General somatic efferent
General somatic
efferent fibers carry motor impulses to somatic skeletal muscles.
GSE neurons innervate
striated muscle of embryonic somite & limb buds origin
Nerves contain GSE functional components:
·
All Spinal nerves,
·
4 pure Motor Cranial nerves
1.
III (oculomotor ),
2.
IV(trochlear nerve ),
3.
VI (abducent nerve ), and
4.
XII (hypoglossal) carry these fibers.
General Somatic Efferent Nuclei
Spinal nerves : The ventral horns of the spinal cord (lamina
IX of Rexed ) contains somatic efferent neurons (motor
neurons) arranged into clusters called motor nuclei. There are two groups of
nuclei, medial and lateral .
Medial motor nuclei (column) extend
the entire length of the spinal cord and contain motor neurons to the axial musculature
The larger lateral motor nuclei (columns)
of cervical and lumbosacral enlargements
contain neurons to the musculature of upper and lower extremities. The alpha
motor neurons of lateral nuclei are larger than the medial motor nuclei .
Cranial nerves :
1. Oculomotor nucleus
2. Trochlear nucleus
3. Abducent nucleus
4.
Hypoglossal nucleus
Muscles supply by
General somatic efferent
Spinal nerves:
Medial motor nuclei (unlabeled) innervate axial
musculature and are present at all levels of spinal cord. Lateral motor nuclei
(labeled below) innervate limb musculature and are found in cervical and
lumbosacral enlargement segments.
In spinal nerve this functional components passes through
the ventral roots, carrying motor impulses to skeletal muscle through
a neuromuscular junction. As shown below, lateral motor nuclei are
somatotopically organized. Proximal muscles are ventral; distal muscles are
dorsal. Cranial muscles are lateral; caudal muscles are medial.
Cranial nerves
1. Oculomotor nucleus: extra ocular
muscles except superior oblique and lateral rectus
2. Trochlear nucleus: superior oblique
3. Abducent nucleus:
lateral rectus muscle
4.
Hypoglossal nucleus: muscles of tongue
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