Lecture note 12: deep face, infratemporal fossa

13.3.2011

Done by: Nurul kauthar, wan Muhammad najib, zulkhairi, kamal

(Min 4.00)

Ok, we learned previously about the superficial face and today’s lecture is about the Deep Face including both Temporal and Infratemporal Fossa. So, this is lateral view of the skull showing you Temporal Fossa.

As you could see, The Temporal fossa is bounded by the Zygomatic process of the Frontal Bone and the Frontal process of Zygomatic bone (Anteriorly), Temporal line (superiorly); both Superior line & Inferior line. And those lines are also bounding the Temporal fossa (posteriorly).

Now, the medial wall of Temporal Fossa forms the floor of Temporal Fossa. It is formed by Frontal Bone, Parietal Bone, Temporal Bone (the squamos part of Temporal Bone) as well as Great Wing of Sphenoid Bone. And if you remember the circular area (which is circled in the picture) which is the junction for all those 4 bones are called Pterion (P is silent).

Now, inferiorly, the Temporal Fossa is bounded by Infratemporal surface of Greater wing of Sphenoid bone medially and Zygomatic process laterally. The lateral wall of Temporal fossa is open but in fact it is formed by temporal fascia which is the fascia that covers the Temporal fossa.

The temporal fascia is attached superiorly to the Temporal line (Superior Temporal Line), inferiorly to the Zygomatic arch. In fact, it is attached to Zygomatic arch by 2 layers; the inner layer is attached to the Inner surface of the Zygomatic arch and the outer layer is attached to the outer surface of the Zygomatic arch.

So, Temporal fossa contains the Temporalis muscle, and its covering Temporal fascia in addition to the nerves and blood supply to the Temporalis muscle. Of course there is some pad between the {two layers of temporal fascia} the Temporal fascia.

Temporalis muscle is one of the muscles of mastication. There are 4 muscles of mastication. The temporalis muscle arises from the Floor of Temporal fossa; its action is to close the mouth by elevating the mandible. SO remember that you have different orientation of fibres in Temporalis muscle so that you have the ones that are anterior and superior they are almost vertical and therefore they elevate the mandible. Whereas the postertior ones are almost horizontal so they act on retracting the mandible.

Temporalis muscle is inserted on the anterior border. Here is Coronoid process, near to the Masetter muscle, and it (Temporalis muscle) inserts on the anterior border and the Deep surface of Coronoid process.

Temporalis muscle is innervated by anterior and posterior deep temporal nerves which are branches of Mandibular division of Trigerminal nerve that you will see in a few minutes.

Now the Infratemporal fossa: If you remember, the Infratemporal fossa is located inferior to Temporal fossa. Going back to the skull, this here (Lateral view of skull) is Infratemporal fossa. It is medial to Ramus and Coronoid process. In fact, you have to break this Zygomatic arch down and remove the ramus of the mandible to see the view of Infratemporal fossa.

Now, the infratemporal fossa is bounded Anteriorly by Posterior surface of Maxilla, posteriorly by Tympanic plate, Styloid process and Mastoid process of Temporal Bone, Superiorly by Infratemporal surface of Greater wing of Sphenoid, Laterally by Ramus of Mandible and Coronoid process. Inferiorly is bounded by level of Medial Pterygoid Muscle attachment to the medial aspect of the Angle of Mandible.

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As you can see, there are those muscles in the infratemporal fossa, so those who are the two heads of the lateral pterygoid muscle and this is the medial pterygoid muscle. Now remember that the medial pterygoid muscle lies on the medial surface or deep to the ramus of the mandible and the angle of the mandible in fact it lies opposite to the masseter muscle which lies on the lateral surface of the ramus of the mandible.

So, this is lateral pterygoid muscle, it has two heads of ‘region’, the superior head arises from infratemporal surface of greater wing of the sphenoid bone whereas the inferior surface arises from lateral surface of the lateral pterygoid plate and both heads join to insert on to the articular disk of temporamandibular joint and the neck of the mandible. Lateral pterygoid muscle asses in opening the mouth, not closing the mouth.

Then, the medial pterygoid plate arises from the medial surface of lateral pterygoid plate of the sphenoid bone and it has a small origin from the tubercle of the maxilla. It inserts on the medial surface of the angle of the mandible. It lies opposite to the masseter muscle superficial to the ramus of the mandible. Of course this here is buccinators muscle which has been reflected in order to be able to see the medial pterygoid muscle.

And this is part of the table! containing the muscle of mastication who have the origin insertion, innervations and the action.

The doctor repeats what she has just said…

The infratemporal fossa also contains the temporomandibular joint. Temporomandibular joint is very important for you and it is formed by three bones which are first the condyle / head of the mandible which is the superior part of the condylar process of the mandible and then you have mandibular fossa of the temporal bone and anterior to the mandibular is the articular tubercle which is also a part of temporal bone.

Temporomandibular joint, as another joint is supported by ligament. Now, remember that first, temporomandibular has the articular disk which is a fibrocartilagenous disk separating this cavity. Now temporomandibular joint is a synovial joint and it has synovial cavity. That is divided by this articular disk into two compartments; superior one and inferior one.

This joint is surrounded by a capsule. This capsule is thickened or strengthened laterally by additional bundles of collagen forming ligament called the lateral temporomandibular ligament. There are also two

accessory ligaments supporting this temporomandibular joint. So, here you have the capsule and here you have the lateral temporomandibular ligament.

The accessory ligaments supporting the temporomandibular joint are spinomandibular ligament and the stylomandibular ligament. The spinomandibular ligament arises from the spine of sphenoid bone and it inserts on the lingula of the mandible (the medial projection that medial to the mandibular foramen on the medial aspect to the ramus of the mandible). So, this is the spinomandibular ligament.

Remember that between the spinomandibular ligament and the neck of the mandible you have the maxilliary artery passing. It’s passing in that space form between spinomandibular ligament and the neck of the mandible. Remember that spinomandibular ligament is the thickening of investing fascia that covers pterygoid muscle.

Regarding the stylomandibular ligament, as the name indicate, it extends from the styloid process of the temporal bone to the angle of the mandible. It’s a thickening of the fascia of carotid gland. The stylomandibular ligament separates the submandibular gland from sublingual gland.

This is lateral view, and this is medial view. So this is where the lingula of the mandible is, and here the spine of the sphenoid form. So this is the sphenomandibular ligament against stylomandibular ligament. You have Styloid process and angle of the mandible [17.10].

Look here, you have stylomandibular ligament, neck of the mandible, in between is maxilliary artery.

This is here foramen ovale through which mandibular division of trigeminal nerve passes to leave the middle cranial fossa and enter the infratemporal fossa. Just below the foramen ovale on the medial surface / aspect of the mandibular division of the trigemninal nerve, you have the otic ganglion. Otic

ganglion is parasympathetic ganglion containing postganglionic paraympathetic neurons.

Do you remember the parasympathetic system? How many neurons are involved in parasympathetic system? How do they differ from the motor neurons?

The parasympathetic system involves two neurons; the first set of neuron is called 'pre-ganglionic parasympathetic’ neurons and then you have post-ganglionic parasympathetic neurons. The fibers that project from pre-ganglionic parasympathetic neurons are called pre-ganglionic parasympathetic fibers and they have to synapse on post-ganglionic parasympathetic fibers to give rise to the post-ganglionic parasympathetic fibers which are just the axons of post-ganglionic parasympathetic neurons and similarly pre-ganglionic parasympathetic fibers are the axons of pre-ganglionic parasympathetic neurons.

For the otic ganglion it contains the post ganglionic parasympathetic neurons and therefore it is receiving the pre-ganglionic parasympathetic neurons. In fact, those fibres are originating from the glossopharyngeal nerve and linking the Otic ganglion through Lesser Petrosal nerve. The lesser petrosal nerve is a branch from glyssopharyngeal nerve that contains pre-ganglionic parasympathetic fibres innervating or synapsing on the neuron of optic ganglion. Now, the axons of the post-ganglionic parasympathetic neurons present in otic ganglion travel via auriculartemporal nerve (one of mandibular division of trigimenal nerve) and those fibers distant to the parotid gland.

Now remember that the parasympathetic fibers or system provides innervations to salivary glands and smooth muscles. Whereas the skeletal muscles are innervated by somatic motor neurons and fibers. (important!)

So again, the post ganglionic parasympathetic fibers arising from otic ganglion travel to the parotid gland via auriculartemporal nerve. Therefore auriculartemporal nerve has two types of fibers; sensory to the skin in front of the ear and scalp, and now post-ganglionic parasympathetic fibres to the parotid gland. In addition, it innervates the the posterior medial part of the temporalmandibular joint.

So remember again … just below the foramen ovale, medial aspect of the mandibular division of the trigeminal nerve is the Otic gangilion.

Now, the maxillary artery. As you already know, maxillary artery is one of the terminal branches of the external carotid artery it travels deep to the neck of the mandible. The maxillary artery can be divided into three branches or portions based on its relationship with lateral pterygoid muscle. So, from its origin to the lateral pterygoid muscle, it is called as mandibular portion, and from that point to the pterygoid maxillary fissure, it is called as pterygoid portion, and by that point, when it exists the pterygoid maxillary fissure it is called as pterygopalatine portion.

Again, external carotid artery gives its terminal branches which are superficial temporal artery and maxillary artery. And from its point of origin to the lateral pterygoid muscle, this is called as mandibular portion. And then from the beginning of lateral pterygoid muscle to the pterygoid maxillary fissure, we call it as pterygoid portion. And branches of mandibular portion are, there are two small branches supplying the ear, they are called deep auricular artery and anterior tympanic artery.

And here you have medial meningeal artery. It travels between the two roots of the auriculotemporal nerve as it arises from the mandibular division of trigimenal nerve. So here is the mandibular division of trigimenal nerve leaving the foramen ovale giving up this auriculartemporal nerve by two roots separated by this middle meningeal artery. In fact the middle meningel artery enters the middle cranial fossa through foramen spinosom. Foramen

spinosum is posterior to foramen ovale. Another branch that travels to the middle cranial fossa is the accessory meningeal artery. And In fact it goes to the middle cranial fossa via foramen ovale.

Then you have mandibular portion. Mandibular portion gives off you the muscular artery. Those arteries supply muscles of mastification. So you have … artery to masseter muscle or known as massetric artery. So it travels in mandibular notch to go to the masseter muscle. And then you have here artery to the lateral pterygoid, and opposite to it you have artery to the medial pterygoid. Those two arteries are the ones that enter the deep surface of temporalis muscle to supply it. They are anterior and posterior deep temporal arteries. Then you have this buccal artery which goes to the buccinators muscle to supply it.

Then you have, this is called the pterygoid plexus of vein, which is associated with the 2 pterygoid muscles, the medial & lateral pterygoid muscles. Remember that the pterygoid plexus empties into the maxillary artery. In fact it communicates with the inferior ophthalmic artery through the inferior orbital fissure and it also communicates with the facial vein through the deep facial vein. The pterygoid plexus of veins is very important bcoz it can be away of infection spreading due to its communications with the other veins likes the facial vein for example.

Ok, finally, there is the mandibular division of the trigeminal nerve. Of course you know that the trigeminal nerve is the cranial nerve no 5 (V). It arises from mid pons and it divides into 3 divisions (Ophthalmic, maxillary & mandibular).

Now the mandibular division is that division that leaves the middle cranial fossa through foramen ovale to enter the infratemporal fossa.

Now, you have to know branches from each part of mandibular divisions. So, there are branches giving off the main trunk, and there are branches giving off the anterior division of the mandibular nerve & other branches giving off the posterior division of the mandibular nerve. Now regarding the nerves that are giving off the main trunk, this is here called the mentalic branch and it is travel with the middle meningeal artery through the cranial

spinosum to innervate the dura mater. Another branches that are coming from main trunks is called nerve to medial pterygoid and as it is indicated, it innervate the medial pterygoid muscle, in addition it innervate 2 muscles, these are called tensor veli palatine & tensor veli tympani.

Then branches from the anterior divisions of mandibular nerves are, you have those temporal nerves, both anterior & posterior deep temporal nerves which innervate the temporalis muscle. Then, you have nerve to lateral pterygoid which innervates the lateral pterygoid muscle. Then, you also have nerve to massetter muscle. There is the nerve which innervates the messectric muscle and in fact it is a mixed nerve, its motor to the mastoid musles & it’s sensory to the anterior & lateral part of the temporamandibular joint. Then,

you have the buccal nerve. The buccal nerve travels between the 2 heads of lateral pterygoid muscle going to the cheek. At the anterior edge of the mastoid muscle, it becomes subcutaneous.

Now remember, buccal nerve travels with the buccal artery and buccal nerve is a sensory. It doesn’t innervate the buccinator muscle.

Which nerve innervates the buccinators muscle?

So, remember the buccal of the mandibular is sensory. It does not innervate the buccinators muscle. Buccinator muscle is innervated by buccal of facial nerve.

Now, the branches of the posterior division include:

1) You have this, auriculotemporal nerve which again arises by 2 roots created by the middle meningeal artery and as you already know the auriculotemporal nerve receives the post-ganglionic parasympathetic fibers from the aortic ganglion to innervate the parotid gland. It is sensory to the skin in front of the ear & the skull. It is also sensory to the posterior medial part of the temporomandibular joint. So, the temporomandibular joint is innervated by 2 nerves:

1) Massetter nerve

2) Auriculotemporal nerve

Then, you have the inferior alveolar nerve which enters the mandibular foramen, so that it supplies the lower teeth. Before it rained the mandibular foramen, the inferior alveolar nerve gives off the mylohyoid nerve or the nerve to the mylohyoid. If you remember, nerve to mylohyoid innervates mylohyoid muscles and the anterior belly of the gastric.

Finally, you have this nerve here is the lingual nerve. If you can see, the lingual nerve receives this nerve here which is called chorda tympani .Chorda tympani is a branch of the facial nerve. It has 2 types of fibers:

1) Special sensory fibers for taste … from the taste buds of the anterior 2/3s of the tongue.

2) Pre-ganglionic parasympathetic fibres. Distant to the submandibular ganglion.

Now, so you have chorda tympani is a branch of the facial nerve. It joins the lingual nerve… since it has pre-ganglionic parasympathetic fibers, those fibers need to synapse on post-ganglionic parasympathetic neurons which are present in the submandibular ganglion, hanged up by this lingual nerve. So, the fibers innervate here synapse on post-ganglionic parasympathetic neurons, then post-ganglionic parasympathetic fibers synapse on the submandibular ganglion and travel by/with lingual nerve to the sublingual salivary gland. Therefore, the lingual nerve contains here, the pre-ganglionic parasympathetic fibers, taste fibers or special sensory fibers & somatic sensory fibers. Here, the lingual nerve contains post-ganglionic parasympathetic fibers, somatic sensory fibers & special sensory fibers.

Here, the somatic is sensory to the mucosa of the anterior 2/3s of the tongue & the oral cavity over the mandible. Of course remember that the inferior alveolar nerve enters into the mandibular foramen & it exits to the external surface of the mandible as the mantel nerve. It innervates the skin on the chin.

That’s all

Good luck ^^;

Prayers …