(kă-nal′)

[L. canalis, channel]
A narrow tube, channel, tunnel, or passageway.
SEE: duct; SEE: foramen; SEE: groove; SEE: space

adductor canal

A canal of connective tissue through which the femoral artery, femoral vein, and saphenous nerve pass inside the lower half of the inner thigh between the femoral triangle and the popliteal fossa. The canal is surrounded by the vastus medialis, adductor longus, and adductor magnus muscles and is covered by the sartorius muscle.
SYN: SEE: Hunter canal; SEE: subsartorial canal

Alcock canal

SEE: Pudendal canal.

alimentary canal

The digestive tract from the mouth through the anus.

alveolar canal

In the skull, any of the two or three canals leading from small holes along the middle of the infratemporal surface of the maxilla. These canals transmit the posterior superior alveolar blood vessels and nerves, which supply the upper molars and their surrounding gums.
SYN: SEE: maxillary canal

anal canal

The 1.5-in-long (4-cm) terminal section of the large intestine, beginning where the rectum passes downward and forward through the pelvic diaphragm and ending in the anus. The entire length of the anal canal is surrounded by sphincter muscles, and the canal remains closed except during defecation and passage of flatus.

atrioventricular canal

In the embryo, the segment of the heart tube between the developing atria and ventricles. This segment eventually gives rise to the mitral and tricuspid valves and to portions of the interatrial and interventricular septa.

birth canal

The canal comprising the cervix, vagina, and vulva, through which the products of conception, including the fetus, pass during labor and birth.

bony semicircular canal

Any of several canals located in the bony labyrinth of the internal ear and enclosing the three semicircular ducts that open into the vestibule. They are enclosed within the petrous portion of the temporal bone.

carotid canal

The canal followed by the internal carotid artery and its accompanying sympathetic nerves as it passes through the bone of the skull. The carotid canal runs forward until, passing over the foramen lacerum, it turns up and opens into the middle cranial fossa along a groove at the base of the sella turcica.

central canal of neural tube

The central lumen of the neural tube of the embryo. It is lined by the foot processes of radial glial cells. The central canal of the neural tube develops into the ependyma-lined ventricles of the brain, the cerebral aqueduct of the brainstem, and the central canal of the spinal cord.

central canal of spinal cord

The remnant of the lumen of the caudal aspect of the neural tube. It is largely obliterated in the adult spinal cord.

cervical canal

The canal through the center of the cervix.

Cloquet canal

SEE: Cloquet canal

cochlear canal

SEE: Cochlear duct.

condylar canal

A canal in the occipital bone of the skull for passage of the emissary vein from the transverse sinus. It opens anterior to the occipital condyle.

canal of Corti

SEE: Corti, Alfonso Giacomo Gaspare

craniopharyngeal canal

In the embryo, a temporary canal in the cartilage of the base of the sphenoid bone, enclosing the developing pituitary gland.

dental canal

SEE: alveolar canal; SEE: mandibular canal

Dorello canal

SEE: Dorello canal

ethmoidal canal

Either of two canals, the anterior and posterior ethmoidal, that run transversely across the lateral mass of the ethmoid bone to the cribriform plate and lie between the ethmoid and frontal bones. The anterior ethmoidal canal transmits the anterior ethmoidal vessels and the nasociliary nerve; the posterior ethmoidal canal transmits the posterior ethmoidal vessels and nerve.

external auditory canal

The open tubular canal from the pinna (auricle) of the ear to the tympanic membrane (ear drum). It is lined by thin, sensitive skin, which continues as the outer covering of the tympanic membrane. The medial two thirds is a bony canal in the temporal bone; the outer one third is cartilaginous. It contains hair and ceruminous glands.
SEE: external auditory meatus

facial canal

The canal followed by the facial nerve through the temporal bone. Inside the skull, the facial canal begins in the internal auditory canal; outside the skull, it ends at the stylomastoid foramen. Within the bone, the canal makes two bends as it bypasses the inner ear. The first bend houses the geniculate ganglion, which sends sensory axons toward the brainstem as the intermediate component of the facial nerve. Near the second bend, the facial nerve gives off a branch to the stapedius muscle. In the final segment of the canal, the facial nerve gives off the chorda tympani nerve; thus, only motor axons remain as the facial nerve exits the canal.

fallopian canal

A canal in the petrous portion of the temporal bone. The facial nerve passes through it.
SYN: SEE: aqueductus Fallopii

femoral canal

1. The medullary (central) canal inside the shaft of the femoral bone.
2. The most medial compartment of the femoral sheath. A femoral hernia is a bulge of intestine that has been pushed down into the femoral canal through its upper opening, the femoral ring.

gastric canal

A longitudinal canal extending from the esophagus to the pylorus on the inner surface of the stomach following the lesser curvature.

greater palatine canal

In the skull, a thin vertical canal between the nasal surface of the maxillary bone and the perpendicular plate of the palatine bone that contains the greater (anterior) and lesser (middle and posterior) palatine nerves and the greater and lesser palatine vessels.

Guyon canal

SEE: Guyon canal

haversian canal

In compact bone, tiny canals in the center of concentric cylinders of mineralized tissue. Nerves and blood vessels run through these channels, all of which interconnect. Each Haversian canal is the center of an osteon.
SEE: bone; SEE: Havers, Clopton

Hunter canal

SEE: Adductor canal.

hyaloid canal

A canal in the vitreous body of the eye, extending from the optic papilla to the central posterior surface of the lens. It serves as a lymph canal. In the fetus the canal contains the hyaloid artery. This normally disappears 6 weeks before birth.

hypoglossal canal

A canal in the skull, just above the foramen magnum in the occipital bone, through which the hypoglossal nerve and a branch of the ascending pharyngeal artery pass.
SYN: SEE: anterior condyloid foramen

inferior alveolar canal

SEE: Mandibular canal.

infraorbital canal

An anterior-posterior bony canal in the floor of the orbit. The infraorbital artery and nerve run in this canal, which opens anteriorly as the infraorbital foramen.

inguinal canal

A canal made of the transversalis fascia and the aponeuroses of the abdominal wall muscles just above the inguinal ligament. The inguinal canal is a cylindrical passageway 4 cm long from the retroperitoneal space to the subcutaneous fascia. It begins at the deep (internal) inguinal ring inside the abdominal wall, approx. halfway between the anterior superior spine of the iliac bone and the pubic symphysis, 0.50 in (1.25 cm) above the inguinal ligament. It continues downward and toward the midline, and it ends at the superficial (external) inguinal ring under the skin at the pubic crest. The inguinal canal contains an outpouching of the peritoneum, blood and lymph vessels, and the ilioinguinal nerve. In males, it contains the spermatic cord; in females, it contains the round ligament of the uterus.

internal auditory canal

The canal in the petrous portion of the temporal bone through which the vestibulocochlear and facial nerves exit the cranial cavity.
SYN: SEE: meatus acusticus internus

intestinal canal

The alimentary canal from the stomach to the anus.

lacrimal canal

SEE: Nasolacrimal canal.

mandibular canal

The canal within the mandible, through which the inferior alveolar blood vessels and nerve pass to supply the lower teeth and gums.
SYN: SEE: inferior alveolar canal

mandibular incisive canal

The final segment of the mandibular canal, containing the nerves and blood vessels for the lower incisors and surrounding gums.

maxillary canal

SEE: Alveolar canal.

medullary canal

The marrow canal of long bones.

membranous semicircular canal

A semicircular duct.
SEE: semicircular duct

nasolacrimal canal

A small bony canal in the skull inside the medial wall of the orbit between the lacrimal bone and the maxilla. Its top opens into the nasolacrimal fossa, its bottom into the nasal cavity under the inferior nasal concha. It contains the membranous nasolacrimal duct, which drains tears from the eye.
SYN: SEE: lacrimal canal

neurenteric canal

A temporary canal in the vertebrate embryo between the neural and intestinal tubes. It is the temporary communication between cavities of the yolk sac and the amnion.

nutrient canal

A tiny tubular canal in bone, filled by vessels and nerves running to and from the osteons and the other basic metabolic and growth units.
SEE: bone

obturator canal

A canal in the obturator membrane of the hip bone that transmits the obturator vessels and nerve.

optic canal

In the skull, a roughly spherical canal through the lesser wing of the sphenoid bone connecting the middle cranial fossa and the superior-medial edge of the back of the orbit. The optic nerve and the ophthalmic artery pass through the optic canal.
SYN: SEE: optic foramen

pericardioperitoneal canal

SEE: Pleuroperitoneal canal.

Petit canal

SEE: Petit, François Pourfour du

pharyngeal canal

A canal between the sphenoid and palatine bones that transmits branches of the sphenopalatine vessels.

pleuroperitoneal canal

A tubular canal extending ventrally and laterally from the coelom inside each half of the embryo and destined to form the pleural cavity for the lung.
SYN: SEE: pericardioperitoneal canal

portal canal

The connective tissue (a continuation of Glisson capsule) and its vessels (interlobular branches of the hepatic artery, portal vein, and bile duct and lymphatic vessel) located between adjoining liver lobules.

pterygoid canal

In the skull, a small horizontal canal beginning inside the canal of the foramen lacerum (in the middle cranial fossa), passing through the root of the pterygoid process of the sphenoid bone, and opening into the pterygopalatine fossa behind and below the medial wall of the orbit. It transmits the pterygoid nerve and vessels to the pterygopalatine ganglion.
SYN: SEE: vidian canal

pterygopalatine canal

A canal between the maxillary and palatine bones that transmits the descending palatine nerves and artery.

pudendal canal

A canal inside the obturator fascia along the lower pelvic surface of the internal obturator muscle and running along the inner lower edge of the ramus of the ischium. It contains the pudendal nerve and the internal pudendal vessels.
SYN: SEE: Alcock canal

pulp canal

SEE: Root canal (1).

pyloric canal

The canal inside constricted region of the pyloric segment of the stomach that opens through the pyloric sphincter into the duodenum.

root canal

1. The canal inside the tooth that extends from the pulp chamber to the apical foramen. It contains arteries, veins, lymphatic vessels, and sensory nerve endings.
SYN: SEE: pulp canal
2. Colloquially, the procedure for preserving a tooth by removing its diseased pulp cavity.

sacral canal

The continuation of the vertebral canal into the sacrum.

canal of Schlemm

SEE: canal of Schlemm

semicircular canal

One of the three perpendicular canals, each forming two-thirds of a circle, that extend from the vestibule of the labyrinth in the inner ear. The semicircular canals are the bony shells that contain the similarly shaped semicircular ducts, membranous sensory organs that detect the angular acceleration and the orientation of the head.

spinal canal

The continuous canal through the central foramina in the vertebrae, which contains the spinal cord and the spinal nerve roots in their meningeal coverings.
SYN: SEE: vertebral canal

subsartorial canal

SEE: Adductor canal.

uterine canal

The cavity of the uterus.

uterocervical canal

The cavity of the cervix of the uterus.

uterovaginal canal

The combined cavities of the uterus and vagina.

vaginal canal

The cavity of the vagina. The vaginal walls can expand but are normally in contact with each other; thus, this cavity is a potential space.

vertebral canal

SEE: Spinal canal

vidian canal

SEE: Pterygoid canal.

Volkmann canals

SEE: Volkmann canals