What are the segmental supplies of the left kidney?

Segmental Arterial Supply of the Left Kidney

The left kidney receives blood supply through five main arterial segments: apical, upper (anterior superior), middle (anterior middle), lower (anterior inferior), and posterior segments, with the renal artery typically dividing into anterior and posterior divisions before branching into these segmental arteries.

Standard Segmental Anatomy

The left renal artery divides into two primary divisions:

• Anterior division - supplies four segments through its branches: apical segmental artery (ASA), upper segmental artery (USA), middle segmental artery (MSA), and lower segmental artery (LSA) 1, 2
• Posterior division - continues as the posterior segmental artery (PSA), which is typically single and smaller, supplying the posterior surface of the kidney 1, 2

Specific Segmental Patterns

Apical Segmental Artery (ASA):

• In 60% of cases, the ASA has a common origin with the upper segmental artery 2
• In 40% of cases, it originates directly from the main renal artery 2
• Supplies the apical (superior) pole of the kidney 1

Upper Segmental Artery (USA):

• Present in 98% of kidneys, absent in only 2% 3
• Shows four distinct anatomical patterns with varying frequencies: Type 1 (40%), Type 2 (28%), Type 3 (20%), and Type 4 (10%) 3
• Supplies the upper anterior segment of the kidney 1, 2

Middle and Lower Segmental Arteries:

• Both arise from the anterior division with variable branching patterns 1, 2
• The lower segmental artery supplies the inferior pole 1
• These arteries show significant variation in their origin points and entry into the kidney parenchyma 1

Posterior Segmental Artery:

• Consistently single branch from the posterior division 1, 2
• Comparatively smaller than anterior branches 2
• May enter the kidney substance without further branching 4

Clinical Significance

These segmental arteries function as end arteries:

• Each creates an independent renal segment with no collateral circulation between segments 3
• This anatomical arrangement is critical for partial nephrectomy, as damage to a segmental artery results in infarction of that specific segment 1, 3

Surgical implications:

• Knowledge of segmental anatomy is essential for kidney transplantation, renal trauma management, and endoscopic surgeries 1, 4
• The close relationship between segmental arteries and the collecting system requires careful identification during intrarenal surgeries and stone removal 3
• Variations in segmental branching patterns must be identified preoperatively through imaging to prevent complications 1, 4

Common Anatomical Variations

The anterior division may show a "ram horn" configuration:

• The anterior division can divide into two segmental branches with a peculiar curved appearance before entering the hilum 4
• Multiple patterns of hilar structure arrangement exist, with six distinct patterns identified, Pattern 1 being most common at 30.3% incidence 1

Important caveat: The segmental arteries show considerable variation in both their site of origin from the main renal artery and their point of entry into the kidney parenchyma, making preoperative angiography or CT angiography essential for surgical planning 1, 2, 5.