How is the human body used in Wilfred Owen's poem 'Mental Cases'?

The human body is broken down in 'Mental Cases' and is detached from the soldiers. Owen dehumanises the men, to better establish how the horror of the First World War is impacting them. He compares them to some sort of demon, unable to view them as human any more, 'Sure we have perished / Sleeping, and walk hell; but who these hellish?'. He struggles to identify with them, as established by the opening rhetorical question of 'Who are these?' Additionally, even the men's faces are no longer human, 'Thus their heads wear this hilarious, hideous, / Awful falseness of set-smiling corpses'. Owen describes the human body using abstract terms to dehumanise the soldiers, highlighting how their trauma is impacting them and making them forever different from the rest of humanity.Beyond the soldiers, Owen uses the body as a way of describing the world around the patients. Here, he is highlighting how the war has bled into all of the world the soldiers are experiencing and they are unable to get the images of death out of their minds, 'Sunlight seems a bloodsmear: night comes blood-black; / Dawn breaks like a wound that bleeds afresh'. The trauma the soldiers have experienced is causing them to visualise their memories everywhere and they are unable to view reality without remembering images of death and bodies. This makes clear Owen's anti-war message, and shows a great awareness for the effects PTSD has on these patients.