If you feel a tendon in your neck bulging up with pain, the possible causes are jugular varicose vein accompanied by phlebitis, cervical spine muscle strain, cervical spine disease and so on. 1. Jugular varicose vein: Jugular varicose vein is a clinical sign of increased pressure in the jugular vein caused by various diseases, which is manifested by the expansion of jugular vein filling, and the contour of the blood vessel can be clearly seen on the surface of the body, so it is like “a tendon bulging up”. If there is pain, it may be accompanied by inflammation of the veins and pain. 2. Neck muscle strain: due to poor posture, long-term work, lack of exercise, etc., the neck muscles may be strained, neck muscles, ligaments, fascia and other tissues spasm, so there is a “tendon bulge” symptoms, due to spasm, accompanied by pain, and even turn the head, head down, raise the head, and other activities are limited. 3. Cervical intervertebral disc disease: If the patient has cervical intervertebral disc herniation and other underlying diseases, the protruding nucleus pulposus can stimulate the surrounding nerve tissues, resulting in radiating pain in the neck and shoulder muscles, ligaments and other tissues, and feeling like a tendon bulging in the neck, and the patient can also have symptoms such as fatigue and numbness in the limbs. Feeling like a tendon bulging in the neck accompanied by pain, there are many reasons, it is recommended to go to the regular hospital in time to identify the cause and timely treatment.