(ak′sĭs )

(ak′sēz″)
pl. axes [L. axis, axle, axis]

1. A real or imaginary line that runs through the center of a body or about which a part revolves.
2. The second cervical vertebra (epistropheus). It bears the odontoid process (dens), about which the atlas rotates.
SYN: SEE: odontoid vertebra

basicranial axis

The axis connecting the basion and the gonion.

basifacial axis

The axis from the subnasal point to the gonion.

biauricular axis

The axis between the two auricular points.

brain-gut axis

The relationship between the gastrointestinal tract and the central nervous system, specifically between digestive and mental health.

cardiac axis

A graphic representation of the main conduction vector of the heart, determined through measurements of direction and amplitude of the complexes in several leads on a 12-lead electrocardiogram. The normal axis is zero to +90°.

celiac axis

The axis between the celiac artery and the abdominal aorta.

cerebrospinal axis

SEE: Central nervous system.

condylar axis

SEE: Hinge axis

coronal axis

SEE: Frontal axis.

enteroinsular axis

The hormones and neurotransmitters from the gastrointestinal tract that regulate the secretion of hormones by the pancreas (esp. insulin).

frontal axis

An imaginary line, running from side to side in the frontal plane, about which the anterior to posterior movement occurs.
SYN: SEE: coronal axis

hinge axis

An imaginary line connecting the condyles of the mandible. Movement of the mandible is rotation around this line.
SYN: SEE: condylar axis ; SEE: mandibular axis ; SEE: transverse mandibular axis

long axis

SEE: Sagittal plane.

mandibular axis

SEE: Hinge axis

neural axis

SEE: Central nervous system.

optic axis

A line that connects the anterior and posterior poles of the eye.

phlebostatic axis

An anatomic reference point on the surface of the body, used to approximate the position of the right atrium and pulmonary artery in critical care.

PATIENT CARE
The line is identified by drawing two lines on the supine body: one, in the right midaxillary position, descending from head to foot; and the other, from the anterior to the posterior of the chest, at the level of the fourth intercostal space. The intersection of these two lines is the axis. It is used in critical care to provide a reproducible location for the zeroing in on and leveling of hemodynamic monitoring systems such as pulmonary artery catheters.

principal axis

In optics, a line that passes through the optical center or nodal point of a lens perpendicular to the surface of the lens.

sagittal axis

An imaginary line running anteriorly-posteriorly, about which frontal plane motion occurs.

short axis

In imaging studies of anatomical structures (such as the heart), a synonym for transverse axis.
SEE: transverse axis

transverse axis

An axis that connects one side of the body to the other. It is parallel to the ground and perpendicular to both the sagittal and the anteroposterior axes of the body.

transverse mandibular axis

SEE: Hinge axis

visual axis

The line of vision from the object seen through the pupil's center to the macula lutea.