Serratus Posterior Inferior: Pain Pattern and Treatment
The serratus posterior inferior is a thin sheet across the lower back of the rib cage, running from the upper lumbar spine out to the last four ribs. It steadies those ribs against the pull of the diaphragm. Its documented pattern is a local one: a nagging ache over the lower ribs at the back that does not travel. It is the ache left behind after the bigger low-back muscles have been treated.
Attachments and action
Origin: The spinous processes of the lower two thoracic and upper two or three lumbar vertebrae, through the thoracolumbar fascia.
Insertion: The lower borders of the ninth through twelfth ribs, beyond their angles.
Action: Draws the lower ribs down and back, steadying them against the diaphragm during breathing; assists rotation and extension of the trunk.
Where the pain is felt: Over the lower ribs at the back, on one side, spreading a short way across the low back. It stays where it is; it does not run into the buttock or leg.
Common causes: Twisting while lifting; a long reach across a bed or a counter; a forceful cough or sneeze; rowing and paddling; sleeping twisted on a soft mattress.
Patients say: "It is right over my lower ribs, and it nags." "Everything else got better and this one spot stayed." An ache that a deep breath or a twist finds.
When to get evaluated: Pain over the lower ribs with fever, blood in the urine, or pain that arrives in waves needs medical evaluation for the kidney first. Rib pain after a fall needs assessment for a fracture.
How this muscle is examined and treated
Examination tests trunk rotation and a deep breath, then presses the lower ribs at the back for the point that reproduces the familiar nag. Needling here addresses the muscle over the ribs at a shallow angle. Assessment and treatment happen in the same visit.
Related conditions
Low Back PainChronic Pain PatternsSports & Performance Injuries
This page is educational. It describes muscle referral patterns commonly associated with pain; it does not diagnose your condition. Individual patterns vary. For evaluation of your specific pain, see a licensed clinician. Seek immediate medical care for emergencies. Eugene Baek, L.Ac. · New Jersey License 25MZ00080600