By Q. Leif. University of Notre Dame.
Spinal Cord Syndromes 69 A Complete transection of the spinal cord 1 3 4 5 6 2 B Brown–Séquard’s syndrome in hemisection of the spinal cord 2 5 C Dissociated anesthesia in case of injury to the central spinal cord Kahle discount 30 pills rumalaya forte with mastercard, Color Atlas of Human Anatomy order rumalaya forte 30 pills with amex, Vol. The peripheral nerves may contain four different types of fibers: Nerve Plexusus (B)! Somatomotor (efferent) fibers (A1) for At the level of the limbs, the anterior striated muscles branches of the spinal nerves form networks! Somatosensory (afferent) fibers (A2) for (plexusus) in which fibers are exchanged. Visceromotor fibers (A3) for smooth tend to the periphery, possess a newly or- muscles ganized supply of fibers derived from differ-! The somatomotor fibers pass from the nerves originate here: the lesser occipital anteriorhorncells(A5)throughtheanterior nerve (B18), the greater auricular nerve root (A6); the somatosensory and (B19), the transverse nerve of the neck viscerosensory fibers originate from the (B20), the supraclavicular nerves (B21), the nerve cells of the spinal ganglia (A7); and phrenic nerve (B22), and also the roots of the visceromotor fibers of the lateral horn the deep cervical ansa (B23). Anterior and posterior roots (A9) join arm is formed by the anterior branches of to form the spinal nerve (A10), which con- spinal nerves C5 to C8 and by a part of the T1 tains all types of fibers. We distinguish between a section trunk then divides into four branches: lying above the clavicle, the supraclavicular! The meningeal branch (A11), a recurrent part, and a section lying below the clavicle, sensory branch extending to the spinal the infraclavicularpart. The anterior branches meninges pass through the scalene gap into the poste-! The posterior branch (A12) rior cervical triangle, where they form three! The superior trunk (B24) (C5, C6) The posterior branch supplies motor fibers to! The inferior trunk (B26) (C8, T1) back and sensory fibers to the skin areas on The nerves that originate here form the su- both sides of the vertebral column (p.
With further encir- cling generic rumalaya forte 30pills line, the inner protein layers of the cell membrane make contact as well and fuse to form the dense major period line (A5) rumalaya forte 30 pills otc. At the end of the process, the start of the duplica- tion lies inside the myelin sheath, the inter- nal mesaxon (AB6), while the end lies out- side, the external mesaxon (7 in A, B). Development of Unmyelinated Nerve Fibers (A) Unmyelinated nerve fibers (A8) are en- veloped by sheath cells, each of which en- circles several axons. The margins of the grooves may also form a membrane dupli- cation (mesaxon) but without fusion of the membrane layers. Myelin Sheath 39 4 6 7 1 3 5 2 8 A Development of the myelin sheath (according to Hamilton, Boyd and Mossman) 9 10 7 6 12 B Central nerve fiber, electron-microscopic diagram (according to Bunge) 11 C Oligodendrocyte with myelin lamellae (according to Bunge) Kahle, Color Atlas of Human Anatomy, Vol. This mode of conduction is much borders on a basal lamina (AB2), which en- faster and requires less energy than the con- velops the entire peripheral nerve fiber. The Schmidt–Lanterman The peripheral nerve fiber is surrounded by clefts (A4) are depicted in longitudinal sec- longitudinal collagenous connective-tissue tionascytoplasmiccrevicesofthemajorpe- fibrils; together with the basal membrane, riod lines. The struction, they appear as spirals in which nerve fibers are embedded in a loose con- the cytoplasm communicates between the nective tissue, the endoneurium (D8). At the node of Ranvier able number of nerve fibers is collected into (B5), the Schwann cell processes (AB6) slide bundles or fascicles (C10) by the perineurium over the paranodal region and over the axon (CD9) which consists mainly of circular (ABD7). The innermost layer of the per- dense envelope around the node of Ranvier. The perineural endothelial cells myelin sheaths in CNS and PNS are il- possess a basal membrane at their per- lustrated in B. They represent a barrier its myelin sheath, the distance between the between nerve and surrounding tissue, sim- nodes of Ranvier, and the conduction ilarly to the endothelial cells of cerebral velocity of a nerve fiber. The mechanical cumference of an axon, the thicker the en- strength of the peripheral nerve is based on closing myelin sheath and the longer the in- its content of circular elastic fibers. When myelinated nerve fibers are nerves of the limbs, the perineurium is rein- still growing (e. The epineurium limbs), the internodes are growing in (CD11) borders on the perineurium; its length.
A motor branch 30pills rumalaya forte with visa, the stylopharyngeal branch (B17) generic rumalaya forte 30 pills free shipping, in- The motor fibers (AB4) originate from the nervates the stylopharyngeal muscle, while cranial part of the ambiguous nucleus some sensory tonsillarbranches (D18) extend (AB5), while the visceroefferent fibers to the tonsils and the soft palate. The nerve (secretory fibers) (AB6) originate from the divides below the tonsils into the lingual inferior salivatory nucleus (AB7). The cells branches (D19), which supply the posterior oftheviscerosensoryfibers(AB8)andthetaste third of the tongue including the vallate fibers (AB9) lie in the inferior ganglion and papillae with sensory as well as taste fibers descend in the solitary tract (B10) to termi- (D20). The first branch, the tympanic nerve (B12), originates from the inferior ganglion with viscerosensory and preganglionic secretory fibersinthepetrosalfossula. Itruns through the tympanic canaliculus into the tympanic cavity, where it receives fibers from the plexus of the internal carotid artery via the caroticotympanic nerve and forms the tym- panic plexus. It supplies sensory fibers to the mucosa of tympanic cavity and auditory (eustachian) tube (C). The secretory fibers run as lesser petrosal nerve to the otic gan- glion (p. Apart from connections with the vagus nerve, facial nerve, and sympathetic nervous system, the inferior ganglion gives off the (viscerosensory) branch of the carotid sinus (B13), which descends to the bifurca- tion of the common carotid artery and ter- minates in the wall of the carotid sinus (B14) and in the carotid glomus (B15) (see vol. Ninth Cranial Nerve 119 11 9 7 8 5 6 4 A Nuclear region of the glossopharyngeal nerve 7 C Sensory innervation of the middle ear 5 6 4 2 10 9 12 3 8 11 1 13 B Exit of the glossopharyngeal nerve 17 16 15 14 18 19 20 D Sensory innervation E Sensory innervation of of the tongue; taste the pharynx Kahle, Color Atlas of Human Anatomy, Vol. Only a small por- The eighth cranial nerve is an afferent tion reaches directly into the cerebellum via nerve consisting of two components, the the inferior cerebellar peduncle (restiform cochlear root for the organ of hearing and the body). The vestibular nuclei lie in the floor of the Cochlear Root (A) rhomboid fossa below the lateral recess: the superior nucleus (Bechterew’s nucleus) The nerve fibers originate from the bipolar (B14), the medial nucleus (Schwalbe’s nu- neurons of the spiral ganglion (A1), a band of cleus) (B15), the lateral nucleus (Deiters’ cells following the spiral course of the nucleus) (B16), and the inferior nucleus cochlea. The primary vestibular fibers termi- cells terminate at the hair cells of Corti’s nate mostly in the medial nucleus. Second- organ; the central processes form small ary fibers run from the vestibular nuclei to bundles that organize into the foraminous the cerebellum and into the spinal cord (ves- spiral tract (A2) and combine in the floor of tibulospinal tract) (B18). The The function of the vestibular apparatus plays latter extends, together with the vestibular an important role for balance and upright root (B) inside a common connective-tissue posture. Thetractstothecerebellumandthe sheath, through the internal acoustic meatus spinal cord serve this purpose. At the entrance of the bulospinal tract has an effect on muscular eighth cranial nerve into the medulla ob- tension in various parts of the body.