Dr. Ebraheim’s educational animated video describes the anatomy of the long thoracic nerve in a very easy and simple animation.
The long thoracic nerve travels in a distal direction behind the brachial plexus between the anterior and middle scalene muscles. It also passes under the clavicle and over the first rib. The nerve runs along the midaxillary line for 22-24 cm to reach the serratus anterior muscle. Due to the fact that it is a longer nerve, it is susceptible to traction related injury. Injury may occur due to axilla dissection or by aggressive retraction of the middle scalene muscle. If the nerve is injured, there will be weakness or paralysis of the serratus anterior muscle which causes medial winging of the scapula.
What is the function of the serratus anterior muscle? The serratus anterior pulls the scapula away from the midline and forward (scapular abduction). It also rotates the scapula upwards. The most important function of the serratus anterior is that it helps to stabilize the scapula so that the other muscles attached to the scapula can work properly.
Serratus anterior palsy: there will be a prominence of the scapular inferomedial edge with medial displacement and downward rotation. The position of the resting scapula is upwards and medial because the trapezius muscle dominates the motion of the scapula.
How do you diagnosis an injury to the nerve? The patient will complain of dull shoulder aches, pain and weakness in association with scapular winging. Injury to the long thoracic nerve (medial winging of the scapula) is checked by having the patient perform the wall push-up test for serratus anterior muscle weakness.
•Usually winging of the scapula will cause dull pain due to fatigue of the serratus anterior muscle.
•If there is severe acute pain in addition to winging of the scapula, this is a sign of brachial neuritis that needs to be excluded.
•EMG and nerve studies are very helpful in diagnosing problems of the long thoracic nerve.
•Treatment is usually nonsurgical (observation for at least 6 months)
o Muscle strengthening and bracing
o May take up to a year or longer for recovery
•Surgical treatment (with failure of nonsurgical methods)
o Can be helpful when there is a space occupying lesion pushing on the nerve (decompression of the long thoracic nerve)
o Split pectoralis major transfer for serratus anterior palsy (sternal head of the pectoralis major muscle may be transferred to the inferior border of the scapula).
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