Intercostal Muscle Strain
Clinically Relevant Anatomy
Intercostal muscles are muscles that present within the rib cage. Consist of three layers of muscles external, internal, and innermost layer they combine to fill the space between the ribs. External intercostals muscle are the outermost layer lies directly under the skin originate from the lower border of rib above run obliquely and insert into the upper border of the rib below. It expands the chest wall during inhalation. Internal intercostals the intermediate layer originate from the costal groove near the inferior border of the rib above to the upper border of the rib below, help to collapse the Lung during expiration. Innermost intercostals muscle, cross more than one intercostal space, and assist the internal and external intercostals in their function.
Intercostal muscles strain vary according to the type and intensity of injury, strain of intercostal muscles causes rib/chest pain, upper back pain, and affect the breathing pattern the patient will present with shallow short breathing pattern due to pain. It is an injury affect the muscles between two or more ribs
Mechanism of Injury
Intercostal muscles strain don't happen usually with daily life activities, it happens when the muscles are weakened, overexertion of muscles, direct trauma from falling or car accident, or blow from contact sports such as hockey, or repetitive torso twisting.
- A direct blow to the rib cage: such as falling, car accident, or trauma from contact sports such as football, hockey. In which the intercostal muscles will stretch or tear as ribs are suddenly forced to move apart.
- Twisting the torso: twisting while lifting, twisting from dancing position/yoga posture, and some sports such as tennis, golf. In which the ribs are moved apart from its normal range, excessive torso twisting may occur during sports.
- Reaching overhead: prolonged time of overhead activities or lifting above shoulder place undue stress on the muscles as we can see in painting the ceiling.
- Repetitive forceful movement: such as rowing, hitting a tennis ball.
- Physical labor: such as activities that include repetitive twisting, prolonged overhead activities, frequent weight lifting.
- High-thrust sports: where there's repeated use of the arm, shoulder, and upper back that put stress on intercostal muscles.
- Contact sports: when a direct sudden force hits the upper body.
- Sudden severe pain, in the upper back or rib cage due to a direct blow or sudden impact to the chest or sudden increase in the physical activity.
- Muscle tension and stiffness, muscles respond to injury by tensing up, causing upper back pain and stiffness with movement.
- Gradual worsening pain, pain worsening within days or weeks if the intercostal muscles are still under tension of repetitive, gradual stress. this type is common after sports such as baseball.
- Difficulty breathing, with intercostal muscle strain the breathing pattern will be affected due to pain and it will be a short shallow breathing pattern to avoid pain. That may lead to less blood oxygenation.
- Tenderness of the affected muscles and adjacent ribs.
- Inflammation, a strained muscle may be associated with swelling and increased sensitivity in the affected area.
- Some rare cases swelling of intercostal muscles lead to a blood clot around muscle causing a hematoma
- Pain from intercostal muscle strain increase with coughing, sneezing, or breathing deeply,
Diagnostic imaging X-ray, MRI not needed for the diagnosis of an intercostal strain, but it's used to rule out the possibility of rib fracture or internal organ injury.
Diagnosis is based on patient history and physical examination:
Patient history, ask the patient about current symptoms, pain when and how it started, and if there is a history of recent trauma and patient's physical activities,
Physical examination, palpation to define the area of tenderness, swelling. Instructions to do active movements of the torso/trunk to know to what extent it affects the function and movement.
Intercostal muscle strain may be mistaken by upper back pain, it is relatively hypomobile part and its injury is rare.
Upper back pain is due to poor posture for a long time, its pain described as a sharp burning pain that can spread down to the neck, shoulder, and the pain is intermittent.
Intercostals strain, is a result of trauma overexertion activity and its area of pain can be located by the patient, unlike the pain from a lung disorder, it is difficult to pinpoint.
Healing depends on the severity of the injury, the time range from a few days to 8 weeks in the majority of cases and in some cases lasts longer other last longer cause upper back pain. The first advice for the patient is resting for a few days and apply ice back in the first two days of pain to eliminate the inflammation.
Holding a pillow to stabilize the injured, painful area during deep breathing and coughing.
Pain relief medication: such as acetaminophen to interfere with pain signals sent to the brain and minimize overall pain levels.
Muscle relaxant medications: in acute severe pain for a short term effect to reduce muscle tension and spasm.
Physical Therapy Intervention
Physical therapy starts once the inflammation is reduced, it will focus on pain relief modalities, stretching under supervision, strengthing exercises for endurance, improving posture, and breathing exercise.
Breathing exercise, deep breathing exercise patient is instructed to apply diaphragmatic breathing with holding a pillow stabilizing the area of pain.
Stretching, tight muscles can cause muscle imbalance and improper mechanism stretching under supervision within the limit of pain such as roller stretch, some yoga positions, or upper back extension, but if the strain is caused by overstretching of the muscle more stretch may trigger pain and result in muscle weakness and this should be controlled by strengthing program.Strengthing exercise if there's muscle imbalance, thoracic extension exercises with breath holding for a few seconds, and breath out slowly and backward weight lifting exercise has shown to improve thoracic kyphosis and decrease intercostal muscle pain. 
The Anatomy of the External Intercostals. Verywell health
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