You are facing the problem of differentiating between strong, weak, and mixed declension of adjectives. I will illustrate the three forms with the adjective kalt.

Strong declension

The form kalte, which you think was correct, is called strong declension. It appears when there is no article or another word declined like an adjective:

kalte Venen

In your example, however, the strong declension does not work, because the pronoun meine is also declined like an adjective.

Weak declension

The weak declension appears in connection with a definite article:

die kalten Venen

Mixed declension

Finally, when there is yet another adjective, or a word that is declined like an adjective (such as meine), then mixed declension is used:

meine kalten Venen

This is actually the form used in your example.

You are facing the problem of differentiating between strong, weak, and mixed declension of adjectives. I will illustrate the three forms with the adjective kalt and the plural noun Venen in accusative case.

Strong declension

The form kalte, which you think was correct, is called strong declension. It appears when there is no article or other word declined like an adjective:

kalte Venen

In your example, however, the strong declension does not work, because the pronoun meine is also declined like an adjective.

Weak declension

The weak declension appears in connection with a definite article:

die kalten Venen

Mixed declension

Finally, when there is yet another adjective, or a word that is declined like an adjective (such as meine), then mixed declension is used:

meine kalten Venen

This is actually the form in your example.

You are facing the problem of differentiating between strong, weak, and mixed declension of adjectives. I will illustrate the three forms with the adjective kalt.

The strong declension appears when there is neither an article nor another adjective:

kalte Venen

The weak declension appears in connection with a definite article:

die kalten Venen

When there is yet another adjective, or a word that is declined like an adjective, mixed declension is used:

meine kalten Venen

You are facing the problem of differentiating between strong, weak, and mixed declension of adjectives. I will illustrate the three forms with the adjective kalt.

Strong declension

The form kalte, which you think was correct, is called strong declension. It appears when there is no article or another word declined like an adjective:

kalte Venen

In your example, however, the strong declension does not work, because the pronoun meine is also declined like an adjective.

Weak declension

The weak declension appears in connection with a definite article:

die kalten Venen

Mixed declension

Finally, when there is yet another adjective, or a word that is declined like an adjective (such as meine), then mixed declension is used:

meine kalten Venen

This is actually the form used in your example.