Sem 2 - R - Parotid gland & temporal region - Parotid gland/duct, facial nerve, muscles of mastication/expression,C.N V3, E.C.A Flashcards
What type of cells are present in the parotid gland?
There are serous acini cells only in the parotid gland (cluster of cells resembling a many lobed structure = acini, serous cells produce watery fluid which contains a lot of proteins)
The parotid gland can be divided into superficial and deep by which structure? Will discuss this in more depth later
The parotid gland can be divided into superficial and deep by the facial nerve
The parotid gland has a connective tissue capsule and a fibrous capsule What does this capsule extend as?
The parotid gland capsule extends as the stylomandibular ligament intervening between parotid and submandibular salivary gland capsules
Where does the parotid duct lie proximally?
There is one single duct coming from the parotid gland that lies 1 finger’s breadth below the zygomatic arch
The parotid duct lies one finger’s breadth below the zygomatic arch Where does the parotid duct then travel?
The parotid arises from the anterior surface of the parotid gland and is found one finger’s breadth below the zygomatic arch
It will then traverse the masseter before taking a sharp medial turn to pierce the buccal fat pad and buccinator muscle to enter the oral cavity at the upper second molar
When is the partoid duct sometimes palpable?
The partoid duct may be palpable when tensing the masster
One the facial nerve exits the skull through which foramen? where does it go?
Once the facial nerve exits the skull through the stylomastoid foramen it enters the parotid gland dividing it into superficial and deep branches before dividing into its different branches
What muscles does the facial nerve give motor innervation to?
Facial nerve gives motor innervation via its branches to the muscles of facial expression, the posterior belly of digastric (arises from mastoid process), stylohyoid and stapedius muscles
Once the facial nerve exits the skull, what are the branches given before the facial nerve terminates into five terminal branches?
The first extracranial branch to arrive from the facial nerve is the posterior auricular nerve -
- Our Anatomy Lectures state this nerve (posterior auricular) gives off supply to the posterior belly of dgiastric and stylohyoid
- Other sources state that the nerves to posterior belly of digastric and nerve to stylohyoid are given off after posterior auricular
Once the facial nerve enters the parotid gland it will divide into its terminal branches? What are the terminal branches of the facial nerve?
- Temporal nerve
- Zygomatic nerve
- Buccal nerve
- Marginal mandibular nerve
- Cervical nerve
Name each of the muscles of facial expression supplied by the branches of the facial nerve Temporal - 3 muscles Zygomatic - 1 muscle Buccal - 11 muscles Marginal mandibular - 3 muscles Cervical - 1 muscle
- Temporal - Frontalis, orbicularis oculi, corrigator supercili,
- Zygomatic - Orbicularis oculi
- Buccal - Zygomaticus major and minor, levator labii superioris, levator labii superioris alaeque nasi, levator anguli oris, buccinator, orbicularis oris, risorius, nasalis, procerus, depressor septi nasi
- Marginal mandibular - Depressor anguli oris, depressor labii oris, mentalis
- Cervical - Platysma
The ECA will also give its terminal branches within the parotid gland What are these branches?
The external carotid artery terminates as the superficial temporal and maxillary artery
Which vein is found in the parotid gland and what forms it? What is the other nerve apart from facial found in the parotid gland? it runs with the superficial temporal vessels?
The retormandibular vein is found in the parotid gland formed from the union of the superficial temporal vien and the maxillary vein
The other nerve found is the auriculotemporal nerve which runs with the superficial temporal vessels (branch of CN V3)
Facial nerve is described as dividing the parotid gland into superficial and deep parts What are the structures in the parotid gland that are deep to the facial nerve? In order
Deep to the facial nerve lies the
- retromandibular vein (superficial temporal unites with maxillary vein),
- then the external carotid artery (terminates as superficial temporal and maxillary arteries) and
- then the auriculotemporal nerve
Which nerve lies superficial to the parotid gland?
The great auricular auricular nerve lies superficial to the parotid gland, travels superiorly once emerging at the middle of the posterior border of the SCM
Which nerve gives branches to supply the parotid gland with parasympathetic secretomotor innervation? How is sympathetic innervation the gland supplied?
The glossopharyngeal nerve (CN IX) supplies the parotid gland with parasympathetic secretomotor innervation
Postganglionic sympathetic fibres form plexuses around the ECA to innervate the parotid gland via its branches (ECA to maxillary to middle meningeal)
Describe how CN IX supplies parasympathetic secretomotor to the parotid gland?
- CN IX exits the skull via the jugular foramen.
- It will give a tympanic branch which will travel to tympanic cavity to form the tympanic plexus.
- From here, the lesser petrosal nerve , will emerge and will travel through the foramen ovale to synapse in the otic ganglion .
- Postganglionic fibres will then hitch a ride on the auriculotemporal nerve to reach the parotid gland.
Parasympathetics via CN IX to the parotid gland (could also say from lesser petrosal nerve) Sympathetics from arterial plexus on ECA
LETS NOW TALK ABOUT MUSCLES OF MASTICATION
What are the four main muscles?
- Temporalis
- Masseter
- Medial pterygoid
- Lateral pterygoid
What is the innervation to the muscles of mastication? What movements are possible at the mandible?
The muscles of mastication are all innervated by branches of the mandibular division of the trigeminal nerve (CN V3)
Movements - Elevation, depression, protrusion, retrusion, lateral sliding
What can cause depression of the mandible?
Depression can be by gravity or against force using the supra-hyoid muscle or by the lateral pterygoid muscle
Temporalis What is the temporalis covered by? What are the attachments of the temporalis?
The temporalis is covered by the tough temporal fascia
The temporalis attaches from the temporal fossa and fascia to the cornoid process and anterior border of the ramus of the mandible
What is the function of the temporalis? What is the nerve supply to the temporalis?
- The anterior and superior fibres of the temporalis elevate the mandible
- The posterior fibres of the temporalis retract the mandible
Innervation - Deep temporal nerves (x2) from the anterior division of CN V3
What is the attachment, function and nerve supply of the temporalis?
- Attachment - Temporal fossa and fascia to the coronoid process and anterior border of the ramus of the mandible
- Function - anterior and superior fibres elevate the mandible whilst posterior fibres retract the mandible
- Innervation - Deep temporal nerves (x2) from anterior division of CNV3
What is the attachment of the masseter?
Masseter attches from the zygomatic arch to the lateral aspect of the ramus of the mandible
Restate the attachment function and nerve supply of the masseter?
- Attachment - zygomatic arch to the lateral border of the ramus of the mandible
- Function - elevate the mandible
- Innervation - Masseteric nerves from anterior division of CN V3
When taking the mandible and zygomatic arch away, we are able to enter the infratemporal fossa
- It is within the infratemporal fossa where we will find the pterygoid muscles
The sphenoid bone has a pterygoid process on either side with a medial and lateral pterygoid plate coming from each process
- Which plate do the pterygoids attach to?
The lateral pterygoid muscles attaches to the lateral side of the lateral pterygoid plate
The medial pterygoid muscles attach to the medial side of the lateral pterygoid plate
What is the attachment of the lateral pterygoid muscle?
Upper head attaches from the infratemporal surface of the greater wing of the sphenoid
Lower head attaches from the lateral surface of the lateral pterygoid
- The two heads will insert onto the neck of the mandible and the articular disc
RESTATE THE attachment, function and nerve supply to the lateral pterygoid
- Attachment -
- Upper head from the infratemporal surface of the greater wing of sphenoid bone.
- Lower head from the lateral surface of the lateral pterygoid
- Inserts into the neck of mandible and articular disc of TMJ
- Function -
- Bilateral - pulls neck of mandible forward with articular disc (protrusion),
- Unilateral - helps lateral chewing movements with medial pterygoid, depresses mandible
- Innervation - Nerve to lateral pterygoid from anterior division CN V3
What are the attachments of the medial pterygoid muscle?
Superficial head attaches from the tubercle of the maxilla
Deep head attaches from medial surface of lateral pterygoid plate of sphenoid bone
- Inserts into the medial surface of the angle of the mandible
What is the function and nerve supply of the medial pterygoid muscles?
Function - Assists in elevation of mandible, assists in lateral chewing of mandible with lateral pterygoid
Innervation - Nerve to medial pterygoid form the main trunk of the mandibular division of the trigeminal nerve
STATE THE * ATTACHMENTS * FUNCTION * INNERVATION Of the muscles of mastication
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State all the nerves coming off CN V3
- CN V3 main trunk
- Meningeal nerve
- Nerve to medial pterygoid - gives off - Nerve to tensor tympani & Nerve to tensor veli palatini
- CN V3 anterior division
- Masseteric nerve , Nerve to lateral pterygoid, Deep temporal nerves (x2)
- Buccal nerve
- CN V3 posterior division
- Inferior alveolar nerve (gives nerve to mylohyoid)
- Auriculotemporal nerve, Lingual nerve
Where does the common carotid artery end? What are the terminal branches branches?
CCA ends in terminal branches behind the neck of the mandible - superficial temporal and maxillary artery
Where does posterior auricular artery go?
Posterior auricular artery rises at the level of the upper border of posterior digastric and travels to the scalp posterior and superior to the external ear
Where does the facial artery arise? What does it pass deep to? What branches does it give off?
Facial artery arises above the tip of the greater cornu and passes deep to the posterior belly of digastric. It gives off superior and inferior labial branches and an angular artery
TERMINAL BRANCHES OF ECA
- Where do they arise?
- Where does it superficial temporal travel and what does it divide into?
- What does maxillary artery provide branches to?
The terminal branches arise within the parotid gland behind the neck of the mandible
- Superficial temporal ascends in front of auricle and divides into anterior and posterior branches to supply frontal and temporal regions
- Maxillary artery travels into infratemporal fossa to supply various structures
Veins of the face are essentially same as arterial
- A difference is the facial vein
- How does this drainage differ?
The facial vein drains back to join with the anterior division of the retromandibular vein and drain into IJV
However some branches drain deep into the pterygoid venous plexus and cavernous drual venous plexus - these are routes of potential infection (meningitis)
Lymphatic drainage of the face is extensive Where do the deep cervical nodes sometimes lie?
Deep cervical nodes can often be found at the posteiror border of the scm
