Organ of gripping, it has above all a driving role. There are 39 muscles (not counting those of the hand) divided as follows: 16 muscles in the shoulder forming the scapular belt, 3 muscles in the arm and 20 muscles in the forearm divided into 3 lodges, which end up on the wrist, itself formed with the hand of 27 bones, including 8 at the carp.

The nerves that pass through these muscles come from the cervico-brachial plexus, which can be trapped in different parts of the upper limb, from its vertebral exit, this is called CervicoBrachial Neuralgia (NCB), or "top sciatica" to the various trunks or muscle nerve endings, and thus can create a canalary syndrome, in an inextensible channel.

The most common are hand carpal tunnel syndrome compressing the median nerve, the syndroma of the ulnar nerve at the elbow, or the thoraco-brachial syndrome at the shoulder, which corresponds to the compression of the vasculo-nervous package between the anterior and middle scalene muscles of the neck.

All pains related to these pathologies can be relieved in Osteopathy, which can reduce the allopathic anti-inflammatory drug treatment that treats the symptoms and not the cause (not to mention the side effects, including NSDAs on the gastric mucosa), or even sometimes if taken in time to avoid possible surgery.

Remember that the junction between a nerve (motor neuron) and a striated muscle is called a neuromuscular spindle, or motor plate, and that the junction between 2 nerves (between an axon and a dendrite) is called a synapse, a place of ion exchange, where nerve information is transmitted through neurotransmitters including acetylcholine.

The cell bodies of motor neurons are found mainly in the ventral horns of the spinal cord (grey substance), but also in the brainstem.

The energy needed to contract the muscle is brought in the form of ATP, synthesized by the mitochondria of muscle cells, thanks to the breakdown of carbohydrates (glycolysis), fats and proteins, in the KREBS cycle.

It is produced during breathing in the aerobic phase (anabolism), and during fermentation (the formation of lactic acid causing aches) in the anaerobic phase (catabolism) during significant intensity or time-based efforts.

This creates a reconciliation of the actin and myosin fibers that make up the muscle's myofibrils.

This nerve conduction is measured with an ElectroMyoGram (EMG), and it is saltatory because it jumps from knot to knot (from Ranvier) the myelin sheaths.