Arms Imbalance

In my left arm, there are bones,
Which I suppose is pretty good,
There are sinews, there are tendons,
But there isn’t any blood.
There are arteries and muscles,
And veins are ten a penny,
But rich, red haemoglobin?
I’m afraid there isn’t any.

My right arm, on the other hand,
[Excuse the dreadful pun]
Is bursting at the seams with blood,
When all is said and done.
The Irish Blood Transfusion Board
Can never figure out
Why my right arm has a glut whereas
The left arm has a drought.