Cylinder head

Hello,

I recently pulled a cylinder head off a GM 262 V6 engine. I noticed that the middle cylinder has an exhaust tract with two ports-one which faces the exhaust manifold like all the others, and another that faces the intake side. I have circled it in the picture below. The intake side of the head therefore has six holes: two for water, one for each cylinder, and then the extra one that comes from the exhaust valve.

I cannot figure out why this may be the case and what this exhaust port is for. This cylinder head has also cracked right near the exhaust valve on the same center cylinder. Thanks!