so in terms of the more distal components of the upper limb skeletal muscle let's talk about the
hand and this is a fairly complex muscle there a lot of muscles in this region depending on
but they're more compartmentalized so we'll discuss compartments and hopefully it won't
be too overwhelming so two terms I want you to know right off the bat thenar and hypothenar
thenar is indicating muscles associated with your first digit or the thumb and then hypothenar are
associated with your fifth digit or your pinky finger and really it's important to know the
difference and they have a separate innervation most of the muscles of the hand are going to
be innervated by the ulnar nerve hypothenar is similar to that the thenar compartment has its own
individual own individualized innervation which is your median nerve specifically the recurrent
branch so if you have damage to just the median nerve it's not going to affect most of the muscles
of the hand just associated with your first digit and one thing I want to note here is that we use
the same terms in terms of the actions of the thenar compartment so you use flexion extension
abduction and adduction but the planes by which these movements occur are different than what
we typically think so if we think if we look here if you look at flexion and extension you can see
that if an anatomical position these are going to be moving in the frontal or coronal plane
which is opposite of what it typically does so how I always remember this if you think of
extension I think of loser that's extension of your thenar compartment whereas flexion you're
moving this way with abduction and adduction this is going to be in this sagittal plane and I always
think for abduction if you'd like puppet hands like this I'm ABducting my thenar compartment
and then ADducting is just going back toward towards more anatomical position now one thing
that makes primates unique is the ability of the opposable thumb so the ability to kind
of combine a lot of these movements and specific joints within this region to allow for you to reach
across and be able to pick things up its a big part of being able to pick things up so unique
to primates alright if we reflect those muscles out of the way those more superficial muscles
were getting into the lumbrical muscles and lumbrical muscles are really unique in terms of their
flexor digitorum profundus attachment and you can see in this specific visual here here your
profundus tendons moving into the digit region to attach to your distal phalanges and you have
these worm-like muscles right here that are going to have a proximal attachment to the profundus
tendons and then a distal attachment in order to be able to affect your MP joints which are your
metacarpophalangeal joints it's going to flex these so flexing your knuckles and extend your IP
joints okay so your proximal interphalangeal and your distal interphalangeal deep to the lumbrical
muscles and the deepest muscles of the hand are going to be your interossei muscles and that makes
sense they're going to be in between your ossei or your bones now your dorsal interossei muscles
which are what you can see here are going to allow for you to abduct your digits okay abductor digits
2 through 5 not including 1 whereas your palmar which we don't have a visual of here these are
going to allow for you to ADduct alright now when we're talking about by which plane
or which a digit we're abducting or adducting by this is going to be your third digit okay so
this digit right here that's you're moving away from the third digit or back to the third digit
and similar to most muscles of the hand these are going to be innervated by the ulnar nerve