영어문장 설명좀 부탁드립니다..

Three years ago, when I found out that my father had suffered a severe stroke in his brain stem, I walked into his room in the ICU at the Montreal Neurological Institute and found him lying deathly still, tethered to a breathing machine.

Paralysis had closed over his body slowly, beginning in his toes, then legs, torso, fingers and arms.

It made its way up his neck, cutting off his ability to breathe, and stopped just beneath the eyes.

He never lost consciousness.

Rather, he watched from within as his body shut down, limb by limb, muscle by muscle.

2.

beginning in his toes, then legs, torso, fingers and arms.

여기서 beginning in 을

뭐라고 해석해야하는게 좋은지

그리고 이게 분사구문인건지 아니면 그냥 전치사처럼 쓰인건지 잘 구분이 안가네요 ㅠㅠ

1.

Rather, he watched from within as his body shut down, limb by limb, muscle by muscle

여기서는

rather이 그냥 오히려.. 라고 쓴게 맞는지

그리고 within이 명사로 "안, 내부"가 맞는지 궁금합니다.. 이걸 명사로 쓰는걸 본게 처음이라 ㅠㅠ