Skeletal Muscle Triad question...

[danhook]

From 1985 Anatomy Exam
Question 8 of 98

In skeletal muscle, a triad consists of

a "T" tubule and associated mitochondria.
a "T" tubule and invagination of the sarcolemma.
a zone of attachment between adjacent cells.
terminal cisternae and sarcoplasmic reticulum.
terminal cisternae and a fingerlike invagination of the sarcolemma.

Answer according to the key of this test along with a couple others I have seen is terminal cisternae and a fingerlike invagination of the sarcolemma. I was under the impression that a skeletal triad consisted of a T tubule and two sarcoplasmic reticulum cisternae. Thoughts?

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[drmanglore]

hi
look at the diagram in Guyton's text book of human physiology, in the chapter on skeletal muscle.......
u'll get the idea, b4 my xam even i was under that impression, but then i looked in text books n got my doubt cleared.......

 

[drmanglore]

the entire complex is c/a T tubule. As such there is no structure c/a T tubule.....

 

[danhook]

I found it... When they say fingerlike invagination of the sarcolemma they are describing the t tubule or Transverse tubule which is found in skeletal and cardiac muscle and is an invagination of plasma membrane or sarcolemma it is a NAMED STRUCTURE which acts as a site for depolarization.