this video was sponsored by kenhub more on them at the end of the video hello and welcome my name is
patrick and in this video i'll teach you some of my tips and tricks for remembering all the
skeletal muscles of the upper limb that you would see in an anatomy class and to make this lesson
more manageable for beginners i'll present the list in smaller chunks of 4 to 8 muscles
you can find a list of the sections and the time stamps in the description below and with that
out of the way let's get into the muscles a few of the muscles that control movement of the arm start
all the way back on the spine so for our first chunk we'll talk about the muscles that people
usually refer to when they say it's back day the trapezius is this big muscle that inserts on the
scapula and clavicle but originates all the way from the base of the skull to the lowest thoracic
vertebrae sometimes you'll see this described especially in the fitness world as the upper
middle and lower trap muscles but it's important to remember that they all make up a single muscle
different sections of it just have different angles of fibers so this one muscle can move the
shoulder in multiple ways but it's still a single muscle the easiest way to remember this one is by
looking at both sides of the muscle together it looks like a trapezoid which gives it its
name trapezius the other big superficial muscle is the latissimus dorsi often just referred to as the
lats it's the widest muscle in the body spanning from shoulder to shoulder and from the thoracic
vertebrae down to the bottom of the sacrum and all of those fibers meet up to insert on the humerus
if the lat's name doesn't stick for you then you can use the latin naming conventions of this
muscle latissimus refers to how lateral these muscles are and dorsi refers to its location
on the back just like the dorsal fin of a dolphin if we cut away the superficial trapezius muscles
we'd see three more muscles that originate on the spine and move the shoulder blade the
rhomboid major and rhomboid minor both originate on the spine and insert on the scapula helping
us retract our shoulder blades and maintain good posture the rhomboid major is rhomboid shaped as
the name implies but the rhomboid minor is really more cylindrical in real life my tip for this
one is to identify rhomboid major first then look right above it for its little buddy rhomboid minor
also people tend to mix up the rhomboid major and the serratus posterior superior muscle yeah
they're in similar spots but the rhomboid is more superficial while the sps is deep the other big
cue is the shape the rhomboid has those straight geometric edges while the serratus has serrated or
jagged attachment finally a muscle we talked about in the neck unit the levator scapulae which does
exactly what you think it elevates the scapula but be careful there are lots of neck muscles in this
area that run superior to inferior the levator scapulae will be the only one that attaches
vertebrae way high in the neck to the top of the scapula the next chunk includes the muscles of the
chest and you probably know the root for this one already pectoralis the big familiar one on top is
the pectoralis major literally meaning big chest muscle but underneath that is the pectoralis minor
it follows a similar path to the pec major but doesn't extend all the way to the sternum and
is clearly much smaller hence pec minor as we move inferiorly we see this cool looking muscle
called the serratus anterior named so because its jagged pattern makes it look serrated or
sawtooth like a bread knife for those who like to find these muscles with touch you can feel both
your pec major and your serratus interior contract when you punch forward with a straight arm
your pec is easy to feel but you may have to press a little harder near your armpits to feel your sa
finally the intercostal muscles are between each rib costal is the latin root for rib so
intercostal literally translates to between the ribs see this video if you want a little more
info on those the next big chunk is the shoulder joint most of the muscles that move the joint
made of the glenoid fossa and the head of the humerus the glenohumeral joint the biggest and
most superficial is the deltoid named because it looks like the greek letter delta a triangle once
you peel away the deltoid you'll find the four muscles of the rotator cuff what i learned as the
sits muscles the first three the s-i and t can be easily found on the posterior side of the scapula
and use the big bony landmarks to find their name the supraspinatus is superior to the spine
of the scapula while the infraspinatus is inferior to the spine of the scapula
meanwhile the teres minor makes an angle with each humerus that looks kind of like an m for teres
minor finally the subscapularis the s in the sitz groups literally means under the scapula if you
think of the scapula like a rock you could pick it up turn it over and if you looked under the rock
that's where this muscle would be the last muscle of the shoulder chunk is the teres major which
takes a similar path to the teres minor but as the name implies something about it is bigger
and actually i don't bother looking at its size i look at its position it originates further down
the scapula and further down the humerus which means that this thing has some leverage that
the teres minor doesn't have in fact the teres major is more like the powerful latissimus dorsi
your pull-up muscle than it is like a rotator cuff muscle so the teres major is a major mover of the
arm the muscles of the upper arm are a crash course in latin names and as long as you know
the regional term brachii for upper arm everything else is intuitive you probably already know the
biceps brachii the two-headed muscle of the upper arm and the triceps brachii the three-headed
muscle we got brachii to denote the upper arm and the by and try to denote the number of heads
or seps the coracobrachialis straight up tells you what it does it attaches the coracoid process of
the shoulder blade to the upper arm likewise the brachioradialis connects the humerus the upper
arm bone to the radius there's also the brachialis the stubbiest of elbow flexors honestly i just use
the process of elimination to remember this one the biceps and brachioradialis had more intuitive
names so the last upper arm muscle has to be the brachialis finally there's a small muscle on the
back side of the arm that extends the elbow a little bit it's called the anconeus it's not
as powerful as the tricep so it's a wee accessory muscle at this point i remember this one because
if you make a cone out of your arm the very tip is the anconeus i hope you enjoyed the simplicity
in this chunk because the next two are uh more involved you could say like look at this forearm
all of our human hand dexterity comes at the price of having a lot of tiny muscles and anatomists
didn't want to give them all fun whimsical names they get names like the flexor carpi radialis
what's it do it flexes the carpi or hand and it's on the side nearest your radius the flexor carpi
ulnaris it does the same thing but on your ulnar side anatomists gave them intuitive names but that
concentrates a lot of multi-syllable muscle names into the forearm take the palmaris longus a small
muscle with a long tendon that inserts at the base of the palm for that palmaris part fun fact
quite a few people don't have this muscle on one of their two hands and some people don't have it
at all i made a video all about that which you can check out here the pronator teres has a long but
straightforward action name it pronates the arm pivoting your hand down you can actually palpate
it easily if you put your finger in front of your medial epicondyle and pronate your hand the other
pronator is a square-shaped muscle all the way down at your wrist its action pronation and
square shape quadratus give us the name pronator quadratus these other muscles also use action
plus anatomical region like the flexor digitorum superficialis it flexes the digitorum or fingers
primarily at the proximal interphalangeal joint this knuckle closest to your wrist here you have
plenty of other muscles to flex and extend the small interphalangeal joints but we'll get to
those later now as the name implies if there's a superficial then there's a deep or what anatomists
call profundus when we're talking about hand muscles so the flexor digitorum profundus is also
a finger flexor but it's deep to the superficial version finally there's a special latin root for
thumb it's called pollux so the flexor pollicis longus is a long muscle that bends the thumb
considering how important it is to be able to bend your thumb to grip anything it makes sense that
this muscle would have such a big muscle belly now just like the anterior forearm the posterior
side has superficial and deep sections luckily they follow the same predictable naming patterns
we'll start from the outside in the anterior arm had all the flexors so the posterior side has all
the extensors most of the time that leaves us with mirror opposites like the extensor carpi ulnaris
which follows the same convention it extends the wrist joint and inserts on the ulnar side
or the extensor carpi radialis longus same thing it extends the wrist and inserts on the radial
side and while this one is a longus there's also an extensor carpe radialis brevis that follows
the same rules it's just shorter this muscle is the extensor digitorum which extends the fingers
it's got a big muscle belly on the forearm and inserts on the dorsal side of the hand
likewise the extensor digiti minimi extends a finger but adorably only the tiniest most
minimal finger the pinky and you can feel all of these too if you put your arm down on the table
you'll feel the different muscles pop up for the whole hand or just the fingers or just the pinky
it's a great technique to come back to if you're ever lost on a test when we go a little deeper we
see more action-specific names and the pinky isn't the only finger with its own dedicated muscle the
extensor indices starts on the ulnar side of the forearm and is solely responsible for extending
the index finger or forefinger then there's the thumb again if you spread out your fingers you'll
notice a bunch of tendons around the thumb which are sometimes called the anatomical snuff box
because you could put some cocaine there and snuff it a lot clive owen's character in the
nick but there's an anatomic significance too this snuff box is made of the tendons
that extend and abduct the thumb and these long tendonous muscles originate on the forearm itself
those muscles are the abductor pollicus longus extensor polycast longus and extensor polycus
brevis and you'll notice that these muscles insert at different points on the thumb which helps us
identify them the abductor inserts on the thumb's metacarpal and has this almost diagonal pull to it
whereas the extensors both longus and brevis cross over the top of the carpe metacarpal joint at the
base of the thumb the abductor pulls sideways the extensors pull up from there the difference
between extensor policus longus and brevis is just the size finally we already saw the pronator
muscles on the anterior forearm so the muscle that performs the opposite motion must be on
the posterior forearm and it is the supinator muscle is found all the way up at the elbow
sprawling across the ulna radius and a bit of the humerus too here's how i remember this one
all of the other muscles of the forearm control the hand and you can tell because they have long
tendons that insert at the hand but the supinator only really interacts with the two forearm bones
so supination is the only thing that it can do the next chunk is the thenar mass a group of
four short muscles that make up the fleshy mass of your palm collectively they're special muscles
that move the thumb and their names reflect that because the muscles are named after their actions
my biggest advice is to know your movement terms and look at the angle of pull the flexor policus
brevis originates at some of the carpal bones and inserts on the first phalanx and thumb flexion
looks similar to thumb opposition bringing the thumb and pinky together because of that
relationship the muscle responsible for opposition is called the opponent's pollicis and is directly
underneath the flexor in reality both of these muscles work together when curling the thumb like
during writing so it's hard to say that like this muscle just does this action the next muscle gets
another movement name the adductor pollicis for this one you just need to know that thumb flexion
is more of a bending while thumb adduction is like bringing your thumb parallel to the other fingers
from there you can see how the adductor pollicis just brings the thumb towards the midline finally
the abductor pollicis brevis is the odd one out it abducts the thumb bringing it away from the palm
so it runs from the medial carpels to the dorsal side of the thumb and has this giant muscle belly
just slopped along the metacarpal look at it there's no way that muscle is bringing the thumb
toward the midline it must be an abductor also pro tip you can palpate the abductor relax your thumb
put your finger on the thenar mass abduct your thumb and it'll pop up so at this point we've
covered a lot of those hand and finger muscles but there are still a handful left we had athenar mass
of muscles that control the thumb but we also have the hypothenar mass made of muscles that move the
pinky remember how we said that opposition is touching the thumb to the pinky well it takes
two muscles to tingle to finger tango what i'm trying to say is that the opponent's digitized
minimi is responsible for opposing the pinky thus completing the motion of opposition it's easy to
see given its diagonal path especially when you contrast that to the flexor digitized minimize
brevis which pulls directly parallel to the pinky which curls or flexes it and it's a short guy so
brevis the last in the hypothenar mass is the abductor digiti minimi this hearty slab
of muscle on the medial side of the hand which abducts the pinky no surprises there now there's
another misfit muscle near the hypothenar group called the palmaris brevis it hooks up to a band
of connective tissue called the palmer aponeuresis and despite its location it doesn't have anything
to do with moving the pinky it actually pulls on the connecting tissue which lets our hand maintain
a strong grip it's a short muscle connected to the palm hence palmaris brevis finally there are
a few muscles found directly between the fingers that let us spread or bring our fingers together
the lumbricals are tiny muscles that originate on tendons on the palmer side of your hand and insert
on structures at the phalanges called the extensor expansions and the fact that they cross multiple
joints and twist around from palm to dorsum gives them a unique action they flex the carpometacarpal
joints and extend the interphalangeal joint giving us a hand that looks like an l luckily that helps
us remember the name its action gives you an l for lumbrical the last two are the interossei muscles
literally translating to between bones in this case they're between the metacarpals
the palmar interossei adduct the fingers or bring them together while the dorsal interossei abduct
the fingers or spread them apart unfortunately they look super similar so i use the mnemonic
pad dab to remember them polymer causes adduction while dorsal causes abduction
fun fact the only reason that spock can do the vulcan greeting is because of these muscles it
involves both finger adduction and abduction now these are just the tricks that i personally use
to remember these muscles but if you want another great resource for learning anatomy then you need
to check out kenhub i use them all the time when researching and writing these videos and for this
series in particular their written articles and atlas of muscles have been extremely helpful in
refreshing my knowledge of some of those deeper smaller muscles they've also got an enormous
library of in-depth videos about muscles histology vasculature nerves and everything else you'd need
to know in anatomy class all those beautiful illustrations that you saw in this video came
from them and in addition to their library of content i also love kenhub's quiz feature
they allow you to build custom quizzes with different difficulties and they give you feedback
so you can figure out where your weaknesses are you can use most of kenhub's features for free but
if you want full access to all of their learning content and quizzes then go to khub dot me slash
corporis to get 10 off your subscription they've also got a no questions asked seven day money back
guarantee so you can try out the premium version for seven days and if you don't like it get your
money back if you want to see the next video in the muscle memorization series then check out this
playlist here otherwise subscribe leave a like on the video have fun be good thanks for watching