Hello everyone and welcome to this the quick revision series this is a fourth video in this series so because these are the quick revision videos so I presume that you already read about them so we'll just very quickly go through them It's not that these are the only topics which are important, but looking at the current scenario, the present pattern of examination, the recent few last year questions, I believe that these are the topics that you just cannot miss on. So, the first section that I'm looking at here is a head, neck and face section in which I'll be talking a bit about the parasympathetic ganglion. So, one which I marked in red are the most important, although everything is important here.
So, we'll talk. something about the muscles of mastication. We'll talk about the cavernous sinus, its relations and its incoming and outgoing channels. I'll also talk about the parasympathetic ganglion. We'll talk about the deep cervical fascia, the great auricular nerve and something about the cranial nerve columns.
So we'll try to take all these topics as quick as possible. And again, you don't have to write anything because whatever I'll discuss here, the images and even the notes will be provided to you in a soft copy format. Without wasting any time, let's get on with this.
Okay, so we are starting with the head, neck and face part first. And although it's a topic, basically it belongs to the cranial nerve, nuclei is part of a neuron at me, but we are taking it in the HNF portion here. So cranial nerve, nuclei and cranial nerves.
So very quickly, 7th nerve, 9th nerve. 10th now probably the most important nerves and on which the questions are asked the 7th 9th and 10th now now these nerves they have all the columns. They're all kindle of columns except first and last Except first and last.
If you know what is the first column, guys, what is the first parasympathetic, what is the first column, cranial nerve column? That is called as GSE or simply SE. That is general somatic efferent.
And the last column is what? SSA. That is special somatic afferent. Usually these questions are not about, if it's not a PGI exam, in rest of the exam, you just have to a identify that which of the column is not related to the seventh nerve, ninth nerve and tenth nerve. So rather than remembering all the columns, remember that what is not related to it.
That's easy. GAC and SSA. Apart from these two columns, if any column comes in front of you, SVE, GVA, SVA, all are related to the seventh nerve, ninth nerve and tenth nerve.
That's one thing. This GSE, because I've written this general somatic efferent, the word somatic is for the muscles which are derived from the somites or the somatic muscles. And in this head and neck region, it's the extraocular muscles and tongue muscles. Extraocular and tongue muscles which are actually the somatic muscles.
These are called as the somatic muscles. So any nerve which is supplying the extraocular muscle and tongue muscle must be having this GSE. So essentially, this GSE is present in the third nerve.
4th nerve and the 6th nerve because they are supplying the muscles, extraocular muscles and when I say tongue muscle, tongue muscles are supplied by the hypoglossal nerve. So GSE column is the one which is having these 4 cranial nerve nuclei 3, 4, 6 and 12. First, second nerve and eighth nerve. There's something special about these nerves.
First, second and eighth nerve. These nerves are carrying the special sensation but the structures which are developmentally somatic in nature. That's why the last column guys the column which is not related to Which nerve?
7, 9 and 10. That is GSE and SSA. So that SSA column is the one which is having this first nerve, second nerve and the eighth nerve. Special somatic afferent.
This column is made up is having these three nerves. The first, second and eighth nerve comes into SSA column. Special somatic afferent.
Another important nerve that you should know about is the fifth nerve, the trigeminal lobe. The two important column of the fifth nerve is SVE, special visceral efferent because of the pharyngeal arch muscle, muscles of mastication. SVE, special visceral efferent and GSA. General somatic afferent because trigeminal nerve carries all the sensation from the face, from the skin, from the somatic structure.
So GSA is also there in the fifth nerve here. In some books, it is written that first nerve, the olfactory nerve, the column is written as general somatic afferent, not the special visceral afferent. It's not visceral guys as per Grace 41st edition, it is SSA, it's special somatic afferent.
So this is something that is like must know information when it comes to the cranial nerve columns and the cranial nerves. I'll very very quickly go through this again. First I said 7th, 9th and 10th nerve.
When it comes to these nerves, every column is related to them except the first one and the last one. First is GAC, last is SSA. GAC column is important because it is having the extraocular muscle and tongue muscle which are supplied by what nerve? 3, 4, 6 and 12. SSA column is the one which is having what nerve?
1st, 2nd and 8th. The nerves which are carrying a special sensation from the somatic structures. And fifth nerve, the important nerve, the trigeminal nerve is again having two columns here.
One is SVE column because it is supplying the muscles of mastication and GSA column because it is creating all the general sensation from the face. So that is a quick recap on the important cranial nerve nuclei and cranial nerve columns. Moving on in this series, now let's move on to the parasympathetic ganglion.
I got to go very quickly through these topics otherwise this become very very long video. The parasympathetic ganglion guys. The four parasympathetic ganglion I'm sure you all know there is a ciliary ganglion, we have pterygopelatine ganglion, there is a otic ganglion and we have submandibular ganglion. I hope you're not writing it because you don't have to. I'll be providing you with every the all soft copy written by my own hand so just don't bother writing.
Ciliary ganglion, pterygopelatine, otic and submandibular ganglion. Let us look at the secretor motor pathway of all the major glands in the head and neck. With that, we also will be covering the parasympathetic ganglion also. Okay. There is superior salivatory nucleus.
In the pons, if this is a section of a pons here, there is a nucleus here called a superior salivatory nucleus. There are two nucleus. One is superior salivatory, one is inferior salivatory. That's a superior salivatory nucleus.
Although the name is superior salivatory nucleus, but it is also supplying the lacrimal gland. That means lacrimal gland secretor motor pathway also come from superior salivatory. The nerve for the superior salivatory nucleus is the facial nerve.
So let us say if this here is the facial nerve, that's the genome of the facial nerve. That's how the typical facial nerve will look like. From the genu of the facial nerve, you will see one nerve coming out from here and that nerve is called as a greater petrosal nerve. I am sure you all heard about the greater petrosal nerve.
It is a branch of the facial nerve only coming out of the genu, external genu. This greater petrosal nerve, after it forms the vedian nerve, it will go and relay into this ganglion and that ganglion is pterygopalatine ganglion. The relay ganglion is a pterygopelatine ganglion.
One thing that you should know about all these ganglions is when you see a nerve coming inside the ganglion and relaying it, that type of nerve is called as a functional nerve. So greater petrosel nerve or I can say facial nerve is a functional nerve for this ganglion because it is coming and relaying inside. But these nerves they come inside the ganglion but you will not see the nerve going out of the ganglion.
postganglionic fibers are always carried by the trigeminal nerve and its branches. So whenever you see ciliary, otic, pterygopelatine or any of these ganglions, from the ganglion to the gland, it's never the facial nerve or glossopharyngeal nerve or any of the functional nerve. It is always the branch of trigeminal nerve. So after this ganglion, you will see from the pterygopelatine ganglion, the postganglionic fibers are carried by the branches of maxillary Then also by the branch of ophthalmic nerve called as lacrimal nerve, the names are not very important here, and ultimately go and supply the lacrimal gland.
That's how the lacrimal gland is supplied by the fascial nerve. Fascial nerve gives off greater petrosyl nerve, relays into perigopelatine ganglion, and post ganglionic fibers are carried by the branches of the maxillary and ophthalmic nerve that I told you that after the ganglion, it has to be trigeminal. Another branch of facial nerve guys which will go through the middle ear cavity if let's say there's somewhere in his middle ear cavity here the branch of facial nerve which is going through this middle ear cavity is a cauda tympani that's a cauda tympani nerve and this cauda tympani nerve will once it comes out of the middle ear cavity in the infra temporal fossa it will go and join with the lingual nerve. it will join with the lingual nerve the lingual nerve is the one which is connected to the submandibular ganglion the lingual nerve which is connected to the submandibular ganglion that means this time the preganglionic fibers are carried by the caudate empenni They're going through lingual nerve and then relaying into what ganglion? Submandibular ganglion.
You know the story that postganglionic fibers will actually go through the trigeminal nerve only. Lingual nerve is a branch of mandibular. Lingual nerve is a branch of mandibular nerve. So it is a trigeminal. So postganglionic fibers are carried by the lingual nerve and ultimately they will go and supply the submandibular and sublingual gland.
They'll supply the submandibular and the sublingual gland. That's the secretor motor pathway of the two important glands and something about these ganglions also. Erigopelatine ganglion, the topographic nerve, the functional nerve is a greater petrosal nerve and ultimately they have to supply lacrimal gland.
Submandibular gland, the functional nerve is caudate impenny because it's the caudate impenny via lingual nerve comes and relays inside and postlingual fibers will supply the submandibular and sublingual gland. So remember about these two important secretor motor pathway. Lacrymal done, submandibular, sublingual done.
One more gland that is a perotid gland. We should know also about this perotid gland. For the perotid gland, the nucleus is actually situated in the lower part of pons and that's why the nucleus is also called as a inferior salivatory nucleus.
So superior salivatory nucleus took care of the submandibular, sublingual gland as well as lacrymal. This is inferior salivatory nucleus which is present in the pons. Inferior salivatory nucleus is one of the nucleus for the glossopharyngeal nerve.
So guys let us say this nerve here is the glossopharyngeal nerve. There is a branch of glossopharyngeal nerve which will go into the middle ear cavity and this branch of glossopharyngeal nerve is called as the Jacobson's nerve. Once this Jacobson's nerve reaches the medial cavity, on the medial wall of middle ear, there is a promontory and on that promontory, it forms a plexus which is called as a tympanic plexus. So, Jacobson's nerve branch of glossopharyngeal nerve forms a plexus called as a tympanic plexus.
Then, ultimately from this tympanic plexus, a resultant nerve which comes out is called as lesser petrosal nerve. We saw greater petrosal nerve was coming from facial nerve. Lesser petrosal nerve I can say it is a branch of glossopharyngeal nerve indirectly.
So it is lesser petrosal nerve coming out of the tympanic plexus and this lesser petrosal nerve is the one which comes out of the foramen ovale and just below the foramen ovale it finds a ganglion and this time the ganglion is aortic ganglion. This time ganglion here is a aortic ganglion. Once again the same story after the otic ganglion it's not the glossopharyngeal nerve or any other functional nerve it has to be trigeminal.
So postganglionic fibers are carried by the auriculotemporal nerve which is a branch of mandibular. Again justifying that that postganglionic fibers are always made up of the trigeminal nerve. So auriculotemporal nerve which is a branch of mandibular nerve will carry the postganglionic fiber to what to the parotid gland. That's how the parotid gland is supplied. So that's the secretor motor pathway of the parotid gland here.
This time the nucleus is inferior salivator nucleus, the nerve is glossopharyngeal nerve, gives off jacobus nerve, tympanic plexus, lesser petrosyl nerve goes into aortic ganglion and then the post ganglion fiber again coming through the branch of trigeminal, that is auriculotemporal nerve supplying the parotid gland. So with that we are done with the otic ganglion, pterygopelatine ganglion and we are also done with the submandibular ganglion. Still one is left and that is what ciliary ganglion. About ciliary ganglion guys, this time we have to look at the midbrain. Let's say there's a section of the midbrain at the level of superior colliculus.
Here's a midbrain. In the midbrain we have a third nucleus and we also have this eddinger westphal. So what you'll see if this is let us say this is a third nerve nucleus.
The third nerve coming out of this third nerve nucleus, after crossing the cavernous sinus, the third nerve divides into the upper division and the lower division. I'm not talking about the detailed course. It goes in the lateral wall of cavernous sinus and then it comes into the orbit. It enters the orbit by dividing into two branches.
There's a nucleus present close by and that nucleus is called as Edinger-Westphal. This Edinger-Westphal nucleus fibers, they run along with the oculomotor nerve. Then they will run with the lower division and ultimately they will separate and relay into the ganglion which is in the orbit that is ciliary ganglion. And then from the ciliary ganglion all these short ciliary nerves are coming out and they are the one which supplies the sphincter pupillae. and ciliary muscle.
That's about the ciliary ganglion. That's how it operates. That eddinger westphal fibers joins with the third nerve, goes with the lower division, then they separate from there, relays into ciliary ganglion and ciliary ganglion fibers are coming out, the short ciliary nerves coming out and supplying the sphincter pupillae and ciliary muscle. So that's the overall view of the four parasympathetic ganglion, that which nucleus is connected to them, what cranial nerve is related to them.
what are the post-tangleric fibers and then what are exactly they're going to supply which supplies the parotid gland submandibular gland and all the criminal gland etc Another question which is a recent question again, it is about the relations of the ganglion. Out of all the ganglions, the two most important ganglion for which we should know the relation, one is otic ganglion, definitely the most important, and also ciliary ganglion location inside the orbit, because they are already asking a lot of questions about the orbit and extraocular muscle, so we should know that. So, very, very quickly, if I go about the relations of these, or the location of the ganglion, the ciliary ganglion, guys, If this here is the transfer section of the orbit, here is the eyeball and that is an optic nerve, right?
That nerve is an optic nerve here. And let's say this muscle here on the lateral side, that is a lateral rectus muscle. If that's a lateral side, so obviously that is a rectus, lateral rectus muscle.
Ciliary ganglion is situated between the optic nerve and lateral rectus close to the apex of the orbit like this. That's the location of the ciliary ganglion. If the question is asked on the relation here, it is present between a nerve and a muscle.
The nerve is optic nerve. And on the lateral side, we have a lateral rectus. So it is sandwiched between those two structures, but close to the apex of the orbit.
It is very close to the apex of the orbit. Pterygopelatine ganglion is in the pterygopelatine fossa only. So nothing to bother about it.
Another important relation that I should know is a submandibular ganglion. For the submandibular ganglion guys, if this is a hyoid bone, there is a muscle which is originating from hyoid bone and going into the tongue and that muscle is called as a hyoglossus muscle. The muscle is called as a hyoglossus muscle.
On this hyoglossus muscle, the nerve running is a lingual nerve. Lingual nerve runs superficial to the hyoglossus muscle and then this lingual nerve as we know is topographically connected to this submandibular ganglion. Just below the submandibular ganglion, you will see the duct of submandibular gland that is a Vorten's duct. So that's enough kind of relation that you should know about the submandibular ganglion.
It is situated superficial to what muscle? Hiocloss. If it's a hioclossus muscle, it is superficial to it. What is above?
Obviously, it is connected to lingual nerve. So lingual nerve is above. And what is below?
It's a duct of submandibular gland. The Wattens duct is seen just below the Wattens duct and gland is seen below the ganglion. And then comes the third and probably the most important that is aortic ganglion. Now this I have to tell you in slightly more detail here about the location of the aortic ganglion. For this aortic ganglion, let us say this here is the foramen ovale.
The foramen ovale is giving passage to the mandibular nerve, you know male structures passing through foramen ovale and that is the mandibular nerve, the trunk of mandibular nerve coming out of foramen ovale. Otic ganglion is actually present medial to the mandibular nerve. This is one important thing that you should remember.
Based on that, there was a, two years back, there was a question in Ames also. The location of the otic ganglion is actually medial to the nerve. So now it is situated medially. And more medially, I mean medial to the ganglion, there is a muscle. And that muscle is tensor veli pellitini.
that muscle is tensor valley pelotiny just like ciliary ganglion even otic ganglion is situated between a nerve and a muscle nerve is what mandibular nerve muscle is what tensor valley pelotin so it's situated between the two more relation if i have to tell you here anteriorly although it's not easy to justify the relation here anteriorly we have medial pterygoid muscle Antirelation we've got medial pterygoid muscle and posterior relation is easy to remember because behind the foramen ovale there is a foramen called as foramen spinosum and this foramen spinosum is giving passes to the main artery of the dura mater that is a middle meningeal artery. So clearly I can say that medial pterygoid is actually forming the anterior relation of the otic ganglion. Foramen ovale is present in the roof of the ganglion. Mandibular nerve is present lateral to the ganglion. It is forming the lateral relation.
Tensor valley pelitini is a medial relation to ganglion. And middle meningeal artery is the posterior relation of the otic ganglion. These are the important relations of otic ganglion based on which a question was also asked in recent time. So, pterygopelatine ganglion, don't bother, it is in the pterygopelatine fossa only, the name is pterygopelatine ganglion, so it's in the pterygopelatine fossa.
I would say the two most important, ciliary ganglion and otic ganglion, both are between a nerve and a muscle. That is between the optic nerve and lateral rectus and this one is between the mandibular nerve and tensor valley pelatine. It is between the mandibular nerve and tensor valley pelatine. Because we've talked about the secretor motor pathway of the lacrimal gland and also about the submandibular gland, so the major important examination point of view part of the facial nerve is done in that only.
But one more nerve guys, which we usually don't pay much attention on, but it is like directly or indirectly, a lot of questions are asked on it and that is a mandibular nerve. Another, this 2019 January NEET question was a question asked on the inferior alveolar nerve, which is a branch of mandibular nerve only. That was a picture based question.
Okay, so let me just give you a quick recap of the mandibular nerve, not the entire detail here. Mandibular nerve is a mixed nerve. Mandibular is one mixed nerve here.
It comes out of the foramen ovale and mandibular nerve, it divides into the anterior division and the posterior division. This trunk of mandibular nerve, when it comes to muscles, this trunk of mandibular nerve supplies one muscle of mastication which is again a question asked and that is medial pterygoid. Medial pterygoid is the only muscle of mastication which is supplied by this trunk.
This is a trunk, I'm writing T here for the trunk. This is anterior division and that's the posterior division. So that's one potential question.
Another important question from here itself, the nerve which is supplying medial pterygoid, it is not only supplying medial pterygoid, it also supplies the two tensor muscles in head and neck, that is tensor valley pelitone and tensor tympani. And these are the muscles which are more likely to be asked because they are not the muscles of mastication but still they are supplied by the mandibular nerve which makes them quite unique. Tensor valley pelitoneum and tensor tympanum the two muscles with the name tensor are supplied by the nerve to medial pterygoid. Anterior division, posterior division. Well anterior division will supply the remaining muscles of mastication.
the remaining muscles of mastication lateral pterygoid temporalis and mesenter but there is one sensory branch comes from the anterior division and that sensory branch is called as the buccal nerve that's the only sensory branch coming from the anterior division the buccal nerve and why buccal nerve is important because buccal nerve it pierces the buccinator muscle but it doesn't supply it it's a sensory nerve so it is piercing the box usually as per the rule if any nerve is piercing a muscle it also supplies it But it is one exception in which you see a nerve is piercing a muscle but doesn't supply it. Buccinator is supplied by the buccal branch of facial nerve. This is a buccal branch of mandibular nerve.
So we have two buccal nerve, the two different buccal nerve. Buccal branch of mandibular nerve pierces buccinator, doesn't supply it. Buccal branch of facial nerve, it supplies buccinator because that's a motor nerve, it is a sensory. posterior division of the mandibular nerve guys it gives off three branches one is the auriculotemporal nerve the nerve which supplies the auricle and temple and parotid gland we just saw that it is supplying the parotid gland that is auriculotemporal nerve Another branch coming from the posterior division is the lingual nerve.
We also discussed lingual nerve. Lingual nerve was the one which was connecting what ganglion? Submandibular ganglion. That is lingual nerve.
Submandibular ganglion, we were connected to it. And the one which was asked in the exam recently, in this need itself, that was about this third nerve and that nerve is called as the inferior alveolar nerve. Why inferior alveolar?
Because it goes inside the mandible. If this here is the mandible, guys. The nerve will be seen running inside the mandible in the mandibular canal and comes out as the mental nerve. It comes out as a mental nerve.
This nerve here is called as inferior alveolar nerve. This nerve is the inferior alveolar nerve. It enters into the mandible, comes out as mental nerve.
Obviously it is supplying all the alveoli, that's why the name is inferior alveolar. But see what is important here, this inferior alveolar nerve comes out as mental nerve to supply the skin of the chin region. So first of all please remember this mental nerve is a sensory branch. It is not supplying any muscle or mentalis nothing like that.
It is just supplying the skin of the chin region. But this inferior alveolar nerve before entering into mandible it gives off a branch which again comes down and supplies two muscles in the floor of the mouth here. The muscles in the floor of the mouth that is myelohyoid myelohyoid and anterior belly of digastric. myeloid and anterior belly of digastric.
So I would say that these four muscles, the one which are highlighted here, are the one that you should remember because they're worth asking the exam. Muscles of mastication supplied by mandibular nerve, no big deal. Everyone knows muscle of mastication is by mandibular nerve.
Which muscle of mastication is by the trunk of mandibular nerve? That is a question. And that muscle is what? Medial pterygoid.
And then what other muscles which are not the muscles of mastication? but still supplied by mandibular nerve, that is tensor valley pelotinia and tensor tympani, supplied by nerve to medial pterygoid. And myelohide and anterior belly of digastric, supplied by inferior alveolar nerve, the branch of inferior alveolar nerve, before entering into mandible, supplies these two muscles. So that's a quick recap of the cranial nerve nuclei, the columns, the parasympathetic ganglion, and the things which I feel are very, very important from the cranial nerve part, especially the mandibular nerve. The second important thing, guys, we talk about here, is a deep cervical fascia.
We'll take one section here and let's quickly look into that deep cervical fascia and some related questions to it. Okay, that's a picture. It's a transfer section.
This also is one of the image-based questions asked in the AIMS exam and they even gave a longitudinal section also and this cervical fascia has always been an important here, whether it's a NEET exam or AIMS exam. Okay. Now, if we just quickly go through this picture here, the muscle that you see, when you take a transfer section, the muscle that you see present most anterior lateral, that is sternocleidomastoid, and the muscle present posteriorly, that is trapezius muscle. The most superficial muscle and the huge muscle here, sternocleidomastoid, this one here, and that's the transfer section of the trapezius. And look at this red colored fascia, which is covering these muscles.
This fascia here, guys, is called as the investing layer of deep cervical fascia. there is an investing layer of deep cervical fascia. Investing layer is investing many other structures. It's not only the muscle, it invests some glands also, some spaces as well, it forms some ligaments.
But as of now, in this section, I can see the two muscles which are enclosed in the investing layer, that is a sternocleidomastoid and trapezius. This here is a vertebral column, and obviously the muscle that you see around the vertebral column, these are the pre-vertebral muscles, all the scalene muscles will be there. And this orange colored fascia which is shown here is called as a pre. vertebral fascia. The pre-vertebral layer or the pre-vertebral fascia.
And this pre-vertebral fascia, pre-vertebral layer, it is, the name says pre-vertebral layer, that doesn't mean it is only in front of the pre-vertebral muscle. It is actually all around. It is covering the pre-vertebral muscle all around here.
Before we go to the pre-vertebral fascia, let me mark the third major fascia here. That is a thyroid gland that you can see in front of the trachea. That's a trachea there, guys, right?
And in front of the trachea that you can see, that fascia here is a pre-tracheal layer. The fascia there is a pre-tracheal layer. This pre-tracheal layer is covering this thyroid gland. That's a thyroid gland which is enclosed inside the pre-tracheal layer and it is forming the false capsule of the thyroid gland here.
So these are the three primary or major modifications of the deep cervical fascia, the investing layer, the pre-tracheal layer and pre-vertebral layer. By the contribution of all these three, investing, pre-tracheal, pre-vertebral, this sheath is formed which you can see present posterior lateral to thyroid gland. And this sheath guys is called as a carotid sheath.
The sheath is called as a carotid sheath and it is situated posterior lateral to the thyroid gland, the carotid sheath. Talking a bit about carotid sheath, this again is a recent question only. In the carotid sheath, we have common carotid artery and internal carotid artery because the external goes out.
Common carotid and internal carotid artery, there is a vagus, the nerve inside along with internal jugular vein. So guys regarding the content if I just may write the content on the side here the content is the common carotid artery and internal carotid artery in the upper part. The nerve inside will be vagus nerve.
and the vein here is the internal jugular vein these are the contents of the carotid sheath they are held inside the carotid sheath but what are the relations of carotid sheath just anterior to the carotid sheath guys in the upper part although this section is quite low you will see the answer cervicalis the loop of answer cervicalis is made up of two limbs one is called as descendants hypoglossi descendant cervicalis so if this is like carotid sheath for me you will see answer cervical is formed right in front of the carotid sheath In fact, it is adherent to the anterior wall of carotid sheath. And the posterior relation of the carotid sheath is by the sympathetic chain. The posterior relation is a sympathetic chain.
Anterior relation is ansa cervicalis and posterior relation is sympathetic chain. But see, here is the catch. If it is an image-based question, it's not difficult to identify the vagus nerve. When they gave this question in the AIMS exam actually, last year, they asked the vagus nerve to be identified there.
No big deal. If you can identify the carotid sheath, easily one nerve inside, that is a vagus nerve. The more challenging structure is the ansa cervicalis, sympathetic chain, and especially phrenic nerve. Now let me show you, let me take you back to this section and enlarge this section further. What you see here, this is a transverse process of the cervical vertebrae.
And look at these muscles which are attached to the tip of the spinous transverse process. These are scalene muscles. This here is a scalenous anterior. This one is the scalenus medius and this one here is the scalenus posterior muscle. The three scalene muscle can be seen there.
I'm sure you can identify this nerve is inside the carotid sheath. So this nerve is what? That's a vagus nerve. It is inside the carotid sheath.
And this here is the sympathetic chain. Right, makes sense that is sympathetic chain, it is behind the carotid sheath, but in front of the prevertebral fascia. Look at that nerve is actually present in front of that orange colored fascia.
So that's an important thing to note in the transverse section, that the sympathetic chain, it is behind the sheath, carotid sheath, but in front of the prevertebral fascia. Whereas, the nerve that you see very, very close to vagus nerve only, but if you look carefully, this nerve is behind the prevertebral fascia. Vagus nerve is inside the carotid sheath.
Then we have prevertebral fascia and behind prevertebral fascia, look at that nerve, you can appreciate that, that is the phrenic nerve. One important relation of scalenus anterior also, it is a nerve which is running in front of the scalenus anterior, I discussed that in the cadaveric images of the upper limb also where I showed you scalenus anterior muscle in the brachial plexus part and there was a nerve running in front of it, that is a phrenic nerve. Same story here, that is a phrenic nerve in front of scalenus anterior.
And then you can also see a nerve between scalenus anterior and scalenus medius. It's actually the roots of the brachial plexus. The brachial plexus emerges between the scalenus anterior and medius.
So these are the cervical root values which are going to form the brachial plexus. C6, C5, C7, all these will be coming out between the scalenus anterior and medius. So especially this part guys, this is the portion you got to be careful about. Vagus nerve inside the sheath. Sympathetic chain behind the sheath but in front of prevertebral fascia.
Behind prevertebral fascia, in front of scalenus anterior. What nerve? Phrenic nerve.
And the nerve that you see between scalenus anterior and scalenus medius, these are the nerves which are going to form the brachial plexus. The spinal nerves forming the brachial plexus. And one more important nerve that you should notice here is the nerve which is present between the trachea and esophagus.
In the tracheoesophageal groove and that is recurrent laryngeal. nerve. If you could see that nerve present in the tracheoesophageal groove, these nerves are the recurrent laryngeal nerve. So, in the transfer section, this is the important thing to identify is either the content of carotid teeth or the nerves. That is what they can ask you and I believe this knowing the relation that what to find where does not matter it is a real time section or it is a schematic picture, we can easily identify that if you know the relations.
Okay, from... Moving on from here guys, from this picture of the deep cervical fascia, let me talk about some important relations and the aspects of the cavernous sinus. Another very, very important topic and very frequently asked in the exam is the cavernous sinus relations also and cavernous sinus incoming and outgoing channels as well. So, I am going to start with the cavernous sinus.
the channels first. So let's keep it very simple and quick here. If this is the cranial cavity, there is an anterior cranial fossa, the middle cranial fossa and the posterior cranial fossa here. Let's say this is for a magnum.
Cavernous sinus is situated in the middle cranial fossa on both the side of pituitary gland. On the pituitary fossa, let's say this is a cavernous sinus. Now cavernous sinus is receiving the blood from three major sources. Cavernous sinus has received the blood from the orbit.
from the brain and from the meninges, from the orbit, from the meninges and from the brain. When I say brain, what veins are coming from the brain and draining into cavernous sinus? One is called as superficial middle cerebral vein, superficial middle cerebral vein and one is the inferior cerebral vein. inferior cerebral vein, not internal cerebral vein, be careful, it is inferior cerebral vein. Orbit, when we say orbit guys, the two veins which are mainly coming from the orbit is a superior ophthalmic vein and inferior ophthalmic vein, superior ophthalmic and inferior ophthalmic vein and sometime even the central vein of retina also, not always, central vein of retina can also be seen draining into the cavernous anus directly.
So two veins are coming from the orbit from the brain two or maybe three veins are coming from the orbit to drain into the cavernous sinus and m meninges when I said m is for the meninges that means some dural venous sinuses are draining into cavernous sinus which dural venous sinus directly drains into cavernous sinus one is called as a sphenoparietal sinus there's a sinus called a sphenoparietal sinus will be seen along with the lesser wing of sphenoid that is sphenoparietal sinus and another one is a middle Meningeal sinus, sphenoparietal sinus and middle meningeal sinus. So that's one question, these are all incoming channels or incoming tributaries of the cavernous sinus. Superficial middle cerebral vein, inferior cerebral vein, superior inferior ophthalmic vein, central vein of retina and the two from the meningeal, that is sphenoparietal sinus and middle meningeal sinus, they are all incoming channels. When it comes to outgoing channels, whatever blood now comes into cavernous sinus, it drains mainly through these two sinuses.
One is called as superior petrosal sinus because it runs with the upper border of Peter's temporal bone. And one is inferior petrosal sinus. Superior petrosal and inferior petrosal. And just to tell you guys, the superior petrosal is the one which is going to drain into transverse sinus. And this transverse sinus ultimately becomes a sigmoid.
So inferior goes into sigmoid. So what I'm saying is this here is a transfer sinus, let's say, and this transfer sinus is going to become sigmoid sinus. It will continue as a sigmoid sinus to come out of the jugular foramen, and that's what you're looking at here.
The two outgoing channels of the cavernous sinus, SPS, superior petrosal sinus, and IPS, inferior petrosal sinus, they are the ones which are draining back and draining into the transfer sinus. and sigmoid sinus respectively. That's a question also. Superior petrol sinus drains into transverse and inferior petrol sinus it drains into the sigmoid sinus. Cavernous sinus also gives up some emissary veins which goes out of the foramen lesserum.
But these are the two major tributaries, the major outwing channels of the cavernous sinus here. Both cavernous sinus are connected to each other by the anterior and posterior intercavernous sinus. These are simply intercavernous sinus connecting both the cavernous sinus in front and behind the pituitary fossa. But see what is important to note here.
When they ask you this question that what are the incoming channels of cavernous sinus. Okay, all these are incoming channels or you can say they are the tributaries. They are all incoming channels or tributaries. So basically if you have a 2 plus 3 plus 2, these are all incoming channels.
Outgoing channels. I can say superior petrosal inferior petrosal but there is one channel which is outgoing as well as incoming and that again could be a question here and guys this is super fear this is superior ophthalmic vein superior ophthalmic vein please note it is an emissary vein it is an emissary vein and if it is an emissary vein the blood can come in also and through the same the blood can go out as well so this is one channel the superior ophthalmic vein which you have to count in both incoming channel as well as opening channel so now if i say all these are incoming channels outgoing channel is superior petrosel and inferior petrosel and again superior ophthalmic vein because it is an emissary vein so it is counted in both incoming as well as outgoing Another important thing about the cavernous sinus, the most important thing about cavernous sinus that you should remember is the relations. If I take a coronal section of the cavernous sinus that gives me a fair idea about it. Here is the body of the sphenoid and that is the cellar tersica. These are sphenoidal air sinuses and let's say this is a pituitary gland which is hanging in.
Cavernous sinus is situated just lateral to it. That's the situation of cavernous sinus. It is present lateral to the pituitary gland, cellar, tursic and all that.
This is cavernous sinus. In the lateral relation of cavernous sinus as per Gray's 41st edition, the three nerves are seen. The third nerve. The fourth nerve and ophthalmic nerve.
Although majority of the books claims that maxillary nerve is also in the lateral wall, but I'll go with the 41st grace. It says that maxillary nerve is present below the cavernous sinus outside it. So it's not in the relation here.
It's a third nerve, fourth nerve and ophthalmic nerve. They are the one which are forming the lateral relation of the cavernous sinus. And along with these nerve, there is one part of the cerebrum called as uncus. It's a primary olfactory area.
Cannot draw it here so that uncut also remember is also in the lateral wall third now fourth now of thelmic now and Uncus they are forming the lateral relation of cavernous sinus medial relation I don't have to say you can see in the picture only medial relation is by the pituitary gland It is by this cella tercica. It's by the sphenoidal air sinus and the body of sphenoid They are all present in the medial relation. They are all forming the medial relations of the cavernous sinus What is in the floor guys?
The floor of the cavernous sinus is made up of foramen lesserum. So cavernous sinus basically is present on the foramen lesserum and that's why there are some emissary veins which are going out of the foramen lesserum to join with the pterygoid venous plexus as well. What is inside and above the cavernous sinus?
Inside the cavernous sinus is the internal carotid artery and the just inferior lateral to internal carotid artery there is abducent nerve as well. So these two structures, the internal carotid artery and sixth nerve, the abducens nerve, they are the ones which are present inside cavernous sinus. They are present inside the cavernous sinus.
This internal carotid artery is a direct continuation of common carotid. Embryologically, when you say the vasculogenesis, it's an example of vasculogenesis only. The common carotid artery is there and the same pharyngeal arch artery will continue to form the internal carotid also.
If internal carotid is a direct continuation of common carotid, the pressure in the internal carotid is very, very high. You cannot give the blood to the brain with such a strong pulsation. So to dampen these pulsations, what happens is internal carotid artery comes in, it makes a loop and then goes back into the cerebrum. That is called as a carotid siphon. You can very well appreciate the carotid siphon in the carotid angiogram also.
That is why internal carotid artery, when it makes a loop, goes forward and comes back, is also seen above the cavernous sinus along with the optic chiasma. So when it comes to the relations of the roof, again you will see internal carotid artery and optic chiasma. chiasma will be seen. These are the structures which are present in the roof of the cavernous sinus. So these are the must-know relations of the cavernous sinus, the one structure is inside, in the lateral wall, including the uncus, in the floor we have foramen lesrum, then we have internal carotid artery, optic chiasma above and medial relations are all the cell atarsica, pituitary gland, the sphenoidal layer sinus etc.
So, this is like the most important thing the channels of cavernous sinus here and also about the incoming and outgoing channels what do you say the relations of the cavernous sinus. So, guys moving on in this topic the next very next we will go on to the Some important muscles which needs an attention because these muscles they keep repeatedly ask these questions. The questions are pretty simple. It's all about identifying the muscles and then we have to like answer those questions based on it.
Although they might give you a coronal section, but I chose to take a picture in which the entire muscle can be seen. So at least you can see the relations here. Now, there's a picture of the left orbit we are looking at and the rectus muscle are simple to identify.
It's the oblique muscle that we need to focus on. Well in this picture, the muscle that you will see present here, this muscle is the superior rectus, this is inferior rectus, that's the lateral rectus and this one is the medial rectus. Now if you look carefully, you can see one more muscle which is present above the superior rectus guys.
The muscle which is above the superior rectus, you can see it peeping slightly toward the medial side. This muscle is not superior oblique, that is LPS. It's a levator palpebrae superioris muscle, the one which is present above the superior rectus. The muscle which is present more superior medially here and you can see it is even hooking around this the pulley here you may not see the pulley when you take a coronal section of the orbit but just make sure you remember the relation here the one which is above the superior rectus is lps the one which is between the superior rectus and medial rectus here that is the superior oblique muscle that's a superior oblique muscle inferior oblique muscle is present somewhere here because it originates from the floor of the orbit only and then it goes backward so i'm not able to see the the the belly of the muscle because it starts on the floor of the orbit more present inferior laterally here that is inferior oblique what they do at times is they give you a picture of a muscle and then they will ask that the nerve supplying this muscle is is originating from where and all so we know that so4 lr6 that mnemonic we all know that lso4 and lr6 superior oblique supplied by the fourth nerve And you know fourth nerve guys it is starting from the midbrain.
The origin of the fourth nerve is from the midbrain is supplied by the fourth nerve and fourth nerve originates from where from the midbrain and what level of the midbrain that level is an inferior colliculus. The question is all about this. So they might put an arrow on the muscle that is superior oblique muscle and will ask you that the nerve supplying this muscle, it originates at what level? So the nerve is fourth nerve.
Fourth nerve comes from where? Midbrain. And what level of midbrain?
That is the inferior colliculus of the midbrain. If the arrow is on the LPS, SR, MR, all these muscles, they have all common nerve supply. They are all supplied by what?
Third nerve. Let me just give them a different color here. The levator palpibus superioris, medial rectus, superior rectus. inferior oblique, inferior rectus, all these are supplied by the third nerve. Third nerve is also originating from where?
From the midbrain. But this time, the level is what? Superior colliculus. So third nerve, it originates from the midbrain at the level of superior colliculus.
Whereas LR6 of course the lateral lactose is supplied by the abducen nerve, the 6th nerve. It is supplied by the 6th nerve and 6th nerve it starts from the pons and in the pons guys we have facial colliculus. If you remember facial colliculus we talked about in the cadaveric image of the fourth ventricle also that there is a facial colliculus which is formed by the facial nerve winding around the abducen nucleus. So the colliculus is facial colliculus.
So three colliculus you should remember. The third nerve is coming out from the level of the superior colliculus. Fourth nerve is coming out from the level of inferior colliculus and sixth nerve is seen emerging at the level of the facial colliculus. Next, from this extraocular muscle. The another important set of muscle on which the questions are probably asked here that is the the laryngeal muscles.
Well till now they've given always given the the schematic picture or the the atlas image of the the laryngeal muscle because it's not very easy to identify the muscles if it is given a section here. But I found one good section in which we can compare the muscle if it is a schematic atlas picture or it's a cadaver picture. Let's try to compare the laryngeal muscles how will you identify them. So here we go, this is, when you see this picture here, that's a hyoid bone, with the hyoid bone which is cut in this section here, and that is the epiglottis, if I just, just for the orientation sake guys, this is the hyoid bone, this here is the epiglottis, same thing, that is epiglottis here, that's a thyroid cartilage, okay, that's a section through the thyroid cartilage. Here is a cricoid cartilage, you can see that cricoid over there.
Now look at, just let's identify the muscles on this picture here, that will be easy for us to mark it there. If you look here, this muscle here, the two muscles that you see attached to the cricoid and then attached to the arytenoid. Arytenoid obviously cannot be seen, it is inside, but that is a site for the arytenoid cartilage. This muscle is attached posterior to the cricoid and that is attached lateral to cricoid. So this muscle is called as a posterior cricoarytenoid.
The muscle is a posterior cricoiretinoid and this posterior cricoiretinoid is the only abductor of the vocal cord. It's a life-saving muscle, the safety muscle of larynx, the only abductor of vocal cord that is the posterior cricoiretinoid. Whereas this muscle which is attached to the lateral side of the cricoid cartilage, it is lateral cricoiretinoid.
It's a lateral cricoiretinoid muscle and lateral cricoiretinoid muscle is the adductor of the vocal cord. Not the only adductor but yeah it is the adductor of vocal cord and it is also called as the muscle for whispering. So when we whisper, we close the vocal cord and the air is coming out between the two arytenoid cartilage. That is a muscle of whispering called as lateral cricoarytenoid.
So abduction is by posterior cricoarytenoid and adduction is by lateral cricoarytenoid. That's how we identify them on the picture here. Just look at the cricoid cartilage because on the arytenoid, the attachment is same only. They both are attached to the muscular process of the arytenoid. It's about where they are attached on the cricoid cartilage.
If I take you from this picture to the real-time section, let's try to identify the muscle here. See. not no problem this one here is the posterior cricoretinoid and this one here is the lateral cricoretinoid so we need to have a fair idea about that where the muscle is seen because in the cadaveric image it will not be very very clear when you compare it with the rest of the thing okay let me again take you back here Now another muscle that you'll appreciate here look at this coming from a thyroid cartilage and going to the outer surface of arytenoid this muscle is thyroarytenoid muscle thyroarytenoid.
Thyroarytenoid muscle is responsible for the relaxation of the vocal cord. Because when this muscle will contract, it will bring the arytenoid clue and thyroid cartilage close to each other. And the vocal cord, which is stretching like this in this manner, obviously inside that vocal cord will get relaxed. So thyroarytenoid muscle, one of the relaxer of the vocal cord, it's for the relaxation of vocal cord.
But if you look at the upper fibers of this thyroarytenoid muscle, they are spanning upward and they're going toward the epiglottis. It's a modification of the thyroarytenoid muscle only. The muscle is called as the thyro.
epiglotticus. The muscle is thyroepiglotticus. It is a morphological extension of thyroretinoid only.
The muscle is called as thyroepiglotticus. What is the function of thyroepiglotticus? When this thyroepiglotticus muscle pull the epiglottis forward, it will pull the epiglottis in this direction, in the forward direction.
And that is helping in what? That is helping in the opening of the inlet of larynx. So this is the muscle which helps in the opening of inlet of the larynx.
You pull the epiglottis backward, that is a closing of inlet of larynx. You take it forward, it is an opening of inlet of larynx. This is a muscle for the opening of inlet of the larynx.
If I take you back to that again cadaveric picture, let's try to compare it here. There is this muscle here, the muscle, look at this, this tuft of muscle here, this is the thyroaretinoid muscle. I've labeled it well in the handouts.
So that's thyroideatinoid muscle. And the upper fiber of thyroideatinoid, look at these fibers here. The one which are, this is thyroideatinoid and these fibers which are spanning upward, these are thyroepiglotticus.
Thyroideatinoid and these fibers are thyroepiglotticus. Thyroideatinoid and thyroepiglotticus. Other muscles, we are not able to appreciate it well in this picture because we have to turn it and then see it from this side.
But at least let us see it on this part here. I can see this muscle which is marked as D, the muscle which is running horizontally here between the two arytenoid. This is a transverse arytenoid. This muscle is a transverse arytenoid muscle.
this D and look at this on the transverse arytenoid present on the transverse arytenoid is an oblique arytenoid. It is present more superficially and behind it. So we have a transverse arytenoid and behind that we have this oblique arytenoid. An oblique arytenoid muscle, it is not only limited to the arytenoid cartilage, it goes even further and look at this extension of the oblique arytenoid which is called as the aryepi. glotticus and this area epiglotticus is the one which will pull the epiglottis backward and that is why this is a muscle for closing of inlet of larynx.
That is the muscle for the closing of the inlet of the larynx. So that is an important laryngeal muscle that you should be able to identify if they remove the thyroid cartilage from one side and show it from the side. If this gives you a transfer section that becomes very easy.
Lateral cricoid into the lateral side, posterior to the posterior side. It's this picture in which it is a bit challenging to identify the muscles there. This muscle B here that's a cut section of cricothyroid.
So just don't bother here because thyroid cartilage is cut, they have not shown it completely. So it's a cricothyroid, it's a cut section of cricothyroid muscle which is shown as B here. Apart from laryngeal muscle, one more topic which I want to discuss here regarding the muscles of the, in the head and neck region is the muscles of mastication.
Well, I don't have to tell you that this is probably one of the most frequently asked question, the image based question asked in fact on the muscles of mastication. mastication. But you know rather than discussing different type of images, schematic pictures and cadaveric images, if you understand the exact attachment of the muscles of mastication and the direction of the muscle fiber, neither you will have a problem in identifying the muscle nor you will have a problem in knowing that what is the function of that muscle. So I am going to use this picture here of the mandible to explain you how exactly muscles of mastication are attached on it and then based on it I will show you some cadaveric images on which we can try to identify the muscles as well. Guys, this process here is called as a coronary process.
and this process that is the head of the mandible here and that notch is called as a mandibular notch. That's a ramus of mandible obviously that is a body here and you can see one foramen which is present here the mental foramen. So let me try to discuss like as many things as I can on this picture.
First start with the muscle here. Muscles of mastication, the temporalis muscle will be seen inserted on the anterior border of the ramus of mandible. and also slightly to the medial surface and tip of this coronoid process.
Look at that. That muscle which is coming here and attaching there is temporalis muscle. That's a temporalis muscle. So important thing is it is inserted on the anterior border of ramus of mandible and also to the tip of the coronoid process and also slightly on the medial surface also. So as any you look at the medial surface of the ramus of mandible and say it's a medial pterygoid muscle.
No, no, no. If you're looking close to the anterior border, it is supposed to be temporalis. The muscle which will go backward and attach to the neck of mandible and also to the capsule of the TMJ, this muscle is running horizontally backward.
This is lateral pterygoid muscle. The muscle is lateral pterygoid. The muscle that you see present on the medial surface of ramus of mandible inserted like this below the mandibular foramen in this part here close to the angle of mandible that muscle is medial pterygoid i'm saying mandibular foramen guys that is a site for the mandibular foramen can you see a hook like projection a small tongue like projection over there that small tongue like projection if you can see that that is actually called as lingula And this lingual or this tongue-like projection that you see, just deep to it, there is a foramen called as mandibular foramen, which we discussed, giving passage to the inferior alveolar artery as well as the inferior alveolar nerve will enter through it. Inferior alveolar artery and inferior alveolar nerve.
We discussed the inferior alveolar nerve, branch of mandibular nerve, we'll enter through this only, and then ultimately the nerve will come out from the foramen. On this side you can see that is a mental foramen, that will give passage to the inferior alveolar nerve coming out as mental nerve, inferior alveolar artery as mental artery. And the muscle that you will see present on the ramus of mandible, on the outer aspect, running downward and slightly backward, this muscle, this big muscle here is the masseter muscle. This muscle here is the masseter.
So see, just don't bother about that, just don't mug up the relation, what do you say, the action of these muscles. It's very, very simple. If you look at temporalis muscle, the fibers, look at the vector of the fibers here. The muscle is running downward and it is also running forward.
If any muscle is running downward and forward if a muscle is running downward and forward now look at this Hey, if a muscle goes downward and forward it will elevate the mandible and it will also retract the mandible It will pull the mandible up and it will pull the mandible backward here. That's why the function of temporalis muscle is the retraction in fact, it's the only muscle for the retraction and Elevation retraction and elevation On contrary, lateral pterygoid is muscle which is running backward. So, obviously this muscle is running in this direction, in the backward direction.
So, that muscle when it contracts, if a muscle runs backward, every time this muscle will contract, it will pull the mandible forward. So, this is a muscle for the protraction. It's a main muscle for the protraction. And it is the only muscle for the depression.
depression of the mandible requires a slight protraction also that's a biomechanics of the TMJ so protraction is needed for the depression as well so protraction is the main function of lateral pterygoid and it also helps in the depression depression can be done by the gravity only there is no muscle needed it is like it's just if you just relax the muscle of mastication the automatically mouth will open but the one muscle which helps if the question is asked which muscle of mastication is needed for the depression or lowering the jaw that is lateral pterygoid Medial pterygoid muscle is again it is running downward so when this muscle is running downward it will pull the mandible up so it is another muscle for the elevation. Elevation of mandible or you can say closing of mouth and so is the masseter muscle. Masseter is also running downward the only thing is medial pterygoid is inside and masseter muscle is outside.
So the main function of both masseter and medial pterygoid is what? The elevation of mandible. Sideways movement of the jaw is done by the alternate action. one side medial pterygoid, other side lateral pterygoid, that is a sideways movement.
But when you talk about the unique feature, the new function of these muscles, it's the temporalis muscle, retraction and elevation, lateral pterygoid muscle, protraction and depression. And I very, very strongly feel that if it is an image-based question on the muscle of mastication, the two muscles that you should remember is a temporalis and lateral pterygoid. Lateral pterygoid is asked in aims like twice, and the NEET PG 2019, they gave a coronal section in which the temporalis was marked here. And Looking at their action of these muscles, the uniqueness about this action of these muscles, I believe that even when this question is asked again, they probably will be focusing on the temporalis and lateral pterygoid. If you understood the direction of these muscle fiber, now if I show you the cadaveric image, we can try to justify the muscle on this picture here.
So I just collected few images for you from the atlas. Look at this guys. We can, although the picture initially may look a bit messed up, but we can easily identify these muscles here. Let me start with first image here.
Look, this is a picture on the side of the face. That's how you're looking at here. And in this picture you can see, you can appreciate the nose and the lips part and chin part here. This muscle which is running downward on the outer surface of ramus of mandible Nothing else can be seen. You can see zygomatic process because the muscle take origin from zygomatic process also.
So this muscle is the masseter muscle. Running downward and slightly backward, that's masseter muscle. Very, very strong muscle. When you clench your teeth, that's a muscle you can feel on the outside here.
One important relation if I may tell you here, that anterior inferior angle of meseter, that meseter muscle and just anterior inferior angle of meseter muscle, you can see facial artery present there. That's how the facial artery enters the face from the anterior inferior angle of this meseter muscle. That's external auditory canal, you can see these, some major artery present here, maxillary artery is going inside here and that is superficial temporal artery, that's the maxillary artery. and this one the one which goes above there is a superficial temporal artery the two terminal branches of the external carotid well we are not bothered about it we are looking at the muscle now if i remove the meseter muscle then obviously i'll be able to see the ramus of mandible and that's what you see in the next picture here in this picture you can once the meseter muscle is removed i can see the ramus of mandible and here it was a coronoid process anteriorly and look at this muscle which is coming downward and few fibers are coming forward here what muscle is that that is the temporalis muscle. The muscle which runs downwards and forward toward the coronoid process and that's why the muscle is for elevation and the retraction.
The only muscle for the retraction that is temporalis. So basically we are going from superficial to deep. If a picture is showing the most superficial dissection of the face, the masseter muscle will be seen. Remove the masseter, temporalis will be seen.
Remove the temporalis, lateral pterygoid will be seen. Look at that. Now in this picture, the temporalis muscle is removed. They have cut the coronoid process.
Can you see that? This time the coronoid process is cut here. You can see this, what is a mandible or notch can be seen here. And if this is a neck of mandible here, look at this muscle going backward.
We just discussed, if you see a muscle running in this direction, was it? Yeah. If you see a muscle running backward toward the neck of mandible, that muscle is what?
That's a lateral pterygoid muscle. And that's what it is here. That's the neck of the mandible. Here is the head and the neck of the mandible. And look at this muscle.
We have upper belly and lower belly. There are two bellies actually. There are two, what do you say, the heads of this muscle.
That's the upper head and that's the lower head. But yes, the muscle is what? Lateral pterygoid muscle.
This muscle is lateral pterygoid. It is lateral pterygoid because it is laterally placed inside the in the infratemporal fossa. If I remove the lateral pterygoid muscle, if I cut the fiber of lateral pterygoid muscle, the next muscle I will see here is a medial pterygoid. The deepest muscle that I see is a medial pterygoid and guys medial pterygoid muscle has to come and attach to what to the ramus of mandible on the inner aspect. So that muscle obviously has to come downward.
So if this portion is also dissected and you're seeing the deepest part here with all the branches of maxillary artery and all that here, look at that muscle present deep to it and look at these fibers they're all going downward here. That muscle is the medial pterygoid muscle. I can just pray that examiners not as so cruel to ask the medial pterygoid muscle in this kind of section but yeah even if they do I'm pretty sure they probably will remove these arteries and everything but if you see the ramus of mandible cut you will see some maxillary artery and all you can see that and then you'll see a muscle even deep to all those blood vessels and running downward and backward look at that's coming downward and backward to attach the medial surface of ramus of mandible that's medial pterygoid so masseter temporalis lateral pterygoid and deepest is medial pterygoid here. So even if it is a transverse section or coronal section, at least remember when you see the muscle, what sequence you will see it in. From outside to inside, the four muscles will be in that sequence.
So that is about some... Probably the most most important topic I would say in the head and neck part that you cannot miss. Obviously, it's examiner's choice to ask whatever they want, but these are topics that you should not miss on.