The big seal script of character Stretch ischaracter Person (Post 37), and the right is character Extend (Post 544). A person extends his body, which is Stretch.
The small seal script of character Stretch is
The clerical script of character Stretch is
The left is Radical of Person, the right is character Extend.
The Pinyin of the character is Shen1, same as 申.
伸 is not just stretching, but reaching out too. He reaches out to shake her hand, which he is not stretching his arm and hand, just nature moving his hand forward, in Chinese, use 伸。