Elbow and Wrist anatomy Flashcards
how many degrees of freedom does the elbow have?
one
where do the flexor muscles originate?
medial epicondyle of the humerus
where do the extensor muscles originate?
lateral epicondyle of the humerus
which ligament anchors radius to the ulna?
anular ligament
what type of joint is the radioulnar jt?
pivot (pronation, supination)
when is there no contact between humerus and radius?
extension
what reinforces the elbow capsule?
ligaments and tendons of muscles
it is otherwise weak
what is normal carrying angle of the arm?
cubitus valgus (15 degrees)
what are the parts of the medial (ulnar) collateral ligament?
anterior (most resistant to valgus force)
oblique
posterior
what is the shape of the lateral (radial) collateral ligament?
fan shaped
which elbow ligament is stronger?
ulnar collateral
who are major elbow flexors?
biceps brachii
brachialis
bracioradialis
who are the major elbow extensors?
triceps
anconeus
where does the short head of the biceps originate?
coracoid process
how many joints does the biceps affect?
2 (shoulder, elbow)
2 joint muscles tend to cause more clinical problems
what is the function of the coracobrachialis?
primarily a shoulder flexor
where does the brachialis insert?
coronoid process of the ulna
which is the thickest of the flexor muscles?
brachialis
where is the O/I of the brachioradialis?
O: lateral supracondylar ridge
I: radial styloid process
when is the brachioradialis NOT active?
eccentric contraction
when is brachioradialis MOST active?
load and forearm is pronated (biceps is best during supination)
where does the long head of the triceps originate?
infraglenoid tubercle of scapula
where do the medial and lateral heads of triceps originate?
humerus
where do all 3 heads of the triceps insert?
olecranon
what is the anconeus muscle?
small triangle muscle
O: lateral epicondyle to olecranon
assists triceps
what lines the inside of the annular ligament?
hyaline cartilage
which forearm bone takes 80% of the weight bearing?
radius
what are the ligaments present at the radioulnar joint?
annular
quadrate
oblique
when is the interosseus ligament tense?
when forearm is neutral (its relaxed when fully pronated or supinated)
what type of bone is the pisiform?
sesamoid bone
what type of joints are the midcarpal joints?
plane joints with no true capsule
which muscles make up the snuff box?
extensor pollicus longus
extensor pollicus brevis
why are snuff box injuries dangerous?
low, low perfusion
what are the dorsal radiocarpal ligaments??
from radial styloid to the lunate and and triquetrum (contact between lunate and radius)
what are the volar radiocarpal ligaments?
radiocapitate
radiotriquetral (strongest and supports lunate)
radioscaphoid
what are attachments of ulnar collateral ligament of the wrist?
from ulna to pisiform and triquetrum
what are the attachments of radial collateral ligament of the wrist?
from radius to scaphoid, trapezium and 1st MC
what are the attachments of the ulnocarpal ligament?
triangular fibrocartilage to lunate and capitate
which nerve innervates most of the flexor muscles of the forearm?
median nerve (except for flexor carpi ulnaris)
what action do flexor digitorum superficialis do?
movement at PIP joint (not DIP) phalnx 2-5
what does flexor digitorum profundus cause?
DIP joints of phalnx 2-5
what innervates flexor digitorum profundus?
ulnar and median nerve
what action does flexor pollicis longus do?
thumb motion
what innervates most of the extensor muscles?
radial nerve
who is the largest carpal bone and the keystone of the proximal transverse arch?
capitate bone
what gives MCP joints their stability?
ligaments
what joint is doing the work for the thumb?
CMC joint (that’s the saddle joint) not the MCP
what is the functional positional of the hand?
claw look (beer grasp) tenodesis (important for quadroplegics)
which nerve innervates the intrinsic hand muscles?
ulnar
what are lumbricals?
intrinsic muscle of the hand that pulls hand into a bucket position
what is the role of the interossei muscles?
ab/adduct hands
which palmar interosseus is responsible for abduction of the hand?
dorsal
