Cranial nerve, third: The third cranial nerve is the oculomotor nerve. The cranial nerves emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column. There are twelve cranial nerves.
The oculomotor nerve is responsible for the nerve supply to muscles about the eye:
The upper eyelid muscle which raises the eyelid;
The extraocular muscle which moves the eye inward; and
The pupillary muscle which constricts the pupil.
Paralysis of the oculomotor nerve results in drooping eyelid (ptosis), deviation of the eyeball outward (and therefore double vision) and a dilated (wide-open) pupil.
- Cranial nerves
Cranial nerves: The nerves of the brain, which emerge from or enter the skull (the cranium), as opposed to the spinal nerves, which emerge from the vertebral column. There are 12 cranial nerves, each of which is accorded a Roman numeral and a name: Cranial nerve I: the olfactory nerve Cranial nerve II: the optic […]
Cranio-: Referring to the cranium, the top portion of the skull, the bony vault that protects the brain. As in craniocleidodysostosis, craniology, craniopharyngioma, craniotomy, etc.
Craniocleidodysostosis: A genetic (inherited) disorder of bone development characterized by: Typical cranial and facial abnormalities with square skull, late closure of the sutures of the skull, late closure of the fontanels (the soft spots), low nasal bridge, delayed eruption of the teeth, abnormal permanent teeth, etc. Absent or incompletely formed collar bones (the “cleido-” part […]
Craniology: The study of variations in size, shape, and proportion of the skull (cranium). Also known as phrenology, it was a pseudoscience of the 18th and 19th centuries based on the belief that a person’s character could be learned by looking with care at the shape of their head and noting each and every bump […]
- Craniometaphyseal dysplasia
Craniometaphyseal dysplasia: An inherited skeletal condition that involves abnormal bone formation and abnormal mineralization of the skull as well as the long bones. There is increased density of craniofacial bones beginning at the base of the skull during early childhood. The progressive thickening of the bones of the skull can lead to severe visual and […]