Efferent
Efferent (from Latin effere , `` carry out ' ' , `` lead out '') are the neurophysiologically called processes of nerve cells through which signals from a certain area are transmitted to and from other cells. This general marking according to the direction of the signal line can be used for different structures on different levels:
- At the cellular level in relation to the nerve cell body , the neurite is referred to as efferent.
- At the regional level, based on a certain brain region , the pathways leading away are also called efferents in contrast to the incoming afferents .
- At the systemic level in relation to the central nervous system (CNS), the emerging nerve fibers , through which signals emanate, are collectively referred to as efferent nerve fibers or "efferents" and are divided into somatic and visceral. Opposite these are afferents for the signal input. Afferent and efferent thighs are used as components of a reflex arc .
In relation to the direction of the signal line, afferents are the counterpart to efferents and thus nerve fibers through which signals from other cells flow afferently to a nerve cell (whose perikaryon is located in the CNS, for example).
Efferents from the CNS
Areas in the central nervous system - a brain region or a spinal cord segment - receive signals via afferents , process them and can transmit signals to various other core areas of the brain and / or the spinal cord via efferents.
In certain core areas - the (motor) core columns of the spinal cord and (motor) nuclei of cranial nerves - there are nerve cells whose neurites emerge from the CNS. In the anterior roots of spinal nerves and with some cranial nerves , these nerve fibers leave the central area and form parts of (peripheral) nerves or nerve branches of the peripheral nervous system . These efferent nerve fibers are collectively referred to as efferents (on the systemic level). They include the (motor) nerve fibers, which transmit signals to skeletal muscles and smooth muscles . Depending on the respective organ of success, these efferents then influence different services. Efferents can be further differentiated according to their destination.
The somatic efferent (SE, of lat. Soma , body ' ) are motor nerve fibers ( motoneurons ) to the skeletal muscles and belong to the somatic nervous system ; they are also known as somatomotor .
The visceral efferents (from Latin viscera , entrails ), on the other hand, belong to the vegetative nervous system and are also referred to as visceromotor . Some authors further divide them into the general visceral efferents (AVE; English general visceral efferent GVE) and the special visceral efferents (SVE). The AVE convey information to the smooth muscles, the heart muscles and the glands . The SVE innervate the musculature derived from the gill arches ("branchial motor efferents"), i.e. the masticatory muscles , the mimic muscles , the muscles of the pharynx and larynx, as well as the sternocleidomastoid and trapezius muscles .