Biological compression occurs when external or internal forces physically narrow the space around a nerve or blood vessel, disrupting its normal function. This pressure can be generated by various factors, including fluid accumulation, inflammation from injury, the formation of bone spurs, or the protrusion of disc material. When a nerve is compressed, its internal blood supply and the flow of nutrients along the axon are often compromised, leading to symptoms like numbness, tingling, and pain.
The resulting nerve dysfunction is similar to a kinked garden hose, preventing the transmission of electrical signals. These anatomical “bottlenecks” are found where nerves or vessels pass through confined, rigid spaces bordered by bone, ligament, or muscle. The location of the compression dictates the specific symptoms felt, often far from the actual site of pressure.
Spinal and Central Body Compression
Compression along the central axis of the body, particularly the spine, affects major nerve roots and is a frequent source of chronic symptoms. The most common form is spinal stenosis, a condition characterized by the narrowing of the bony channels that house the spinal cord and the nerve roots exiting the column. This narrowing often results from age-related changes, such as the thickening of spinal ligaments or the development of bony overgrowths called osteophytes.
A herniated disc represents another central compression mechanism. The intervertebral discs, which act as shock absorbers between the vertebrae, have a soft, gel-like center. If the tough outer layer tears, the inner material can push out, or herniate, directly pressing on an adjacent spinal nerve root.
Compression in the lower back, or lumbar spine, is a primary cause of sciatica, where the pressure is applied to the roots that form the large sciatic nerve. This nerve root compression typically causes pain, numbness, or weakness that radiates down the buttock and leg. Similarly, cervical radiculopathy involves nerve root compression in the neck, or cervical spine, causing symptoms to travel down into the shoulder, arm, and hand.
Upper Body Compression Hotspots
The upper body contains several vulnerable sites where nerves pass through tight anatomical tunnels, making them susceptible to entrapment. The wrist is the site of the most common nerve compression disorder, carpal tunnel syndrome, which affects the median nerve. This nerve runs through the rigid carpal tunnel, a confined space at the base of the palm formed by the wrist bones and covered by a thick ligament.
Swelling from repetitive strain, injury, or underlying conditions like fluid retention can reduce the space within the carpal tunnel, squeezing the median nerve. Symptoms usually manifest as numbness and tingling in the thumb, index finger, middle finger, and half of the ring finger. Moving up the arm, the cubital tunnel at the elbow is another frequent compression site, involving the ulnar nerve.
Chronic pressure from prolonged elbow flexion or direct trauma can lead to cubital tunnel syndrome, causing numbness and weakness primarily in the ring and little fingers. In the shoulder and neck area, thoracic outlet syndrome (TOS) involves the compression of the brachial plexus nerves, subclavian artery, and subclavian vein as they exit the neck. This compression typically occurs in the scalene triangle, bordered by the collarbone, the first rib, and the scalene muscles.
Lower Body Compression Sites
Peripheral nerve entrapments are also common in the lower body, often occurring at points where nerves transition from deep muscle layers to superficial areas. One such condition, meralgia paresthetica, involves the compression of the lateral femoral cutaneous nerve as it passes near the anterior superior iliac spine, often beneath the inguinal ligament in the hip area. This nerve is purely sensory, and compression causes burning pain, tingling, and numbness exclusively on the outer side of the thigh.
Around the knee, the common peroneal nerve is highly vulnerable to entrapment as it winds around the head of the fibula, the prominent bone on the outside of the knee. Because the nerve is superficial at this point, it can be compressed by external forces like tight casts or prolonged leg crossing. Entrapment here can lead to foot drop, an inability to lift the front of the foot, along with numbness on the top of the foot and outer leg.
Further down at the ankle, tarsal tunnel syndrome is similar to carpal tunnel syndrome, affecting the posterior tibial nerve. This nerve is compressed as it runs through the tarsal tunnel, a rigid space behind the medial malleolus. The tunnel is formed by bone and a ligament called the flexor retinaculum, and pressure from swelling or injury can trap the nerve, resulting in burning pain and tingling in the sole of the foot and the toes.
Finally, a more acute and severe form of pressure, called compartment syndrome, can occur. This happens when swelling within a muscle compartment, often after trauma, rapidly compresses the nerves and blood vessels.