Glossary of Anatomical Terms

anterior:
Located near or toward the head in lower animals. Opposed to posterior

axon:
A long process of a neuron, that carries efferent (outgoing) action potentials from the cell body towards target cells. A nerve cell communicates with another nerve cell by transmitting signals from the branches at the end of its axon. At the terminal end of the axon, the impulses are transmitted to other nerve cells or to effector organs.

branchial:
Of or pertaining to branchi[ae] or gills.

chorion:
The outer membrane enclosing the embryo in reptiles, birds, and mammals. In placental mammals it contributes to the development of the placenta.

dendrite:
A long, branching outgrowth or extension from a neuron, that carries electrical signals from synapses to the cell body, unlike an axon that carries electrical signals away from the cell body. Each nerve cell usually has many dendrites.

distal:
Anatomically located far from a point of reference, such as an origin or a point of attachment.

dorsal:
Of, toward, on, in, or near the back or upper surface of an organ, part, or organism.

endotoxin:
A toxin produced by certain bacteria and released upon destruction of the bacterial cell

ganglion:
A group of nerve cells forming a nerve center, especially one located outside the brain or spinal cord.

gill:
The respiratory organ of most aquatic animals that breathe water to obtain oxygen, consisting of a filamentous structure of vascular membranes across which dissolved gases are exchanged

haemal:
Relating to or located on the side of the body that contains the heart and principal blood vessels (opposite: neural or dorsal)

hemocyte:
A cellular component of the blood, especially of an invertebrate

neural:
Of, relating to, or located on the same side of the body as the spinal cord; also dorsal.

olfactory:
Of, relating to, or contributing to the sense of smell.

ommatidium:
One of the structural elements, resembling a single simplified eye, that make up the compound eye of insects and other arthropods.

ostium:
an opening; a passage

pericardium:
The membranous sac filled with serous fluid that encloses the heart and the roots of the aorta and other large blood vessels.

rhabdome:
One of numerous minute rodlike structures formed of two or more cells situated behind the retinulae in the compound eyes of insects, etc.

seta, setae:
A bristle or stiff hair

venous:
Of, relating to, or contained in the veins

ventral:
a. Relating to or situated on or close to the abdomen; abdominal.
b. Relating to or situated on or close to the anterior aspect of the human body or the lower surface of the body of an animal.