Superficial nerves of the face and scalp.
Hello, everyone! This is Joao from Kenhub, and welcome to another anatomy tutorial where, this time, we're going to be talking about the superficial nerves of the face and scalp. So, what we are going to be doing is looking at an image like the one you see on your screen right now where you’re looking at the anterior view of the face and scalp and you see all these yellow structures which are the superficial nerves of the face and scalp and we’re going to be talking about them. And before I do so, I’ll also want to show you here this image of the lateral view of the head so you can see also all these structures that we’re going to be talking about from a different perspective. So, these 2 are the main perspectives, the main images that we’re going to be exploring throughout this tutorial.
And before we continue to on, I would like to list the different structures we’re going to be talking about. First one is going to be then the facial nerve. Also going to talk about the posterior auricular, the auriculotemporal, the greater and lesser occipital nerves, the supraorbital and infraorbital nerves, the supratrochlear and infratrochlear nerves, zygomaticotemporal and zygomaticofacial, the external nasal branch of the anterior ethmoidal nerve, the buccal, the greater auricular, and finally, the mental nerves.
Let’s start off with the very first one on the list that you see here highlighted in green - these are known or this is known as the facial nerve. As you can see have one on each side of your head. They’re also known as the 7th cranial nerves. The facial nerve emerges from the brainstem between the pons and the medulla. This nerve is going to be controlling the muscles of facial expression, and functions in the convenience of taste sensation from the anterior 2/3 of the tongue and oral cavity. This nerve is also going to be supplying the preganglionic parasympathetic fibers to several head and neck ganglia.
There are different nerves that branch off of the facial nerve. One is the posterior auricular nerve, and then there are 5 major facial branches which we’re going to be covering here on this tutorial which include the temporal, the zygomatic, the buccal, the marginal mandibular, and the cervical. And the best thing when you have to memorize all this list is to have a mnemonic with you, and for the facial nerve I suggest you use “To Zanzibar By Motor Car” which T stands for temporal, Z for zygomatic, B for buccal, M for marginal mandibular, and C for cervical.
We’re moving on and talking about this nerve that you see here highlighted in green which is one of the branches of the facial nerve that we talked about - the posterior auricular nerve. So, this is a branch of the facial nerve which divides into 2 branches - the auricular and the occipital. The auricular branch is going to be innervating or supplying the auricularis posterior muscle and the intrinsic muscles on the cranial surface of the auricle or, in other words, the ear. The occipital branch will be supplying and, keep in mind that this one is a larger, this is larger than the auricular branch, will be supplying or innervating the occipitalis muscle.
We’re going to look at other branches of the facial nerve. Now, these are the temporal branches of the facial nerve. The temporal branches of the facial nerve cross the zygomatic arch to the temporal region and it will be supplying then the auricularis anterior and auricularis superior muscles.
Next on our list, we’re going to be seeing the zygomatic branches of the facial nerve seen now highlighted in green on this lateral view of the head. The zygomatic branches of the facial nerve run across the zygomatic bone to the lateral angle of the orbit where they will be supplying the orbicularis oculi muscle which is this muscle here.
Deep further down, we’re going to be highlighting the buccal branches of the facial nerve. The buccal branches of the facial nerve of larger size than the rest of the branches, they pass horizontally forward to be distributed below the orbit and around the mouth. They give off 3 types of branches that supply the following structures. So, the superficial branches will be supplying the superficial muscles of the face and skin. The deep branches will be supplying the small muscles of the nose and the zygomaticus and levator labii superioris muscles. Now, there are also other branches known as the lower deep branches which will be supplying or innervating the buccinator and the orbicularis oris muscles. On this image, you can see here the orbicularis oris muscle.
Next on our list, we’re going to be seeing the marginal mandibular branch of the facial nerve. The marginal mandibular branch of the facial nerve supplies the following muscles of the lower lip and chin. The depressor labii inferioris and the depressor anguli oris which lowers the corner of the mouth down and laterally, and also the mentalis muscle which will be raising and protruding the lower lip as it wrinkles the skin on the chin. So, all these muscles are found in this area here.
The last branch of the facial nerve that you see here on this image on the anterior view - notice these branches here highlighted in green, these are the cervical branches of the facial nerve. The cervical branches of the facial nerve, they run forward beneath the platysma muscle which you can also see here on this image and forms a series of arches across the side of the neck over the suprahyoid region. It will be supplying the platysma and also the depressor anguli oris muscles.
Next on our list, we’re going to turn again to the lateral side so we can see the auriculotemporal nerve highlighted in green. So, you have one on each side of your head. This is a branch of the mandibular nerve, a branch that runs with the superficial temporal artery which you can also see here on this image, and the vein. The auriculotemporal nerve will be providing sensory innervation to various regions on the side of the head. This nerve has 2 roots - a somatosensory root which is found superiorly and a parasympathetic one which is found then inferiorly. Now, what happens is that the somatosensory root will be supplying the auricle or the ear, the external acoustic meatus, the outer side of the tympanic membrane, the skin in the temporal region, and the temporomandibular joint. And the parasympathetic route, the inferior one, will be carrying postganglionic fibers to the parotid gland - which you can also see here, the parotid gland.
We’re going to go back to - this is the back of your head as you can see here, we just stripped all the muscles to just be left with the nerves and skull. We were showing you here the greater occipital nerves - so 2 as you can clearly see highlighted on this image. The greater occipital nerves are spinal nerves and they will be innervating the scalp at the top of the head over the ear and over the parotid glands. On their course, they’re going to be passing through several neck muscles such as the trapezius or the obliquus capitis inferior.
Next, we’re going to be turning again to the lateral side where you see these structures highlighted or this structure which is one of the 2 lesser occipital nerves. Now, this nerve is a cutaneous spinal nerve which arises between the second and third cervical vertebrae along with the greater occipital nerve. Lesser occipital nerve is going to be innervating the scalp in the lateral area of the head posterior to the ear.
We’re going to move on and talk about these that are highlighted here in green. These are known as the supraorbital nerves. And notice here on this image how we just removed this muscle here - the orbicularis oculi muscle. So, this is removed on the left side of the face. Now, the supraorbital nerve is a terminal branch of the frontal nerve and it will be supplying the several structures including the upper eyelid, the conjunctiva of the eye, the frontal sinus, and the skin from the forehead extending back to the middle of the scalp. This nerve then ascends upon the forehead and ends in 2 branches, a medial and lateral, which will be supplying the integument of the scalp and the pericranium.
Next, we’re going to be seeing these nerves that we’re highlighting and found a bit more medially. These are known as the supratrochlear nerves, one on each side, as you can see on this image. They are branches of the frontal nerve but they are smaller than the supraorbital nerves. The supratrochlear nerves divide into branches which supply the following areas: the skin of the lower part of the forehead close to the midline, the conjunctiva, and the skin of the upper eyelid.
We’re moving onto another set of nerves. This one that you see on the lateral view - the zygomaticotemporal nerve. The zygomaticotemporal nerve is a nerve in the face. It is derived from the maxillary nerve and it runs along the lateral wall of the orbit in a groove in the zygomatic bone and enters the temporal fossa, as you can see here on this image. This nerve will be supplying the forehead skin.
Another nerve that you see here highlighted in green now from the anterior view, these really tiny nerves as noticed here highlighted in green, these are known as the zygomaticofacial nerve. They are branches of the zygomatic nerve. They pass along the inferolateral angle of the orbit and emerge upon the face through the zygomaticofacial foramen in the zygomatic bone. As you can see here, these foramina, this is where the zygomaticofacial nerve will be coming out through. This nerve will be supplying the skin over the prominence of the cheek.
Next on our list, we’re going to be seeing this nerve here which you also have on the other side. These are known as the infratrochlear nerves. This is a branch of the nasociliary nerve just before it enters the anterior ethmoidal foramen and will be supplying certain structures including the skin of the upper eyelids and bridge of the nose, the conjunctiva, and the lacrimal sac as well as the caruncle.
Next, we’re going to be seeing here on the anterior view, these are known as the infratemporal nerves, one on each side of the face, and these are continuation of the maxillary nerve in the infraorbital canal. These nerves will be innervating the lower eyelid, the upper lip, and part of the nasal vestibule.
Next on our list, we’re going to continue on with the anterior view of the head. And you can see these highlighted nerves which are known as the external nasal branches of the anterior ethmoidal nerve. The anterior ethmoidal nerve is a nerve which provides sensory branches to the nasal cavity. Within the nose, this nerve gives off sensory fibers to the anterior part of the nasal septum. The external nasal branch will be innervating the skin on the lateral sides of your nose.
Next, still on the anterior view, you see these highlights here. These nerves are known as the buccal nerves, and the buccal nerve is a nerve of the face. This is a branch of the mandibular nerve that will be transmitting sensory information from skin over the buccal membrane and from the second and third molar teeth. Please note this and write it on you notes. Do not confuse it with the buccal branch of the facial nerve which transmits motor information to the buccinator muscle. We talked about this one at the beginning of this tutorial.
Next on our list, we’re going to be seeing this one here highlighted in green which is known as the greater auricular nerve. It originates from or it comes from the cervical plexus and gives off 2 branches - an anterior and also a posterior branch. Now, the anterior branch of the great auricular nerve will be supplying the skin of the face over the parotid gland. The posterior branch will be supplying the skin over the mastoid process on the back of the auricle except at its upper part. Also the auricular lobe and the lower part of the nasal concha.
Finally, we’re going to be seeing these 2 nerves here on your chin and these are known as the mental nerves. They’re branches of the posterior trunk of the inferior alveolar nerve. It is a general somatic sensory nerve which provides sensation to the anterior aspects of the chin, also the lower lip, also the buccal gingiva of the mandibular anterior teeth, and the premolars.