Mid back pain most often comes from muscle strain, poor posture, or joint stiffness in the thoracic spine, the 12 vertebrae between your neck and lower back. But because this region connects to your rib cage and sits near several vital organs, the list of possible causes is broader than many people expect. Some are minor and resolve on their own, while others need medical attention.
Muscle Strains and Ligament Sprains
The most common cause of mid back pain is simple overuse or injury to the muscles and ligaments that support the thoracic spine. Lifting something heavy, twisting awkwardly, or even sleeping in a bad position can strain the muscles that run along either side of your spine. Ligament sprains happen when the tough bands connecting your vertebrae get stretched or torn, usually from a sudden movement or impact.
These injuries tend to cause a dull, aching pain that worsens with movement and improves with rest. Most muscle strains and sprains heal within a few weeks with basic self-care: gentle movement, ice or heat, and over-the-counter pain relief. If the pain lingers beyond four to six weeks, something else may be going on.
Posture and Muscle Imbalances
Hours of sitting hunched over a desk or phone puts constant stress on the muscles and joints of the mid back. Over time, the body adapts by tightening some muscles and letting others weaken. This pattern, sometimes called upper crossed syndrome, shifts the load on your spine and can produce persistent aching between the shoulder blades.
What’s interesting is that the “tightness” and “weakness” people feel in this pattern aren’t always true shortening or loss of strength. The nervous system adjusts how it activates muscles based on pain, fatigue, and perceived threat. So what feels like a knot in your mid back may actually be your brain’s protective strategy: keeping certain muscles switched on to guard against further discomfort. This is why stretching alone sometimes doesn’t fix the problem. Retraining movement patterns, strengthening the upper back, and reducing prolonged static positions often work better.
Rib Joint Dysfunction
Each of your 12 thoracic vertebrae connects to a pair of ribs through small joints called costovertebral joints. These joints allow your rib cage to expand when you breathe. When one of them gets stuck or restricted, it can cause sharp, localized pain in the mid back that worsens with deep breaths, twisting, or prolonged sitting.
People often describe this as feeling like a rib is “out of place.” Ribs don’t actually dislocate easily, but the joint can lose its normal range of motion from poor posture, a sudden twist, or repetitive loading. When the joint is restricted, the rib can’t pivot properly during inhalation, and the surrounding soft tissue gets compressed. The result is a catching or stabbing sensation, sometimes with tenderness you can feel by pressing on the area near the spine. This is one of the more common causes of mid back pain that gets overlooked, partly because it doesn’t show up on imaging.
Disc Problems in the Thoracic Spine
Herniated discs get a lot of attention in the neck and lower back, but they can happen in the mid back too. A thoracic disc herniation occurs when the cushion between two vertebrae bulges or ruptures, potentially pressing on nearby nerves or the spinal cord. That said, it’s far less common here than in other parts of the spine. Thoracic disc surgery accounts for less than 4% of all disc procedures.
Here’s the tricky part: imaging studies show that 11% to 37% of people have thoracic disc herniations on MRI without any symptoms at all. So even when a scan reveals a bulging disc, it may not be the source of your pain. When a thoracic herniation does cause problems, symptoms can include pain that wraps around the rib cage, numbness or tingling, and in rare cases, weakness in the legs. Because these symptoms overlap with neck and lower back conditions, diagnosis is sometimes delayed.
Age-Related Wear and Tear
Spondylosis is the medical term for the gradual breakdown of the discs, joints, and bones of the spine that comes with aging. In the thoracic spine, this typically causes stiffness and pain when bending forward or backward. The cartilage cushioning the joints wears thin, bone spurs may develop, and the discs between vertebrae lose moisture and height.
These changes are nearly universal in people over 50 and often show up on X-rays without causing any pain. When they do cause symptoms, the pain tends to be worse in the morning or after long periods of inactivity, then eases with gentle movement.
Compression Fractures
The thoracic spine is the most common site for vertebral compression fractures, especially in older adults with osteoporosis. These fractures happen when weakened bone collapses under pressure. In severe osteoporosis, something as minor as sneezing, coughing, or getting out of a car can cause one.
The hallmark symptom is sudden back pain that gets better with rest and worse with movement. You may also notice tenderness at one specific spot, muscle spasms, and over time, a loss of height as the compressed vertebra shortens. Some mild fractures cause little or no pain and go undetected. But the numbers are striking: an estimated 40% to 50% of people aged 80 or older have experienced at least one compression fracture. Women who have been through menopause and anyone over 50 with low bone density are at highest risk. A previous compression fracture significantly raises the chance of another.
Scheuermann’s Disease
In teenagers and young adults, a condition called Scheuermann’s disease is the most common cause of structural, progressive rounding of the mid back. It develops before puberty and worsens during adolescence, typically appearing around age 10 to 12. It affects anywhere from 0.4% to 8.3% of the population, with no clear difference between boys and girls.
The condition involves wedge-shaped deformities in at least three consecutive vertebrae, creating an exaggerated forward curve that can’t be corrected just by standing up straighter. That’s a key distinction: postural rounding (the slouch many teens have) is flexible and can be straightened voluntarily, while Scheuermann’s kyphosis is rigid and angular. Pain is common but not universal, usually centered in the mid back and worse after activity or prolonged sitting. X-rays show characteristic changes in the vertebral endplates and sometimes small herniations of disc material into the bone itself.
Organ-Related Referred Pain
Not all mid back pain originates in the spine. Several internal organs can refer pain to the thoracic region, which is why persistent or unusual mid back pain sometimes warrants a broader investigation.
- Gallbladder and liver problems can send pain to the right shoulder blade, the area between the shoulder blades, or the right side of the chest wall. Gallstone attacks often produce this pattern alongside nausea and pain after eating fatty foods.
- Pancreatic issues can refer pain to the mid back near the shoulder blades, sometimes described as a deep, boring ache that radiates from the abdomen to the back.
- Kidney stones or infections typically cause flank pain that can wrap around to the mid or upper back, often accompanied by changes in urination, fever, or waves of intense cramping.
- Heart and lung conditions can also produce upper back or mid back discomfort, particularly pulmonary embolism, pneumonia, or in rare cases, heart attack (more common in women, who are more likely to experience back pain as a cardiac symptom).
The key signal that your mid back pain may be organ-related rather than musculoskeletal is its behavior. Pain that doesn’t change with movement or position, comes with fever, nausea, or breathing difficulty, or started suddenly without any physical trigger deserves prompt evaluation.
Warning Signs That Need Attention
Most mid back pain is mechanical and resolves with time. But the thoracic spine is less forgiving than the lower back when serious conditions are involved, because the spinal cord runs through it with very little extra room. Pay attention to pain that comes with numbness or weakness in your legs, difficulty with balance or coordination, unexplained weight loss, or pain that wakes you from sleep and doesn’t respond to position changes. A history of cancer, recent infection with fever, or significant trauma (even a minor fall if you’re over 50 or have osteoporosis) also shifts the picture toward something that needs imaging or further workup.