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Axon. An axon (from Greek ἄξων áxōn, axis) or nerve fiber (or nerve fibre: see spelling differences) is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action potentials away from the nerve cell body. The function of the axon is to transmit information to ...
The axons from the nasal half cross the brain at the optic chiasma to join with axons from the temporal half of the other eye before passing into the lateral geniculate body. Although there are more than 130 million retinal receptors, there are only approximately 1.2 million fibres (axons) in the optic nerve.
Trochlear nerve (cranial nerve 4) – eye rotation. Trigeminal nerve (cranial nerve 5) – sensation from the face and certain motor functions such as biting and chewing. Abducens nerve (cranial nerve 6) – certain eye rotation. Facial nerve (cranial nerve 7) – facial expression and taste sensations from the tongue.
The adult human brain weighs on average about 1.2–1.4 kg (2.6–3.1 lb) which is about 2% of the total body weight, [2] [3] with a volume of around 1260 cm 3 in men and 1130 cm 3 in women. [4] There is substantial individual variation, [ 4 ] with the standard reference range for men being 1,180–1,620 g (2.60–3.57 lb) [ 5 ] and for women ...
There is also a distinct pathway from layer 3 of the EC directly to CA1, often referred to as the temporoammonic or TA-CA1 pathway. Granule cells of the DG send their axons (called "mossy fibers") to CA3. Pyramidal cells of CA3 send their axons to CA1. Pyramidal cells of CA1 send their axons to the subiculum and deep layers of the EC.
Some neurons are responsible for conveying information over long distances. For example, motor neurons, which travel from the spinal cord to the muscle, can have axons up to a meter in length in humans. The longest axon in the human body belongs to the Sciatic Nerve and runs from the great toe to the base of the spinal cord. These are ...
Commissural fiber. The commissural fibers or transverse fibers are axons that connect the two hemispheres of the brain. Huge numbers of commissural fibers make up the commissural tracts in the brain, the largest of which is the corpus callosum. In contrast to commissural fibers, association fibers form association tracts that connect regions ...
They send these signals by means of an axon, which is a thin protoplasmic fiber that extends from the cell body and projects, usually with numerous branches, to other areas, sometimes nearby, sometimes in distant parts of the brain or body. The length of an axon can be extraordinary: for example, if a pyramidal cell (an excitatory neuron) of ...