Answer:
When he was nearly thirteen, my brother Jem got his arm badly broken at the elbow.  When it healed, and Jem’s fears of never being able to play football were assuaged, he  was seldom self-conscious about his injury. His left arm was somewhat shorter than his  right; when he stood or walked, the back of his hand was at right angles to his body, his  thumb parallel to his thigh. He couldn’t have cared less, so long as he could pass and  punt.
Phrases:
my brother Jem - noun phrase
about his injury - prepositional phrase
couldn't have cared less - verb phrase
Clauses:
When he was nearly thirteen - dependent (adverb) clause
Jem’s fears of never being able to play football - dependent (noun) clause
His left arm was somewhat shorter than his  right -  main clause
