Proximal

Definition

Situated nearer to the point of attachment or origin; toward the body or base relative to a reference point on an appendage, structure, or organ. In arthropod limbs, proximal describes segments closer to the body wall (coxa, trochanter) as opposed to distal segments toward the tip (tarsus, pretarsus). The term applies to any elongated structure measured from its proximal origin to its distal termination.

Etymology

Latin proximus, 'nearest'

Example

In a grasshopper hind leg, the femur is proximal to the tibia, while the tarsus is distal to the tibia; the femoro-tibial joint lies between proximal and distal leg segments.

Synonyms

• proximate (in some anatomical contexts)
• basal (when referring to base of structure)

Related Terms

• Distal
• basal
• Apical
• medial
• lateral
• Coxa
• Tarsus

Usage Notes

Contrast strictly with distal; do not confuse with medial (toward midline) or superficial. In antennae and mouthparts, proximal segments are numbered from the head outward. In wing venation, proximal veins arise nearer the wing base. The term is relative: a structure may be proximal to one feature yet distal to another.