Accessorius in Latin

Grammatical forms and agreement rules

The Latin adjective accessorius changes its ending depending on the gender of the noun with which it agrees in the term. All three gender forms are found in anatomical nomenclature:

• Masculine (-us): used with masculine nouns. A prominent example from the urogenital system (systema urogenitale) is ren accessorius (accessory kidney). It may occur as an anatomical variation alongside the normal left kidney (ren sinister), having its own renal cortex (cortex renis) and poles (extremitas renis).
• Feminine (-a): used with feminine nouns, which is especially common when describing blood vessels. For example, vena cephalica accessoria (accessory cephalic vein) or vena hemiazygos accessoria (accessory hemiazygos vein).
• Neuter (-um): strictly agrees with neuter nouns. In the digestive system (systema digestorium), the classic example is pancreas accessorium — the accessory pancreas.

Accessory structures in the venous system (Angiology)

In the study of the cardiovascular system (systema cardiovasculare), the term "accessory" regularly appears in the detailed description of superficial and deep veins.

In the upper limb, the v. cephalica accessoria is distinguished. This vein complements the main cephalic vein of the arm (v. cephalica), actively participating in blood outflow from the superficial layers of the forearm. It works in a single hemodynamic complex with other superficial vessels, such as the basilic vein (v. basilica), median cubital vein (v. mediana cubiti), and also collects blood flowing through the dorsal venous network of the hand (rete venosum dorsale manus).

In the thoracic cavity, the v. hemiazygos accessoria (accessory hemiazygos vein) plays a crucial topographical role. It belongs to the extensive superior vena cava system (v. cava superior). Its main anatomical function is collecting venous blood from the posterior intercostal veins (vv. intercostales posteriores) of the left side of the chest.

The role of accessory veins in collateral circulation

Accessory venous vessels, in particular the v. hemiazygos accessoria, are critical elements of caval-caval anastomoses. These are backup blood outflow pathways bypassing the heart, directly connecting the basins of the superior and inferior venae cavae (v. cava superior and v. cava inferior).

Blood from the accessory hemiazygos vein is emptied into the hemiazygos vein (v. hemiazygos) and then flows into the azygos vein (v. azygos). This complex venous network is also closely connected to the vertebral venous plexus (plexus venosus vertebralis) and the ascending lumbar vein (v. lumbalis ascendens), which in turn connects the iliac veins to the azygos and hemiazygos venous system. This architecture ensures reliable collateral circulation during any obstruction in the main venous trunks.

Accessory organs in internal systems

In addition to blood vessels, the term accessorius describes additional elements of large parenchymatous organs.

Clinical splanchnology mentions pancreas accessorium. This is a cluster of tissue functioning as an addition to the main pancreas. The main gland itself has a complex anatomy, including the neck (collum pancreatis), and is fixed by ligaments, such as the pancreaticosplenic ligament (ligamentum pancreatosplenicum).

In the urinary system, besides the basic kidney structures — the renal cortex (cortex renis), the base of the renal pyramid (basis pyramidis renalis), and the renal poles (extremitas renis) — a ren accessorius sometimes forms. This is an independent accessory organ that acts as an anatomical variation of the urogenital system structure.

Class and exam questions

What else to study on this topic

• Portosystemic and caval-caval anastomoses
• Superficial and deep veins of the upper limb
• Anatomical terminology of the digestive system (systema digestorium)
• Structure and ligamentous apparatus of the liver (hepar)
• Venous plexuses: esophageal and rectal

Other topics in the "Additional Topics" section

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