
origin :
- the smaller superior head originates at the infratemporal surface of the sphenoid bone
- the larger inferior head originates at the lateral aspect of the lateral pterygoid plate
insertion :
- the smaller superior head inserts at the anterior attachment of the mandibular condyle
- the larger inferior head inserts at the pterygoid fovea
action :
- its involved in the protraction of the mandible at the TMJ
What shape is the medial pterygoid muscle ?
it is a quadrangular muscle
What shape is the lateral pterygoid muscle ?
it is a triangular shape
What is the posterior attachment of the lateral pterygoid muscle ?
the temporomandibular joint
Describe the innervation of the muscles of mastication
they are all innervated by the mandibular division of the trigeminal nerve
What is the innervation of the temporalis muscle ?
the deep temporal branches
What is the innervation of the masseter ?
masseteric nerve
What is the innervation of the medial pterygoid muscle ?
medial pterygoid nerve
What is the innervation of the lateral pterygoid muscle ?
lateral pterygoid nerve
Where does the maxillary artery originate from ?
it is a branch of the external carotid artery and starts at the level of the neck of the mandible
Describe the course of the maxillary artery
- it is deep to the neck of the mandibular condyle
- it crosses the infratemporal fossa
- it enters the pterygopalatine fossa through the pterygomaxillary fissure
What are the 3 parts of the maxillary artery ?
The maxillary artery can be split into 3 parts in relation to the lateral pterygoid muscle
- the first part is posterior to the lateral pterygoid
- the second part is superficial or deep to the lateral pterygoid
- the third part is anterior to the lateral pterygoid
Describe the distribution of the maxillary artery in relation to the nerves
- the distribution aligns with other parts of the trigeminal nerve
- parts 1 and 2 align with branches of the mandibular division
- part 3 aligns with branches of the maxillary division
What does the maxillary artery supply ?
- nasal cavity
- teeth
- dura mater in the cranial cavity
What is the pterygoid venous plexus ?
it is a network of nerves associated with the infratemporal fossa
What does the pterygoid venous plexus drain ?
- nasal cavity
- roof and lateral wall of the oral cavity
- teeth
- muscles of the ITF
- paranasal sinuses
- nasopharynx
Why is the pterygoid venous plexus a potential route of infection ?
it contains emissary veins which are connected to the cavernous sinus in the skull
e.g. infection can spread from the teeth to the cranial cavity
Describe the trigeminal nerve
- it arises in the middle cranial fossa
- it has a large sensory component and a small motor component
Describe the origin and course of the mandibular division of the trigeminal nerve
- arises in the middle cranial fossa from the trigeminal ganglion
- passes through the foramen ovale
- it almost immediately divides into a smaller anterior branch and larger posterior branch
- the stem is attached to the otic ganglion
What are the 4 ganglions found in the head ?
- ciliary ganglion
- otic ganglion
- pterygopalatine ganglion
- submandibular ganglion
What type of ganglion is the otic ganglion ?
it is a parasympathetic ganglion
What are the branches of the stem of the mandibular division of the trigeminal nerve ?
- medial pterygoid (motor)
- meningeal branch (sensory) > it then travels back up the foramen spinosum
What are the branches of the anterior branch of the mandibular division of the trigeminal nerve ?
- masseteric (motor)
- deep temporal (motor)
- lateral pterygoid (motor)
- buccal (sensory)
What are the branches of the posterior branch of the mandibular division of the trigeminal nerve ?
- auriculotemporal (sensory)
- lingual (sensory)
- inferior alveolar (sensory)
What are the 2 branches of the inferior alveolar nerve ?
- nerve to mylohyoid (motor)
- mental (sensory)
Why is it important to understand the sensory nerves of the mandibular nerve ?
they are important for the application of anaesthetic
Describe the function of the buccal nerve
it supplies the molars and the associated soft tissues of the buccal region
Which nerve supplies the incisors ?
the incisive nerve
Describe the function of the lingual nerve
- it travels over the surface of the medial pterygoid and goes towards the oral mucosa and floor of the mouth
- it supplies the lingual gingiva and the tongue
Which cranial nerve gives off the chorda tympani nerve ?
CN VII - facial nerve
What are the 2 aspects of the sensory innervation of the tongue ?
- general sense : pain, temperature and touch
- special sense : taste
How is the tongue split ?
the circumvallate papillae splits the tongue into :
- anterior 2/3
- posterior 1/3
Describe the sensory innervation of the posterior 1/3 of the tongue
both the general and special sense is supplied by the glossopharyngeal nerve
Describe the sensory innervation of the anterior 2/3 of the tongue
general sense - lingual nerve
special sense - chorda tympani
Why might the lingual nerve get damaged ?
the lingual nerve lies very close to the molars and so it may be damaged when a tooth is being extracted
Describe the function of the chorda tympani nerve in terms of salivary secretion
- the preganglionic parasympathetic fibres will synapse with the postganglionic parasympathetic fibres in the submandibular ganglion
- signals will be sent to the sublingual and submandibular glands to secrete saliva