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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Anatomical terms of neuroanatomy | 2/2 | https://en.wikipedia.org/wiki/Anatomical_terms_of_neuroanatomy | reference | science, encyclopedia | 2026-05-05T07:13:49.992851+00:00 | kb-cron |
Axial or "transverse" or "horizontal", the plane that is horizontal and parallel to the ground with the body standing in the standard anatomical position. It contains (and thus is defined by) the lateral and the medial axes of the brain. Coronal, a vertical plane that passes through the coronal suture of the skull (or through both ears), or any plane parallel to this. There is no term "paracoronal" comparable to the commonly used "parasagittal". Sagittal, a vertical plane that passes from between the nostrils, and between the cerebral hemispheres, dividing the brain into left and right halves. "Median plane" specifically defines the midline between left and right sides of the body. It contains the dorsoventral and medial axes of the brain. A parasagittal plane is any plane parallel to the sagittal plane.
== Nerves ==
=== Function === Specific terms are used for peripheral nerves that originate from, or arrive at, a specific point. An afferent nerve fiber is a fibre originating at the present point. For example, a striatal afferent is an afferent originating at the striatum. An efferent nerve fiber is one that arrives at the present point. For example, a cortical efferent is a fibre coming from elsewhere, and arriving to the cortex. That is the opposite of the direction in which the nerve fibre conducts signals.
=== Nerve fibre crossings === Specific terms are also used to describe the route of a nerve or nerve fibre: A chiasm (from Greek Chi) is used to describe different types of crossings of or within peripheral nerve fibres between the cerebral hemispheres. The major example in the human brain is the Optic chiasm. A decussation (from Latin decussis 'ten', written as a capital X) refers to nerve fibers that cross the sagittal plane from one side of the central nervous system to the other, and connect different brain regions. There are two kinds:
Type 1 crosses the sagittal plane in the same brain region or spinal segment where the cell body is located. Examples are Mauthner cells in fish and amphibians. Type 2 crosses the sagittal plane in a different brain region. Example: pyramidal decussations. The first type is known also for invertebrates, whereas the second type only occurs in vertebrates. The second type is thought to be due to an axial twist, such that each hemisphere of the forebrain represents predominantly the contralateral side of the body. A commissure is a bilateral connection of axons connecting the left and right side of the same brain region. For example, nerve fibre tracts that cross between the two cerebral hemispheres, are the anterior commissure, posterior commissure, corpus callosum, hippocampal commissure, and habenular commissure. The spinal cord contains a commissure as well: the anterior white commissure. A ganglion can also have the form of crossing nerves, but a ganglion always contains synapses between neurons as well as their cell bodies. The other kinds of nerve crossings never contain synapses of cell bodies of neurons. The difference between a chiasm and a decussation is that the first refers to peripheral nerves whereas the latter refers to crossings inside central nervous system. A commissure connects the same brain region of each side whereas a decussation connects different brain regions.
== Brain ==
Specific terms are used to represent the gross anatomy of the brain: A gyrus is an outward folding of the brain, for example the precentral gyrus. A sulcus is an inward fold, or valley in the brain's surface - for example the central sulcus. Additional terms used to describe these may include:
Annectent gyrus, for a small gyrus hidden in the depth of a sulcus sulcal fundus, for the bottom of a sulcus, an inward fold A fissure is used to describe:
A deep groove produced by opercularisation. An example is the Sylvian Fissure. A deep groove produced by the differentiation of the telencephalic vesicles. An example is the longitudinal fissure, also known as the interhemispheric fissure.
== Imaging == Specific acronyms are used to represent imaging. Some common acronyms include MRI (Magnetic Resonance Imaging) and CT (Computed tomography).
== See also == Anatomical terms of muscle Anatomical terms of motion
== References ==