canal
(kă-nal' 
)
[L. canalis, channel]
A narrow tube, channel, tunnel, or passageway.
SEE: duct; foramen; groove; space.
adductor c.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: Hunter canal; subsartorial canal.
alimentary c.The digestive tract from the mouth through the anus.
alveolar c.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: maxillary canal.
anal c.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.
SEE: illus.
atrioventricular c.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 c.The canal comprising the cervix, vagina, and vulva, through which the products of conception, including the fetus, pass during labor and birth.
bony semicircular c.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 c.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 c. 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 c. 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 c.The canal through the center of the cervix.
SEE: Cloquet canal.
condylar c.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.
SEE: under Corti, Alfonso Giacomo Gaspare.
craniopharyngeal c.In the embryo, a temporary canal in the cartilage of the base of the sphenoid bone, enclosing the developing pituitary gland .
SEE: alveolar canal; mand ibular canal.
SEE: Dorello canal.
ethmoidal c.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 c.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 gland s.
SEE: external auditory meatus.
facial c.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 c.A canal in the petrous portion of the temporal bone. The facial nerve passes through it. SYN: aqueductus Fallopii.
femoral c.1The medullary (central) canal inside the shaft of the femoral bone. 2The 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 c.A longitudinal canal extending from the esophagus to the pylorus on the inner surface of the stomach following the lesser curvature.
greater palatine c.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.
SEE: Guyon canal.
haversian c.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; Havers, Clopton.
hyaloid c.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 c.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: anterior condyloid foramen.
inferior alveolar c.Mand ibular canal.
infraorbital c.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 c.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 c.The canal in the petrous portion of the temporal bone through which the vestibulocochlear and facial nerves exit the cranial cavity. SYN: meatus acusticus internus.
intestinal c.The alimentary canal from the stomach to the anus.
lacrimal c.Nasolacrimal canal.
mand ibular c.The canal within the mand ible, through which the inferior alveolar blood vessels and nerve pass to supply the lower teeth and gums. SYN: inferior alveolar canal.
mand ibular incisive c.The final segment of the mand ibular canal, containing the nerves and blood vessels for the lower incisors and surrounding gums.
medullary c.The marrow canal of long bones.
membranous semicircular c.A semicircular duct.
SEE: semicircular duct.
nasolacrimal c.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: lacrimal canal.
neurenteric c.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 c.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 c.A canal in the obturator membrane of the hip bone that transmits the obturator vessels and nerve.
optic c.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: optic foramen.
pericardioperitoneal c.Pleuroperitoneal canal.
SEE: under Petit, François Pourfour du.
pharyngeal c.A canal between the sphenoid and palatine bones that transmits branches of the sphenopalatine vessels.
pleuroperitoneal c.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: pericardioperitoneal canal.
portal c.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 c.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: vidian canal.
pterygopalatine c.A canal between the maxillary and palatine bones that transmits the descending palatine nerves and artery.
pudendal c.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: Alcock canal.
pyloric c.The canal inside constricted region of the pyloric segment of the stomach that opens through the pyloric sphincter into the duodenum.
root c.1The 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: pulp canal. 2Colloquially, the procedure for preserving a tooth by removing its diseased pulp cavity.
sacral c.The continuation of the vertebral canal into the sacrum.
SEE: canal of Schlemm.
semicircular c.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 c.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: vertebral canal.
subsartorial c.Adductor canal.
uterine c.The cavity of the uterus.
uterocervical c.The cavity of the cervix of the uterus.
uterovaginal c.The combined cavities of the uterus and vagina.
vaginal c.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.
SEE: Volkmann canals.