Core stability refer to the ability of the body to control the trunk or core by providing stability of the lumbar spine and the pelvis. There is 2 type of group of muscle that provides stability of the lumbar spine and pelvis; Local Deep muscles and the Superficial Global muscle.
They are a very important stabilizer of the spine because its function is to maintain your body an upright posture by providing stability of the lumbar spine and the vertebrae. Without the dynamic stabilizing activity from that trunk muscle, the spine would collapse in the upright position.
LOCAL DEEP MUSCLE
The local Deep muscles are ” the core muscle” that are directly attached to each individual segment in the lumbar spine; the lumbar spine is located just below your back and this serve as the common area where people complains of pain. In addition to that, it helps maintain each segment in a stable position so that the structures such bones and ligaments are not stressed at the limits of the motion.
There are 4 core muscle: Transverses abdominals, multifidus, diaphragm and pelvic floor muscle. The deep stabilizer muscle works together to hold the trunk in a stable position. The picture below is what multifidus muscle look like, as they are attached to each individual segment.
The Diaphragm muscle is a muscle that is responsible for inspiration, which means that whenever you breathe, your diaphragm is the one that is performing the action. Without it, you will have no choice but to use your accessory muscles such as your neck and chest muscle for breathing as a compensation.
Pelvic floor muscle is an another important muscles that provide great support in your pelvic organs. For instance, it helps the bowel & bladder continence, and it provides intra-abdominal pressures. This is a very a common problem for women when they complain of pain.
SUPERFICIAL GLOBAL MUSCLE
They are a torque producing muscle which their job is to move the body and provide stability of the trunk against perturbation. They are attached onto the ribs, and because of that, they are less able to stabilize the lumbar spine and the pelvis. Overusing of this muscle can decrease the function of the core muscle.There are 4 global muscle: Rectus abdominals, erector spinae muscle, internal and external oblique muscle.
When the deep core stabilizer is weak, this will let the global muscle compensate. The pain in the lumbar spine and pelvis results from the compensation of the global muscle. Treating the painful area may only provide short-term relief of pain. But to treat the pain EFFECTIVELY, you will need to eliminate the compensation by improving your core deep muscle.
Point to remember:
If both of your superficial global and local deep muscles are weak and your body is unable to provide compensate, the spine would be unable to resist the force of gravity and your trunk would collapse; this problem only happen if you have a Neurological conditions like Stroke, Multiple Sclerosis, Cerebral Palsy, Spinal Cord Injury etc.