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a longitudinal assemblage of tissues or organs, especially a number of anatomic structures arranged in series and serving a common function, such as the gastrointestinal or urinary tract; also used in reference to a bundle (or fasciculus) of nerve fibers having a common origin, function, and termination within the central nervous system.
alimentary tract alimentary canal.
biliary tract the organs, ducts, and other structures that participate in secretion (the liver), storage (the gallbladder), and delivery (hepatic and bile ducts) of bile into the duodenum. See illustration.
Anatomy of the gallbladder and biliary tract. From Aspinall and Taylor-Robinson, 2002.
corticospinal t's two groups of nerve fibers (the anterior and lateral corticospinal tracts) that originate in the cerebral cortex and run through the spinal cord.
digestive tract alimentary canal.
dorsolateral tract a group of nerve fibers in the lateral funiculus of the spinal cord dorsal to the posterior column.
extrapyramidal tract extrapyramidal system.
gastrointestinal tract the stomach and intestine in continuity; see also digestive system.
iliotibial tract a thickened longitudinal band of fascia lata extending from the tensor muscle downward to the lateral condyle of the tibia.
intestinal tract see intestinal tract.
optic tract the nerve tract proceeding backward from the optic chiasm, around the cerebral peduncle, and dividing into a lateral and medial root, which end in the superior colliculus and lateral geniculate body, respectively.
pyramidal t's collections of motor nerve fibers arising in the brain and passing down through the spinal cord to motor cells in the anterior horns.
respiratory tract respiratory system.
urinary tract the organs and passageways concerned in the production and excretion of urine from the kidneys to the urinary meatus; see also urinary system.
uveal tract the vascular tunic of the eye, comprising the choroid, ciliary body, and iris.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


(trakt), [TA] Do not confuse this word with track.
1. An elongated area; a passage or pathway.
See also: fascicle. Synonym(s): tractus [TA]
2. An abnormal passage (for example, a fistula or sinus communicating with an abscess cavity).
[L. tractus, a drawing out]
Farlex Partner Medical Dictionary © Farlex 2012


a. A system of organs and tissues that together perform a specialized function: the alimentary tract.
b. A bundle of nerve fibers having a common origin, termination, and function.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


1. A bundle of nerve fibers in the CNS. See Spinothalamic tract.
2. A tube through which a substance or gas flows. See Aerodigestive tract, Biliary tract, Gastrointestinal tract, Olfactory tract, Respiratory tract, Serpiginous tract, Urogenital.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


(trakt) [TA]
An elongated area, e.g., path, track, way.
See also: fascicle
Synonym(s): tractus.
[L. tractus, a drawing out]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


(trakt) [L. tractus, extent]
1. A pathway, course, or channel.
2. A bundle of parallel axons in the central nervous system (CNS) that runs along a stereotyped course from a common originating area to a common termination area.
3. A group of organs or parts that form a continuous pathway.

aerodigestive tract

The anatomic region in the oral cavity and throat through which both air and food pass.

afferent tract

Any axon tract that carries information toward a particular target area.

alimentary tract

Digestive tract.

anterior spinocerebellar tract

Ventral spinocerebellar tract.

ascending tract

An axon tract running rostrally in the spinal cord or brain, often a sensory pathway.
Enlarge picture

biliary tract

The organs and ducts through which bile travels on its way to the duodenum. These are the bile canaliculi, right and left hepatic ducts, common hepatic duct, gallbladder, cystic duct, bile duct, and hepatopancreatic ampulla.
See: illustration; bile ducts; gallbladder; liver

Burdach tract

See: Burdach, Karl

central tegmental tract

An axon tract connecting the subthalamus and the midbrain reticular formation with the inferior olivary nucleus.

corticobulbar tract

An axon tract from the motor cortex that innervates the reticular formation and the cranial nerve nuclei in the hindbrain.


An axon tract from the frontal, parietal, and occipital cortices that innervates the hypothalamus.

corticospinal tract

An axon tract from the motor cortex that travels into the spinal cord, synapsing at all levels. Axons of the corticospinal tract first converge into a bundle in the posterior limb of the internal capsule and continue as a compact bundle through the cerebral peduncle. In the pons, the corticospinal tract separates into several bundles that converge more caudally in the hindbrain as the pyramid. In the caudal hindbrain, the corticospinal tract crosses the midline in the pyramidal decussation and continues down the spinal cord as the lateral corticospinal tract.

cuneocerebellar tract

An axon tract originating in the external cuneate nucleus and synapsing in the ipsilateral cerebellum.

descending tract

Any axon tract running caudally in the spinal cord or brain, often a motor pathway.

digestive tract

The continuous set of tubes that move food from the mouth to the anus.
Synonym: alimentary tract

direct cerebellar tract

Dorsal spinocerebellar tract.

dorsal spinocerebellar tract

An ipsilateral (uncrossed) axon tract originating throughout Clarke's column in the spinal cord. The tract runs in the lateral funiculus of the spinal cord and terminates in the ipsilateral vermis of the cerebellum.
Synonym: direct cerebellar tract

dorsolateral tract

Lissauer's tract.

efferent tract

Any axon tract that carries information away from a particular target area.

extrapyramidal tract

Any of the axon tracts of the extrapyramidal system.
See: extrapyramidal system

frontopontine tract

A tract that passes from the cerebral cortex of the frontal lobe through the internal capsule and cerebral peduncle to the pons.
Synonym: Arnold's bundle

gastrointestinal tract

The esophagus, stomach, and intestines.

geniculohypothalamic tract

An axon tract originating in the lateral geniculate nucleus of the thalamus and innervating the suprachiasmatic nuclei of the hypothalamus. The suprachiasmatic nuclei contain pacemakers of the circadian rhythm system, and the geniculohypothalamic tract provides visual input that helps to entrain the pacemaker cells.

genital tract

In males, the channels by which spermatozoa leave the body. In females, the channels in which the ovum grows and is fertilized and through which the baby leaves the body.
Synonym: reproductive tract

genitourinary tract

The genital and urinary tracts together.
Synonym: urogenital tract

habenulo-interpeduncular tract

Fasciculus retroflexus.

iliotibial tract

A thickened band in the deep fascia along the lateral thigh (i.e., the fascia lata) that extends from the tubercle of the iliac crest to the lateral condyle of the tibia. The iliotibial tract is an aponeurosis shared by both the gluteus maximus and tensor fasciae lata muscles, both of which insert into it.

internodal tract

In the heart, myocardial tissue in the right atrium that preferentially carries sinoatrial impulses to the left atrium, to the intra-atrial septum, or to the atrioventricular node.

intestinal tract

The small and large intestines.

Lissauer's tract

See: Lissauer's tract

lower gastrointestinal tract

The anus, rectum, colon, cecum, ileum and jejunum.

mammillotegmental tract

An axon tract originating in the mammillary body and synapsing in small nuclei near the caudal end of the midbrain tegmentum.

mammillothalamic tract

An axon tract originating in the mammillary body and synapsing in the anterior nucleus of the thalamus. The mammillothalamic tract is an integral component of the loop of neural circuits called the limbic system.

medullary reticulospinal tract

See: reticulospinal tract

mesencephalic tract of the trigeminal nerve

An axon tract of the unipolar sensory neurons of the trigeminal mesencephalic nucleus. Peripheral processes of these neurons run in the mesencephalic tract to reach the mandibular nerve (CN V3) and carry proprioceptive information from the face and the teeth. Axons of these neurons run in the mesencephalic tract and innervate a number of central nuclei, including the trigeminal motor nucleus.
Synonym: trigeminal mesencephalic tract

motor tract

Any axon tract, usually running caudally in the CNS, that transmits output information.

olfactory tract

A white ribbon-like band along the bottom (orbital) surface of each frontal lobe, composed of axons from the mitral cells in olfactory bulb. These axons terminate in the piriform cortex (the primary olfactory cortex) at the base of the cerebral hemisphere.

olivocerebellar tract

An axon tract running transversely (as opposed to longitudinally) in the hindbrain from the inferior olivary nucleus to all parts of the cerebellum via the inferior cerebellar peduncle.

optic tract

The main bundle of axons from the optic nerves caudal to the optic chiasm. Axons from the temporal half of the retina continue in the ipsilateral optic tract; axons from the nasal half of the retina cross the midline of the brain in the optic chiasm and join the contralateral optic tract. Most optic tract axons synapse in the lateral geniculate nucleus of the thalamus; most of the remaining optic tract axons synapse in the superior colliculus (optic tectum) of the midbrain.

pontine reticulospinal tract

See: reticulospinal tract

pyramidal tract

The corticobulbar and corticospinal tracts, which are the major direct outputs of the motor cortex. In cross-sections of the hindbrain, the pyramidal tract has a triangular shape.

reproductive tract

Genital tract.

respiratory tract

The respiratory channel from mouth and nose to the alveoli in the lungs.

reticulospinal tract

Either of two tracts:the pontine reticulospinal tract or the medullary reticulospinal tract. The pontine reticulospinal tract contains axons originating in the pontine reticular formation; the axons run into the spinal cord along the ventral midline (the medial part of the anterior funiculus). The medullary reticulospinal tract contains axons originating in the medial two thirds of the hindbrain reticular formation; these axons run into the spinal cord in the anterior part of the lateral funiculus.

retinohypothalamic tract

The retinal ganglion cell axons from the optic nerves that leave the optic tract at the optic chiasm to innervate the suprachiasmatic nucleus (in the hypothalamus), which contains the pacemaker cells for circadian rhythms.

rubrospinal tract

An axon tract originating in the red nucleus of the midbrain. After leaving the red nucleus, axons cross to the contralateral side and descend into the spinal cord, where they terminate in the ventral horns. The red nucleus is innervated by axons from the motor cortices and the cerebellum, and the rubrospinal pathway is an extrapyramidal route to the spinal cord. A major function of rubrospinal axons is to set and adjust the muscle tone in the flexor muscles.

sensory tract

Any axon tract, usually traveling rostrally in the CNS, that transmits information related to somatic or visceral sensation.

solitary tract

Tractus solitarius.

spinal tract of the trigeminal nerve

A tract of somatic sensory axons from the trigeminal nerve that runs caudally from the midpontine level of the brainstem along the spinal nucleus of the trigeminal nerve. The tract carries pain and temperature information from the face, and its axons synapse topographically in the adjacent nucleus. In the transition zone between hindbrain and spinal cord, the spinal tract of the trigeminal nerve disappears into the tract of Lissauer although a few axons of the spinal tract extend as far caudally as spinal cord segment C3-C4.
Synonym: trigeminal spinal tract


The dorsal or the ventral spinocerebellar tract.

spinothalamic tract

The lateral or the anterior spinothalamic tract. Both tracts are bundles of axons running rostrally in the ventrolateral quadrant (the ventral half of the lateral funiculus) of the spinal cord, originating from contralateral dorsal horn neurons, and synapsing in the ventral posterolateral (VPL) nucleus of the thalamus. The lateral spinothalamic tract carries pain and temperature information from the body; the anterior spinothalamic tract (adjacent and dorsal to the lateral tract) carries light touch information.

supraopticohypophyseal tract

, supraopticohypophyial tract
A tract of fibers arising from cell bodies located in supraoptic and paraventricular nuclei of the hypothalamus and terminating in the posterior lobe of the hypophysis.

trigeminal mesencephalic tract

Mesencephalic tract of the trigeminal nerve.

trigeminal spinal tract

Spinal tract of the trigeminal nerve.

trigeminothalamic tract

Trigeminal lemniscus.

upper gastrointestinal tract

The esophagus, stomach, and duodenum.

urinary tract

The channel followed by urine in the body, from the glomeruli in the kidneys through the ureters, bladder, and urethra.

urogenital tract

Genitourinary tract.

uveal tract

The vascular and pigmented tissues that constitute the middle layer of the wall of the eye. The tract comprises the iris, ciliary body, and choroid.
Synonym: vascular tunic of the eye

ventral spinocerebellar tract

An axon tract originating in the contralateral dorsal and intermediate horns of the lower spinal cord, from the coccygeal through the lumbar segments. This tract runs in the lateral funiculus of the spinal cord, recrosses the midline, and terminates in the ipsilateral vermis of the cerebellum.
Synonym: anterior spinocerebellar tract

ventricular outflow tract

In the heart, the pathway through which blood is normally ejected from the ventricle. For the left ventricle, it includes the walls of the ventricle, the anterior leaflet of the mitral valve, the aortic valve, the ascending aorta, and the arch of the aorta. For the right ventricle, it includes the walls of the ventricle, the pulmonic valve, the pulmonary trunk, and the pulmonary arteries.

vestibulospinal tract

An axon tract that conveys balance and equilibrium information to the spinal cord from the vestibular nuclei in the brainstem. The medial vestibulospinal tract is the continuation of the medial longitudinal fasciculus (MLF) caudally into the spinal cord below the cervical levels; it runs along the medial margin of the ventral quadrant of the cord. The lateral vestibulospinal tract runs caudally in an anterior band in the ventral and ventrolateral quadrant of the spinal cord.

vocal tract

The tissues and organs that produce human vocalizations, including lips, tongue, mouth, nasal cavities, pharynx, and larynx.
Medical Dictionary, © 2009 Farlex and Partners


1. An associated group of organs forming a pathway along which liquids, solids or gases are moved. Examples are the digestive tract, the urinary tract and the respiratory tract.
2. A bundle of myelinated nerve fibres with a common function.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


a bundle of nerve fibres that may run within the CENTRAL NERVOUS SYSTEM or to the peripheral nervous system.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005


1. A bundle of nerve fibres (e.g. the optic tracts).
2. A system of organs serving the same function, e.g. the respiratory tract.
geniculocalcarine tract See optic radiations.
optic tract's Two cylindrical bands of nerve fibres carrying visual impulses. They run outward and backward from the posterolateral angle of the optic chiasma, then sweep laterally, encircling the hypothalamus posteriorly on their way to the lateral geniculate bodies. A few fibres end in the superior colliculi. See incongruous hemianopia; visual pathway.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann


(trakt) [TA]
1. Elongated area; passage or pathway.
2. Abnormal passage (e.g., a fistula or sinus communicating with an abscess cavity).
[L. tractus, a drawing out]
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about tract

Q. While in a conversation with anyone they have about a minute before I loose tract and intrest, Is this ADHD I always feel like I have to go full speed 24/7 and can never relax, sounds strange I know but it seems to be catching up with me.

A. not necessarily...i see that you are 31. those symptoms are new? if so- thee are other conditions that might cause them. hyperthyroid can get you in that state too. so it might be a good idea to go and get checked up.

Q. How to prevent getting a bladder infection? I am worried about getting another bladder infection like I just had now. I am during my second trimester. How can I avoid getting it again?

A. drink more cranberry juice,its 100% natural, and wont harm the baby in anyway.

More discussions about tract
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