A Guide To The Deltoid Muscles
Here is a film giving you a detailed guide to the Deltoid Muscles. Watch and learn techniques surrounding these Deltoid Muscles so you'll soon be able to practise it yourself.
Step 1: Three Deltoids
Within the deltoid region, there’s actually considered three deltoids.
Some books actually say it’s just one deltoid, just right in this region, but there’s actually considered an anterior deltoid. And then the medial deltoid right here, and also the posterior deltoid.
So the origin is the lateral third of the clavicle, so right in here, so that’s the actual origin for the anterior.
And all insertions for the deltoid actually going down to the deltoid tuberosity, so that’s the actual insertion for all three deltoids, so that’s why some books just say it’s actually just one muscle, but other books separate it and say it’s actually three muscles.
Step 2: Trigger Points
And also for the medial one, it’s actually acromion process, acromion and lateral spine of the scapula, so it actually starts in this region here.
So again, the anterior actually goes down like this, the medial, or as some people call it, the lateral deltoid, starts like this. And then the posterior deltoid, lower lip of the spine of the scapula, so the spine of the scapula, when we flip her over, we’ll actually be able to feel – and I’ll show you where the spine of the scapula is, right in that region.
So the deltoids, the medial deltoids, there’s actually four trigger points on that region, so it’s totally lateral right here. So it actually just refers around that region.
And the anterior – there’s only one trigger point, right around here – it will just refer around here, though, okay.
The posterior will just refer around the posterior region. So you know if it’s just totally lateral, more than likely it’s the medial deltoid; if it’s just anterior region it’s going to just be the anterior, and posterior, it’s just going to be the posterior deltoid region.
Step 3: Rotation, Adduction and Abduction
So the actions of it, it actually flexes the humerus so it actually brings the arm up like this.
It also – adduction, so the arm close to the body like this; medial rotation, like this; abduction to 90 degrees. So abduction, it just brings it straight up like this. So that’s for the medial deltoid, that’s the only action it does, is just abduction to 90 degrees. But the other actions are for the anterior deltoid. And then for the posterior deltoid, the actions are – it does extension, when we flip her over I’ll show you extension of that - and then also horizontal abduction, so you have the arm out straight and you just bring it straight back like this, and also lateral rotation, so it’s bringing it back like this then.
Again this is medial rotation, lateral rotation, horizontal adduction, horizontal abduction, adduction, abduction, so those are some of the actions of that region. And some people actually call this the shoulder pad muscle, just because it’s actually a little bit bigger in this region. Remember in the 80s when people actually wore those jackets with the shoulder pads kind of built up in that region? So that’s kind of how it got its name, too, as the “shoulder pad muscle.”
