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Axillary nerve

- Discuussion:
- axillary nerve (C5, C6) originates from and passes backward from posterior cord of brachial plexus  - at level of axilla;
- it arises immediately posterior to the coracoid process and conjoined tendon;
- it crosses the inferolateral surface of the subscapularis, 3-5 mm medial to the musculotendinous border;
- sweeping a finger from superior to inferior along the anterior aspect of subscapularis will catch the axillary nerve;
- it courses along inferior border of the shoulder capsule, & then thru quadrangular space below lower border of teres minor,
where it passes around posterior and lateral humerus on deep surface of the deltoid muscle;
- after passing thru quadrilateral space (at inferior border of subscapularis muscle and posterior aspect of the humeral neck) it divides into
anterior and posterior trunks;
- anterior trunk:
- branches supply the middle and anterior deltoid as it winds around the inner surface of deltoid;
- posterior trunk:
- branch to the teres minor muscle
- posterior part of the deltoid muscle (lie deep in deltoid);
- terminal branches: superior lateral brachial cutaneous nerve
- references:
- The Posterior Branch of the Axillary Nerve: An Anatomic Study.
- Anatomical basis of the variable aspects of injuries of the axillary nerve (excluding the terminal branches in the deltoid muscle).
- The position of the axillary nerve in the deltoid muscle. A cadaveric study.

- Anterior Dislocation of Shoulder:
- because of its relatively fixed position at posterior cord and at deltoid, any downward subluxation of proximal humerus can result in traction
and injury to the nerve;
- also because of its close relationship to the inferior capsule makes it suseptible to injury with anterior dislocations;
- in pts w/ axillary nerve injuries following anterior dislocation, sensory exam over the lateral shoulder will be normal;
- injury causes loss of shoulder abduction  & external rotation;

- Axillary Nerve and Shoulder Reconstruction:
- references:
- Anatomy of the axillary nerve and its relation to inferior capsular shift.
- The axillary nerve and its relationship to common sports medicine shoulder procedures.
- Prevention of Axillary Nerve Injury in Anterior Shoulder Reconstructions. Use of a Subscapularis Muscle-Splitting Technique and a Review of the Literature.
- The Anatomic Relationship of the Brachial Plexus and Axillary Artery to the Glenoid. Implications for Anterior Shoulder Surgery.
- The Relationship of the Axillary Nerve to Arthroscopically Placed Capsulolabral Sutures. An Anatomic Study.
- Determining the Relationship of the Axillary Nerve to the Shoulder Joint Capsule from an Arthroscopic Perspective.

- Axillary Nerve Injury during Rotator Cuff Surgery:
- if deltoid is split anteriorly for > 5 cm, branches of axillary nerve will be damaged, rendering corresponding portion of deltoid  ineffective;
- in smaller patients, the deltoid should not be split more than 4 cm;
- smallest split possible should be made in deltoid to permit sufficient exposure of the rotator cuff;
- arm can be passively moved into various positions to allow this exposure without creating a larger muscle split than is necessary;

- Axillary Nerve and Proximal Interlocking Screws for IM Nailing: (see IM nailing)
- references:
- Relationship of the axillary nerve to the proximal screws of a flexible humeral nail system: an anatomic study.
- Antegrade locked nailing for humeral shaft fractures.
- Percutaneous Pinning of the Proximal Part of the Humerus. An Anatomic Study.
- Anatomic considerations of locked humeral nailing.

The sub-deltoid approach to the metaphyseal region of the humerus.

Repair of isolated axillary nerve lesions after infraclavicular brachial plexus injuries: case reports.

Suprascapular neuropathy in the differential diagnosis of rotator cuff injuries.

Isolated and combined lesions of the axillary nerve. A review of 146 cases.

Surgical anatomy of the axillary nerve.

Is There a Safe Area for the Axillary Nerve in the Deltoid Muscle?

The anatomic relationships of the axillary nerve and surgical landmarks for its localization from the anterior aspect of the shoulder.