Discussions (D)
Terence R. Anthoney in Neuroanatomy and the Neurologic Exam, 2017
Earlier it was pointed out that sometimes a nerve branch or root is also called a trunk, and that sometimes the terms “branch” and “root” are applied to the same structure. Now that the existence of branches, trunks, and roots of plexuses and parts of the peripheral autonomic nervous system have been demonstrated, additional cases can be cited. The major class of examples is formed by the many plexuses and ganglia whose roots are, in fact, the branches of named nerves or other plexuses—e.g., the ventral rami ([Latin] = branches) of spinal nerves form the roots of the brachial plexus (W&W, p. 1094–1095; Haymaker and Woodhall, 1953, p. 210), the descending branch of the hypoglossal nerve is the upper root of the ansa cervicalis (W&W, p. 1082–1083). and the three roots of the ciliary ganglion are branches from the nasociliary nerve, the nerve to the inferior oblique, and from the internal carotid plexus, respectively (W&W, p. (1058; DeJ, p. 168). Another example involves the mandibular nerve, whose sensory root (W&W, p. 1066) is a branch of the semilunar ganglion of the trigeminal nerve (DeJ, p. 165). Since the branches just mentioned can also be considered nerve trunks in their own right (e.g., for branches of the ventral rami of spinal nerves described as trunks: C&S, p. 183), each of them is a branch (of a more proximal structure), a trunk, and a root (of a more distal structure), all at the same time!
Write short notes on the third cranial nerve
Nathaniel Knox Cartwright, Petros Carvounis in Short Answer Questions for the MRCOphth Part 1, 2018
On the lateral side of the posterior clinoid process the nerve perforates the dura to lie in the lateral wall of the cavernous sinus above the fourth cranial nerve: – the oculomotor nerve next runs forwards and receives a sensory branch from the ophthalmic division of the fifth cranial nerve and a sympathetic contribution from the internal carotid plexus– within the cavernous sinus the oculomotor nerve is crossed from its lateral side by the fourth cranial nerve. More distally it is crossed by the ophthalmic division of the fifth cranial nerve.
Physiology of the nervous system
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2015
The ganglia form sympathetic chains. The post-ganglionic fibres leave the ganglia as grey rami communicantes and join the spinal nerves or visceral nerves to innervate the target organ. The grey rami are unmyelinated C fibres. The sympathetic chains extend down the length of the vertebral column and are divided into four parts: A ‘cervical part’ consisting of three ganglia (superior, middle and inferior) supplying the head, neck and thorax. The superior cervical ganglion sends postganglionic fibres to form the internal carotid plexus. The inferior cervical or stellate ganglion is fused with the first thoracic ganglion.A ‘thoracic part’ consisting of a series of ganglia from each thoracic segment. Branches from T1–T5 supply the aortic, cardiac and pulmonary plexuses. The greater and lesser splanchnic nerves are formed from the lower seven thoracic ganglia. The lowest splanchnic nerve arises from the last thoracic ganglion and supplies the renal plexus.‘Lumbar sympathetic ganglia’ are situated in front of the vertebral column as prevertebral ganglia. Some form the coeliac plexus.The ‘pelvic part’ of the sympathetic chain lies in front of the sacrum and consists of the sacral ganglia. The sacral ganglia contribute to the hypogastric and pelvic plexus distributed to the pelvic viscera and the arteries of lower limbs.
A Unique Case of Horner’s Syndrome Following Subintimal Haematoma Within an Atherosclerotic Plaque
Published in Neuro-Ophthalmology, 2018
Mª Lourdes Del Río Solá, Carlos Vaquero Puerta
These sympathetic fibers originate at the level of C8 to T2 in the spinal cord and travel upward to the superior cervical ganglion near the angle of the mandible.3 The posterior neurons form part of the internal carotid plexus and ascend to the cranium, being responsible for the dilation of the iris. Preganglion lesion is the most frequent cause of Horner syndrome secondary to a dissection of the artery, arteritis and surgical procedures.4,5 The effects of phenylephrine are most likely due to the fact that this is a post-ganglionic Horner’s, consistent with the anatomical location of the lesion.6
Supraorbital Nerve and Cavernous Sinus Invasion with Poorly Differentiated Carcinoma of Unknown Primary
Published in Neuro-Ophthalmology, 2018
Saagar N. Patel, Mohammad Obadah Nakawah, Ama Sadaka, Shauna Berry, Juan Ortiz Gomez, Suzanne Powell, Andrew G. Lee
Multiple cranial nerves (III, IV, V1, V2, and VI) and sympathetic fibers (Horner syndrome) from the internal carotid plexus travel through the cavernous sinus as they make their way anteriorly towards the orbit. The abducens nerve (VI) is the only cranial nerve that does not lie on the lateral wall of the cavernous sinus and is positioned inferolateral to the cavernous internal carotid artery. Sympathetic fibers from the internal carotid plexus travel with the abducens nerve at the level of the posterior carotid knee (the transition point of the vertical to horizontal course of the internal carotid artery) before dissociating and meeting the ophthalmic nerve (V1) anterior into the cavernous sinus.6 Our patient demonstrated signs and symptoms of PNI along the supraorbital, ophthalmic, and presumed abducens and sympathetic pupillary nerve fibers at the cavernous sinus. We speculate that the primary carcinoma originated as a carcinoma involving the forehead or adnexal structures with retrograde extension into the cavernous sinus via the supraorbital nerve; however extensive dermatologic and ophthalmic examinations have been unrevealing. Nasopharyngeal carcinoma with superior extension was considered to be less likely as there was no definitive involvement of the pterygopalatine fossa on imaging and otolaryngology examinations were unrevealing. The presence of cavernous sinus syndrome or an intractable trigeminal neuralgia should alert the physician to the possibility of an underlying primary or metastatic cavernous sinus malignancy. To our knowledge this is the only case demonstrating clinical and radiographic involvement of the supraorbital nerve from a poorly differentiated carcinoma presenting with trigeminal pain and a Horner syndrome in the English language ophthalmic literature.4,7,8
Related Knowledge Centers
- Abducens Nerve
- Deep Petrosal Nerve
- Internal Carotid Artery
- Mydriasis
- Pterygopalatine Ganglion
- Pupillary Reflex
- Trigeminal Ganglion
- Nerve Plexus
- Superior Tarsal Muscle
- Iris Dilator Muscle