elbow joints Flashcards
how many joints are within the elbow complex
4 joints
provide increased mobility for the hand and wrist
also provide stability
what does the elbow allow
the hand to approach or extend away from the body
what does the forearm do
adjusts the hand’s approach to an object
joints of the elbow
humeroulnar joint
humeroradial joint
humeroulnar joint
articulation b/w the antero-medial aspect of the distal humerus and the proximal ulna
the trochlea of the humerus and the trochlear notch of the ulna
what is the trochlea and what is the trochlear notch within the humerolulnar joint
trochlear is concave transversely and convex anteroposteriorly
trochlear notch is semicircular shaped concave surface
humeroradial joint
articulation b/w the capitulum and the head of the radius
capitulum –> convex
head of the radius –> concave
humeroradial and humeroulnar joints are…
one compound joint that functions as a hinge joint
uniaxial, diarthrodial joint with 1 degree of freedom
allows for flexion and extension(sagittal plane around a frontal axis)
normal ROM of the humeroulnar and humeroradial joints
0-145 degrees (actively)
0-160 degrees (passively)
anything beyond 0 degrees is hyperextension
what is the axis of motion for the elbow joint
oblique
passes through the center of the capitulum and the trochlea
runs from lateral to medial, superior to inferior
arthrokinematics of the elbow joint in flexion
concave on convex
bone motion, roll and glide are anterior
arthrokinematics of the elbow joint in extension
concave on convex
bone motion, roll and glide are posterior
accessory motions for flexion
adduction
d/t the alignment of the joint axis and shape of the articular surfaces
supination (can be overcome, more of a tendency)
accessory movements for extension
abduction
d/t the alignment of the joint axis and shape of the articular surface
pronation (can be overcome, more of a tendency)
valgus position
when the distal segment of a joint is more lateral than the proximal segment
has to do with frontal plane alignment
valgus stress
a stress that tends to make the distal segment more lateral
varus position
when the distal segment is more medial
varus stress
a stress that tends to make the distal segment more medial
radioulnar joints
superior radioulnar joint
inferior radioulnar joint
intermediate radioulnar joint
superior radioulnar joint
the articulation located on the lateral aspect of the proximal ulna
directly below the trochlear notch
occurs b/w the convex radial head and the concave radial notch of the ulna (1/5)
occurs b/w the radial head and a ring formed by the annular ligament (4/5)
inferior radioulnar joint
the articulation b/w the head of the ulna, the ulnar notch of the radius and the intra-articular disk
intra-articular disk
triangular shaped
articulates proximally with the ulnar head and distally with the carpal bones
concave on both sides
intermediate radioulnar joint
occurs along the 2 shafts of the bones and is held together by the interosseous membrane
is a syndesmosis joint
interosseous membrane primary role
membrane’s primary role is to keep the bones in proper alignment
what type of joints are the superior and inferior radioulnar joints
pivot or trochoid joints
diarthrodial, uniaxial joints with 1 degree of freedom
what motions do the superior and inferior radioulnar joints allow
pronation and supination
transverse plane around a vertical axis
full supination to full pronation ROM
0-150/170
the radioulnar joints are
mechanically linked
motion at one joint is accompanied by motion at another joint
axis of motion for radioulnar joints
longitudinal
extending from the radial head to the ulnar head
moving bone = radius
arthrokinematics in the supinated position
the radius and ulna are parallel
radius is lateral to the ulna
arthrokinematics during pronation
the radius crosses over the ulna and moves medially
the radius is considered the moving bone
arthrokinematics for pronation
bone motion is the radius moving anteriorly
arthrokinematics for supination
bone motion is the radius moving posteriorly
at the proximal radioulnar joint, during pronatio
the convex radial head moves on the concave radial notch of the ulna
ulna moves very little
supination at the proximal radioulnar joint (arthrokinematics)
bone motion and roll –> posterior
glide –> anterior
pronation at the proximal radioulnar joint (arthrokinematics)
bone motion and roll –> anteriorly
glide –> posteriorly
at the distal radioulnar joint
the concave ulnar notch of the radius moves on the convex ulnar head
distal radioulnar joint during supination
radius moves posteriorly
ulnar head moves medially and anteriorly
distal radioulnar joint during pronation
radius moves anteriorly
ulnar head moves laterally and posteriorly
