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