Shoulder Anatomy | Axillary Nerve | Suprascapular Nerve

This video provides a review of the shoulder anatomy and arthroscopic neuroanatomy of the shoulder and describes arthroscopic techniques for decompression. This video is divided into 4 chapters.

Chapter 1

The axillary nerve is a branch of the posterior cord of the brachial plexus. It passes medial and inferior to the coracoid and is just inferior to the sub-scapularous muscle belly as it enters the axillary space.

A standard posterior viewing portal is created to 2 cm inferior and 1 cm medial to the posterolateral edge of the acromium. The anterior and anterolateral portals are created under arthroscopic visualization. Indications of arthroscopic decompression include:

- Iatrogenic compression
- Subcoracoid cyst
- Adhesions

Contraindications include:

- Missing clinical and/or radiological evidence of compression
- Poor visualization
- Inadequate technical skill
- Unfamiliarity with the anatomy
- General surgical risks

During shoulder arthroscopy, great care is taken to avoid damaging the axillary artery and nerve.

Chapter 2

The axillary nerve traverses inferior to the glenohumeral capsule to enter the quadilateral space. A standard posterior viewing portal is used and a 7 o'clock working portal is created under direct arthroscopic visualization. The indications include:

- Comprehensive arthroscopic management (CAM) of osteoarthritis
- Adhesive capsulitis
- Axillary ganglion
- Adhesions prior to surgery or trauma

Contraindications include:

- Missing clinical and/or radiological evidence of compression
- Poor visualization
- Inadequate technical skill
- Unfamiliarity with the anatomy
- General surgical risks

Blunt dissection is used until the axillary nerve is adequately liberated.

Chapter 3

The more anterior branch of the axillary nerve wraps around the humeral neck and enters the middle and anterior deltoid. The nerve is typically located 5 to 6 cm from the edge of the acromium laterally. Indications include:

- Adhesions prior to surgery or trauma
- Cyst compression
- Quadrilateral space syndrome

Contraindications include:

- Missing clinical and/or radiological evidence of compression
- Poor visualization
- Inadequate technical skill
- Unfamiliarity with the anatomy
- General surgical risks

With the arthroscope in the posterior portal, a mechanical shaver is used through the anterolateral and lateral portals to debris the arcomial bursa and any adhesions. It is important not to injure the axillary nerve. A combination of blunt dissection and electric codary is utilized to release adhesions and connected facial bands. Once the nerve is encountered, it is bluntly dissected from adhesive tissues till it is adequately liberated.

Chapter 4

The suprascapular nerve originates from the upper trunk of the brachial plexus. It courses deep to the trapezius muscles and into the suprascapular notch with the suprascapular artery. At the suprascapular notch, the suprascapular nerve passes underneath the trans-scapular ligament and provides to motor branches to the supraspinatus, while the suprascapular artery passes over the ligament. At the spinal glenoid notch the suprascapular nerve can be constricted by the inferior transfer of the ligament or by ganglion cysts.

A lateral viewing portal and the anterolateral and Nevaiser portals are used for suprascapular nerve decompression.

Indications for arthroscopic decompression include:

- Spinoglenoid notch cyst
- Spingolenoid ligament hypertrophy
- Transverse scapular ligament hypertrophy
- Suprascapular notch cyst
- Spraglenoid cyst
- Paralabral cyst

Relative contraindications include:

- Missing clinical and/or radiological evidence of compression
- Poor visualization
- Inadequate technical skill
- Unfamiliarity with the shoulder anatomy
- General surgical risks

During arthroscopy care must be taken to not damage the conoid ligaments. The suprascapular nerve is decompressed.

Following nerve decompression surgery, the first 1-2 weeks include:

- Sling for comfort
- Passive range of motion
- Postural education
- Scapular stabilization exercises
- Active range of motion of C-spine, elbow, wrist and hand
- Initiate active-assisted and active ROM of shoulder per patient tolerance