Explain axillary artery. Uh... Relations. ...in a stromosis with the scapula. Anastomosis. With scapula and its clinicals. Uh, give handwritten-- handmade diagrams. Which easy to draw. And explain. All these things, point to point. Short, short me samjha.

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Now I have all the information needed. Let me compile a clear, point-by-point explanation with diagrams.

Axillary Artery - Complete Notes

(Gray's Anatomy for Students; THIEME Atlas of Anatomy)

1. OVERVIEW

Begins: Lateral margin of rib I (continuation of subclavian artery)
Ends: Lower border of teres major muscle (continues as brachial artery)
Location: Inside the axilla, enclosed in the axillary sheath (derived from prevertebral fascia of the neck)

2. THREE PARTS (divided by Pectoralis Minor)

HANDMADE DIAGRAM - Three Parts:

  Rib I ──────────────────────────────── Teres Major
     |                                         |
     [1st part]──[Pect. Minor]──[2nd part]──[3rd part]
                  ↑ behind it

Part	Position	No. of Branches
1st	Proximal to pect. minor	1 branch
2nd	Behind / posterior to pect. minor	2 branches
3rd	Distal to pect. minor	3 branches

Memory trick: 1-2-3 rule (part 1 = 1 branch, part 2 = 2 branches, part 3 = 3 branches)

3. SIX BRANCHES

Branches of the axillary artery - Gray's Anatomy for Students, p.854

HANDMADE DIAGRAM - Branches:

           AXILLARY ARTERY
                 |
    ┌────────────┴────────────┐
    │  1st Part               │
    └──► Superior Thoracic    │
                              │
    ┌────────────────────────┐│
    │  2nd Part              ││
    └──► Thoraco-acromial    ││
    └──► Lateral Thoracic    ││
                              │
    ┌────────────────────────┘│
    │  3rd Part               │
    └──► Subscapular ─┬─► Circumflex Scapular
                      └─► Thoracodorsal
    └──► Anterior Circumflex Humeral (ACHA)
    └──► Posterior Circumflex Humeral (PCHA)

Branch	Supply
Superior thoracic	Upper axillary wall
Thoraco-acromial	Pectoral, deltoid, clavicular, acromial regions
Lateral thoracic	Medial axillary wall, breast (in women)
Subscapular	Posterior axillary wall + scapular region
ACHA	Anterior surgical neck of humerus, glenohumeral joint
PCHA	Passes through quadrangular space with axillary nerve; surgical neck posteriorly

4. RELATIONS

The axillary artery is surrounded by the cords of the brachial plexus, which are named by their relation to it:

HANDMADE DIAGRAM - Cross-section Relations:

             Medial cord
                 |
  Lateral   ─── AA ─── Axillary Vein (anteromedial)
    cord         |
             Posterior cord

(AA = Axillary Artery)

Key relations:

Medial: Axillary vein (lies anteromedial to artery)
Lateral: Lateral cord of brachial plexus
Posterior: Posterior cord of brachial plexus
Medial side: Medial cord
Anterior: Pectoralis minor crosses the 2nd part
Whole vessel is enclosed in the axillary sheath

5. ANASTOMOSIS WITH SCAPULA - "Scapular Arcade"

This is the most clinically important part.

Scapular Arcade - THIEME Atlas of Anatomy, p.410

HANDMADE DIAGRAM - Scapular Anastomosis:

  Subclavian artery
       │
  Thyrocervical trunk ──► Suprascapular artery
                               │ passes OVER
                               │ Superior transverse ligament
                               ▼
                         Supraspinous fossa
                               │
                               │ passes UNDER
                               │ Inferior transverse ligament
                               ▼
                        Infraspinous fossa
                               │
                    ◄──────────┘  ← ANASTOMOSIS here
                    │
  Axillary artery ──► Subscapular artery
                           │
                    Circumflex Scapular artery
                    (enters via Triangular Space)
                           │
                    Infraspinous fossa ◄────── Also joins:
                                               Dorsal Scapular artery
                                               (deep br. of transverse cervical a.)

Three arteries meet in the infraspinous fossa:

Suprascapular artery (from thyrocervical trunk of subclavian)
Circumflex scapular artery (from subscapular → axillary)
Dorsal scapular artery (deep branch of transverse cervical artery)

6. CLINICAL IMPORTANCE

a) Collateral Circulation after Axillary Artery Ligation/Occlusion

If axillary artery is ligated proximal to the subscapular artery, the scapular arcade takes over via:
- Suprascapular → Circumflex scapular (retrograde) → re-enters subscapular → distal axillary
Blood can reach the arm even if the axillary artery is blocked!
This is why ligation above the subscapular is safer than below it

b) Safe vs. Dangerous Ligation Sites

Proximal ligation (above subscapular):
  ✅ Collateral via scapular arcade INTACT → limb survives

Distal ligation (below subscapular + circumflex humeral):
  ❌ Collateral inadequate → limb ischemia risk

c) Shoulder Dislocation

Anterior shoulder dislocation (commonest) can damage the axillary artery
Also risks injury to axillary nerve (PCHA travels with it through quadrangular space)
Clinical sign: loss of deltoid sensation (regimental badge area) + weakened abduction

d) Quadrangular Space Syndrome

PCHA and axillary nerve pass through quadrangular space
Compression here → shoulder pain + deltoid weakness

e) Axillary Artery Aneurysm

Can present as pulsatile axillary mass
Risk of distal embolism to upper limb

QUICK REVISION SUMMARY

HANDMADE CHEAT SHEET:

Subclavian a. → [Lat margin Rib I] → AXILLARY A. → [Below teres major] → Brachial a.

Parts:  1──[Pect.minor]──2──[Pect.minor]──3
        ↓               ↓↓              ↓↓↓
        1 branch      2 branches      3 branches

3rd Part branches = S-A-P (Subscapular, Ant.CHA, Post.CHA)

Scapular Arcade = Suprascapular + Circumflex Scapular + Dorsal Scapular
                ↑ Subclavian side      ↑ Axillary side

Clinical: Ligation above subscapular = SAFE (arcade kicks in)

Sources: Gray's Anatomy for Students, p.853-855 | THIEME Atlas of General Anatomy, p.404, p.410

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