Purpose <p>This study aimed to compare the electrical activity and ultrasonographic dimensions of cervical muscles in patients with cervical lateral spinal stenosis (CLSS) and asymptomatic controls.</p> Method <p>In this case-control study, 25 patients with CLSS and 25 controls without neck pain, who participated voluntarily. Longuscoli (LC), sternocleidomastoid (SCM), cervical multifidus (MF) and splenius capitis (SC) muscles dimensions were measured by ultrasonography. The electrical activity of the superficial cervical muscles during neck flexion and extension, craniocervical flexion, and rapid shoulder movements were recorded by electromyography.</p> Results <p>The cross-sectional area of the MF muscle in patients with CLSS was smaller than those without neck pain (<i>P</i> &lt; 0.05). Also, relative asymmetry in the cross-sectional area of LC and MF muscles in the patient group was greater than the controls without neck pain (<i>P</i> &lt; 0.05). There was no significant difference in the thickness of superficial muscles and their asymmetry between the two groups (<i>P</i> &gt; 0.05). Electrical activity of erector spin (ES) muscles during extension and craniocervical flexion in patients was higher than that of controls (<i>P</i> &lt; 0.05). The electrical activity of the SCM muscle during craniocervical Flex. was higher in patients than those without neck pain (<i>P</i> &lt; 0.05). There was a significant relationship between ES activity during craniocervical Flex. and pain intensity (<i>P</i> &lt; 0.05; <i>r</i> = 0.418).</p> Conclusion <p>This study showed decreased cross-sectional area of the deep muscles and increased superficial muscle activity in CLSS which may leads to functional muscle disorder in cervical region. Therefore, it seems that rehabilitation therapy focused on training the axial muscles of the cervical spine can be effective in the treatment of these patients.</p>