 Good day everybody. This is Dr. Sanjay Sanyal, professor of department chair This is going to be a demonstration of the cervical plexus and the answer cervical is on the right side of the neck This is supine cadaver. We are standing on the right side So we have removed the sternocleidomastoid. This is the sternocleidomastoid We have exposed the lateral cervical region here and the anterior cervical region here This is the infratemporal fossa. We have removed the ramus of the mandible and all other related structures We are showing the contents of the infratemporal fossa and we have removed the clavicle here to show the root of the neck This gives us a clear exposure to show you all the branches of the cervical plexus The root value of cervical plexus is c12345 Now the cervical plexus has got a lateral component And an anterior component The lateral component is the sensory part of the cervical plexus more or less And the anterior component or the medial component is the motor part of the cervical plexus, which is also called the answer cervical S So let's take a look at the root of the cervical plexus first The c1 is very high up. We cannot see but you can see this root here This is the c2 root We can see this This is the c3 root This is the c4 root remember in the cervical region each spinal nerve comes out above the corresponding vertebra Then we have this one here. This is the c5 root Then we have this this is the c6 This is the c7 And down below this is the c8 And further lower down will be the t1 which we cannot see Before I go to come to the cervical plexus. Let me just quickly complete the trunks of the brachal plexus itself because we can see them here So the c5 and the c6 Roots unite to form the upper trunk of the brachal plexus The c7 root continues as the middle trunk of the brachal plexus and we can see that here And the c8 and the t1 form the lower trunk of the brachal plexus So this is the upper trunk the middle trunk of the lower trunk These three trunks of the brachal plexus they come out in this triangular region here Mounted posteriorly by this muscle This is the skeletalus medius And anteriorly by this muscle This is the Skelliness anterior so therefore and lower down is the first rib. So therefore this triangle is called the skeletal triangle So therefore the trunks of the brachal plexus emerge through the skeletal triangle where they can be potentially entrapped To produce what is known as the skeletal syndrome Having mentioned that now let's come back to the cervical plexus itself First of all, I would draw your attention to these inter communications between the roots of the cervical plexus We can see that the c1 c2 root they form a loop Then there's another loop between the c2 c3. There's another loop between the c3 c4 There's another loop between the c4 c5 These are the primary loops of the cervical plexus. This is a very unique feature of the cervical plexus And emerging from the loops we have these branches These are the three branches and I'm going to name them just now one by one and I'm going to mention their distribution So let's start off with the first one We can see this one coming out here This is The lesser occipital nerve It's a small nerve which runs behind the ear And it supplies the region behind this ear Great auricular lesser occipital. This is the lesser occipital nerve Then we have the next branch here This is the great auricular nerve The great auricular nerve runs across the sternocular mastoid. Suppose the sternocular mastoid had been here It runs across like that And then it supplies the skin of the lobule of the ear The lower half anterior surface and a little bit of the posterior surface And then it also supplies the skin over the parotid gland And the septic glands of the parotid gland. This great auricular nerve is a very important nerve This great auricular nerve is quite often endured during parotid surgery and some surgeons actually Cut the great auricular nerve and repair it later during parotid surgery This great auricular nerve injury Is one of the components which contributes to what is known as the auriculotemporal syndrome or the phrase syndrome or the gustatory sweating which is Seen in many cases after parotid surgery. This is a great auricular nerve This great auricular nerve it supplies the sweat glands and that's why we get gustatory sweating This great auricular nerve also carries pain fibers from the parotid sheath So therefore when there's a parotid inflammation the pain is transmitted by the great auricular nerve The next branch that we can see are these branches They go across like this from the lateral cervical region. They go And medially and they supply the skin on the Medial side of the neck as the anterior cervical region. Therefore, this is called the transverse cervical So we have seen great auricular lesser occipital transverse cervical Most textbooks say that they are all c2c3 roots The transverse cervical supplies this region here Then we can see this branch here This is not one actually there are several This is this supraclavicular nerve and we can see several branches here Supraclavicular is c3c4 And this travels by means of several branches Notably a lateral and intermediate And a medial branch it crosses the surface of the clavicle rarely it can go through the clavicle And it supplies the skin of the upper front of the chest This supraclavicular nerve is the one which is responsible for Referred pain to the shoulder when there's a diaphragmatic irritation And I'll tell you why that is just now in a little while This supraclavicular nerve can be injured when there's a fracture of the clavicle This supraclavicular nerve is c3c4 and we can see it is coming out from c3 and c4 The next branch that we can see here is this one here and I'm going to lift up the lower portion of his first This is the phrenic nerve the phrenic nerve is a mixed nerve sensory and motor The root value is c345 and we can see it is getting contribution from c5 It's getting contribution from c4 and higher up it gets comes from c3. So therefore phrenic nerve typically c345 This runs in front of the scalerus anterior muscle and we can clearly see that here And it was under the pre vertebral layer of deep cervical fascia And then we can also see it is going behind the subclavian vein. This is the subclavian vein It goes behind the subclavian vein. It enters into the thorax And then it runs anterior to the pulmonary hyalum. It supplies the pericardial phrenic Fibrous pericardium and goes down and supplies the diaphragm motor fibers and sensory fibers That coming back to this concept of diaphragmatic irritation producing referred pain to the shoulder The root value of phrenic nerve is c345 The root value of supraclavicular nerve is c345. So therefore there is a commonality of root values between the t's too So whenever there is diaphragmatic irritation like for example, you do any collection of fluid or anything under the diaphragm Or cholecystitis The pain fibers, they are referred and they transmitted through the supraclavicular nerve and they produce referred pain to the shoulder Because of the common root value c34 and c34 So that's about the phrenic nerve Now let's take a look at the answer cervicalis or whatever we can see of the answer cervicalis The basically the word answer means a handle This answer cervicalis has got two loops a superior limb and an inferior limb and I will show that to you just now Take a look at this nerve here This is the hypoglossal nerve and we can see one branch is coming out from the hypoglossal nerve This is the superior limb of answer cervicalis The superior limb of answer cervicalis it comes up from the loop of c1 c2 Let me describe the inferior limb first and then we shall talk about the answer cervicalis as a whole This is the inferior limb of answer cervicalis. So therefore to lift up the whole thing This is the superior limb. This is the inferior limb of answer cervicalis The inferior limb of answer cervicalis comes out by means of two roots from c2 and c3 The superior limb which is also called descending hypoglossi and the inferior limb is also called descending cervicalis The two of them go down and they form a loop here, which is called the secondary loop Which is also called the loop of answer cervicalis This answer cervicalis is actually the motor component of the cervical plexus the superior limb and the inferior limb The descending hypoglossi and the descending cervicalis What does this do? Let's come back to the superior limb The superior limb which came from the c1 c2 loop Most of it it runs with the hypoglossal nerve. This is the hypoglossal nerve going into the tongue But it has got nothing to the hypoglossal nerve Most of the fibers they continue down as a superior limb of answer cervicalis and It forms the loop of answer cervicalis, but some of the fibers they continue with the hypoglossal nerve And they supply the geniohyoid muscle in the floor of the mouth And the thyrohyoid muscle from the thyroid to the hyoid. This is the thyrohyoid muscle Some of the fibers from the superior limb they travel back up with the hypoglossal nerve into the posterior cranial fossa And they supply the meninges of the posterior cranial fossa That is c1 c2. That's the reason why when we have an apathology in the posterior cranial fossa It produces referred pain to the back of the head and the back of the neck because of the Fibers from the c1 c2 When we have the complete formation of the loop of answer cervicalis From the loop of answer cervicalis It gives branches to the remaining infrared muscles and the strap muscles of the neck namely the sternohyoid The sternothyroid which is under that The omohyoid. This is the superior belly of omohyid. This is the inferior belly of omohyid So therefore The answer cervicalis the main purpose is to provide motor supply To the strap muscles of the neck. So that is about the answer cervicalis Before I conclude there's one more thing one more point. I wanted to mention to you about the sensory branches of the cervical plexus I have held up all the branches of the cervical plexus here as a bundle Imagine the sternocleomastoid muscle would have been here They would have all emerged from the posterior border of the sternocleomastoid approximately at this region So therefore this region posterior border of the sternocleomastoid is referred to as the nerve point of the neck Because we can theoretically potentially give a nerve block here in this region along the posterior border of the sternocleomastoid To anesthetize these four branches of the cervical plexus namely the great auricular lesser occipital transverse cervical and supraclabicular and therefore we can anesthetize this much portion of the neck Front side and the front of the chest Therefore this is referred to as the nerve point of the neck. We can determine the nerve point of the neck By locating the posterior border of the sternocleomastoid and seeing the midpoint of it approximately here or We can take the an imaginary line from the mastoid process And drop it straight down to the clavicle And taking the midpoint of that that also will give us the nerve point of the neck So these are the points which I wanted to mention to you about the cervical plexus and the cancer cervicalis Thank you very much for watching. Dr. Sanjay Sanyal signing out Solomon's the camera person If you have any questions or comments, please put them in the comment section below. Have a nice day. Please like and subscribe