Chapter 44
Section 44 of Grey's Anatomy, Part 4. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording from M. L. Cohen, Anatomy of the Human Body, Part 4 by Henry Grey. The Cephalic and Cervical Portions of the Sympathetic System.
The Cephalic Portion of the Sympathetic System. Paracephalica S. Sympathesi. The Cephalic Portion of the Sympathetic System begins as the internal carotid nerve, which appears to be a direct prolongation of the superior cervical ganglion. It is soft in texture and of a reddish color.
It ascends by the side of the internal carotid artery and entering the carotid canal and temporal bone divides into two branches, which lie one on the lateral and the other on the medial side of that vessel. The lateral branch, the larger of the two, distributes filaments to the internal carotid artery and forms the internal carotid plexus.
The medial branch also distributes filaments to the internal carotid artery and continuing onward forms the cavernous plexus. The internal carotid plexus, plexus caroticus interneus, carotid plexus, is situated on the lateral side of the internal carotid artery and in the plexus there occasionally exists a small ganglion-formed swelling, the carotid ganglion, on the undersurface of the artery.
The internal carotid plexus communicates with the semilunar ganglion, the abducent nerve, and the sphenopontine ganglion. It distributes filaments to the wall of the carotid artery and also communicates with the tympanic branch of the glossopharyngeal nerve. The communicating branches with the abducent nerve consist of one or two filaments which
join that nerve as it lies upon the lateral side of the internal carotid artery. The communication with the sphenopalentine ganglion is affected by a branch, the deep petrosal, given off from the plexus on the lateral side of the artery. This branch passes through the cartilage filling up the frame and lesserum and joins the gradal superficial petrosal to form the nerve of the pterygoid canal, vidian nerve, which passes
through the pterygoid canal to the sphenopontine ganglion. Communication with the tympanic branch of the glossopharyngeal nerve is affected by the corticotempanic, which may consist of two or three delicate filaments. The cavernous plexus, plexus cavernosus, is situated below and medial to that part of the internal carotid artery which is placed by the side of the celerotursica in the cavernous
sinus and is formed chiefly by the medial division of the internal carotid nerve. It communicates with the oculomotor, the trochlear, the optomic, and the abducent nerves and with the ciliary ganglion and distributes filaments to the wall of the internal carotid artery. The branch of communication with the oculomotor nerve joins that nerve at its pointed division. The branch to the trochlear nerve joins it as it lies on the lateral wall of the cavernous
sinus. Other filaments are connected with the undersurface of the optomic nerve and the second filament joins the abducent nerve. The filaments of connection with the ciliary ganglion arise from the anterior part of the cavernous plexus and enter the orbit through the superior orbital fissure.
They may join the nasociliary branch of the optomic nerve or be continued forward as a separate branch. The terminal filaments from the internal carotid and cavernous plexuses are prolonged as plexuses around the anterior middle cerebral arteries and the optomic artery. Along the formal vessels, they may be traced to the pia mater, along the latter into the
orbit where they accompany each of the branches of the vessel. The filaments prolonged onto the anterior communicating artery connect the sympathetic nerves of the right and left sides. The cervical portion of the sympathetic system. Par cervicalis S. sympathisi.
The cervical portion of the sympathetic trunk consists of three ganglia, distinguished according to positions as the superior, middle and inferior ganglia, connected by intervening cords. This portion receives no white rami communicantes from the cervical spinal nerves. Its spinal fibers are derived from the white rami of the upper thoracic nerves and enter the corresponding thoracic ganglia of the sympathetic trunk through which they ascend
into the neck. The superior cervical ganglion, ganglion cervicalis superiorius, the largest of the three, is placed opposite the second and third cervical vertebrae. It is of reddish gray color and usually fusiform in shape, sometimes broad and flattened and occasionally constricted at intervals.
It is believed to be formed by the coalescence of four ganglia corresponding to the upper four cervical nerves. It is in relation in front with the sheath of the internal carotid artery and internal jugular vein, behind with the longest capitis muscle. Its branches may be divided into inferior, lateral, medial and anterior.
The inferior branch communicates with the middle cervical ganglion. The lateral branches, external branches, consist of gray rami communicantes to the upper four cervical nerves and to certain of the cranial nerves. Sometimes the branch to the fourth cervical nerve may come from the trunk connecting the upper and middle cervical ganglia.
The branches to the cranial nerves consist of delicate filaments which run to the ganglion nodosum of the vagus and to the hypoglossal nerve. A filament, the jugular nerve, passes upward to the base of the skull and divides to join the petrous ganglion of the glossopharyngeal and the jugular ganglion of the vagus. The medial branches, internal branches, are peripheral and are the laryngopharyngeal branches
and the superior cardiac nerve. The laryngopharyngeal branches, rami laryngopharyngei, pass to the sides of the pharynx where they join with branches from the glossopharyngeal vagus and external laryngeal nerves to form the pharyngeal plexus. The superior cardiac nerve, nervous cardiacus superior, arises by two or more branches from
the superior cervical ganglion and occasionally receives a filament from the trunk between the first and second cervical ganglia. It runs down the neck behind the common carotid artery and in front of the longus coli muscle and crosses in front of the inferior thyroid artery and recurrent nerve. The course of the nerves on the two sides then differ.
The right nerve at the root of the neck passes either in front of or behind the subclavian artery and along the anominate artery to the back of the arch of the aorta where it joins the deep part of the cardiac plexus. It is connected with other branches of the sympathetic. About the middle of the neck it receives filaments from the external laryngeal nerve lower down
one or two twigs from the vagus and as it enters the thoracic it is joined by a filament from the recurrent nerve. Filaments from the nerve communicate with the thyroid branches from the middle cervical ganglion. The left nerve in the thorax runs in front of the left common carotid artery and across
the left side of the arch of the aorta to the superficial part of the cardiac plexus. The anterior branches, nervous carotid external eye, ramify upon the common carotid artery and upon the external carotid artery and its branches forming around each a delicate plexus on the nerves composing which small ganglia are occasionally found. The plexuses accompanying some of these arteries have important communications with other nerves.
That surrounding the external maxillary artery communicates with the submaxillary ganglion by a filament and that accompanying the middle meningeal artery sends an offset to the otic ganglia and a second, the external patrosal nerve to the genicular ganglion of the facial nerve. The middle cervical ganglion, ganglion cervicali media, is the smallest of the three cervical
ganglia and is occasionally wanting. It is placed opposite the six cervical vertebrae usually in front of or close to the inferior thyroid artery. It is probably formed by the coalescence of two ganglia corresponding to the fifth and sixth cervical nerves.
It sends grey rami communicantes to the fifth and sixth cervical nerves and gives off the middle's cardiac nerve. The middle cardiac nerve, nerve cardiacus medius, great cardiac nerve, is the largest of the three cardiac nerves, arises from the middle cervical ganglion or from the trunk between the middle and inferior ganglia.
On the right side, it descends behind the common carotid artery and at the root of the neck runs either in front of or behind the subclavian artery. It then descends on the trachea, receives a few filaments from the recurrent nerve and joins the right half of the deep part of the cardiac plexus. In the neck, it communicates with the superior cardiac and recurrent nerves.
On the left side, the middle cardiac nerve enters the chest between the left carotid and subclavian arteries and joins the left half of the deep part of the cardiac plexus. The inferior cervical ganglion, ganglion cervicale inferioris, is situated between the base of the transverse process of the last cervical vertebra and the neck of the first rib on the medial side of the costocervical artery.
Its form is irregular, it is larger in size than the preceding and is frequently fused with the first thoracic ganglion. It is probably formed by the coalescence of two ganglia which correspond to the 7th and 8th cervical nerves. It is connected to the middle cervical ganglion by two or more cords, one of which forms a
loop around the subclavian artery and supplies offsets to it. This loop is named ansus subclavia via sene. The ganglion sends gray rhamic communicantes to the 7th and 8th cervical nerves. It gives off the inferior cardiac nerve and offsets to blood vessels. The inferior cardiac nerve, nervus cardiacus inferior, arise from either the inferior cervical
or the first thoracic ganglion. It descends behind the subclavian artery and along the front of the trachea to join the deep part of the cardiac plexus. It communicates freely behind the subclavian artery with the recurrent nerve and the middle cardiac nerve.
The offsets to blood vessels form plexuses on the subclavian artery and its branches. The plexus on the vertebral artery is continued on to the basilar, posterior cerebral, and cerebellar arteries. The plexus on the inferior thyroid artery accompanies the artery to the thyroid gland and communicates with the recurrent and external laryngeal nerves with the superior cardiac
nerve and with the plexus on the common carotid artery. End of section 44.
