Questions to consider:

1. What is the function of the dens of C2, and why are fractures in this region so dangerous?The dens, also called the odontoid process, is the portion of the C2 (the "axis") about which the C1 and the head rotate. Because the dens extends superiorly into the ring of C1, it is subjected to shear forces and fracture from C1 in neck injuries. The dens can then impact the spinal cord, injuring or severing it. In this case, although the patient's spinal cord was not severed, impact from the dens caused a spinal cord hematoma resulting in quadriplegia.2. What is spinal immobilization, and why is it used?You'll learn about spinal immobilization later should you choose a specialty that treats trauma; for now, what's important is that any vertebral fracture has the potential to injure the spinal cord. Spinal immobilization is like splinting the spine to prevent uncontrolled movement of potentially fractured vertebrae - see the picture for an example of an immobilized patient. Vertebral fracture can cause spinal cord injury; spinal cord injury can cause paralysis or death (the more cephalic the injury, the higher the morbidity.)

Effects of Spinal Center Stimulation:C1-C2: initiates vagal responses of increased gastric secretion and peristalsis; increased nasal, buccal, and pulmonary mucosal secretions.

C3: initiates phrenic influence to increase depth of diaphragmatic excursions. Note that C3 inhibition is helpful in chronic cough, hiccups.

C4-C5: initiates lung reflex contraction (eg, used in expiratory dyspnea, emphysema) and pulmonary vascular vasoconstriction.

C6-C7: reflex center for increasing generalized vasoconstriction and myocardial tone.

T1-T3: initiates lung reflex dilation (eg, inspiratory dyspnea), dilates stomach body, and contracts pylorus; inhibits heart action (ie, antitachycardia reflex) and gastric hypermotility.

T4: initiates cardiac and aortic dilation and inhibits viscerospasms.

T5: initiates pyloric and duodenal dilation when applied to the right side.

T6: initiates gallbladder contraction when applied to the right side.

T7: initiates slight visceromotor renal dilation when applied bilaterally and stimulates hepatic function.

T8-T9: initiates gall duct dilation.

T10-T11: initiates slight visceromotor renal contraction, enhances pancreatic secretion, relaxes intestines and colon, and stimulates adrenals when applied bilaterally; initiates splenic contraction (and vascular rbc's) when applied on the left.

T12: initiates prostate contraction and tone of the cecum and bladder sphincter.

L1-L3: initiates uterine body, round ligament, and bladder contraction; pelvic vasoconstriction; vesicular sphincter relaxation.

L4-L5: initiates sigmoidal and rectal contraction; increases tone of lower bowel.