hello all this is dr alsup and this is our last video concerning the upper limb and we are
finishing with the distal most muscles which are the muscles of the hand specifically the muscles
that will both originate and insert in the hand so not those forearm muscles that extend that way
so we'll talk about two of the compartments that are on the medial and lateral side
and then we'll finish off with some of the smaller sets of muscles the lumbricals and the interossei
okay so two of the larger areas when we're talking about the intrinsic muscles of the hand
are associated on the thenar or the lateral side and the hypothenar or the medial side so athenar
is going to be associated with the first digit and if you look at the palm of your own hand
you'll see that you'll have kind of a bulge of muscle just deep to the skin and you are looking
if you're looking at the thumb region and you're looking at the thenar compartment there
and then on the opposite side on the medial most side you will have the hypothenar compartment
and you can see some of those deeper muscles if you were to reflect some of those so the
opponent's muscles are going to be on the deeper compartments or part of the compartments here
so these will play a role in terms of really um moving a lot of those fine movements associated
with both the first digit and the fifth digit and you can see that both will have these opponents
muscles that'll play a role in terms of opposition which is that compound movement whereby you can
move the first digit kind of close to the fifth digit if you think about an
opposable thumb something unique in terms of uh primates that's what we're talking about there
the thenar muscle or muscles of the thenar compartment are going to be innervated by
the median nerve which is kind of unique in this area because most of the muscles
of the hand of the intrinsic hand will be innervated by the ulnar nerve which is true
of the hypothenar compartment so thenar again is median nerve similar to most of those muscles of
the anterior forearm but the rest are mostly ulnar nerve
now still looking at the palmer anterior view again here is that hype or excuse me here's the
thenar compartment and here is the hypothenar compartment and coming in through the carpal
tunnel recall that we had tendons of the flexor digitorum superficialis as well as the profundus
and so those are heading all the way to the phalanges and attaching
on the flexor digitorum profundus tendons within the hand you're going to have these kind of worm
shaped muscles that are literally attaching to the tendons of flexor digitorum profundus
called the lumbricals and so you're going to have four lumbricals you can see them numbered here
and these will have kind of a separate innervation as well the more medial ones will be innervated by
the ulnar and the more lateral ones will be innervated by the median nerve so
it's only these two lateral most lumbricals as well as the thenar compartment that are innervated
by the median nerve all the rest is ulnar nerve all the rest of the muscles now these muscles
will when they contract will play a role in terms of flexing the mp joints so kind of
think of flexing your mp joints you're kind of putting all your fingers on your palm
and they will also extend the interphalangeal joints and it does this because the tendon of
the lumbricals are going to attach to the extensor expansion which plays a role in terms of extension
of the digits so that is how you're getting that that extension and kind of an opposite
movement from the flexion and it's because of that distal attachment on the extensor expansions
the interossei are going to have similar movements as to what we just described for the lumbricals
in addition to some other ones and you have both dorsal and palmar interossei you have three palmer
interossei which are located on as the name would suggest more of the palmer side or the anterior
side and then you have four dorsal interossei which are located more on the posterior side
and i know in this image it looks a bit like we have a hand and we have finger that is kind
of flipping us off and that is not why the illustrator chose to have it like this it's
because this third digit which you can see extended in these images are is the number
the number digit by which the fingers will abduct an adduct so recall in typical abduction and
adduction i think shoulder joint hip joint that's moving away from the midline and when we think of
midline we're thinking it kind of going right down the thorax but that's not the same for abduction
and adduction when we're talking about the hand or the foot and so they're either moving away from
or towards a certain digit and when we're talking about the hand it will be the third digit
so the palmer interossei will a deduct which means that that would have these other digits
moving towards that third digit whereas the dorsal interossei will a b duct so away from the third
digit okay so and when we talk about this we're specifically talking about digits two through four
recall um that that first digit kind of has its own muscles uh that are going to play a role there
fifth digit as well sometimes you can still see it described as playing a role
for the fifth digit so you have this nice lovely mnemonic here dab and pad so dorsal interossei
a b duct and palmer interossei a d duct so towards or away from that third digit
and like most of the intrinsic muscles of the hand this is going to be innervated by the ulnar nerve
okay so real quick review here what nerves or which nerves or nerve will innervate
the intrinsic hand muscles is it the median nerve is it the median nerve and radial nerve
is it musculocutaneous is it ulnar nerve and medial nerve or just the ulnar nerve
okay so hopefully this kind of just jumps out at you
we kept going over and over again about how the ulnar nerve is one of the main supplies of the
intrinsic hand muscles so i need to hone in on these answer choices that have ulnar nerve in it
if it doesn't have ulnar nerve and it's certainly not right because that's doing the majority
but and i have medial here that would make this wrong i meant to have this be an n but this is
what i was trying to go for here ulnar nerve and median nerve not mediocre you see people say that
incorrectly all the time and here i go saying it incorrectly or typing it incorrectly here
so the correct answer is going to be ulnar nerve and median nerve not medial nerve so
recall that that thenar compartment as well as a few of the lumbricals will be innervated by
the median nerve while all the rest of the intrinsic hand muscles are the ulnar nerve
so this wouldn't be correct either because we don't want to forget that important contribution
uh particularly with the thenar compartment radial nerve no way that's posterior compartments
of the arm and the forearm it will play a role in terms of sensory innervation
of the posterior hand but not in terms of efferent or motor innervation or causing muscle contraction
and the musculocutaneous will be the anterior compartment of the arm so incorrect as well
okay so that wraps us up for the upper limb now we're going to move into our last set of lectures
or sets of lectures which will be focused on the lower limb the great thing about the lower
limb is that a lot of the themes that we've just discussed in terms of the upper limb will apply
to the lower limb so we'll have lumbricals we'll have interossei we'll have phalanges so a lot of
there will be a lot of similarities in that region as well so fun times we're getting into locomotion
i can't wait to get into it and i will see you in the next video thank you for your time