Anatomy Notes 11-9-11

8/3/2019 Anatomy Notes 11-9-11

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Anatomy Lecture 11-9-2011

Important concepts: Lower limb nomenclatureo a number of structures on the hip. the superior iliac crest, anterior inferior iliac

spine, pubic tubercle. we have a ligament spanning those two projections on thepelvis. Top part of the femur is called the greater trochanter and is part of theinferior hips and you have two sets of hips.

o the bone that connects to the pelvis is the femur. Many of the nerves in the lowerextremities will have some type of femur in their names, like femoral nerve forexample.

o Second set of bones to keep in mind, are the tibia and fibula. The tibia is theshinbone below the knee and it is the larger of the two bones more mediallylocated compared to the fibula. The fibula is the lateral part of lower leg and tibiais medial bone of the lower leg.

o At the very inferior end of these bones you have a structure called maleoli ormalleolus (singular). Maleoli refer to ankle bones or projections we think of asankle bones. Each of the legs have two maleoli, they have lateral malleolus anda medial malleolus. Lateral maleoli is a projection of the inferior part of the fibulaso that will be the lateral ankle, and medial part of ankle is the medial malleolus.Medial malleolus is a projection from the medial bone, which is a projection fromthe tibia

o At the base of the foot the heel bone is called the calcaneus. Things associatedwith the heel bone are referred to as calcaneal, which is referring to the heel.

o ankle projections are so important is b/c that is what you need to figure out iflooking anterior view of the leg or posterior view. Usually in the diagrams theankle will be either labeled as lateral or medial malleolus and that can tell you alittle a bit about the image that you are looking at. Also look at wheres your tibiaand fibula to get some sense of direction with the image that you are looking at.

Lower body plexus: Lumbar Plexuso Looking at the waist down. The area right underneath the abd and including the

upper hips, which might be a little, more superior than the abd. Basically startingoff at the lower torso.

o the lower extremities have two bundles of nerves: the lumbar plexus and sacral

plexus.o Of the two plexus structures, the lumbar plexus is more superior and typically

regarded as originating or receiving contributions from sensory spinal nerves T12to L4, start off at the very bottom of the thoracic spine at T12. Concerned with thepelvis, groin, hips and parts of the superior legs, which are structures that thelumbar plexus will innervate.


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Nerves of the Lumbar Plexuso Subcostal nerve

Originates at T12 and provides sensory innervation to the thorax just belowthe rib cage. Subcostal = just below the ribs.

o Iliohypogastric nerve Originates from T12 and L1 Provides sensory innervation regions of tissue just inferior to the region

innervated by the subcostal nerve. It has 2 main branches.

Anterior branch innervates medial structures in the pelvis: the pubicsymphosis that is midline where the 2 pelvic bones come togetherand the anterior branch provides sensory innervation for the anteriorportion of the pelvis.

Lateral cutaneous branch innervates superficial regions of thelateral hip and located around the superior inferior iliac spine. Solateral meaning out on the sides and cutaneous means superficial.Provides sensory innervation to the lateral portion of the hips that are

just a little bit inferior to where the anterior superior inferior iliac spineis located.

o Ilioinguinal nerve Originates at L1, just a little bit inferior to the iliohypogastric nerve. Doesnt

receive a whole lot of information from the thoracic nerves. Just a little bit inferior to the iliohypogastric nerve. Tends to run in close

proximity to the inguinal ligament as its name would suggest. The nerve


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projects from the back where the lumbar plexus is located and it and wrapsaround the hip and follows the inguinal ligament and provides sensoryinnervation to the region that is fairly close in proximity to the genitalia. Soanterior and medial in a region that is fairly close to the anterior branch ofthe ileohypogastric nerve. So the anterior branch of the ileohypogasticnerve and the ilioinguinal nerve both innervate a region in the inferioranterior part of the pelvis in close proximity to the genitals.

Subcostal is most superior of these three nerves. The iliohypogastric nerveis right underneath the subcostal nerve. And the ilioinguinal nerve is a littlemore inferior to the iliohypogastric nerve.

o Genitofemoral nerve

Originates from spinal nerves L1 and L2

Also has a couple of branches :one of the branches in the genital branch andthe other is the femoral branch. Its name suggests it innervates the genitalsand a region that is femoral in nature.

Femoral being close to the femur


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Genitofemoral nerve Originates from the lumbar plexus from the posteriorback and has to wind its way around anteriorly to provide its innervation toboth the genitals and the femoral region. SPLITS close to the lumbarplexus

Comes in from the top of this diagram here from the ant surface (b/c we arelooking from an anterior view), we can see that the femoral branch innervatesthis region that is femoral or its on top of the femur and a very small area thatis high up in the upper leg and is anterior in nature. A very small patch of realestate on the upper part of the ant leg.

The genital branch innervates the genitalia as per the picture. And theiliohypogastric nerve, we said was the more superior of the two similarlynamed nerves (the iliohypogastric and ilioinguinal nerves); will likely providesensory innervation to a point that is more superior than the ilioinguinal nerve.

The region of the anterior pelvis that the iliohypogastric nerve providessensory information for is just a little bit more superior to the inguinalligament. Inferior to that, would be the region of the anterior pelvis that isprovided sensory information from the ilioinguinal nerve, thats going to be

just a little bit lower than the iliohypogastric nerve and we can see the twobranches and one is going to provide sensory information for this blue-green section here which is the anterior medial part of the upper leg andthen also a region that is just a little bit superior to the real estate that isinnervated by the gentiofemoral nerve.


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If we go in order, basically top-to-bottom:

Subcostal

Iliohypogastric

Ilioinguinal

Genitofemoralo Lateral-Femoral Cutaneous Nerve

Originates from Spinal Nerves L2-L3 Is the large nerve highlighted in RED Name suggests that it provides sensory innervation to the lateral part of the

superficial femur area/anterior portion of upper leg/a little bit out to side,because its lateral, femoral, and cutaneous in nature.

Here is a better view of where the nerve originates/comes from and whereit terminates in the femoral region. It looks fairly superficial because itscutaneous. If we are looking at someones right leg, the nerve would be alateral nerve not a medial nerve. Of course if we do look at the dermatomesections here, we see that the lateral femoral cutaneous nerve provides

sensory innervation to the anterior lateral part of the femoral region. In thislight brown area here (shaded in red.

All images below are for the Lateral-Femoral Cutaneous Nerve


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o Obturator Nerveo Originates from spinal nerves L2-L4o Branches off three spinal nerves from the lumbar plexus and descends

inferiorly through the pelvis and through an opening called the Obturatorforamen. We have our pelvis here, and these notches are where the femurhead fits in here the divot here is called the acetabulum. Right next to theacetabulum, there is a foramen here where very large blood vessels run inaddition to some ligaments, but the main nerve the passes through thatopening is the Obturator nerve and this is the Obturator foramen.

o As far as sensory make up is concerned, it doesnt really innervate a whole lotof real estate. It innervates just a small piece of the femoral part of the leg,

just superior to the knee in a region that is superficial and medial. This leg we


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are looking at here would have to be a view of the medial right leg. TheObturator Nerve provides sensory innervation for just a small chunk of realestate in the upper medial part of the leg, we would say this is a femoralregion because its located on a part of the leg that has the femur in it.

o If youre doing a knee replacement with a regional block, youre definitelygoing to have to knock out the Obturator nerve, because that is in fairly closeproximity to the area the surgeon will be working on. Its small in the area it

provides sensory innervation for, but none the less its important for lowerextremity procedures especially concerning the knee

o Femoral Nerveo The last branch of the lumbar plexus is the femoral nerveo Originates from SN L2-L4o Like a number of the more superior nerves it has two branches: the anterior

cutaneous branch and the saphenous branch The anterior cutaneous branch of the femoral nerve its name would

suggest that it provides sensory innervation to the anterior femoral

region, so the upper part of the leg on the anterior side. In that it mightbe somewhat superficial in nature. It may innervate things that aredeep, but if you are looking where sensory information is coming from,most of it is going to be relayed by the anterior cutaneous branches ofthe femoral nerve if you are applying some type of pressure/stimuli tothe anterior part of the upper leg.

The Saphenous branch covers a region that goes below the knee(inferior to the knee). The saphenous branch of the femoral nervetends to provide sensory innervation to the medial knee area andalso extending into the lower half of the leg (below the knee) onthe anterior medial side of the lower leg depicted in purple here,and now highlighted in red. The saphenous nerve is in closeproximity to the saphenous vein. This can be used for bypasssurgery. Some blood vessels in the leg, if theyre taking thesaphenous vein, it is a fairly disposable vein and that is the areatheyre taking veins from in cardiac surgery.


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Obturator Foramen:

o So, these are the terminal branches of the lumbar plexus. Or at least, I dont think itsnearly as bad as the brachial plexus, maybe a little worse than the cervical plexus.

Sacral Plexuso Next structure down from lumbar plexus is the sacral plexus and in most literature, the

sacral plexus is originating from spinal nerves L4-S3o A structure associated with the sacral plexus is the lumbosacral trunko Lumbosacral trunk

o Spinal nerves derive from L4-L5o Dont need to know function, be aware that it refers to a collection of nerves

somewhere in between the lumbar plexus and the sacral plexus there is a bundleof nerves called the lumbosacral trunk. Testing not ask anything about


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lumbosacral trunk, just know that its a structure that is located in the lower bodyneuro anatomy; our book doesnt have a good picture depicting where that is.

o First nerve superior gluteal nerve o Originates from L4, L5, S1 (dont have to know for class)o Name would imply that it provides sensory innervation of the upper regions of the

gluteus maximus muscleo Inferior to the superior gluteal nerve is the inferior gluteal nerve.

o Inferior gluteal nerve o Originates from L4, L5, S1 (dont have to know for class)o Name would suggest it provides sensory innervation to the lower parts of the

gluteal muscle.o In this picture (gluteal region innervation) they are showing the innervation of the

gluteal region and showing the inferior gluteal nerve. The superior gluteal nerveis in close proximity to the inferior gluteal nerve and of course thats going toprovide sensory innervation to the posterior muscle you all sit on.

o For the gluteal nerves, for our class you dont have to know the origin, just be

aware that they are part of the sacral plexus and they provide sensoryinnervation to the back side.o Sciatic Nerve

o Main nerve that provides sensory innervation for part of the leg, below the knee.o When we were talking about the lumbar plexus and the femoral nerve, we said

the saphenous portion innervated a small section of the lower leg, this smallsection is innervated by a part of the lumbar plexus, all the rest of the lower leg isinnervated by the sciatic nerve of the sacral plexus.

o The sciatic nerve is very large as the picture suggestso It originates from L4-S3 (entire sacral plexus)o Two branches: Tibial nerve and the Fibular nerveo We have two bones that make up our lower leg: tibia and fibula, and we have two

nerves that provide sensory innervation to the bulk of the lower leg; theyrenamed Tibial nerve and fibular nerves. These bones are represented in theneurovasculature by the two divisions of the sciatic nerve.

o In the drawing of the sacral plexus it shows that the sciatic nerve has twodifferent parts: Green part and blue part representative the two main divisions.

o The Tibial nerve Receives sensory innervation from spinal nerves L4-S3

o The Fibular Nerve Receives sensory innervation from spinal nerves L4-S2


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o If we look at where the two branch points are of the sciatic nerve; this is a view ofthe posterior knee after youve taken off a couple of layers of connectivetissue/muscles

o At the very top of this we have the sciatic nerve thats coming down from sacralplexus and it branches into a Y here. One of the branches is the Tibial nerveand the other branch is the fibular nerve. If we were to look a little bit closer wecan see the branches of the sciatic nerve. We can see here that if this is two

branches of the sciatic nerve, one is definitely bigger than the other. The largernerve is the Tibial nerve and the smaller nerve is the fibular nerve.

o The Tibial nerve is a little bigger than the fibular nerve. The bigger of the twonerves looks to me like its staying midline with the large artery and large vein, thesmaller of the two (fibular nerve) is branching off to the side. The side in the legthat the fibular nerve is branching to is the lateral side, and the lateral side of thelower leg is where you have the fibula. It branches off to the side of the lower legwhere the fibula is located. Thats where it gets its name, it tends to run a little bitlateral and in the leg, lateral lower leg is where the fibula is.

o It would make sense if we look at the origins of these two divisions of these twobranches of the sciatic nerve the bigger nerve will originate from more spinalnerves than the smaller nerve. The Tibial nerve is bigger and it would makesense that it comes from more spinal nerves than the smaller branch of thesciatic nerve.

o We can see the division between the two main branches of sciatic nerve. Thosebranches have multiple branch points from the first main branch point

o The fibular nerve o Three Main branches:

Lateral Sural Cutaneous Nerve

Superficial Fibular Nerve Deep Fibular Nerve

o What Id like to do is to draw a schematic here to look at the sciatic nerve.The reason I want to do is this is because even though I know what Imdoing with the anatomy, nonetheless it took me a fairly long time to puttogether these collections of slides. Theyre out of order and there are anumber of errors in the nomenclature in the atlas and the errors are slight,but theyre just enough to give you a hard time if you dig into the materialheavily, here is one error in the atlas I wanted to point out to you, bottom of

p.441 in the atlaso At the bottom here, they have a branch of the sciatic nerve that called

medial Sural cutaneous nerve. They showed it here as projection ofcommon fibular nerve, so what they referring here is the fibular division ofsciatic nerve. The medial Sural cutaneous nerve actually originates fromthe other division of the sciatic nerve which is the tibia nerve. There arecouple place where the nomenclature is a little bit not the best. So in orderto simplified things, sometimes its nicer to take a step back to draw asimple chart.


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o The Diagram of the Fibular Nerve o The start point is sciatic nerve and it got 2 parts to it: one of them is tibia

nerve, the other one is fibular nerve. We will say the red one is fibularnerve, the black one is tibia nerve. So these are the 2 main branches ofthe sciatic nerve.

o So off the fibular nerve, there are number of branches comes of it. One of the first branch come of the fibular nerve is a branch called

lateral Sural cutaneous nerve. So the lateral Sural cutaneousnerve is a branch of the fibular nerve

Fibular nerve cont. descending inferiorly, and there are other

divisions later then lateral sural cutaneous nerve. The next branchpoint of the fibular nerve is called the superficial fibular nerve.

Fibular nerve keep descending inferiorly, and at some point, thereare really not many further main branching, so the last point of thefibular nerve, for our purposes, we can call that deep fibularnerve.

o So we have the fibular nerve coming out the sciatic nerve, there arebasically 3 parts to the fibular nerve. Got lateral Sural cutaneous nerve,superficial fibular nerve and deep fibular nerve.

o So those are the 3 branches here, lateral Sural cutaneous nerve,superficial fibular nerve, and deep fibular nerve.

o So after coming back, before the break, we were talking about branchesof fibular nerve. And we said there were 3 branches.

o This is the image in the PowerPoint slide. But it would be nice we canzoom in and out on it. So we said on previous slide, where we can seethe split or fork of the 2 divisions of sciatic nerve. We said the fibulardivision run lateral and run along where the fibular is, is located in thelower leg. So for saying that, the fibular nerve run laterally at leastcompare to the Tibial nerve. Then it would make sense to be on the


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lateral side of the lower leg. And that is where at least a big chunk of thatnerve is located.

o So this would a diagram of the lower leg, and its telling us its the rightleg. We are looking at lateral side of it. Like I said, the first thing I look foris which malleolus we are looking at, are we looking at lateral or medialmalleolus .so this tells us if we are looking at the lateral side of the legor medial side of the leg.

o So I know I am looking at the lateral side of the lower leg. And at the top,we have the common fibular nerve. Which is another term of regularfibular nerve for shot. And we have 3 branch of that:


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o One of them is lateral sural cutaneous nerve. It branch off fairly early partof the fibular nerve. And lateral sural cutaneous nerve going to providesensory innervation to lateral part of the lower leg. There where lateralsural cutaneous nerve comes in to place

o If we go back to the flowchart, have the fibular nerve, and the first branch islateral sural cutaneous nerve. Then the fibular nerve cont until there is

another branch point, the superficial fibular nerve, the second one we arelooking for here.o The superficial fibular nerve branch of the common fibular nerve right here,

just little below the knee. Superficial fibular nerve going to be fairlysuperficial in nature, close to the surface. And we can see that it run downthe lateral side of the leg, and again, its fairly superficial, we dont havemuch lot of muscle peel back off this image. We can see superficial fibularnerve cont down on top of the foot, we have our cutaneous nerve that areon top part of your feet. Like in region where your feet get sun burn reallybad, the superficial fibular nerve is the nerve picking up on that.

o So the superficial fibular nerve runs fairly superficial, along the side of theleg, and branch out to take care lots of the sensory innervation from the topof the foot. And if we look at a different perspective. So it will be right limb,right leg. And we are looking at anterior part of the right leg, the land markis medial malleolus, at lateral side, we have the lateral malleolus. We cansee that superficial fibular nerve, again, run lateral side of the lower leg,and it cont and branches to provide innervation for the top of the foot. Andthis is a fairly superficial view of the top of the foot. We are not looking allthat deep, maybe just a liitle underneath the skin.

o So these nerves are running on much ofthe superficial part of the foot, those arebranches of superficial fibular nerve.

o So, what about the last division of thefibular nerve? We still have to cover thedeep fibular nerve. Coming back to thelateral view of the right leg, said there thesuperficial fibular nerve. It run fairlysuperficial, lateral side of the leg. The


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remaining part of the fibular nerve is then called deep fibular nerve. Thedeep fibular nerve is more deep into the tissue compare with superficialfibular nerve. And again, run outside of the leg, but fairly deep, and coverby a lot of the muscles in this diagram. So its deep and not well visible.Where it is visible is back to anterior view of the right leg. We havesuperficial fibular nerve running outside of the leg, and if we take themuscle and pull them apart, underneath them, will able to see deep fibular

nerve. It run deep along the front part of the leg, cover by lots of muscles.The deep fibular nerve cont down into the foot. The vast majority of thesuperficial top of the foot is innervated by superficial fibular nerve. Thedeep fibular nerve is difficult to see where it terminate in the foot orinnervate the foot.


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o But if we peel back some of the tendons and BV and nerves, look deep atthe tissue that is just a little interior deep to the previous pic here. Here, wecan see all the ligament has been cut, and now we are looking at a deeper

image here. If we peel back the superficial fibular nerve and all theconnective tissue, we can see that the deep fibular nerve run underneathall of that stuff. And the deep fibular nerve runs deep. From the pic, itseems like it provide sensory innervation to the big toe and second toe. Sothe deep fibular nerve is best known for its role to provide sensoryinnervation deep between first 2 toes. So there is a little section here of adermatone between first 2 toes, that is innervated by the deep fibularnerve.

o So the superficial fibular nerve provide sensory innervation to the vastmajority of the top of the foot with exception between first 2 toes. Between

first 2 toes is innervated by deep fibular nerve.

o If we look at the dermatome pic of the leg. We can see where the fibularnerve innervate at the lower part of the leg. So this is the anterior part ofthe lower leg below the knee. We can see the branches of common fibularnerve, they innervate 3 different color section here.

o There is a gray section (that would be the lateral part of the lower leg. It isinnervated by lateral sural cutaneous nerve)

o the brown area in the diagram, it include most of the top of the food. Wejust said that most top of the foot is innervated by sensory neurons that arepart of superficial fibular nerve

o the third part of leg dermatome we have to account for is that small sectionbetween the first 2 toes of the foot, between big toe and second toe. region in green innervated by deep fibular nerve

o so out flowchart here, help kind of break up the fibular nerve intomanageable segments, and we can explain what part of the lower leg havesensory innervation from those branches of fibular nerve.


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The Tibial Nerve o The other half of the sciatic nerve we have to deal with is Tibial nerve.o The Tibial nerve has 3 main branches that I like you to focus on:

o The medial sural cutaneous nerve

o Sural nerve

o

Plantar nerveso


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o Tibial Nerve Continued o The best way to approach this is to take another swing like we did for the fibular

nerve, the tibial nerve, again thats the second branch of the sciatic nerve.o One of the branches of the tibial nerve is the medial sural cutaneous nerve. So well

say that thats the first main branch point off the tibial nerve and tibial nerve inferiorto that branch point is sometimes referred to as the sural nerve. So some books willdepict that theres a separate branch point for the sural nerve some other texts willsay or suggest that the tibial nerve is fairly continuous with the sural nerve.

o So for our purposes just note that the sural nerve is the lower part of the tibial nervemost likely inferior to the medial sural cutaneous nerve, and then at the very bottomof the tibial nerve we have our plantar nerves, we have one medial and one lateralplantar nerve. Okay and we have one medial and one lateral on each side of thebody. So thats not too bad.

o So if we come back again to look at that view of the lateral leg, so we had justdiscussed the branches of the fibular nerve and so now were looking at branches of

the tibial nerve, the largest of those two that make up the fork.o Alright, if we look at a larger depiction of whats going on in the leg here we see that

the tibial nerve runs along the posterior side of the leg and it runs fairly deep. Heretheyve cut away both the soleus muscle and the gastrocnemius muscle so this isreally deep into the leg; its almost all the way to the bone. So we can see the tibialnerve after the branch point where the fibular nerve breaks off and then here we cansee a number of the divisions of the tibial nerve.


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o So we have our medial sural cutaneous nerve that branches off the tibial nerve at afairly superior part. And we said that as the tibial nerve descends and a branch of itthat runs along the back of the leg is typically called the sural nerve.

o In this depiction here the tibial nerve will have to be deep to the sural nerve becausehere we can see (pauses.)so I know we just said that the sural nerve was thepoint of origin between the lateral and medial plantar nerves.

o The other way of looking at the system here is to say that the sural nerve is a

completely different branch point of the tibial nerve that can run parallel to the moredeep tibial nerve the way we depicted this is a little more simplistic than thediagrams that I have to work with in the book.

o So weve got the tibial nerve, weve got the main branch points thats fairly superiorto that would be the medial sural cutaneous nerve and then lower than that is thesural nerve, then beyond that we really cant see more of whats s going on in thefoot because were looking at a superficial view that shows the medial suralcutaneous nerve and below that we have the sural nerve And below that we reallycant see much of whats going on with the foot because were looking a superficial

picture.


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o If we come back to this pic here we can see a bit more detail about whats going on,whats not visible in this view would be the large part of the tibial nerve b/c we saidthat its deep to a lot of these muscle.

o Here is the gastrocnemius muscle that is on the back of your lower leg and heresthe soleus muscle, on the image that we were just looking at we show a lot of thosemuscles resected and cut away if we look at one with muscles it going to be hard tosee the underlying structures but what we can see is the (pauses)we can seesural nerve and the medial sural cutaneous nerve.

o The medial sural cutaneous nerve looks like it provides sensory innervation for theback of the lower leg; one of the features of the medial sural cutaneous nerve is thatit provides sensory innervation to the lower leg around the gastrocnemius, the suralnerve then provides sensory innervation to the region of the lower leg inferior to thegastrocnemius muscle.

o So we described some of the innervation of the top of the foot that we said wascoming from the superficial fibular nerve but what weve left out here is what aboutthe side of the footwhat about the side of the foot, this is the lateral foot and itlooks like a diff nerve innervating the side of the foot than that innervating the top ofthe foot.


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o The nerve that innervates the side of the foot, including the lateral malleolus, is thesural nerve. So the sural nerve provides sensory innervation to the lateral lowerparts of the lower leg. So thats a superficial view of the lateral side of the leg.

o And if we look at the bottom of the foot now, so before the image was of the top ofthe foot, here if we look at the bottom of the foot we can see the region of thebottom of the foot thats innervated by the plantar nerve.

o So here were looking at the bottom of the foot and on the bottom of the foot wehave the medial plantar nerve which provided innervation to the medial side of thefoot and then the second division of the plantar nerve innervates the lateral part ofthe foot.

o Basically what Im trying to highlight in green here. So, Medial foot, medial planternerve; lateral foot, lateral plantar nerve. The origin of the plantar nerves is the tibialnerve. I know that we depicted it a couple of different ways in our drawings; wesuggested that the sural nerve could divide into both the medial and plantar nervesor the sural nerve might be a division of the tibial nerve in and of itself and then the

tibial nerve later itself then divides into both branches of the plantar nerves. Either ofthose schemas will work for us as the exam.o The origin is the tibial nerve, you definitely need to know that and you definitely

need to know where the medial cutaneous nerve and the sural nerve providesensory innervation. We said the sural nerve is the lateral part of the foot includingthe lateral ankles. The medial sural cutaneous nerve we said was around the regionof the lower leg, probably the back part of the calf containing the gastrocnemiusmuscle.


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The origin of the plantar nerves is the tibial nerve.

Sural nerve can dividie both the medial or lateral nerve or sural nerve is a division ofthe tibial nerve in itself and then the tibial nerve later on then divides to the branchesof medial or lateral plantar nerve. The origin is the tibial nerve. We need to knowthe medial sural cutaneous nerve and the sural nerve where they provide sensory

information. The sural nerve provides sensory information to lateral foot including lateral ankle.

The medial sural cutaneous nerve is around the region of the lower leg, includingthe back part where it contains the gastrectemious muscle, the back part of the calf.

The dermatome diagram, here we dont have a whole lot of territory on the anteriorpart of the leg left to explain. We already explained sensory innervation for anteriorpart of the leg.

To give more details about the lateral part of the foot, top part of the foot and lateralankle, lateral ankle is cut off between sural nerve and fibular nerve sensory. To be


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anatomically correct, we will have to add a small slice of the lateral top of the footreceiving sensory innervation from the sural nerve. Thats the only part of theanterior part of the lower leg that is innervated by branches of the tibial nerve. If weflip the leg over and look at the posterior part of the leg including the bottom of thefoot, we can see what the tibial nerve innervates.

In this diagram, the upper region colored in yellow, that is the back part of the lowerleg and the back part of the calf and the big muscle running in the back part of thecalf is the gastrocnemius muscle and that is provided sensory information by themedial sural cutaneous nerve. The outside of the lateral ankle, that is innervated bythe sural nerve and then the base of the foot, the sensory innervation is via thebranch of the tibial nerve called the plantar nerve. There are two parts to the plantarnerve: the medial and lateral. The base of the foot, the lateral ankle and the middleof the calf is primarily innervated via sensory fibers that come from the tibial nerve.

Nomenclature sometimes call the tibial nerve is called the sural nerve below the

knee.

The plantar nerves comes off the tibial nerve is best nomenclature discussed in

class.

Sural comes off the fibular nerve, the tibial nerve. The word sural is used loosely in

the lower extremities. It usually refers to the lower leg. It is a general word attached

to nerves in the lower leg.

Posterior femoral cutaneous nerve: arises from spinal nerve S1, S2, S3. It derivessolely from sacral spinal nerve. Its name imply that it providesinnervation to the posterior femoral region, so posterior part ofthe leg and somewhat superficial in nature. Posterior part of the

leg is called the hamstring. The posterior femoral cutaneousnerve provides sensory innervation to the hamstring or the backof the upper leg.

last nerve that comesoff the sacral plexus is thepudendal nerve and itoriginates from, all sacral spinal nerves, its regarded ascoming from S2 and S4 and

the pudendal nerve innervates part of the lowerpelvis. It comes from the sacral plexus andwinds its way through the pelvic cavity aroundthe back, and back towards the front, moreanterior portion of the pelvis. It provides sensory and motor innervation to thenumber of things in the pelvis. It branches in 2 different parts: perineal and therectal branch. The perineal branch of the pudendal nerve innervates number ofstructures and many of them are reproductive structures.


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robotic assisted surgery. Robot assisting surgeons tend to cut down problems with

neural lesions during the procedure.

posterior view of the region just posterior to the pelvis.The gluteal muscle has been sectioned and pulledaway from body. Looking at the area of interest rightunderneath the gluteal muscle, we can see a largenerve coming down w/c is called the sciatic nerve.There are 2 smaller nerves that originate just medial tohe sciatic nerve which are the 2 lower branches of thesacral plexus. The 2 lower branches of the sacralplexus: pudendal nerve, posterior femoral cutaneous nerve. These 2 nerves are visible

rom a posterior deep section view. They are underneath the gluteal muscle and justmedial to the sciatic nerve.

The concept of femoral triangle: anatomical term used to describe a region of tissue justnferior to the inguinal ligament.

A region of tissue between the inguinal ligament and Sartorius muscle (straplike

muscle that runs in an angle b/w superior

anterior iliac spine and the medial knee)

Looking just superior to Sartorius and inferior tothe inguinal ligament is the femoral triangle which

can be an accent point to the artery, nerve and

the vein.

Looking at anatomy, as you go from medial to

lateral, blood vessels and nerves are going to be

the same in this region.


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The most medial of the 3 is the femoral vein, lateral to femoral vein is the femoral

artery, lateral to femoral artery is the femoral nerve.

The femoral triangle is consists of 3 main things: femoral nerve, femoral artery, and

femoral vein.

Know where the nerve in respect to those 2 structures. To figure out where nerve

is, take pulse to that region and move a cm or 2 cm lateral to the pulse is where the

nerve is going to be. Pulse is used as a landmark to locate the nerve or the vein in

that region.

Anatomy Notes 11-9-11

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Transcript of Anatomy Notes 11-9-11