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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Anatomical terms of location | 2/5 | https://en.wikipedia.org/wiki/Anatomical_terms_of_location | reference | science, encyclopedia | 2026-05-05T07:26:06.044970+00:00 | kb-cron |
=== Dorsal and ventral === These two terms, used in veterinary anatomy, are also used in human anatomy mostly in neuroanatomy, and embryology, to describe something at the back (dorsal, posterior) or front (ventral, anterior) of an organ, or organism. The dorsal (from Latin dorsum 'back') surface, (also dorsum) of an organism or organ, refers to the back, or upper side, such as in the human, the dorsum of the tongue, the dorsum of the hand, and the dorsum of the foot. If talking about the skull, the dorsal side is the top.
The ventral (from Latin venter 'belly') surface refers to the front, or lower side, of an organism, or organ such as the undersurface of the tongue. In a fish, the dorsal fin is on the upper surface and its ventral fins (pelvic fins) are on the belly or undersurface. The terms are used in other contexts, for example in dorsal and ventral gun turrets on a bomber aircraft.
=== Medial and lateral === These terms describe how close something is to the median plane. Lateral (from Latin lateralis 'to the side') describes something to the sides of an animal, as in "left lateral" and "right lateral". Medial (from Latin medius 'middle') describes structures close to the median plane, or closer to the median plane than another structure. For example, in a human, the arms are lateral to the torso. The genitals are medial to the legs. Temporal has a similar meaning to lateral but is restricted to the head. The terms "left" and "right", or sinistral and dextral, refer to the halves of a bilaterally symmetrical body divided by the median plane. Terms derived from lateral include:
Contralateral (from Latin contra 'against'): on the side opposite to another structure. For example, the right arm and leg are controlled by the left, contralateral, side of the brain. Ipsilateral (from Latin ipse 'same'): on the same side as another structure. For example, the left arm is ipsilateral to the left leg. Bilateral (from Latin bis 'twice'): on both sides of the body. For example, bilateral orchiectomy means removal of testes on both sides of the body. Unilateral (from Latin unus 'one') one-sided or single-sided: on one side of the body. For example, unilateral deafness is hearing impairment in one ear. Varus (from Latin 'bow-legged') and valgus (from Latin 'knock-kneed' ) are terms used to describe angulation or bowing of a bone or joint within the coronal plane, where the distal portion deviates towards (varus) or away from (valgus) the midline.
=== Proximal and distal ===
The terms proximal (from Latin proximus 'nearest') and distal (from Latin distare 'to stand away from') are used to describe parts of a feature that are close to or distant from the main mass of the body, respectively. Thus the upper arm in humans is proximal and the hand is distal. The main mass is taken as the center, the chest, or the heart. "Proximal and distal" are frequently used when describing appendages, such as fins, tentacles, and limbs. Although the direction indicated by "proximal" and "distal" is always respectively towards or away from the point of attachment, a given structure can be either proximal or distal in relation to another point of reference. Thus the elbow is distal to a wound on the upper arm, but proximal to a wound on the lower arm. This terminology is also employed in molecular biology and therefore by extension is also used in chemistry, specifically referring to the atomic loci of molecules from the overall moiety of a given compound.
=== Rostral, cranial, and caudal ===
Specific terms exist to describe how close or far something is to the head or tail of an animal. To describe how close to the head of an animal something is, three distinct terms are used:
Rostral (from Latin rostrum 'beak, nose') describes something situated toward the oral or nasal region, or in the case of the brain, toward the tip of the frontal lobe. Cranial (from Greek κρανίον 'skull') or cephalic (from Greek κεφαλή 'head') describes how close something is to the head of an organism. Caudal (from Latin cauda 'tail') describes how close something is to the trailing end of an organism. These terms are generally preferred in veterinary medicine and not used as often in human medicine. For example, in horses, the eyes are caudal to the nose and rostral to the back of the head. In humans, "cranial" and "cephalic" are used to refer to the skull, with "cranial" being used more commonly. The term "rostral" is rarely used in human gross anatomy and refers more to the front of the face than the superior aspect of the organism. But it is used in embryology, and neuroanatomy. Similarly, the term "caudal" is used more in embryology and neuroanatomy, and only occasionally in human gross anatomy. The "rostrocaudal axis" refers to the curved line of the neuraxis from the forehead (rostral) towards the tail end (caudal).
=== Central and peripheral === Central and peripheral refer to the distance towards and away from the centre of something. That might be an organ, a region in the body, or an anatomical structure. For example, the central nervous system and the peripheral nervous systems. Central (from Latin centralis) describes something at, or close to the centre. For example, the great vessels run centrally through the body; many smaller vessels branch from these. Peripheral (from Latin peripheria, originally from Ancient Greek) describes something that is situated nearer to the body's surface, such as a peripheral nerve.