S1: Gross Anatomy : 8:00-9:00Scribe: Andrew Treece

Friday, February 6, 2009Proof: Sunita Jagani

Dr. G. SalterSuperficial Face, Eyelids, Lacrimal Apparatus & ScalpPage1 of 6

Dr. Salter kind of jumped around from picture to picture but I tried to keep up with it the best I could. Most of it was all included in the lecture slides as well.

Figures on Board: You have got to know the trigeminal nerve and facial nerve.

Left Diagram: Facial nerve enters the internal auditory meatus, it comes into the skull 19mm long before it divides into a branch anteriorly, the greater petrosal nerve, which carries a lot of parasympathetic fibers that eventually reach the lacrimal gland. The main portion of the facial nerve then extends and forms a part of the middle ear. If you have otitis media, infection of the middle ear, a common facial nerve may be involved. This facial nerve comes out of the stylomastoid foramen, when this comes out of the foramen it looks like the second facial nerve picture drawn on the board. Again, the facial nerve also sends out a branch called the greater petrosal nerve anterior. The picture on the left is of the facial nerve lying in the temporal bone. It gives off two branches in the middle ear, a branch to the smallest muscle in the body the stapedius muscle that goes to the stapes one of the smallest bones in the body. If this muscle contracts it keeps the stapes from going back and forth like a piston and it dampens sound. The second branch in the middle ear is called the chorda tympani nerve, and whenever you see the palprebral think eyelid, when you see tympanic think middle ear, so the chorda tympani is a nerve in the middle ear that looks like a chord. It has a couple of functional components in it meaning that fibers go to two places, the blue are the sensory taste fibers to the anterior two thirds of the tongue. The purple fibers are parasympathetic preganglion fibers that extend down to the submandibular ganglion which is close to the submandibular gland. Postganglionic fibers then go from the ganglion to the submandibular gland and then to the sublingual gland later on.

Mid Left Diagram: This is the facial nerve coming out of the stylomastoid foramen. It gives off branches, and when you think of the facial nerve coming out onto the face it does so in a series of five branches. These branches supply the muscles of facial expression, every one of them. Remember: To ZanzibarBy Motor Car.

T=temporal branches (sometimes called the frontal branch because they go to the frontalis muscle)

Z=zygomatic (he wrote zanzibar but it’s zygomatic) mainly going to the orbicularis oculi muscle to close the eye

B = buccal, which means cheek (malar means cheek also) and these run with the parotid duct

M= mandibular, which runs along the margin of the mandible and supplies the inferior oral area

C= cervical, supplies the platysma muscle in the neck

Trigeminal nerve diagrams (the two on the right): Trigeminal nerve comes off the pons, and has a lot of sensory fibers in it. Those have their cell bodies in the trigeminal ganglion. The fibers initially leading into the trigeminal ganglion where the cell bodies are located most of those fibers are sensory so they are called central processes of the cell bodies. Peripheral processes from this single cell body, these are sensory fibers coming in from wherever V2 goes, V1 goes, V3 goes. Cell body’s sitting right in the trigeminal ganglion, middle cranial fossa, then the sensory fibers comprise the sensory root of the trigeminal nerve. There is also another bunch of fibers running with the sensory fibers, they are motor fibers to eight skeletal muscles, the muscles of mastication and that is all you need to know right now. The fibers drawn do not go with V1 or V2, they are strictly sensory. The V1 and V2 fibers are the peripheral processes of the single axons that come down and have their cell body in the trigeminal ganglion. Then other sensory fibers run from this trigeminal ganglion down and comprise most of the fibers in V3, but again these motor fibers sitting in the pons come out and form the motor root of the trigeminal nerve. These motor root fibers come out and pass only with V3, and as they pass to the periphery they supply those eight different muscles (4 of mastication, 4 others).

Introduction [S1]
Bones of the Face [S2]
Skull (Anterior View) [S3]
Note that plate numbers are on most slides with figures from Netter’s Atlas.
Here is the big frontal bone, which has a supraorbital notch (or foramen) where the supraorbital artery, vein, and nerve pass. The nerve coming out of there sends sensory branches to a space inside the frontal bone called the frontal sinus. When you press on the supraorbital nerve, a branch of V1, you transiently depolarize the electrical impulses within that nerve and you are relieved of pain stemming from a headache for a while, although it comes back.
The maxilla is the upper jaw. There is a foramen here called the infraorbital foramen where a branch of V2 comes out. Then if you follow the line from the supraorbital foramen down it would intersect the infraorbital foramen and then intersect the mental foramen. There is a terminal cutaneous branch of V3 comes out of the mental foramen. (Three foramen, three branches of Cranial Nerve V)
The maxilla is hollow because of a maxillary air sinus that lies within it.
You need to know where the lacrimal bone is.
The nasal bones are easy to break because they are really thin.
There is a frontal process of the maxilla extending superiorly toward the frontal bone. There is a crest on that called the anterior lacrimal crest, and there is also a posterior lacrimal crest, and these form the boundaries of the lacrimal fossa where the lacrimal sac sits. You can feel anterior lacrimal crest on yourself.
The zygomatic bone is the most frequently fractured bone in the face.
In the mandible you should know ramus, body, mental tubercle, mental protuberance, mental foramen (mental means chin)
Note that there is an alveolar arch of the maxilla which has pockets in it that resemble the alveoli of the lungs. The same is true for the mandible, an alveolar process that has the mandibular teeth sitting in sockets.
Skull (Lateral View) [S4]
You need to know everything here about the mandible. The junction of the ramus and the body is called the angle. You should know the condyloid process that has a head and neck on it, and it has a coronoid process and between the two is the mandibular notch which can be used to access the inner portion of the face called the infratemporal fossa.
There are five parts of the temporal bone: the mastoid process, the styloid process, a tympanic portion, a squamous portion, and where the middle and inner ear lie is the petrous portion.
Squamous is flat, mastoid looks like a breast, tympanic plate, styloid process, and again in the inside is the petrous bone.
The portion that extends towards the zygomatic bone is called the zygomatic process, and a small portion is considered the temporal portion of the zygomatic bone. Regardless, this is called the zygomatic arch sometimes called the zygoma, easily fractured and is the most easily fractured region, not necessarily the whole zygomatic bone but the arch.
The lacrimal bone sits between the eye and nose, and the frontal process of the maxilla has the anterior lacrimal crest while the lacrimal bone has the posterior crest. Between the two crests sits the lacrimal sac and the nasolacrimal duct drains down into the nose after that.
Two alveolar arches one for the maxilla and one for the mandible.
Mandible (Medial View) [S5]
If we look on the internal aspect of the lower jaw bone we have along this condyloid process a little neck that has a depression called the pterygoid fovea which means depression where the pterygoid muscle attaches.
The lingula is a little spike of bone that denotes the location of the mandibular foramen. You can palpate this to know where to inject the inferior alveolar nerve.
There is a mylohyoid line, mylo referring to molar and the line extends posterior to the third molar, it begins there if you will and then extends anteriorly. The mylohyoid muscle is there, and you have one on the other side.
On either side of that line you have a fossa. The upper fossa is for the sublingual gland that lies in the oral cavity because this muscle right in here is a continuous sheet of muscle dividing the oral cavity from the neck.
Superior to that is the sublingual fossa for the sublingual gland lying in the oral cavity, below that is the submandibular fossa for the submandibular gland to reside in the neck.
Plate 15, Mandible of Older Person[S6]
If we look at an older person’s bone, it shows a mandible and how this mandible bone resorbs.
There are no teeth here, and if you want to put on a plate of teeth for the lower jaw for the mandible that plate may fit over that hole, the mental foramen, which is sensory. So a plate there may cause a lot of pain.
Maxillary Sinus (Relationships) [S7]
This is the maxilla with a hole in it, the maxillary sinus or space.
Some of you are getting confused with the perinasal spaces and dural venous sinus. The perinasal sinuses are air sinus that have grown out from the nose whereas the dural venous sinuses are vascular and contain blood.
Notice the alveolar processes of the teeth extending up into the alveolar process for the maxilla. We will talk about horrible pain dealing with the trigeminal nerve that may cause people to commit suicide, trigeminal neuralgia. They usually come into the dentist’s office complaining of pain in the upper teeth, and that is V2 which supplies sensory fibers to the upper teeth so when they think they have a dental problem it is actually a problem with the trigeminal ganglion.
Picture of Bones of Face [S8]
The maxilla lies inferior to the orbit, posteriorly there is an infratemporal fossa, and anteriorly is the facial surface of the maxilla.
We will talk about septal cartilages and other nasal cartilages later.
Muscles of Face [S10]
Muscles of Facial Expression[S10]
If you compromise the temporal branch of the facial nerve that supplies the frontalis muscle, you can’t raise the frontalis muscle until those fibers regenerate.
Zygomaticus major allows you to smile.
Don’t worry about the Rizorius muscle.
Corrugator supercilii Dr. Tubbs likes to find.
Nasalis muscle wrinkles up the nose.
Procerus muscle probably won’t be asked.
Muscles of Facial Expression Derived from Pharyngeal Arch 2 [S11]
All of the muscles of facial expression come from the second pharyngeal arch. As the muscle layer is laid down there is a single layer of muscles, and depending upon how much we use the muscles of facial expression they will hypertrophy accordingly. If the cadavers have been in a nursing home, there may not have been a need to use the facial muscles to cry, smile, whatever, so they may have atrophied and not hypertrophied.
They all come from the second pharyngeal arch, and depending on which portion of the face they reach, they can contract and cause movement and increase in size.
Muscles of Facial Expression (side view) [S12]
The facial nerve fibers supply all of these muscles, and the most important fibers are the Zygomatic, Buccal, and Mandibular branches. Who cares if you can’t raise your frontalis muscle, but closing your eye is important and brought about by the zygomatic branches. The eye will dry out and you’ll get an ulcerated cornea.
The muscles of the nose are pretty important, and the muscles of the upper and lower lip are extremely important and they are supplied by branches of the buccal branch and mandibular branch.
So the ones right in the middle are the most important.
Study these muscles on your own.
The orbicularis oculi muscles supply the eye. There is a part on the bone that is called the orbital portion and a part on the eyelid that is called the palpebral portion, palpebral means eyelid.
The orbicularis oris (oral cavity) muscle receives the insertion of a lot of muscles that bring about the opening and closing of the oral cavity.
Look for the smile muscle, the zygomaticus major, and there may or may not be a minor muscle associated with it coming from the zygomatic bone and extending toward the oral cavity.
The platysma extends superiorly toward the oral cavity.
There is an elevator and depressor of the oral cavity, and an elevator and depressor of the angle of the mouth when you smile the angle of your mouth turns up. So the zygomaticus muscle and the levator anguli oris muscle elevates it. The levator labii superioris, labii means lip, so it elevates the lip. There is a depressor labii inferioris also.
All of these muscles are innervated from facial nerve, and usually from the deep aspect of the muscle.
Muscles of Face, Scalp, Anterior View[S13]
There’s another picture to look at for review.
Buccinator Muscle [S14]

a. This forms the major component of the cheek. If you take the tip of your tongue and stick it into your cheek, the major component between the tip of your tongue and your cheek is the buccinator muscle. Buccal means cheek.

b. It is the muscle that trumpeters use, and is a muscle of facial expression.

c. The parotid duct pierces the muscle to enter the oral cavity. The parotid gland along with the submandibular and sublingual glands are the three major salivary glands that produce secretions which help digestion to take place. These glands all have openings into the oral cavity.

Function of Buccinator Muscle [S15]
Now we said the buccinator muscle is a muscle of facial expression, but if you have a piece of food lying in between the teeth while chewing, to keep that food in the oral cavity you contract that buccinator muscle and it forces the food into the oral cavity proper. Sometimes if you have facial nerve palsy the food will collect out in the vestibule of the cheek because that muscle doesn’t compress the cheek and force it back into the oral cavity.
It is considered an accessory muscle of mastication.
Superficial Arteries and veins of the face and scalp [S16]
This is a great slide that isn’t labeled, but it’s pretty much what we were supposed to do in lab.
The facial vein and artery parallel one another and extend up toward the medial angle of the eye, the medial canthus, and the facial artery ends there and the vein begins there. Notice that the artery is anterior (a=anterior) to the vein.
Remember the parotid gland is around the ear, with the duct crossing right across the anterior portion masseter muscle and penetrates the buccal muscle.
There is also a superficial temporal artery and vein that should be visible in lab.
The frontalis muscle has a companion called the occipitalis muscle, which is also a muscle of facial expression, and although it isn’t on the face it’s connected to the frontalis muscle which lies on the face. There is a specific branch off of the facial nerve supplying the occipitalis muscle.
Nerves of Face [S17]
Facial Nerve (VII) exits cranial cavity via internal auditory meatus [S18]
Facial nerve passes through the internal auditory canal or meatus along with the eighth nerve
VII Emerges from Stylomastoid foramen[S19]
Most of its fibers that come out of the stylomastoid foramen give out the TZBMC branches and other branches as well.
Facial Nerve Branches in Parotid Gland [S20]
This is a depiction of the parotid gland, and the facial nerve passes through it and divides into its temporal branches and its zygomatic branches, both of which are said to cross the zygomatic arch and extend superiorly.
The main function of the temporal branch is to supply the frontalis muscles.
The zygomatic branches supply mostly the orbicularis oculi.
The buccal branches surround the parotid duct. Notice most of these facial nerve fibers run horizontally, whereas trigeminal nerve fibers run vertically.
The marginal mandibular branch runs along the margin of the mandible and it always runs superficial to the artery and vein.