The cervical vertebrae are the most frequently injured vertebrae because they are the most mobile part of the spine and because they are so small and delicate. ²⁷ The rib cage provides stability to the vertebrae from T-1 to T-10 and keeps this portion of the spine relatively immobile. Because the thoracic vertebrae are so strong, fractures and/or dislocations at this level should increase suspicion for spinal cord injury. ¹⁹ The lumbar vertebrae are the largest and strongest in the vertebral column. ^{27. and 33.}

Ligaments attach to the transverse and spinous processes to connect the vertebral bodies and provide support and stability to the vertebral column. They also limit the spinal column from excessive flexion and extension. Between the vertebral bodies are discs that act as shock absorbers and articulating surfaces for the adjacent vertebral bodies. ^{33. and 35.}

The spinal cord extends from the brain, through the foramen magnum, and down the vertebral column to the level of L2. This mass of nerve tissue regulates body movement and function through transmission of nerve impulses. The diameter of the spinal cord is largest in the cervical and lumbar regions and tapers in the lower thoracic area. In adults it terminates in a cone-shaped structure, known as the conus medullaris, at the L1 or L2 level. Spinal nerve roots that exit below the conus medullaris are referred to as the cauda equina. ^{5.27. and 31.}

The primary function of the spinal cord is to regulate bodily function and movement by transmitting nerve impulses between the brain and the body. Cross-sectional views of the spinal cord reveal a butterfly-shaped core composed of gray matter, surrounded on the outer edges by white matter. The gray matter contains nerve cell bodies and is divided into three distinct regions, each with specific characteristics: the posterior (dorsal), intermediolateral (lateral), and anterior (ventral) horns. The posterior, or dorsal, horn contains sensory interneurons and axons whose cell bodies are located in the dorsal root ganglion. The intermediolateral, or lateral, horn contains cell bodies with autonomic nervous system function. The anterior, or ventral, horn contains somatic motor neurons that leave the spinal cord via the spinal nerves. ^{27. and 31.}

The white matter of the spinal cord consists of multiple ascending and descending pathways (referred to collectively as “spinal tracts”), which are individually named based on their origins and terminations. These tracts run parallel to the spinal cord’s vertical axis and transmit action potentials to and from the brain to other parts of the spinal cord. Table 22-1 lists some of these specific tracts and describes their functions. ^{27. and 31.}

The spinal cord has 31 pairs of spinal nerves that exit the spinal cord bilaterally and provide pathways for involuntary responses to specific stimuli. There are 8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves, 5 sacral nerves, and 1 coccygeal nerve. The spinal nerves innervate voluntary striated muscle and are responsible for the majority of the communication between the spinal cord and the rest of the body. Each of these nerves has a posterior root that transmits sensory impulses from the periphery into the spinal cord and an anterior root that transmits motor impulses from the spinal cord out to the periphery. Table 22-2 lists the spinal nerve muscle innervations and their corresponding expected patient response. The dorsal root of these nerves innervates a distinct region of the body surface known as a dermatome. ^{27. and 33.} Assessment of the 28 dermatomes provides information about function to sensory areas of the spinal cord. Figure 22-1 illustrates the sensory dermatomes.

The vascular supply for the spinal cord comes from branches of the vertebral arteries and the aorta. The anterior and posterior spinal arteries branch off the vertebral artery at the cranial base and descend parallel to the spinal cord. ³¹ Because spinal cord arteries cannot develop collateral blood supply, injuries to these arteries can be devastating.

Mechanisms of spine injury include blunt and penetrating forces. The vertebrae, spinal cord, and nerve roots may be injured as a result of fractures, dislocations, or subluxation. The cord may also be injured through direct penetration by a bullet, knife, or other sharp object, or by adjacent injuries resulting in localized edema that compresses the spinal cord. Six basic types of movement can injure the spinal cord. These are illustrated in Figure 22-2 and summarized in Table 22-3.

The following mechanisms have been identified as being commonly associated with cervical spine injuries: fall from a height greater than or equal to 3 feet or five stairs; axial loading; motor vehicle collision at a high rate of speed with rollover or ejection; collision involving a motorized recreational vehicle; and bicycle collisions. ³⁰ In addition, spinal injuries should be suspected if a fall results in fractures of the heels⁷ or if an unrestrained (no seat belt) patient presents with facial injuries.

In addition to the mechanism of injury, the following pieces of history may indicate a potential spinal cord injury: history of significant trauma and altered mental status from intoxication; history of seizure activity since the incident; any complaint of neck pain or altered sensation in the upper extremities; complaint of neck tenderness; history of loss of consciousness; injuries to the head or face. When obtaining the history, the emergency nurse should ask the patient about neck pain and changes in sensation or movement since the time of injury. Any history of incontinence before arrival in the ED is important to identify because it may signal a spinal cord injury. ^{11.18. and 30.}

If the patient is unconscious, prehospital history may be the only source of information available concerning the patient’s condition and behaviors immediately after the incident; thus the emergency nurse should obtain as much information from prehospital personnel as possible. Patients who are unconscious or have any altered mental status and those with distracting injuries are at a higher risk for missed cervical spine injury because their injuries are more easily overlooked and they are unable to report any indicative symptoms. 14. ^{and 30.}

The emergency nurse should observe the patient for obvious signs of spinal injury, including deformity of the vertebral column, cervical edema, and ballistic wounds in the neck, chest, or abdomen. Abrasions or contusions at the level of the lap or shoulder belt in restrained patients can indicate spinal injuries at those levels. ¹⁴

The patient’s ventilatory pattern and effort may also indicate a cord injury. Injuries to the spinal cord between C3 and C5 can result in progressive respiratory insufficiency secondary to significant respiratory muscle dysfunction when diaphragmatic innervation by the phrenic nerve is altered. Injuries to the cord below C5 lead to decreased intercostal and abdominal muscle function, in turn altering the normal mechanics of ventilation and increasing the work of breathing. ^{5.18. and 34.}

The patient’s ability to move and perceive pain during procedures such as arterial punctures or intravenous catheter insertion is another important observation. The patient should be able to wiggle his or her toes and fingers and to lift arms and legs. The inability to do so indicates some type of spinal injury. Continued penile erection (priapism) can occur with loss of sympathetic nervous system control and may indicate a cervical spine injury. ¹⁹

Leakage of cerebral spinal fluid (CSF) from the nose or ears may also be noted. Confirm the presence of CSF using the halo test (as discussed in Chapter 21). Due to the high incidence of simultaneous closed head injuries and cervical spine injuries, patients with CSF leaks raise even higher suspicion for serious spinal trauma.

Pulse rate and quality should be palpated. In neurogenic shock the pulse is slow and strong, whereas in hypovolemic shock it is rapid and weak. ⁵

Strength and symmetry of movement in all four extremities should be evaluated (see Table 22-2). A quick motor evaluation should include flexion and extension of the arms, flexion and extension of the legs, flexion of the foot, extension of the toes, and sphincter tone.

Sensory status may be assessed by evaluation of dermatomes. The patient should be able to distinguish between sharp and dull sensations using a safety pin or cotton swab. Testing should begin at the level of no reported sensation and proceed upward to identify the level at which feeling returns.

The presence of sacral or perineal sensations should also be assessed. ¹⁴ If sacral sensations are present in patients with other focal deficits (termed “sacral sparing”), an incomplete spinal cord injury should be suspected.

Finally, the patient’s entire spinal column should be gently palpated for pain, tenderness, crepitus, and step-off deformity. Palpation requires that the patient be logrolled by at least three team members to maintain spinal alignment. ¹⁴ If the cervical collar is removed for this procedure, manual stabilization must be maintained.

The emergency nurse may perform an assessment of the patient’s reflexes. Reflexes are summarized in Table 22-4.