Nerve - epaule Toulouse

The nerves

A nerve is a sort of two-way power cable from the spinal cord and the brain.

It allows at the level of a member to:

control the muscles to perform movements (motor role);

to report various information to the brain such as sensation (sensory role), pain (nociceptive role), position in limb space (proprioceptive role);

also to control the cutaneous heat, the circulation of the blood by means of micro-vessels (vegetative role);

And many other things ! …

Some nerves are mixed (motor and sensory control), pure motor or purely sensory

We will confine ourselves here to the main nerves of the shoulder after having briefly evoked their origin, namely the brachial plexus.

Brachial plexus

plexus-et-artère-axillaire-570x545 — Rapports du plexus brachial avec le squelette de l’épaule et les vaisseaux du membre supérieur

It has an hourglass shape whose narrow portion corresponds to the passage between the clavicle and the first rib, with:

an upper triangle formed by the 5 cited roots that meet in
- 3 upper, middle and lower primary trunks,
- they themselves give rise to lateral, medial and posterior lateral trunks (because they are superlative around the axillary and then the humeral artery).

Secondary trunks emerge from the nerves to the scapular region such as the suprascapular nerve or the pectoralis nerves (pectoralis loop)

an inferior triangle (under the costoclavicular cleft) formed by the terminal branches of division of the secondary trunks, called terminal trunks numbering 7
- musculo-cutaneous nerve
- axillary nerve (former name = circumflex)
- median nerve
- ulnar nerve (old name = ulnar)
- radial nerve
- medial brachial dermal nerve
- Medial anti-racheal cutaneous nerve

Only nerves that we think have an interest in the pathology of the shoulder have been highlighted and are the subject of a dedicated page (click on it).

The brachial plexus corresponds to the origin of the nerves for the upper limb, originating from the nerve roots emerging from the cervical spine.

5 nerve roots participate in the brachial plexus: C5, C6, C7, C8, and T1 (C for cercival, T pout thoracic).

The brachial plexus provides motor and sensory innervation of the entire upper limb and is located at the lower part of the neck.

plexus-brachial-face-complet-modifié — plexus brachial

Axillary nerve

The axillary nerve is an end branch of the posterior (and therefore secondary) branch of the brachial plexus.

His former name is circumflex nerve because presents a circular path.

It is a relatively short nerve since it bypasses the humerus at the level of its surgical collar.

It has relationships with the lower region of the glenohumeral joint, lower articular capsule and lower edge of the subscapular muscle and tendon.

Once the humerus is bypassed from the back, it travels to the deep surface of the Deltoid muscle that it innervates and contributes to the sensitivity of the shoulder stump of the lateral aspect of the arm.

His traumatic pathology is met with in certain dislocations of the shoulder since the nerve accompanies the humerus during its displacement, in the accidents of the road (motorcycle in particular).

The pathology will be further detailed in one chapter (pathology -> other -> neurological shoulder).

Musculocutaneous nerve

The musculocutaneous nerve is an end branch of the lateral (secondary) trunk.

Its course is also close to the shoulder area since it is internal, close to the coracoid along the origin of the coraco-biceps tendon.

He keeps intimate contact with the coraco-brachial, biceps and brachial muscles to which he distributes nervous twigs.

It is therefore the nerve of the flexion of the forearm on the arm through these muscles.

Its terminating branch is sensitive anterior aspect of the forearm and outer edge of the wrist (inconstant).

Suprascapular Nerve

The supra-scapular nerve is one of the main nerves of the rotator cuff.

The supra-scapular nerve originates from the upper (primary) trunk consisting of the union of the C5 and C6 roots.

he quickly joins the scapula (scapula) near the coracoid process which he crosses medially through a tunnel under the transverse ligament at the level of the coracoidal exchanger.

He then joins the posterior face of the scapula to the deep surface of the supraspinous muscles and then, near his passage from the spine of the infra-spinous scapula, he innervates these 2 muscles (pure motor nerve)

He thus participates in the abduction of the arm (especially in the first third of the movement by the supraspinous) and the external rotation (by the infraspinous).

The nerve has fixed points at the level of the coracoid notch and passage of the spine of the scapula near the posterior surface of the glenoid (‘spino-glenoid’ notch).