Just a word on the suffering Jesus experienced.
Isaiah tells us Jesus, the suffering servant, was beaten so badly he resemblance to being human was lost. You all have been hit so hard that it caused a bruise, whether the blow came from inadvertently hitting your shin on something, having a heavy object dropped on some body art, or a deliberate punch or kick. Generally speaking, it takes a while before a contusion turns into a bruise but repeated blows in the same place can hasten to bruising as multiple blood vessels are broken beneath the skin. In the case of numerous blows, the meat of the flesh softens. The area swells as blood enters the subcutaneous area with nowhere else to go. With enough blows to the same area the skin will burst but that will not alleviate the swelling of the already blood-laden area. when this happens in multiple adjacent areas that entire portion of the body will turn black, blue, and brown. This damage is enhanced when the skin is wet, either as a consequence of sweat or being spit upon.
It is likely Jesus was struck with fists and clubs all over his body and, as a consequence, his entire body swelled from blows to every part of his body. Scripture tells us he was beaten while being interrogated by the Jewish leaders who mocked him and played a "game" where one person would strike him, and he'd then be asked to identify the pugilist by name. After being taken from the Sanhedrin to Herod and the Romans, Jesus was sent out for a scourging, Pilate hoping the abuse would assuage the Jewish crowds. There Jesus was again mocked and beaten, and a ring of throned branches was forced onto his skull, piercing the skin and blood vessels therein. The skin surrounding the skull is filled with blood vessels and even small wounds to the face and head can bleed profusely. On top of this a scourging could be brutal, especially when done by someone with a lot of experience and orders not to kill the victim. Such a man, a Roman soldier, would have plenty experience in Israel given the problem of zealotry with which the Romans constantly dealt. A scourge was a whip made of rawhide into which stones and glass had been woven or cemented. Due to the force with which a whip can be wielded, the lashes would cause contusions a fist couldn't. Sharp rocks and glass would lacerate the skin and repeated lashes pull the meat off the bone, leaving it hanging, severing muscles, making it difficult to flex or move while being whipped. The open flesh also med it easy to identify where previous lashes had landed so the scourger could vary the placement. A scourging could also cause the whip to wrap around the torso, and the returning pull would tear and remove the flesh from all sides and what wasn't lacerated or removed bruised and then swelled. And since all of humanity's sin was poured upon him it is likely he was raped or sodomized with various objects, causing the same kind of damage described above to internal organs. It was an offense to the Jews that Jesus would claim to be the son of God and make himself equal to God. It was also an offense that Jesus would make claims that necessitated his superiority over Caesar (and therefore over every Roman citizen, too). In the minds of his torturers anything that happened to him was justified.
In short, it is likely Jesus' entire body was swollen from thigh to skull, especially in the torso and face. Being swollen, it was also black, blue, and dark brown from the bruising the lines of his normal torso were disrupted wherever the flesh was torn and/or hanging. I sometimes joke that in my youth, when I was exercising often, I was "V" shaped, but now in my old age and hearty appetite I am "O" shaped. The shape of Jesus body was unidentifiable using the alphabet.
I fell off a mountain once. I fell a hundred feet, bouncing down the side of the mountain, with each bouncing causing contusions and lacerations. I suffered lacerations over every part of my body but my feet, which were protected by my hiking boots. I fractured my skull. My friends managed to find a hunter who drove us all to the local hospital, from which I was evacuated by helicopter to a better equipped urban alternative. I was fastened to a backboard during the transit because it hadn't been determined whether any spinal injury has occurred. I was wearing BDUs (military combat pants with plenty of room with which to stretch and move around). Both of my knees had swollen to the point the otherwise roomy pants restrained the swelling. One knee was as big as a soccer ball. After two days in the hospital, still strapped to the back board, and many rounds of doctors coming in to poke me, probe me, xerox me and wonder what next to do (it was a university teaching hospital) I was allowed to get up off the backboard, out of the bed, and take a shower. I was still wearing the clothes in which I'd been backpacking. I hurt so bad all over it took two hands to undo a button. I had to concentrate to do so, the pain was so great. The whole time I was undressing I was unaware the wall to my left in the bathroom was mirrored from ceiling to floor. When I finally got all my clothes off, I looked up and around and jumped from being startled. I know this sounds silly, but I literally thought my hospital room must have been next to a rendering or meat packing plant because I thought I saw a carcass standing or hanging in the next room. It was only that the carcass also jumped that I realized the carcass was me. I'm normally a white guy. That guy in that bathroom was black, and I mean blacker than any black person you've ever met. Black like coal. I had lacerations all over my body and the blood had run all down and around my body underneath my clothes. One laceration went down the side of my face under my jaw and across my neck, but there were scores of smaller cuts all over my body. A portion of my face were still white but much of it was brown and blue from where some of the subcutaneous blood was dissipating. Otherwise, my entire body underneath my clothes, underneath the caked, dried blood was black with marbled areas of dark red, brown and blue.
That's what happens when a human body meets rocky ground and a little gravity. Jesus's wounds were caused deliberately. The force of a human punch can range anywhere from 500 to 1000 Newtons. The force of a 180 lb person falling two stories is about 800 Newtons when hitting the ground. Most people dismiss or minimize or sin because we're not as bad as what we hear about in the news, but they'd have killed Jesus long before he hung on the cross if God had permitted it. There were Jeff Dahmers and Josef Mengeles in those rooms where he was beaten, individuals who took delight in causing excruciating pain with maximum psychological effect..... while prolonging the inevitable.
Isaiah 52:13-14
Behold, My servant will prosper, he will be high and lifted up and greatly exalted. Just as many were astonished at you, My people, so his appearance was marred more than any man and his form more than the sons of men.
Isaiah 53:4-5, 10
Surely our griefs he himself bore, and our sorrows he carried; yet we ourselves esteemed him stricken, smitten of God, and afflicted. But he was pierced through for our transgressions, he was crushed for our iniquities; the chastening for our well-being fell upon him, and by his scourging we are healed. But the LORD was pleased to crush him, putting him to grief; If he would render himself as a guilt offering, he will see his offspring, he will prolong his days, and the good pleasure of the LORD will prosper in His hand.
In this light I will suggest penal substitution is true, but also inadequate. Few, if any, have suffered as Jesus did and I've given only a brief summary of the physical effects of his beatings. He suffered psychologically beyond our comprehension as well. So, aside from considering the magnitude of Christ's suffering, consider the magnitude of sin when contemplating the atonement.