Temporal, Infratemporal and Submandibular Regions, and the Temporomandibular joint

Question 1

Dissection of the temporal fossa: 6-minute video

Answer 1

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Question 2

Dissection of the infratemporal fossa: 18-minute video

Answer 2

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Question 3

Cadaveric demonstration of the lingual artery: 3-minute video

Answer 3

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Question 4

[4-minute video]: the Maxillary Nerve

Answer 4

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Question 5

State the boundaries of the temporal fossa.

Answer 5

Anterior: Zygomatic and frontal bones
Posterior: Inferior temporal line and supramastoid crest
Superior: Superior temporal line
Inferior: Zygomatic arch
Floor: Parts of frontal, parietal and temporal bones and greater wing of sphenoid bone

[Diagram: Temporal Fossa]

Question 6

What forms the zygomatic arch?

Answer 6

Anteriorly by the temporal process of zygomatic bone
Posteriorly by the zygomatic process/zygoma of temporal bone
[Diagram]

Question 7

List the contents of the temporal fossa.

Answer 7

1. Temporalis muscle
2. Temporal fascia (overlies the temporalis muscle)
3. Superficial temporal artery [one of the terminal branch of ________________ artery]
4. Superficial temporal vein [unites with maxillary vein to form the ________________ vein]
5. Auriculotemporal nerve [branch of mandibular nerve]
6. Zygomaticotemporal nerve
7. Temporal branch of facial nerve
8. [Diagram]

Question 8

State the clinical relevance of temporal fossa.

Answer 8

Temporalis flap

Question 9

List the boundaries of the infratemporal fossa.

Answer 9

Laterally (superficial): ramus of the mandible
Medially (deep): lateral pterygoid plate
Anteriorly: posterior aspect of the maxilla
Posteriorly: tympanic plate, mastoid and styloid processes of the temporal bone
Superiorly: the inferior (infratemporal) surface of the greater wing of sphenoid [Notice the infratemporal crest on the infratemporal surface of greater wing of sphenoid]

[Diagram 1] [Diagram 2] [Cadaveric image]

Question 10

State the contents of the infratemporal fossa.

Answer 10

1. Inferior part of the temporalis muscle
2. Lateral and medial pterygoid muscles
3. Maxillary artery
4. Pterygoid venous plexus
5. Mandibular, inferior alveolar, lingual, buccal, chorda tympani nerves
6. Otic ganglion
7. [Diagram: Some of the contents of infratemporal fossa]

Question 11

Click on Answer to view a linked image showing connections of infratemporal fossa.

Answer 11

[Diagram]

Question 12

The medial and lateral plates of pterygoid process are parts of the ________________ bone.

Answer 12

sphenoid
[Diagram]

Question 13

List the muscles of mastication.

Answer 13

1. Medial pterygoid muscle
2. Lateral pterygoid muscle
3. Masseter
4. Temporalis
5. [Diagram]

Question 14

Medial pterygoid muscle
1. Origin
2. Insertion
3. Innervation
4. Action

Answer 14

1. Origin:
   Deep head—medial surface of lateral plate of pterygoid process and pyramidal process of palatine bone
   Superficial head—tuberosity of the maxilla and pyramidal process of palatine bone
2. Insertion: Medial surface of mandible near angle
3. Innervation: Nerve to medial pterygoid from the mandibular nerve [V3]
4. Action: Elevation and side-to-side movements of the mandible. It can assist in protrusion of mandible, but that is a weak action of medial pterygoid.
5. [Diagram 1] [Diagram 2]

Side-to-side movement is done during chewing.

Question 15

Lateral pterygoid muscle
1. Origin
2. Insertion
3. Innervation
4. Action

Answer 15

1. Origin:
   Upper head—roof of infratemporal fossa
   Lower head—lateral surface of lateral plate of the pterygoid process
2. Insertion: Capsule of temporomandibular joint in the region of attachment to the articular disc and to the pterygoid fovea on the neck of mandible
3. Innervation: Nerve to lateral pterygoid directly from the anterior division of the mandibular nerve [V3] or from the buccal branch
4. Action: Protrusion, side-to-side movements and depression of the mandible
5. [Diagram 1] [Diagram 2]

Further notes:
✓ Side-to-side movement is done during chewing.
✓ Among all the four muscles of mastication (medial pterygoid, lateral pterygoid, masseter, and temporalis), the lateral pterygoid is the only muscle that participates in depressing the mandible.

Question 16

Masseter
1. Origin
2. Insertion
3. Innervation
4. Action

Answer 16

1. Origin: Zygomatic arch and maxillary process of the zygomatic bone
2. Insertion: Lateral surface of ramus of mandible
3. Innervation: Masseteric nerve from the anterior division of the mandibular nerve [V3]
4. Action: Elevation of mandible
5. [Diagram: Masseter]

Question 17

Temporalis
1. Origin
2. Insertion
3. Innervation
4. Action

Answer 17

1. Origin: Bone of temporal fossa and temporal fascia
2. Insertion: Coronoid process of mandible and anterior margin of ramus of mandible almost to last molar tooth
3. Innervation: Deep temporal nerves from the anterior division of the mandibular nerve [V3]
4. Action: Elevation and retraction of mandible
5. [Diagram: Temporalis]

Question 18

a) What type of joint is the temporomandibular joint (TMJ)?
b) Articular surfaces of the TMJ?

Answer 18

a) (Compound) Condylar synovial joint
b) Superiorly: mandibular fossa and articular tubercle.
Inferiorly: head of the mandible.

[Diagram: TMJ] [Diagram: Mandible]

Note: The articular tubercle prevents dislocation.

Question 19

The articular disc divides the synovial cavity into an upper and lower cavity. State the actions that each facilitate.

Answer 19

1. Upper cavity: for protrusion and retraction
2. Lower cavity: for elevation and depression

[Diagram]: compare the sizes of the superior and inferior synovial cavities during depression of mandible.

Question 20

(a) List 3 accessory ligaments of the TMJ and their functions.
(b) State the:
(i) arterial supply to the TMJ.
(ii) nerve supply to the TMJ.

Answer 20

(a) Ligaments and their functions
✓ Lateral temporomandibular ligament: prevents posterior displacement of mandible
✓ Sphenomandibular ligament (from spine of sphenoid to lingula of mandible): limits distension of the mandible in an inferior direction
✓ Stylomandibular ligament: limit excessive protrusion of the mandible
[Diagram: Accessory ligaments of the TMJ]

(b) Neurovascular supply
(i) maxillary and superficial temporal arteries
(ii) auriculotemporal nerve and masseteric nerve

Question 21

Name the structure that attaches at the lingula of the mandible.

Answer 21

sphenomanibular ligament

Question 22

For the following movements of the TMJ, list the muscles involved:
(a) protrusion
(b) retraction
(c) elevation
(d) depression
(e) side to side movement (chewing)

Answer 22

(a) protrusion: lateral pterygoid, medial pterygoid, superficial fibers of masseter
(b) retraction: posterior fibers of temporalis
(c) elevation: temporalis, masseter, medial pterygoid
(d) depression: lateral pterygoid, digastric, geniohyoid, mylohyoid and gravity
(e) side to side movement (chewing): medial pterygoid, lateral pterygoid

Question 23

State the origin and course of maxillary artery.

Answer 23

✓ the larger terminal branch of external carotid artery
✓ arises behind the neck of the mandible, runs horizontally forward up to the lower border of lower head of lateral pterygoid.
✓ now it turns upwards and forwards, crosses the lower head of lateral pterygoid superficially (sometimes deep).
✓ after emerging between the two heads of lateral pterygoid it enters the pterygopalatine fossa by passing through pterygomaxillary fissure. Here it ends by giving its terminal branches.

Note:
The maxillary artery enters the infratemporal fossa by passing forwards, between the neck of mandible and the sphenomandibular ligament.

[Diagram 1]; shows the relation of the parts of the maxillary artery to the lateral pterygoid.
[Diagram 2]
[Diagram 3]
[Radiograph]

Question 24

The maxillary artery has a wide territory of distribution. What does it supply?

Answer 24

(a) upper and lower jaws,
(b) muscles of temporal and infratemporal fossae,
(c) nose and paranasal sinuses,
(d) palate and roof of pharynx,
(e) external and middle ear,
(f) pharyngotympanic tube, and
(g) dura mater.

Question 25

a) The maxillary artery is divided into three parts by the ________________________.
b) List the three parts, extents of those parts and relations if possible.

Answer 25

a) lower/inferior head of lateral pterygoid muscle
b) parts, extents and relations:
1st part/mandibular part: from origin to lower border of lower head of lateral pterygoid. It lies between the neck of the mandible laterally and sphenomandibular ligament medially. The auriculotemporal nerve lies above this part.
2nd part/pterygoid part: From lower border to the upper border of the lower head of lateral pterygoid (i.e., second part lies on or deep to lower head of lateral pterygoid).
3rd part/pterygopalatine part: From upper border of the lower head of lateral pterygoid to pterygopalatine fossa. In pterygopalatine fossa it lies in front of the pterygopalatine ganglion.

Further notes:
✓ Most of the branches from the first and second parts of maxillary artery accompany the branches of the mandibular nerve.
✓ Branches from the third part of the maxillary artery accompany the branches of maxillary nerve and pterygopalatine ganglion.
✓ Branches from the second part of the maxillary artery are muscular only and supply muscles of mastication.
✓ All the branches (1st and 3rd part) of the maxillary artery pass through bony foramina and fissures except branches from its second part.

Question 26

List the branches of the maxillary artery from the first part. (5 branches) [know which ascend superiorly and which descend inferiorly]

Answer 26

1. Deep auricular: to external acoustic meatus
2. Anterior tympanic artery: to the tympanic membrane
3. Middle meningeal: to dura mater and calvaria
4. Accessory meningeal: to the cranial cavity
5. Inferior alveolar artery/Inferior dental artery: to the mandibular gingiva and teeth, and gives out an artery to mylohyoid
6. [Diagram]

Things to note on a cadaver:
✓ Auriculotemporal nerve encircles the middle meningeal artery with its two roots.
✓ Auriculotemporal nerve runs posteriorly with superficial temporal vessels.

Question 27

List the branches of the maxillary artery from the second part. (4 branches) [know which ascend superiorly and which descend inferiorly]

Answer 27

1. Deep temporal arteries (usually two in number; anterior and posterior)—ascend up on the lateral aspect of the skull deep to the temporalis muscle, which they supply.
2. Pterygoid branches—supply the medial and lateral pterygoid muscles.
3. Masseteric artery—passes laterally through the mandibular notch and supplies the masseter muscle from its deep surface.
4. Buccal artery—supplies buccinator muscle.
5. [Diagram]

Question 28

List the branches of the maxillary artery from the third part. (6 branches). What is the terminal branch of the maxillary artery?

Answer 28

1. Posterior superior alveolar artery
2. Infraorbital artery
3. Descending palatine artery
4. Pharyngeal artery
5. Artery of pterygoid canal
6. Sphenopalatine artery/nasopalatine artery (Terminal branch)
7. [Diagram]

Note:
The greater palatine artery is a branch of the descending palatine artery.
[Diagram]

Question 29

The maxillary vein is a short venous trunk, which accompanies the first part of the maxillary artery.
a) It is formed by?
b) Within the parotid gland, it unites with the superficial temporal vein to form the ________________________.

Answer 29

a) the confluence of veins from the pterygoid venous plexus.
b) retromandibular vein

[Diagram]

Question 30

The pterygoid venous plexus is a network of very small veins that lie around and within the lateral pterygoid muscle.
(I) State the communications of the pterygoid venous plexus.
(II) The pterygoid venous plexus is drained by ______________ which is formed at the lower border of the lateral pterygoid muscle.

Answer 30

(I) The pterygoid venous plexus communicates:
(a) with inferior ophthalmic vein via inferior orbital fissure,
(b) with cavernous sinus by emissary veins via foramen ovale or foramen of Vesalius, and
(c) with facial vein through the deep facial vein.
(II) maxillary vein

[Diagram: Communications of the pterygoid venous plexus]
[Diagram: Venous drainage of the face]
[Diagram: Venous drainage of the face and scalp]

Question 31

The pterygoid venous plexus is sometimes referred to as a peripheral heart. Why?

Answer 31

During yawning when the mouth is widely open due to contraction of lateral pterygoid muscle, the stagnant venous blood is pumped up into the cavernous sinus and maxillary vein. Possibly this is the reason why people yawn in the morning when they get up from sleep.

Question 32

Origin and functional components of mandibular nerve?

Answer 32

Origin: Trigeminal ganglion in the middle cranial fossa.
Functional components: GSA, SVE

Question 33

Course of mandibular nerve?

Answer 33

✓ Begins in the middle cranial fossa as two roots: a larger sensory root and a smaller motor root.
✓ The large sensory root arises from lateral convex part of the trigeminal ganglion and immediately leaves the cranial cavity by passing through foramen ovale to enter the infratemporal fossa.
✓ The small motor root arises from the pons, lies deep to the trigeminal ganglion and the sensory root. It also passes through foramen ovale to join the sensory root just below the foramen ovale in the infratemporal fossa, thus forming the main trunk.
✓ The mandibular nerve trunk is short and after a short course divides into a small anterior and large posterior division.

Question 34

State the branches of the mandibular nerve from the:
(a) main trunk
(b) anterior division

Answer 34

(a) main trunk
1. nervus spinosus (meningeal branch): sensory
2. nerve to medial pterygoid: supplies medial pterygoid, tensor veli palatini/tensor palati/tensor muscle of the velum palatinum and tensor tympani

(b) anterior division
1. masseteric nerve: supplies masseter and temporomandibular joint (TMJ)
2. deep temporal nerves: they are two; anterior and posterior. They supply temporalis from its deep aspect.
3. nerve to lateral pterygoid: runs with the buccal nerve and enters the deep surfaces of both the heads of lateral pterygoid muscle, which it supplies.
4. buccal nerve: contains all sensory fibers of the anterior division. Gives branches to the skin of cheek, supplies mucous membrane of the cheek and gum of the lower jaw opposite the molars and second premolar teeth.

[Diagram]

Question 35

The posterior division gives three branches. Name these branches.

Answer 35

1. Auriculotemporal nerve
2. Lingual nerve
3. Inferior alveolar nerve

NB: All the branches of posterior division of the mandibular nerve are sensory except nerve to mylohyoid (a branch of inferior alveolar nerve), which is motor.

[Diagram]

Question 36

State the branches and distribution of the auriculotemporal nerve.

Answer 36

1. Auricular branches - supply skin of the tragus, upper part of the pinna, external auditory meatus and tympanic membrane. The lower parts of these regions are supplied by great auricular nerve and auricular branch of the vagus nerve.
2. Articular branches (sensory) - TMJ
3. Superficial temporal branches - skin of the temple [don’t forget we have deep temporal branches too from the anterior division of the mandibular nerve]
4. Carries post-ganglionic secretomotor fibers from the otic ganglion to the parotid gland. (remember, it’s not the auriculotemporal nerve that performs secretomotor innervation)
   [Diagram]

Question 37

Inferior alveolar nerve
This is the larger terminal branch of the posterior division of the mandibular nerve. State its branches and distribution. What are the terminal branches of the inferior alveolar nerve?

Answer 37

(a) Nerve to mylohyoid arises from the inferior alveolar nerve before it enters the mandibular canal. It pierces the sphenomandibular ligament to reach the mylohyoid groove. It supplies mylohyoid and anterior belly of digastric muscle.
(b) Dental branches supply molar and premolar teeth.
(c) Mental nerve emerges out through mental foramen to supply skin of the chin and skin and mucus membrane of the lower lip.
(d) Incisive branch, supplies canine and incisor teeth.

(c) and (d) are terminal branches of inferior alveolar nerve.
[Diagram]

Question 38

Lingual nerve. The smaller terminal branch of posterior division of the mandibular nerve. State its distribution.

Answer 38

It is sensory to the mucous membrane of anterior two-third of the tongue except vallate papillae, the floor of the mouth, and the lingual gingivae.

[Diagram]

Question 39

The chorda tympani nerve is the slender branch of facial nerve. It is so named because of its intimate relationship to the middle ear (tympanum). State its functional components.

Answer 39

1 General visceral efferent fibres: These are preganglionic parasympathetic (secretomotor) fibres to submandibular and sublingual salivary glands.
2 Special visceral afferent fibres: These fibres carry taste sensations from anterior 2/3rd of tongue (except vallate papillae).

Note:
Chorda tympani nerve joins the lingual nerve in the infratemporal fossa.

Question 40

The otic ganglion is located in the infratemporal fossa, just below the foramen ovale. State its roots or connections.

Answer 40

1. Parasympathetic motor (secretomotor) from lesser petrosal nerve.
2. Sympathetic from sympathetic plexus around the middle meningeal artery.
3. Sensory from auriculotemporal nerve.
4. Somatic motor: Nerve to medial pterygoid. It passes through the ganglion to supply medial pterygoid, tensor palati, and tensor tympani muscles.
5. [3-minute video: Otic ganglion]

Question 41

Describe the pathway of secretomotor innervation to the submandibular gland.

Answer 41

(a) The preganglionic parasympathetic fibres arise from superior salivatory nucleus in the pons and pass successively through facial, chorda tympani, and lingual nerves; and terminate in the submandibular ganglion, which serves as a relay station.
(b) The postganglionic fibres arise from this ganglion and directly supply the submandibular gland.

Question 42

Describe the sympathetic and sensory supply to the submandibular gland.

Answer 42

1. Sympathetic supply: The preganglionic fibres arise from T1 spinal segment and enter the cervical sympathetic trunk to relay in its superior cervical sympathetic ganglion. The postganglionic fibres arise from superior cervical sympathetic ganglion, form plexus around facial artery, and thus reach gland through this artery.
2. Sensory supply: The gland gets its sensory supply by the lingual nerve.

Question 43

Describe the origin and course of the lingual artery.

Answer 43

Origin: It arises from the front of the external carotid artery opposite the tip of the greater cornu of the hyoid bone. It is the main artery to supply blood to the tongue. It may arise in common with the facial artery (linguofacial trunk).
Course: It then runs upwards and forwards forming a characteristic loop over the greater cornu of the hyoid and disappear deep to the hyoglossus muscle. Before disappearing it gives rise to suprahyoid artery, which runs superficial to hyoglossus above the hyoid.

Note: The loop of lingual artery above the greater cornu of hyoid bone permits free movements of hyoid bone without damaging the artery.

[Diagram 1] [Diagram 2] [Cadaveric image 1] [Cadaveric image 2]

Question 44

(a) The lingual artery is divided into three parts by the ________________ muscle.
(b) Describe these three parts of the lingual artery.

Answer 44

(a) hyoglossus
(b) (i) First part lies in the carotid triangle and forms a characteristic loop with convexity upwards above the greater cornu. The loop is crossed superficially by the hypoglossal nerve. The loop permits free movement of the hyoid bone.
(ii) Second part lies deep to the hyoglossus muscle along the upper border of the hyoid bone.
(iii) Third part (also called arteria profunda linguae) or deep lingual artery first runs upwards along the anterior border of the hyoglossus muscle and then forwards on the undersurface of the tongue, where it anastomoses with its fellow of opposite side.
[Diagram 1] [Diagram 2]

Question 45

Name the branches from each part of the lingual artery.

Answer 45

(a) From first part—suprahyoid branch. It anastomoses with its fellow of opposite side.
(b) From second part—dorsal lingual branches usually two in number, to the dorsum of tongue and tonsil.
(c) From third part—sublingual artery, to the sublingual gland.
[Diagram]

Further notes:
The deep lingual artery is the terminal branch and continuation of the lingual artery after giving off the sublingual branch.