"The Amazing Zigless-Zagless....Only One Chance to See the Show" 
Chad R. Zimmerman © 2003 Copyright. All Rights Reserved.
The Single Bullet Theory
On November 22, 1963, President John F. Kennedy was gunned down in Dallas, Texas. Governor John Connally, seated in front, slightly below, and to the left of President Kennedy was critically wounded with one shot to the head and one to the upper back/lower neck. Bystander, James Tague, was nicked on the right cheek. Numerous witnesses saw a gunman firing from the 6th floor of the Texas School Book Depository. The vast majority of witnesses in Dealey Plaza heard 3 shots. The Dallas Police entered the TSBD. On the 6th floor, they found 3 spent shell casings on the floor, near a window facing out to Dealey Plaza. Between some rows of boxes, a M91/38 6.5mm Carcano was found hidden. Three shots, three empty shells. One man fatally wounded, one man critically wounded, one man scathed.  
The gun had the fingerprints of Lee Harvey Oswald, an employee at the TSBD, and avid Marxist.  
The problem. One fatal headshot equals one bullet. 2 left. One non-fatal wound of the upper back/lower neck equals one bullet. Governor Connally was hit in the back, it exited below the right nipple. He was hit in the right wrist, breaking the radius bone. He also had one slight, barely penetrating wound of the left lower thigh. One bullet? James Tague, standing near the triple underpass, was glanced on the face by something. A bullet? A fragment? Concrete? Is this another bullet? As you can see, the Warren Commission had little to work with. They had a gun and three empty shells, 3 shots heard and 3 victims. Now, they had to reverse engineer the scenario...which included more evidence accumulation and the formulation of ...The Single Bullet Theory.
The Wounds
President Kennedy's Back/Neck Wound
Now, part of any forensic investigation includes the wounds and their characteristics. President Kennedy had one wound in the upper back/lower neck, just to the right of the spine about an inch or so. This wound was slightly ovoid, measuring 7mm by 4mm. The wound had an abrasion collar which definitively marks it as an entrance wound. Abrasion collars are formed as the bullet hits the skin. The skin stretches and wipes any gunpowder, oil or dirt off of the bullet. This creates a 'halo' of residue around the entrance wound. In addition, the skin bruises, adding to the halo appearance. Exit wounds do not have abrasion collars.  
When Kennedy was examined at autopsy, the examiners tried to probe the wound. They were unaware of a wound to the front of his lower neck because that wound had been opened at Parkland Hospital to insert a breathing tube. However, they were unable to penetrate the wound without creating a false wound tract. This is likely because the underlying muscles had moved from the time he was shot to the time he ended up at Bethesda for the autopsy. Or, as we now know, the right transverse process of the first thoracic vertebra had fractured and may have contributed to the obstruction. In addition, the muscles stiffened as a part of rigor mortis. The wound tract had been obscured, so the examiners had to correlate a wound path by examining the neck and upper thorax. X-rays were taken, but were unavailable to the doctors when the final report was written. Bullets travel at high velocities. They do no hit soft tissue and stop after a distance of an inch or less without hitting dense bone. Such an impact would have to cause extensive damage to the bone. Let's try to narrow down the wound tract by looking at the available information. 
In Dr. Humes' final autopsy report, he notes the correlative damage to the upper thorax and neck that describes where the bullet went.  
"Situated on the upper right posterior thorax just above the upper border of the scapula there is a 7 x 4 millimeter oval wound. This wound is measured to be 14 cm. from the tip of the right acromion process and 14 cm. below the tip of the right mastoid process." 
"Situated in the low anterior neck at approximately the level of the third and fourth tracheal rings is a 6.5 cm. long transverse wound with widely gaping irregular edges." 
"The second wound presumably of entry is that described above in the upper right posterior thorax. Beneath the skin there is ecchymosis of subcutaneous tissue and musculature. The missile path through the fascia and musculature cannot be easily probed. The wound, presumably of exit, was that described by Dr. Malcolm Perry of Dallas in the low anterior cervical region. When observed by Dr.Perry, the wound measured "a few millimeters in diameter", however it was extended as a tracheostomy incision and thus its character is distorted at the time of autopsy. However there is considerable ecchymosis of the strap muscles of the right side of the neck and of the fascia about the trachea adjacent to the line of the tracheostomy wound. The third point of reference in connecting these two wounds is in the apex (supra-clavicular portion) of the right pleural cavity. In this region there is contusion of the parietal pleura and of the extreme apical portion of the right upper lobe of the lung. In both instances the diameter of contusion and ecchymosis at the point of maximal involvement measures 5 cm. Both the visceral and parietal pleura are intact overlying these areas of trauma." 
Dr. Humes' description of the wound provides exceptional insight to the location of the wound track. There are several points that he made that narrows the field to a very small margin. First, it entered above the shoulder blade. In a normal, neutral position, the superomedial angle of the shoulder blade rests in the upper thoracic region. It is commonly referenced at the T3 vertebral level. So, the wound was above T3. The apical portion of the right lung corresponds to the body of the first thoracic vertebra. In a study by Ronald A. Bergman, Ph.D., Adel K. Afifi, M.D., Jean J. Jew, M.D., and Paul C. Reimann, B.S., the apex of the right lung ranges from the C7 disc to the T1 disc, with the most common point being the upper third of the first thoracic vertebra. Dr. Humes and staff noted a bruising to the right apical portion of the right lung with all pleura intact. Thus, the bullet path was narrowly above the apex of the right lung, causing bruising, but no destructive damage to the lung or pleura around the lung. Effectively, this wound was narrowly above T1. This would correspond to an area above the apex of the lung, above the shoulder blade and above the clavicle. On the anterior-posterior view of Kennedy's lower neck and upper back, the superior portion of the right proximal collarbone is seen at the lower edge of T4. So, a bullet could strike at C7/T1 at a downward angle and not cause bony destruction to the scapula or collarbone. Another point of correlation is the nicking of the 3rd or 4th tracheal ring. When Kennedy was brought into Parkland Hospital, there was bubbling blood emanating from a small wound of the low anterior neck. The nicking of the trachea would cause this by allowing the air flow within the trachea to mix with the blood from the wound tract. We can correlate wound anatomy to this. The 3rd or 4th tracheal rings are below the cricoid cartilage, commonly found at C6 in the neck. So, we have narrowed the wound to between C6 and T1. Since there are two rings of cartilage above the 3rd tracheal ring, the wound is now placed at a location of C7-T1. 
Now, probably the most confusing aspect in the minds of most readers is how the bullet could enter at C7-T1, travel downward and enter an area that is at C7-T1? It's much easier than it sounds, and it does NOT require Kennedy to be leaning forward as depicted in some classic illustrations from some classic conspiracy books. In fact, the entrance wound, the bruised apex of the lung, the damaged trachea at the 3rd or 4th ring fits perfectly with a shooter from above and behind President Kennedy. 
The Parkland emergency staff noted that Kennedy had a small wound of the anterior lower neck. They did not see the wound in the upper back/lower neck. In fact, it led to speculation that the bullet entered the base of the neck, hit the spine, and was deflected upwards into the skull...causing the massive head wound. Talk about a Magic Bullet! One must wonder that, if the Parkland doctors had felt or seen the wound in the back (complete with abrasion collar), would they have speculated that the wound was one of entrance or exit? 
Angle of Entry
If the bullet entered the spine about an inch from the spine and exited through the center of President Kennedy's neck, it would have a right to left trajectory of approximately 9 degrees. This is if President Kennedy's neck was 6 inches thick from front to back. If narrower, the angle would be larger. If thicker, the angle would be reduced. Since only the right side of the trachea was nicked, the bullet may not have come out exactly in the center of the neck, so the angle may be slightly reduced. If Kennedy was facing almost straight forward, this would place a shooter above, behind and to the right of him. The downward angle on a neutral neck would correlate to a downward trajectory of approximately 22 degrees, depending on variants in position and anatomy.
As you can see in the illustration to the left, A bullet entering at the C7-T1 level of the spinous processes, at a downward angle of 22 degrees, will cross just below the C7 disc and out of a point in the neck and exit at the T1 disc. So, in fact, the bullet only traverses one vertebral level. This is due to the curvature of the neck, called a lordosis. This causes a downward tilt to the lower cervical vertebrae, similar in size to a downward trajectory of 22 degrees. Many people do not have such a curve, but since the upper thoracic spine has such a forward curvature, the lower cervical vertebrae almost always have a downward tilt. 
     For many researchers and interested individuals, the autopsy photograph of the wound shows an entrance that is decidedly below the level of the cervical spine. However, this is erroneous to assume as well. You must remember, anything lower than a C7-T1 entrance would likely have perforated the thoracic cavity and the right lung. This did not happen. There is no evidence other than speculative guesses that the wound was lower. The evidence is conclusive that it was the C7-T1 area.
Now, with that narrowed down, there is only one remaining question. Where'd the bullet go? Here's a hint: It was moving downward and to the left when it hit the neck. It continued downward and to the left as it passed through the neck. It was traveling downward and to the left when it exited the neck. Call it intuition, but I'll bet that it went downward, forward and to the left. But, there wasn't any damage to the interior of the limousine in that area. However, one other person was in the direct path. Now you get the gist of where the Warren Commission had to go with this. Connally?