The elbow is an important hinge joint
located on the upper extremity.
It bridges the
shoulder and the hands
and the main function of the elbow is to
position and maximally stabilize the hand
when you try to perform task and when
you try to do anything such as work.
So on the dorsal surface, you can
note that there is a cubital fossa
and frequently this is where you would check for access
when you're drawing blood and for venipunctures.
Posteriorly, this is where you'll find the triceps tendon
when you're testing for a motor function of the triceps
and also you'll find the ulnar groove
where the ulnar nerve passes through.
So the elbow joint consist of
articulations between the humerus
and two bones in the forearm,
the ulna and the radius
This is primarily a hinge joint, so the ulna and
humerus primarily do flexion and extension there.
The radius articulates with the capitulum of the
humerus and the ulna articulates with the trochlea.
So there are many ligaments that helps to
support and stabilize the elbow joint.
There is the medial ulnar collateral
ligament on the medial aspect.
We have the lateral collateral
ligament on the lateral aspect
and then you have a lateral ligament of the
radius which kinda wraps around that radial head
and helps to stabilize the
radius and the elbow joint.
There's a interosseous membrane that
lies between the ulna and the radius
a lot of blood vessels, nerves,
may transport through there.
The fibers vary in different orientation and
it helps to stabilize the ulna and the radius.
This is also an important site for
lymphatic drainage of the upper extremity
any sort of twist, restrictions may
potentially decrease lymphatic drainage
from the upper extremities
and the hand.
So the two basic motions of the elbow
include flexion and extension.
So the major muscles that help
with ulnar-humeral flexion include
the brachialis, brachioradialis
and biceps brachii.
So the brachialis is more on the lower side of the
humerus and inserts into the tuberosity of the ulna
while the brachioradialis also supinates
slightly during extreme pronation
The brachiaradialis is one of those muscles
that we test for reflexes, checking for C5.
The biceps brachii is
the main elbow flexors.
It also has properties to supinate based on
its attachment on the coracoid process
The brachialis is the main muscle
used when the elbow is flexed slowly.
The other function of
the elbow is extension.
So the main muscle that helps
with that is the triceps muscle.
There's some help with the anconeus muscle but
the triceps really is main extensor of the elbow
It has attachments from the shoulder
and so motion of the shoulder
and position of the shoulder
will affect it's efficiency.
If you have hyperextension, there is risk
of injuring and damaging the olecranon.
You could also tear capsules
and ligaments in the region
and sometimes you could also damage
the blood vessels in the region.
So when discussing motion testing at the
elbow joint, we have two main motions.
We could talk about flexion and extension and then
we could also talk about supination and pronation.
which is the articulation between
the ulna and the radius.
So the normal range for
extension is 0 to 5 degrees
so when we talk about the
anatomical neutral position,
this is our anatomical neutral where our elbow
is extended and so extension of the elbow is 0.
Flexion then could come up all the way to about
a 130-145 degrees with active range of motion.
If I then possibly try to push
the elbow further into flexion,
you could get to about
maybe 150 - 160 degrees.
Pronation and Supination.
Pronation you get average about 75 degrees of
pronation is with your hands in a vertical position,
you're going to bring your
palm facing towards the floor.
Supination is going the other way, we're
gonna bring your palms facing the ceiling.
A simple way to remember supination is
that in order to hold a bowl of soup,
you have to turn
your palm facing up.
And so supination is usually a little bit
more than pronation about 85 degrees.
So there is limited motion in
the coronal plane at the elbow.
The elbow based on anatomy is
more flexion and extension
and since as a hinge joint, it has
very little lateral and medial motion
Valgus motion is the motion named when the forearm
and the hand moves a little bit more laterally.
The motion is coupled with
forearm ABduction in supination
and is the movement of the hand
and forearm away from the body.
The simple way to remember valgus is
that there's a letter "L" in the word.
And so when you're kind of bringing the hand
further away, it sort of makes a letter L.
Varus is the other motion.
So varus motion is coupled with
forearm ADduction and pronation
and that is the movement of the forearm and hand
towards the body, a little bit more medial.
So everybody has a
So when we're on anatomical neutral, our
elbow will valgus a little bit more.
Normally you have 5 to
15 degrees of valgus.
Males is a little bit less than females, this is due
to the shape of our different articulating surfaces
and allows the elbow to fit
more closely to the waist.
Sometimes you may have abnormality in that carrying
angle, so Gunstock deformity is also called Cubitus varus
So here, the elbow is stuck more in a
varus position as opposed to valgus.
Sometimes this could be due to a fracture at
the supracondylar or the epicondylar region.
So there are 2 main articulations
at the elbow joint,
flexion and extension occurs about the
elbow joint, that's the true elbow joint,
it's a hinge joint and it's the articulation between
humeral trochlea and ulnar trochlear notch.
Pronation and supination motion of the
forearm is considered elbow motion
but it really is a motion of the radius and
ulna articulating over each other.
So in supination, our ulnar radius are
gonna be straight and then in pronation,
the ulna is going to cross
over the radius bone.
The epicondyles are where most of the
muscles in the forearm originate.
The medial epicondyle primarily has attachment
of the flexor muscles and the pronator muscles
whereas the lateral epicondyle usually
has the extensors and supinator muscles.
This is important to remember because
different pathologies of the wrist and elbow
could be traced back anatomically to the
origin and insertion of these muscles.