Before we can look at the difference between herniated and bulging disc, lets first understand what is meant by a disc.
What is a disc?
In anatomy, a disc refers to a structure which is found between two adjacent vertebrae in the spine. The disc acts as a cushion between two vertebral bones, it performs the role of shock absorption among others.
A disc forms a fibrocartilaginous joint which allows the vertebrae to move slightly. It also functions as a ligament which holds the vertebrae together. Discs also help in protecting the spinal cord which is located inside the vertebral column. Structurally, a disc is made up of a fibrous outer ring known as anulus fibrosus which circumvents an inner nucleus referred to as the nucleus pulposus. The nucleus pulposus contains a gel-like material. Discs are oval in shape.
A human spine consists of a total of 23 discs. The cervical region of the vertebral column consists of 6 discs while the thoracic region consists of 12 discs. The lumbar region consists of 5 intervertebral discs.
There is one intervertebral disc in between any two adjacent vertebrae except in the cervical region where the atlas joins to the axis. The atlas is the first segment of the cervical region. It forms a ring around the axis which is the second segment of the cervical region. The axis is cone-shaped. It provides a pivot around which the atlas can rotate. Rotation of the atlas allows the neck to swivel. It is the reason why one can turn around their neck to look back when he or she is walking towards a given direction.
Difference between herniated and bulging disc
Returning to herniated and bulging discs, these two conditions of the intervertebral disc differ from one another in terms of how they occur. Lets look at each of them so as to understand their differences.
Herniated discs occur as a result of the gel-like material in the nucleus pulposus being forced out of a disc through a tear in the anulus fibrosus part of disc. Herniated discs are also referred to as slipped or ruptured discs. The tear in the anulus fibrosus allows some of the soft inner cartilage to protrude outwards, the disc then bulges towards the outside.
Because of the escape of the gel-like material through the outer disc ring and its exposure to an environment outside the disc, herniated discs are referred to as “uncontained”.
A herniated disc is likely to cause pain. The most common location for a herniated disc is the lower back and for this reason, one is likely to experience lower back as a result of disc herniation. Herniated disc can also put pressure on the sciatic nerve leading to pain which extends down to the legs.
Symptoms of herniated discs include pain and numbness on one side of the body, painful limbs, pain that worsens at night or after walking a short distance and muscle weakness among other symptoms.
A bulging disc occurs as a result of the outer ring of the disc expanding beyond the space it normally occupies. Bulging affects a large part of the disc. A bulging disc is not characterised by a tear or leaking out of nucleus material and for this reason, it is referred to as “contained”.
Bulging discs are the most common of the two discs. They however do not usually cause pain. Bulging discs may occur as a result of the normal aging process of invertbral discs. As they age, discs lose their natural elastic recoil.