Indications and Clinical Considerations
The muscles of the posterior neck are particularly susceptible to the development of acute and chronic pain symptomatology after acute flexion, extension, or lateral bending injuries to the neck or repeated microtrauma secondary to pressure from purse straps, backpacks, or laptop computer cases. These muscles also are adversely affected by chronic stress, a behavioral abnormality that may manifest itself clinically as cervical strain. Myofascial pain syndrome with its pathognomonic myofascial trigger points also may occur, either alone or in combination with cervical strain.
Cervical strain is the result of microtrauma or macrotrauma to the muscle fibers or the musculotendinous unit of the trapezius and the deep muscles of the posterior neck, including the splenius capitis and splenius cervicis. Clinically, cervical strain manifests as aching, tightness, stiffness, and pain in the neck and upper back, with pain radiating into the ipsilateral shoulder. As mentioned previously, cervical strain may coexist with myofascial pain syndrome, and trigger points also may be present. Symptoms of cervical strain can be reproduced with ipsilateral rotation and contralateral bending of the cervical spine. Tenderness to deep palpation is present, but unless myofascial pain syndrome is also present, trigger points should be absent. The pain, spasm, and other associated symptoms of cervical strain are aggravated with physical or emotional stress. Plain radiographs will often reveal straightening of the cervical lordotic curve in patients suffering from acute cervical strain ( Figure 19-1 ).
Clinically Relevant Anatomy
The muscles of the neck work together as a functional unit to stabilize and allow coordinated movement of the head and associated sense organs. Trauma to an individual muscle can result in dysfunction of the entire functional unit. The trapezius, splenius capitis, splenius cervicis, and semispinalis capitis are the primary extensors of the neck, and are part of the group of muscles known as the axioscapular group , which is involved in stabilization and movement of the scapula ( Figure 19-2 ). The upper trapezius originates at the ligamentum nuchae and the spinous processes of the cervical and upper thoracic spine and attaches to the upper margin of the scapula. The middle portion of the trapezius originates from the spinous processes of the upper thoracic spine and attaches to the medial border of the scapula. The lower fibers of the trapezius originate from the spinous processes of the lower thoracic spine and attach to the medial portion of the scapular spine. The splenius capitis arises from the lower part of the ligamentum nuchae and the upper four thoracic spinous processes and inserts into the superior nuchal line of the occipital bone. The splenius cervicis has a similar origin but inserts into the upper transverse process of the upper cervical vertebrae. These points of origin and attachments of these muscles are particularly susceptible to trauma and the subsequent development of strain or myofascial trigger points (see Figure 19-2 ). The injection technique described later serves as both a diagnostic and a therapeutic maneuver.