[Music] hello guys so here in this session we are going to discuss in detail about the gross anatomy of the radial nerve so the radial nerve is the chief nerve of the upper limb along with two other nerves which are ulnar and the median so the radial nerve innervates almost all the muscles of the posterior compartment of the arm and the forearm that is the reason we call it as the nerve of the posterior compartment of the arm and the nerve of the posterior compartment of the forearm so both of these are extensor muscles of the upper limb so if you see the location of the radial nerve in the axilla so we can see so it is pretty much easy to identify in relation to that of the third part of the axillary artery right so we can see the third part of the axillary artery here so at the third part of the axillary artery can you locate the nerves exactly behind the third part of the axillary artery yes and this is also where we can find its associated nerve called as axillary nerve because axillary inner also arises from the posterior cord of the brachial plexus like the radial nerve so radial nerve as well as the axillary nerve originates from the posterior part of the brachial plexus exactly behind the third part of the axillary artery in the axilla this is what is called as origin now let us discuss about the course and its branches so after the origin that is from the posterior chord of the brachial plexus it goes from anterior to posterior via a triangular interval which is bounded by the teres major superiorly and the long head of the triceps medially and the later head of the triceps lateral so from this triangular interval it enters into the posterior aspect and from there it descends in the arm by spiraling around the mid shaft of the humerus in the spiral group so if you remember the osteology of the humerus you might have remembered at the posterior aspect of the humerus what we can appreciate is the spiral groove right so it winds around the posterior aspect of the humerus in the spiral groove which means in the spiral group we have the radial nerve so what are the other structures we can appreciate in the spiral group one of the important verses called as the profanda brachial tree which is also known as the deep branch of the brachial artery so this profanda breakage artery also runs along with the radial nerve through its triangular space and also it continues in the spiral groove that is located at the posterior aspect of the humerus so in the spiral groove we have two important structures one is the radial nerve and another one is the profunda brachii artery so the radial nerve in the arm it supplies lateral medial as well as long head of the triceps now it leaves the spiral groove right we can see the course here very clearly or we can say the radial groove as its distance now the nerve finally emerges at the anterior aspect of the lateral epicondyle of the humerus where it gives off a branch to the brachioradialis and it supplies the brachioradialis muscle which means so here the brachioradialis muscle is supplied by the direct branch of the radial nerve right the branch is given off at the arm so at this particular location the radial nerve also gives off a branch to the anconeus muscle so which is a small vestigial muscle that sits on the posterior aspect of the elbow and abducts the ulna in pronation of the forearm so this anconeus is supplied by the direct branch of the radial nerve so if we talk about the vasculature of the anconeus sometimes it is asked in the exams there's a reason i want to explain that point so anconeus is supplied by the middle collateral artery which is the direct descending branch which is coming from the profandapr artery because this was a previous mcq point there's a reason i have explained this point over here so here it also gives of another branch to the muscle known as extensor carpi radialis longus so brachioradialis extensor carpi radialis longus and corneus as well as the medial and lateral head of the triceps all of these are the branches which are given off before the radial nerve enters into the elbow or the cubital fossa so remember one point here that extensor carpi radialis longus is supplied by the direct branch of the radial nerve because these are the mcq points which we often miss in the exams so now from the anterior aspect of the lateral epicondyle of the humerus you can see the course of the nerve it enters into the anterior aspect of the elbow that is in the cubital fossa so at the level of the elbow that is in the cubital fossa we can see very clearly here the nerve divides into deep as well as superficial branch let us talk about these branches in detail so we can see the deep branch here so the d branch passes into the supinator muscle which means it pierces or passes within the substance of the supinator muscle via radial tunnel which is roofed by the superior border of the supinator called as arcade of frost so what is the arcade of frost it is nothing but a fibrous sheet which is located on the superior border of the supinator which makes a tunnel called as radial tunnel so sometimes it is also called as supinator arch so once it passes through the supinator arch or the orchid of frost once it enter into the substance of the supinator muscle it officially becomes the posterior interosseous nerve which means the deep branch of the radial nerve once it enters into the radial tunnel which is formed at the superior border of the supinator muscle officially becomes the posterior interosseous nerve it is very very important point for us to remember right so the deep branch of the radial nerve entering the substance of the supinator it gives off a branch just before the entering into the supinator muscle itself it gives off a branch to the supinator muscle which means deep branch of the radial nerve is the one which supplies the supinator but not the posterior international right we can see very clearly here so just before the nerve passes within the radial tunnel it has given off a branch to the supinator so that is the reason supinator is supplied by the deep branch of the radial nerve but not by the posterior interactional nor by the main trunk of the radial nerve this is what you have to focus by seeing the picture over here now the posterior intraosseous nerve is formed and this posterior interruptious nerve descends down the posterior compartment of the forearm that is in the facial plane between the superficial and deep muscles of the forearm to supply almost all the muscles of the wrist extensors what are they extends are carpi radialis bravas extensor carpi ulnaris extends are digitorum extents are indices and extends our digitized minimi it also innervates the long-term muscles that is extensor pollicis longus extensor pollicis previous and abidictar pollicis longus and after supplying all these muscles it finally ends as a pseudo ganglion and this pseudo ganglion gives off fibers which gives sensory innervation to the dorsal wrist capsule so which means this posterior intraosseous nerve ends as a pseudoganglion after giving its complete motor innervation to almost all the muscles of the posterior compartment of the forearm so now the deep branch is completed along with the posterior intros now let us talk few points about the superficial branch of the radial nerve here so the superficial branch gives off sensory innervation to the back of the hand let's elaborate this point in much more detail that is sensory innervation so the radial nerve gives off sensory branches all the way along its goals let us see how it gives of sensory nerve supply to the arm forum as well as to the hand so it supplies sensation to the lower outer aspect of the upper arm via the inferior lateral nerve of the arm or we can say the inferior lateral cutaneous nerve of the arm and it also gives of sensory innervation to the posterior aspect of the arm or the posterior surface of the arm by means of posterior cutaneous nerve of the arm it also gives off sensory innervation to the region of the posterior aspect of the forearm via the posterior cutaneous nerve of the forearm and finally the superficial branch of the radial nerve supplies sensation to the thinner eminence and also to the dorsal aspect of the radial three and of digits of the hand so this is what we have to talk about the origin as well as scores and branches of the radial nerve now let us talk about the applied anatomy of the radial nerve so here the radial nerve is vulnerable to the injury in its entire course starting from origin to the termination the injury may be at the level of the axilla or the arm or the forearm or sometimes at the worst so let us talk few points regarding the clinical aspects of the radial nerve injury first is about the injury of the radial nerve in the axilla we generally call it as the saturday night palsy or crutch palsy sometimes we often refer to as the honeymoon palsy right yeah so the radial nerve arises as the terminal branch of the posterior cord of the brachial plexus we know this point and we also know that it sits behind the axillary artery that is third part of the axillary artery in the axilla yes we also know this point so that is the reason it is vulnerable to the compression kind of injuries at this location that is in the axilla that is neuropraxia that is compressive neuropathy can be seen at the level of the axilla let us take some instance if someone is drunk they often rust their armpits on chase and fall asleep or improper crutch use or honeymoon palsy in all these conditions there is injury to the nerve exactly in the axilla the nerve is compressed in the axilla right so because of this what happens is the symptomatology may be seen at the entire level below the level of the lesion so let me give you some of the points regarding the honeymoon policy for example sleeping with the arm draped over a seat especially in the sitting of alcohol or drug intoxication or after sleeping while holding another individual who is exerting pressure on the arm in such condition the pressure on the middle of the upper arm along the course of the radial nerve can cause compressive neuropathy of the radial nerve in the axilla so when they wake up whether maybe it is a saturday night palsy whether maybe because of the honeymoon palsy or maybe because of the long term use of the crutches or the improper use of the crutches they suffer from wrist drop so what is the wrist drop here wrist drop is due to the paralysis or the weakness of the hand and finger extensors that is mainly because of the decreased grip strength and the patient cannot extend their hand at the wrist joint it is completely under flexed position they cannot extend their hand this is called as wrist drop so what they experience in such condition and the radial nerve injury can also be seen when there is a midshaft humeral fracture that is injury of the nerve in the arm so when there is a humeral fracture that is at the midshaft humerus so if you see the mid shaft humerus fracture we already know about the spiral group where we can see the profanda brachiatry as well as the radial nerve both are lying along the spiral groove of the humerus so whenever there's a humeral fracture that can damage so any of the branches of the brachial plexus like agillary radial ulnar muscular cutaneous and median but the most common nerve to be injured in such kind of injuries that is midshaft humeral fracture injuries will be radial because the radial nerve is particularly vulnerable in this condition mainly because it runs in the spiral groove and it is therefore tightly other into the humerus along the majority of its scores in the arm so that is the reason the fracture is therefore highly likely to disrupt the nerve and the symptoms include wrist drop because the wrist extensors are not functioning where they are unable to extend the elbows as the triceps also become diner weighted and there will be a diminished sensation on almost the entire posterior surface of the arm and forearm so this is what is the symptomatology what we can see when there is a midshaft humerus fracture next is about the injury to the radial nerve at the elbow we often call it as radial tunnel syndrome which has anyway a controversial kind of diagnosis so the radial tunnel syndrome may be caused due to a chronic compression within the radial tunnel so this particular condition is characterized by a lateral elbow pain without symptoms of the no fallacy that is weakness sensory deficits or parasthesias so the pain often results from the compression of the posterior interosseous nerve within the radial tunnel we know what is a radial tunnel we already discussed in the course of the radial nerve it is nothing but it is an anatomical space on the lateral aspect of the elbow that extends from the radial height to the distal margin of the supinator muscle so this is about injury to the nerve in the forearm next sometimes the posterior intraces nerve may be injured in the deeper forearm so which is called as posterior intraosseous nerve syndrome so this syndrome is characterized by the weakness of muscles in the extensor compartment of the forearm so more commonly due to fractures of the radial head or chronic soft tissue compression this is called as posterior intraosseous nerve syndrome and coming to the one of the most important clinical scenarios the radial nerve neuropathies will be wartenberg syndrome so we often call it as superficial branch of the radial nerve injury or injury to the radial nerve at the wrist or distal aspect of the forearm which is called as wartenburg syndrome if the wrist is compressed with a tight jewelry over its lateral aspect the superficial branch of the radial nerve will be compressed beneath the tenderness insertion of the brachioradialis muscle so this results in loss of sensation on the dorsal aspect of the radial three end of fingers but there is no motor deficits because the motor branches have all been given off well before the first that is the reason wattenberg syndrome is only associated with the sensory deficits at the posterior aspect of the wrist so here overall we discussed about all the clinical scenarios but the point to be noted here is the higher the lesion which means more proximal the lesion the greater the number of extensor muscles are involved and greater will be the degree of wrist drop so this is about the clinical anatomy of the radial nerve by this we completed the radial nerve its origin course and its branches that is motor and sensory supply and also we discussed in detail about the clinical anatomy