Topic 4 - Face, Mouth, Temporomandibular Joint

Question 1

Describe the bony components and ligaments that make up the TMJ?

Answer 1

The temporomandibular joint (TMJ) is the joint between the mandible and the temporal bone.

Bones: the condyle of the mandible articulates with the mandibular fossa of the zygomatic process of the temporal bone.

There are 3 ligaments associated with the TMJ:

1. the stylomandibular ligament which runs from the styloid process to the angle of the mandible
2. sphenomandibular ligament which runs from the sphenoid bone to the inner surface of the mandible,
3. lateral (or temporomandibular) ligament, which acts as part of the joint capsule and surrounds most of the TMJ

Question 2

Describe the pathway of the facial artery, taking into account its location in relation to the muscles of facial expression.

Answer 2

• The facial artery branches off the external carotid artery.
• It crosses the lower border of the mandible just anterior to the angle of the mandible, and courses in a medial and superior direction across the face, before terminating at the medial corner of the eye. (This occurs on both sides, for the left and right facial arteries).
• It lies deep to the zygomatic major and levator labii superioris.

Question 3

If you have an itchy forehead, what nerve is transmitting the information to your brain?

Answer 3

• Itching is information carried by SENSORY nerves.
• Try not to get confused between sensory (something you feel) and motor (movement using muscles).
• So, sensory information is carried TO the brain from the face by the trigeminal nerve (cranial nerve V).

Just for interest, motor information TO the muscles of facial expression, is via the facial nerve (cranial nerve VII)

Question 4

Describe the detailed motor innervation of the muscles of facial expression.

Answer 4

The facial nerve, cranial nerve VII, supplies all of the muscles of facial expression with motor nerve fibres - this is what makes them move.
The facial nerve emerges from inside the skull at the stylomastoid foramen and forms 5 branches – the temporal, zygomatic, buccal, marginal mandibular, and cervical branches. (There are some great mnemonics to remember these branches.)
These branches innervate muscles as follows:

• Temporal – orbicularis oculi (upper part)
• Zygomatic – upper lip muscles (zygomatic major and minor, levator labii superioris, levator labii superioris alaeque nasi, nasalis)
• Buccal – muscles in the cheek region – buccinator, risorius, upper part of orbicularis oris
• Marginal mandibular – lower lip muscles (lower part of orbicularis oris, depressor anguli oris, mentalis, depressor labii inferioris)
• Cervical – platysma

Question 5

Paralysis of the depressor anguli oris muscle would result from damage to which nerve and branch?

Answer 5

• If a muscle is paralysed, it cannot move. Therefore its motor innervation (not sensory) is likely to be affected.

If there is a loss of sensation then we’re talking about sensory nerves.
The answer to this question then is the facial nerve, marginal mandibular branch. (See the question above where we established that this is the nerve and branch that supplies motor innervation to the depressor anguli oris.)

Question 6

What is the purpose of the sublingual and submandibular glands?

Answer 6

• These are salivary glands.
• They produce saliva which lubricates the oral cavity, and helps to lubricate food during mastication.

Question 7

What’s the dangly bit at the back of your oral cavity called? What does it represent?

Answer 7

Uvula

It represents the cone-shaped ending of the soft palate, and is the uvular muscle or musculus uvulae, covered by mucus membrane.

Question 8

Which tonsils are found in the roof or wall of the nasopharynx?

Answer 8

1. Pharyngeal tonsils (adenoids)

Other tonsils:

1. Palatine tonsils - between the palatoglossal and palatopharyngeal arches

Question 9

Describe the motor and sensory innervation of the TMJ, by cranial nerve and branch.

Answer 9

INNERVATION OF FACE

• motor innervation:
  
  • muscles of facial expression (Facial nerve CN VII)
  • muscles of mastication (Trigeminal nerve CN V)
• sensory innervation
  
  • trigeminal nerve CN V

Question 10

Which vein drains blood from the TMJ?

Answer 10

• The maxillary artery, a terminal branch of the carotid artery, passes via the TMJ to supply deeper structures in the infratemporal fossa, supplying the TMJ as it passes.
• The maxillary vein drains venous blood from. The TMJ area and into the external jugular vein.

Question 11

What are the branches of the facial nerve?

Answer 11

• The facial nerve emerges from the internal skull at the stylomastoid foramen
• as it passes through the large parotid gland anterior to the ear, it forms 5 branches:

1. Temporal branch
2. Zygomatic branch
3. buccal branch
4. marginal mandibular branch
5. cervical branch

Question 12

Which artery provides a pulse point on the inferior border of the mandible?

Answer 12

The facial artery (major branch off the external carotid artery) supplies arterial blood to the facial muscles and other soft tissues.

It crosses the lower border of the mandible and acts as a pulse point about one fingers width across the face, giving off small branches and terminating at the medial corner of the eye.

Question 13

Name the attachments of the medial pterygoid muscle.

Answer 13

• Medial pterygoid muscle - attaches to the lateral pterygoid plate and the medial surface of the mandible near the angle

other muscles of TMJ:

• Temporalis - covers lateral temporal bone and attaches to the coronoid process. Fills much of temporal fossa.
• Masseter - attaches to the zygomatic bone and folds under the angle, ramus and body of the mandible.
• Lateral pterygoid - attaches to the lateral pterygoid plate and the mandibular condyle

Question 14

What is the function of the pterygoid muscles in mandibular deviation?

Answer 14

Deviation - slides the mandible to the L+R

Depression - lowers mandible (open mouth)

Elevation - raises mandible (close mouth)

Deviation - slides mandible L+R

Protrusion (protraction) - push jaw anteriorly

Retrusion (retraction) - pull jaw posteriorly (after protrusion)

Question 15

What is the difference between the hard and the soft palate? Describe in terms of structure and location.

Answer 15

Hard palate

• the anterior part of the palate
• forms most of the roof of the mouth
• formed by maxillary + palatine bones.

Soft palate

• posterior part of the palate
• also contributes to the roof of the mouth
• muscular structure
• ends in cone shaped dangling uvula

Question 16

Name the different tonsils and describe specifically where they are located

Answer 16

Pharyngeal tonsils (adenoids) - found in the roof or wall of the nasopharynx

Other tonsils:

Palatine tonsils - between the palatoglossal and palatopharyngeal arches

Question 17

What are the muscles of mastication? Describe their location and attachments

Answer 17

4 muscles of mastication (chewing):

1. Temporalis
   
   • fan shaped muscle covering lateral aspect of temporal bone
   • Attaches to coronoid process
   • fills much of temporal fossa
2. Masseter
   
   • attaches to zygomatic bone
   • folds under angle, ramus and body of mandible
3. Lateral pterygoid
   
   • attaches to lateral pterygoid plate + mandibular condyle
4. medial pterygoid
   
   • attaches to lateral pterygoid plate + medial surface of mandible near angle

Question 18

Name the different salivary glands and describe specifically where they are located.

Answer 18

Saliva required for lubrication of oral cavity and mastication (chewing) of ingested food.

Saliva produced in 3 major glands:

1. Parotid gland
   
   • largest gland
   • superficially anterior to external ear opening
2. Submandibnular gland
   
   • superficially under inferior body of mandible
3. Sublingual glands
   
   • cluster of small glands under tongue

Question 19

What is the uvula?

Answer 19

• Muscular end of the soft palate
• cone shaped extension
• dangles in back of oral cavity

Question 20

Which is the largest salivary glands?

Answer 20

Parotid gland

• largest
• superficially anterior to external ear opening

Submandibular gland

• superficially under inferior body of mandible

Sublingual glands

• cluster small glands under tongue

Question 21

Describe the bony articulations of the TMJ.

Answer 21

TMJ made up of:

• mandibular condyle and mandibular fossa of the temporal bone
• has an articulate disc (meniscus) in the middle of the joint cavity, separates the condyle and the temporal bone. Meniscus divides joint into superior + inferior spaces

Question 22

What is the mentalis muscle, and where is it located?

Answer 22

The mentalis is a paired central muscle of the lower lip, situated at the tip of the chin.

The mentalis muscle is a paired muscle located at the tip of the chin. It acts as the primary muscle of the lower lip.

This muscle provides stability to the lower lip to allow it to pout. It causes protrusion of the lower lip and elevates the skin of the chin.

Question 23

What is the platysma and where is it located?

Answer 23

• The platysma is under the chin
• It lies in the superficial fascia of the neck
• Depresses the mandible, widens the mouth and tenses the neck
• Expression of horror

Question 24

Which cranial nerve and branch supplies motor function to the risorius and buccinators?

Answer 24

Risorius

• is a dilator muscle
• small muscle attach to corners of mouth, angling slightly upwards.
• pulls the corners of the mouth

Buccinator

• muscle of the cheek
• suckling + chewing (push food against teeth)
• also used when pressure raised in mouth (blow trumpet)
• presses cheeks against back of teeth
• found deep to risorius + zygomatic major

Question 25

Name the major blood vessels that branch off the external carotid artery, supplying structures in the head and face, in order from inferior to superior, and name a structure that each one supplies.

Answer 25

Except for the brain, most of the head structures are supplied by branches of the external carotid artery.

The external carotid artery is responsible for the blood supply to the neck and face (both superficial and deep face) The branches of the external carotid artery are:

1. BranchesSuperior thyroid artery
2. Ascending pharyngeal artery
3. Lingual artery
4. Facial artery
5. Occipital artery
6. Posterior auricular artery
7. Maxillary artery
8. Superficial temporal artery

Mnemonic: Some Anatomists Like Freaking Out Poor Medical Students

Question 26

What is the name for the part of the oral cavity between the lips and the teeth?

Answer 26

2 parts of the oral cavity (buccal cavity)

• Vestibule - between lips + teeth
• mouth proper - between teeth + pharynx, contains tongue

Question 27

Which bones form the hard palate?

Answer 27

Hard palate formed by:

1. maxilla bone
2. palatine bone

Question 28

Name the main muscles of the TMJ and their attachments

Answer 28

Main muscles of TMJ:

• Temporalis - elevates mandible
• Masseter - elevates mandible
• Lateral pterygoid - Protracts mandible, depresses chin, lateral deviation of mandible
• Medial pterygoid - Works with masseter to elevate mandible, aids in protrusion,
• Digastric, Stylohyoid, Mylohyoid, Geniohyoid - Depresses the mandible against resistance when infrahyoid muscles stabilize or depress hyoid bone
• Platysma - Depresses mandible against resistance

The muscles that act on the TMJ are innervated by the mandibular nerve (CN V), the facial nerve (CN VII), C 1, C 2 and C 3.

Question 29

What is the function of the rugae on the hard palate?

Answer 29

On the anterior portion of the roof of the hard palate are the transevese palatine folds (rugae) which are the irregular ridges in the mucous membrane that help facilitate the movement of food backwards towards the pharynx.

Question 30

What is the lingual frenulum?

Answer 30

• The lingual frenulum is a fold of mucus membrane that’s located under the center portion of your tongue
• helps to anchor your tongue in your mouth.
• also works to stabilize the movements of the tongue.

Question 31

Name a muscle most likely used in smiling

Answer 31

• Zygomaticus major

raise eyebrows - frontalis

blow kiss - orbicularis oris

pout - mentalis

sad - depressor anguli oris

smirk - risorius

confused - corrugator supercilli

turn nose up - procerus

smell - nasalis

Question 32

If the temporal muscle is paralysed, which cranial nerve and branch is implicated?

Answer 32

If a muscle is paralysed, it cannot move. Therefore its motor innervation (not sensory) is likely to be affected.

The effects of damage to the facial nerve on whether facial muscles are paralysed or not depends on where in the nerve the damage occurs.

• if damage occurs in the upper nerve, before the fibres cross over, there will be paralysis of the muscles on the lower half of the face on the opposite side
• if damage occurs in the lower nerve after the fibres cross over, there will be paralysis of all the muscles on the same side of the face.

Question 33

What are rugae and where are they located?

Answer 33

Rugae are a series of ridges produced by folding of the wall of an organ.

Located in hard palate immediately behind the upper anterior teeth

Question 34

What is the depressor anguli oris?

Answer 34

• Depressor anguli oris receives motor innervation from marginal mandibular and buccal branches of facial nerve (CN VII).
• it helps expressing feelings of sadness or anger. This is why depressor anguli oris is deemed one of the “frowning muscles”, along with muscles such as corrugator supercilii, procerus and orbicularis oris.
• Depressor anguli oris also aids in functions such as opening the mouth while speaking or eating.
• While opening the mouth, the action of depressor anguli oris modifies the mentolabial sulcus, making it deeper and more horizontal.

Question 35

What is the soft palate?

Answer 35

• The soft palate is the posterior part of the palate
• also contributes to the roof of the mouth
• is a muscular structure that ends as a cone-shaped inferior extension that can be seen dangling in the back of the oral cavity (uvula)

Question 36

Which blood vessel supplies arterial blood to the TMJ?

Answer 36

• The arterial supply to the TMJ is provided by the branches of the external carotid, principally the superficial temporal branch.

Question 37

Name a muscle that attaches to the coronoid process

Answer 37

• The Temporalis covers much of the lateral temporal bone and attaches to the coronoid process.
• it fills much of the temporal fossa

Other muscles of the TMJ:

masseter muscle - attaches to the zygomatic bone. Folds under the angle, ramus + body of the mandible

lateral pterygoid - attaches to the lateral pterygoid plate + the mandibular condyle

medial pterygoid - attaches to the lateral pterygoid plate + the medial surface of the mandible near the angle

Question 38

What are faucial pillars?

Answer 38

• The right and left palatoglossus muscles create ridges in the lateral pharyngeal wall, referred to as the palatoglossal arches (anterior faucial pillars). These pillars separate the oral cavity and the oropharynx — the muscle functions as an antagonist to the levator veli palatini muscle.

Question 39

Describe the features of the mandible.

Answer 39

• The mandible, located inferiorly in the facial skeleton, is the largest and strongest bone of the face.
• It forms the lower jaw and acts as a receptacle for the lower teeth. It also articulates on either side with the temporal bone, forming the temporomandibular joint.

Question 40

What is the temporal fossa and how is it different to the infratemporal fossa?

Answer 40

• The zygomatic process of the temporal bone articulates with the zygomatic bone to form the zygomatic arch.
• The space superior + deep to the zygomatic arch is called the temporal fossa.
• The space inferior + deep to the zygomatic arch is the infratemporal fossa. It’s the space that exists below the temporal fossa
• they communicate with each other

Question 41

Where are the pterygoid plates located? How many are there and what are their exact names?

Answer 41

• pterygoid plate are either of a pair of thin, bony processes that arise from the sphenoid bone.
• They are termed medial and lateral pterygoidplates on each side, serve to bound the infratemporal fossa, and give origin to muscles of mastication.

Question 42

What is the difference between the condyle and the coronoid. Where are they located?

Answer 42

• The coronoid process, as previously mentioned, is the foremost structure at the head of the ramus, attaches to the temporalis muscle, which is utilized during mastication
• The condylar process is the bony extrusion behind the coronoid process, which forms the lower bony component of the temporomandibular joint, along with the temporal bone

At the most superior point of the ramus (top of the mandible), it divides into two processes, which are separated by a mandibular notch. Anteriorly, sits the coronoid process and posteriorly, the condylar process, which articulates with the temporal bone.

Question 43

Name the ligaments associated with the TMJ.

Answer 43

Ligaments of the TMJ:

1. Lateral ligament: an extension of the joint capsule, surrounds most of the joint. Very strong. Helps prevent posterior dislocation
2. Stylomandibular ligament: attaches to the styloid process and the angle of the mandible. For joint stabilisation
3. Sphenomandibular ligament: attaches to the sphenoid bone and the inner surface of the mandible. For joint stabilisation

Question 44

Which muscles allow side to side deviation of the jaw? How is this achieved?

Answer 44

Muscles of TMJ:

• Temporalis - elevates the mandible
• masseter - elevates the mandible
• lateral pterygoid - Protracts mandible, depresses chin, lateral deviation of mandible
• medial pterygoid - Works with masseter to elevate mandible, aids in protrusion,
• Digastric, Stylohyoid, Mylohyoid, Geniohyoid - Depresses the mandible against resistance when infrahyoid muscles stabilize or depress hyoid bone
• platysma - Depresses mandible against resistance