Seljaajunärvi

Seljaajunärvi, also known as the suprascapular nerve, is a mixed peripheral nerve originating from the brachial plexus. It is formed by contributions from the superior and inferior trunks of the brachial plexus, primarily from the C5 and C6 nerve roots. The nerve descends laterally and posteriorly, passing through the posterior triangle of the neck. It then traverses the suprascapular notch, an opening in the scapula, often deep to the superior transverse scapular ligament. Upon entering the infraspinous fossa, it branches to supply motor innervation to the supraspinatus and infraspinatus muscles. These muscles are crucial for shoulder abduction and external rotation, respectively. The suprascapular nerve also carries sensory fibers from the glenohumeral joint and the acromioclavicular joint. Injury to the suprascapular nerve can result from direct trauma, repetitive overhead activities, or entrapment at the suprascapular notch or spinoglenoid notch. Symptoms of nerve damage may include weakness in shoulder abduction and external rotation, pain in the shoulder, and atrophy of the supraspinatus and infraspinatus muscles. Diagnosis typically involves clinical examination, electrodiagnostic studies such as electromyography (EMG) and nerve conduction studies (NCS), and sometimes imaging like MRI. Treatment depends on the cause and severity of the injury and may range from conservative management with physical therapy to surgical decompression or repair.