Vestigial Health Dictionary

The thickening of the cuticular lining of buccal cavity; buccal capsule may be large, small, vestigial or absent. In some nematodes, the cuticle lining within the buccal capsule may be modified to be chitinous teeth or cutting plates as in Ancylostomatidae or a stylet as in Trichinelloidea.... buccal capsule

a bloodsucking insect of the genus Cimex. C. hemipterus of the tropics and C. lectularius of temperate regions have reddish flattened bodies and vestigial wings. They live and lay their eggs in the crevices of walls and furniture and emerge at night to suck blood; although bed bugs are not known vectors of disease their bites leave a route for bacterial infection. Premises can be disinfested with appropriate insecticides.... bed bug

n. (pl. coccyges or coccyxes) the lowermost element of the *backbone: the vestigial human tail. It consists of four rudimentary coccygeal vertebrae fused to form a triangular bone that articulates with the sacrum. See also vertebra. —coccygeal adj.... coccyx

a group of congenital abnormalities caused by failure of the *neural tube to form normally. In *spina bifida the bony arches of the spine, which protect the spinal cord and its coverings (the meninges), fail to close. More severe defects of fusion of these bones will result in increasingly serious neurological conditions. A meningocele is the protrusion of the meninges through the gap in the spine, the skin covering being vestigial. There is a constant risk of damage to the meninges, with resulting infection. Urgent surgical treatment to protect the meninges is therefore required. In a meningomyelocele (myelomeningocele, myelocele) the spinal cord and the nerve roots are exposed, often adhering to the fine membrane that overlies them. There is a constant risk of infection and this condition is accompanied by paralysis and numbness of the legs and urinary incontinence. *Hydrocephalus and an *Arnold–Chiari malformation are usually present. A failure of fusion at the cranial end of the neural tube (cranium bifidum) gives rise to comparable disorders. The bone defect is most often in the occipital region of the skull but it may occur in the frontal or basal regions. A protrusion of the meninges alone is known as a cranial meningocele. The terms meningoencephalocele, encephalocele, and cephalocele are used for the protrusion of brain tissue through the skull defect. This is accompanied by severe mental and physical disorders.... neural tube defects

n. the vestigial remains of part of the embryonic *mesonephros that are found near the testis of the adult. Some of the mesonephric collecting tubules persist as the functional *vasa efferentia but the rest degenerate almost completely. A similar vestigial structure (the paroophoron) is found in females.... paradidymis

n. the vestigial remains of part of the Wolffian duct (see mesonephros) in the female, situated next to each ovary. It is associated with a similar structure, the epoophoron. Both are without known function.... paroophoron

(auricle) n. the flap of skin and cartilage that projects from the head at the exterior opening of the external auditory meatus of the *ear (see illustration). In humans the pinna is largely vestigial but it may be partly concerned with detecting the direction of sound sources.... pinna