Forearm & posterior hand-->sievert Flashcards
T/F There are no muscles in your posterior hand.
TRUE
So, if there are no muscles in your posterior hand, what are there?
tendons from muscles of the forearm
What are phalanges & where are they found?
basically, parts of a finger.
3 phalanges per finger
2 phalanges per thumb
What are the names associated with each phalange of the fingers?
proximal phalange
middle phalange
distal phalange
What are metacarpals & how many of them are there?
there are 5
they are the bones that go in your hand up until the point of phalanges.
What are the joints of the fingers?
MP: metacarpal phalangeal joint
PIP: proximal interphalangeal joint
DIP: distal interphalangeal joint
Can the MP, PIP, & DIP joints be acted on separately? Explain.
- *they can be flexed individually
* *they are all extended at once b/c of the extensor hood arrangment
Which muscle extends the MP, PIP, & DIP joints all at once?
the extensor digitorum
What is the thing that can pull on the extensor hood & cause extension of the fingers?
long extensor tendon
What are the 2 continuations of the extensor hood onto the fingers?
Central band: connects to middle phalanx
Lateral bands: connects to distal phalanx
What are the 2 muscle types that act on the extensor hood? What is their action when they act together?
lumbricals
interossei
Together: extend interphalangeal joints
flex metacarpophalangeal joints
What does the flexor digitorum profundus flex?
DIP joint
What does the flexor digitorum superficialis flex?
PIP joint
T/F Without extensor tendons at your wrist, you couldn’t make a tight fist.
True.
What is the retinaculum? Where is it located?
Retinaculum is a tendon that keeps the tendons from moving around underneath.
It is is right before the wrist. It runs transversely.
On the posterior side of the hand: called extensor retinaculum.
What protects the tendons underneath the retinaculum from being torn up by the retinaculum moving against it?
it is protected by synovial tendon sheaths that surround it. there are a lot of these & they can become infected.
Most posterior forearm muscles come from where?
common extensor tendon
Where does the common extensor tendon attach?
the lateral epicondyle or the supracondylar ridge of the humerus
What are the exceptions to the rule, which muscles of the posterior forearm don’t come from the common extensor tendon? What are some places where these come from?
3 thumb muscles
extensor indices
supinator
**radius, ulna, interosseus membrane
What position is your hand in when it is supinated?
it is in a position to hold a soup bowl!
All posterior forearm muscles are innervated by what nerve?
Radial nerve, mainly the deep branch.
What is the posterior forearm’s rule of 3s?
there are 3 muscles that go to the thumb
there are 3 muscles that go to the fingers
there are 3 muscles that go to the wrist
there are 3 muscles that don’t cross the wrist joint
What are the 3 posterior compartment forearm muscles that go to the thumb?
extensor pollicis longus
extensor pollicis brevis
abductor pollicis longus
What are the 3 posterior compartment forearm muscles that go to the fingers?
extensor digitorum
extensor indicis
extensor minimi
What are the 3 posterior compartment forearm muscles that go to the wrist?
extensor carpi radialis longus
extensor carpi radialis brevis
extensor carpi ulnaris
What are the 3 posterior compartment forearm muscles that don’t cross the wrist joint?
anconeus
supinator
brachioradialis
T/F In the anatomical position, the thumb is in the same plane as the fingers.
FALSE. It is in a different plane. off by 90 degrees, why we are humans & not chimps or something.
What does abduction & adduction look like for fingers?
So…the midline in this case is the middle finger. Abduction is spreading the fingers out & adduction is smooshing the fingers closer together.
What does flexion & extension of the fingers look like?
Flexion: bending fingers @ creases, almost making a fist
Extension: straightening out your fingers.
When your fingers flex, what plane & what axis do they do it in?
Fingers Flex
Plane: sagittal plane
Axis: transverse axis
When your thumb flexes, what plane & what axis does it do it in?
Thumb Flexes
Plane: Coronal Plane
Axis: AP axis
What does extension of the thumb look like?
like a hitch hiker’s thumb
On which axis do you abduct & adduct your fingers?
transverse axis
What is the anatomical snuff box?
sort of the triangular portion of the dorsum of your hand, by your thumb.
Of the posterior forearm muscles to the thumb, which is the most ventral-leaning? Which is the most strictly dorsal? How many joints does each cross? Where does each one insert?
Abductor pollicis longus: more ventralish, crosses 1 joint, inserts @ base of the metacarpals.
Extensor pollicis brevis: middle, crosses 2 joints, inserts @ proximal phalanx
Extensor pollicis longus: most dorsal, crosses 3 joints, inserts @ distal phalanx.
T/F The abductor pollicis longs comes from the lateral epicondyle.
False. Remember, all the thumb muscles are an exception to the rule & don’t come from the lateral epicondyle or the supracondylar ridge.
What are the muscles/tendons that make up the boundaries of the anatomic snuff box?
abductor pollicis longus
extensor pollicis brevis
extensor pollicis longus
What is the most important thing that is found in the snuff box?
**radial artery
this is where the radial artery changes from being on the anterior surface of the hand to being on the posterior surface.
Aside from the radial artery, what else is found in the snuff box?
radial artery
base of the first metacarpal
styloid process of the radius
crossed by dorsal digital branches of the radial nerve
What’s the deal with the extensor digitorum?
this is one of the posterior forearm muscles that supplies the fingers. It divides into 4 tendons, 1 for index, 1 for middle, 1 for ring. Additionally, there is a branch off of the ring finger tendon for the pinky finger.