What is the meaning of "Achor va'Kedem Tzartani"?
Rashi: Front and back [You formed me].
Radak citing his father: This refers to formation of the fetus in the womb. "Tzartani" refers to Tzurah (the form).
Radak (6, citing Ibn Ezra): Tzartani is (You besieged me,) like "v'Tzarta Aleha", "Al Tetzurem" (Devarim 20:12, 2:19).
Malbim: Not only do You know all details of my deeds. You also rule over all my motions, limbs and actions. You surround me in back, front and above. The verse depicts Hashem's power like a strong camp that surrounds a small city, i.e. man. He is besieged on every side and cannot flee in front or in back.
What is the meaning of "va'Tashes Alai Kapecha"?
Radak: This is like they do to cheese - "v'Chagvinah Takpi'eni" (Iyov 10:10). You set a size for the fetus.
Radak (6, citing Ibn Ezra): This is the ultimate siege and affliction. I cannot stand or go without You.
Malbim: I cannot rise above from being under Your authority. (Refer to 139:5:1:3.)
