The Experts below are selected from a list of 6 Experts worldwide ranked by ideXlab platform
Harold Ellis - One of the best experts on this subject based on the ideXlab platform.
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Anatomy of the spinal nerves and dermatomes
Anaesthesia & Intensive Care Medicine, 2009Co-Authors: Harold EllisAbstract:Abstract There are 31 pairs of spinal nerves: eight cervical, 12 thoracic, five lumbar, five sacral and one coccygeal. They form by fusion of a posterior sensory spinal root (bearing its posterior root ganglion) with an anterior motor root. These join at each intervertebral foramen. Typically, the nerve then divides into a posterior and an anterior primary Ramus. The former supplies the vertebral muscles and dorsal skin. The anterior primary Ramus in the thoracic region bears a White Ramus Communicans to the sympathetic ganglion. Each spinal nerve receives a grey Ramus from the sympathetic chain. The nerves T2–T12 supply the skin and muscles of the trunk sequentially. The other nerves are arranged into the cervical, brachial, lumbar and sacral plexuses. The cervical plexus supplies the skin and anterior muscles of the neck and form the phrenic nerve (C3–C5), while the brachial plexus supplies the skin and muscles of the upper limb, and the lumbar and sacral plexuses supply the skin of the lower limb and perineum and the muscles of the posterior abdominal wall, pelvis, perineum and lower limb. The segmental nerves are arranged to supply the skin (dermatomes), while the segmental supply to the limb muscles, the myotomes, is more complex.
Stanley Monkhouse - One of the best experts on this subject based on the ideXlab platform.
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Cranial Nerves: The sympathetic nervous system in the head
Cranial Nerves, 2005Co-Authors: Stanley MonkhouseAbstract:Sympathetic fibres are not conveyed from the brain or brain stem in cranial nerves, but are found in distal branches of some cranial nerves. They are not usually considered components of cranial nerves, but they appear here for the sake of completeness. Functions of the sympathetic system in the head These are similar to those in the rest of the body: secretomotor to sweat glands, vasomotor (especially important for cerebral vessels), muscles of the hair follicles and so on. In addition, various structures in the eye receive a sympathetic innervation, particularly dilator pupillae and part of levator palpebrae superioris muscle. Sympathetic pathways to cranial structures Sympathetic nerve impulses leave the central nervous system only in the thoracolumbar region of the spinal cord. This means that if their destination is the head, they leave the spinal cord in upper thoracic spinal nerves and thence pass back up to the head. The sympathetic chain is the redistribution system by which means they ascend. Preganglionic axons: T1, neck of first rib, cervical chain, synapse in superior cervical ganglion Preganglionic axons arise in lateral grey horn of T1 and/or T2 segments of spinal cord, and possibly also C8. Ventral roots of appropriate spinal nerves, spinal nerve, anterior primary Ramus, White Ramus Communicans. Sympathetic chain at T1 ganglion near neck of first rib. Preganglionic axons for cranial structures do not synapse immediately, but ascend in sympathetic chain, posterior to carotid sheath, on surface, or in substance of prevertebral muscles. […]
