Topic Overview

Anastomoses Around Scapula

Arterial Network

• Ensures collateral circulation between branches of subclavian and axillary arteries.

• Important in ligation/obstruction of axillary artery.

Key vessels involved:

1. Suprascapular artery (from thyrocervical trunk of subclavian).

2. Dorsal scapular artery (from subclavian or transverse cervical).

3. Circumflex scapular artery (from subscapular branch of axillary).

4. Acromial branch of thoracoacromial artery (from axillary).

Pathways

• Suprascapular ↔ Circumflex scapular.

• Dorsal scapular ↔ Circumflex scapular.

• Thoracoacromial ↔ Suprascapular.

Clinical Anatomy

1. Intermuscular Spaces

Quadrangular Space Syndrome

• Compression of axillary nerve → shoulder pain, deltoid weakness, paresthesia in regimental badge area.

Triangular Space

• Injury to circumflex scapular artery → may affect scapular anastomosis.

Triangular Interval

• Radial nerve vulnerable → trauma may cause wrist drop.

2. Rotator Cuff

• Rotator cuff tear → most common in supraspinatus tendon → painful arc syndrome.

• Weakness of abduction or rotation depending on muscle involved.

• Clinical tests:

  • Empty can test (supraspinatus).

  • External rotation test (infraspinatus/teres minor).

  • Lift-off test (subscapularis).

• Chronic tears → shoulder instability, dislocations.

3. Axillary Nerve

• Injury causes:

  • Fracture of surgical neck of humerus.

  • Shoulder dislocation.

  • Improper use of crutches.

• Effects:

  • Paralysis of deltoid → loss of abduction beyond 15°.

  • Paralysis of teres minor → weak external rotation.

  • Loss of sensation over regimental badge area.

• Clinical sign: flattening of shoulder contour.

4. Anastomoses Around Scapula

• Provide collateral circulation if axillary artery ligated proximal to subscapular artery.

• Clinical importance:

  • Maintains blood supply to upper limb in trauma, aneurysm, or surgical ligation.

  • Example: ligation of 1st part of axillary artery → suprascapular and dorsal scapular arteries maintain flow via circumflex scapular.