Flashcards in Parotid, Temporal, and Infratemporal Regions and Temporomandibular Joint Deck (54)
Which cranial nerve pass forward within the parotid gland? What 2 parts of the parotid gland does this cranial nerve divide it into?
The facial nerve and its branches pass forward and divide the parotid into superficial and deep parts
What encloses the parotid gland, and what layer of deep fascia is this derived from?
The parotid sheath encloses it, and is derived from the investing layer of deep fascia
What thickening of fascia separates the parotid and submandibular glands, and what layer of fascia is it derived from?
Stylomandibular ligament separates parotid and submandibular glands, and is derived from the investing layer of deep fascia
What are the 4 main structures within the parotid gland, from superficial to deep?
1. Facial nerve (separates superficial and deep plate)
2. Retromandibular vein
3. External carotid artery
4. Auriculotemporal nerve
What 2 trunks does the facial nerve split into after entering the parotid gland?
Upper (temporofacial) and lower (cervicofacial) trunks
What is the parotid plexus?
Sometimes, the facial nerve branches and anastomose to form a parotid plexus. Regardless, usually leaves at 5 terminal branches
What are the 5 terminal branches of the facial nerve? Which one crosses over the facial artery?
Which surface of the parotid gland does the external carotid artery pass into,
which branch does it give off once it does,
and when does it divide into the 2 terminal branches
(and what are those terminal branches)?
-External carotid artery passes into the inferior border of the parotid
-Gives off the posterior auricular branch once it does
-Divides behind the neck of the mandible into 2 terminal branches
-Superficial temporal and maxillary
Which vein is formed within the substance of the parotid gland, and which two veins join together to form this vein?
The retromandibular vein is formed within the substance of the parotid
Forms by the union of the superficial temporal vein and maxillary vein
Which vein forms in the substance of the parotid, and when does that vein divide into 2 branches?
The retromandibular vein is formed within the substance of the gland
Divides into anterior and posterior branches just below the parotid gland
Is the buccinator a muscle of mastication?
It is an accessory muscle of mastication
What muscle does the parotid duct pierce?
The buccal fat pad and then the buccinator muscle
Describe the path of the parotid duct
Passes forward on surface of masseter a fingerbreadth below zygomatic arch
Pierces buccal fat pad and buccinator
Opens into oral cavity opposite the second upper molar tooth
Transverse facial artery (branch of superficial temporal) runs forward above parotid duct
Which artery runs forward above the parotid duct? What is this artery a branch of?
The transverse facial artery
-branch of the superficial temporal artery, which is one of the 2 terminal branches of the external carotid artery
What 2 nerves provide the general sensory innervation to the parotid gland, its sheath, and the overlying skin?
Great auricular nerve (branch of cervical plexus)
Auriculotemporal (branch of V3)
How do postganglionic parasympathetic fibers reach the gland?
Via the auriculotemporal nerve (V3)
How do postganglionic sympathetic fibers reach the parotid gland?
Derived from the external carotid plexus (recall that because a branch of the auriculotemporal artery from the external carotid artery supplies the parotid gland, it receives its sympathetic innervation from the same place)
What are the 5 contents of the temporal fossa?
Temporalis muscle and fascia
Deep temporal nerves
Deep temporal arteries
Zygomaticotemporal nerve branches
Auriculotemporal nerve and superficial temporal artery and vein
What are the deep temporal arteries branches of?
They are branches off of the maxillary branch of the external carotid artery
Where do the deep temporal nerves enter the temporalis muscle?
They pass around infratemporal crest of sphenoid and enter temporalis muscle on its deep surface
How do the zygomaticotemporal nerve branches enter the temporal fossa?
They enter the temporal fossa through one or more small foramina on the temporal fossa surface of the zygomatic bone
Where with respect to the ear do the auriculotemporal nerve and superficial temporal artery and vein pass?
Ascend immediately in front of the ear
Where with regard to the zygomatic arch is the infratemporal fossa?
Right below the zygomatic arch
What is contained in the infratemporal fossa? (7 things)
Mandibular division of trigeminal
Maxillary artery (1st and 2nd parts)
Pterygoid venous plexus
Medial and lateral pterygoid muscles
Which vein receives most of the blood from the pterygoid plexus?
For regions that are supplied by the maxillary artery, where do the associated veins drain the blood into?
Most of the veins that drain from these areas connect with the pterygoid plexus
What is the only important feature to memorize about the pterygoid plexus for exam 2?
None of these veins have valves so blood can flow in any direction. Infections can spread from the pterygoid plexus into any area that communicates with the pterygoid plexus.
For example, infections in the teeth can spread to the cranial cavity and the cavernous sinus resulting in cavernous sinus thrombosis and cranial meningitis
What nerve supplies the temporalis muscle?
Mandibular division of the trigeminal
Which muscle retracts the mandible after it has been protruded?
The temporalis muscle
What muscles depress the mandible?
(Dogs Go Missing)
What muscles elevate the mandible?
What nerve supplies the masseter muscle?
Mandibular division of the trigeminal
What is the main action of the masseter muscle?
Acts to elevate the mandible during mastication
What is the nerve supply to the lateral pterygoid?
Mandibular division of the trigeminal (in the anterior division, the lateral pterygoid nerve supplies it)
Which muscle of mastication protrudes the mandible forward?
The lateral pterygoid (this is part of opening the mouth)
What nerve supplies the medial pterygoid muscle?
Mandibular division of the trigeminal (branch given off prior to anterior and posterior division of the trigeminal)
What are the 4 muscles of mastication?
**Buccinator muscle is a muscle of facial expression, but is considered an accessory muscle of mastication
What ligament separates the medial and lateral pterygoid muscles?
The sphenomandibular ligament
What is the main function of the temporomandibular joint?
Is a modified hinge joint
Allows opening and closing via a hinge action around a central axis passing through the mandibular condyles as well as anterior/posterior sliding movements
What are the articular surfaces of the TMJ covered by?
Fibrocartilage (unlike other synovial joints)
What are the 2 parts of the TMJ, and what different movements do they allow?
Upper part (which is lax) allows mandible to slide forward and backward
Lower part (taut) allows mainly the hinge -like depression and elevation
-So translation occurs in the upper capsule of the joint
What separates the 2 parts of the TMJ?
The articular disc
What are the 3 accessory ligaments of the TMJ?
Temporomandibular (lateral) ligament
What is the function of the temporomandibular ligament?
Functions as a check ligament to prevent downward and backward displacement of the condyle
What is the function of the stylomandibular ligament?
Functions as a check ligament in the protrusion of the mandible (but only becomes taut upon extreme protrusion)
What is the function of the sphenomandibular ligament?
Functions as a check ligament and is relaxed when jaw is closed and becomes tense as the jaw is opened
When opening the mouth, what movements of the mandible are involved? What is involved with closing the mouth?
Opening the mouth involves both depression and protrusion of the mandible
Closing the mouth involves retraction and elevation of the mandible
What muscles are involved in depression of the mandible?
(3 suprahyoid muscles that raise the hyoid or depress the mandible. most of depression of mandible is by gravity)
(Dogs Go Missing)
What muscles are involved in the elevation of the mandible?
What is the prime mover for protrusion (protraction)? ** What is it assisted by?
Prime mover is the lateral pterygoid
assisted by superficial heads of masseter and medial pterygoid
What is the primer mover for retrusion (retraction)?** What is it assisted by?
Prime mover are posterior fibers of the temporalis
Assisted by deep head of masseter and digastric
What in the TMJ does not have a vascular or nerve supply?
The articular surfaces (if they articulate, bad place for vessels and nerves)
-specifically, the articular tissues and dense part of articular disc
What is the main nerve supply of the TMJ?** What are 2 small sensory supplies?
Main nerve supply is by the auriculotemporal nerve
Smaller sensory supply from posterior deep temporal nerve and masseteric nerve