Behavior is dependent upon two big boxes which are the spinal cord and the brain being able to communicate with each other. If a person has a broken neck, he/she will lack in this ability. Therefore a person with a broken neck will express different behavior from a normal person. The connection between the brain and the spinal cord allows individuals to express various kinds of behavior. An individual with a broken neck will not have this particular connection and therefore will express certain behavioral differences.
An individual with a broken neck will not have control over his/her body. Physical movement will be greatly reduced. However the properties of the spinal cord allow for some movement in certain circumstances. For instance, if a person with a broken neck gets pinched in the foot, the foot will withdraw due to the spinal cord reacting in such situations. This individual will probably not be able to verbally express the pain since the information of the pinched foot has no way to reach the motor neurons in the throat which will allow for verbal expression. A normal individual in this situation will react with withdrawing his/her foot and will have the ability to verbally express their pain. This is since the normal individual has the connection between the brain and the spinal cord which allows for the information to travel between them.
An individual with a broken neck has control over his/her brain to think and express their mental thoughts verbally but can not express physical behavior concerned with the rest of his/her body. He/she can decide to move their limbs but will be unable to follow through with the actual action since the spinal cord will not be able to receive information from the brain. This individual has the ability to feel emotions and thoughts due to functions of the brain but may be restricted to physically express or feel these emotions ( such as physical pain below the neck). For instance, if the individual is deeply sad, he/she may be able to cry but will not be able to wipe their tears with their hands(which is a common reaction when crying) or express their sadness physically otherwise.
Every individual is unique and each individual has the capability to express different behavior. It is important for any individual to have the connection between the brain and the spinal cord in order to function freely. This essential connection between the spinal cord and the brain will allow people to express their mental and physical needs and actions.
Not wiping tears a very nice example of what's disturbed in paraplegics. Careful though about "an individual ... has control over his/her brain". Presumably (at least on brain=behavior presumption) the "individual" IS the brain (or some part of it), so who controlling who? PG