The vagus nerve exits at a slightly more caudal position (A buy cheap clarinex 5 mg line allergy symptoms dogs eyes, drooping of the ipsilateral shoulder accompanied by an inability to turn C clarinex 5 mg with amex allergy testing lynchburg va, D); the shape of the medulla is more square and the fourth ventri- the head to the opposite side against resistance (eleventh nerve). This cranial nerve exits in line its relation to the overall shape of the medulla. This shape is indicative with the abducens nerve found at the pons–medulla junction and in line of a cranial nerve exiting at more mid-to-caudal medullary levels. The note its relationship to the preolivary sulcus and olivary eminence. The twelfth nerve exit is characteristically located laterally adjacent to the hypoglossal exits the base of the skull by traversing the hypoglossal pyramid, which contains corticospinal ﬁbers. A lesion of the hypoglossal nerve results in a deviation of the In axial MRI (B, T2-weighted; C, T1-weighted), note the charac- tongue to the ipsilateral side on attempted protrusion. The Insula 45 Precentral gyrus (PrCGy) Superior frontal Central sulcus (CSul) gyrus Postcentral gyrus (PoCGy) Middle frontal gyrus (MFGy) Gyri longi (GyLon–long gyri of the insula) Gyri breves (GyBr–short gyri of the insula) Central sulcus Transverse temporal of the insula (CSulIn) gyrus (TrTemGy) Limen insulae (LimIn) Temporal lobe (TLob) PrCGy PoCGy CSul MFGy TrTemGy GyBr GyLon CSulIn LimIn TLob CSul PrCGy PoCGy MFGy GyBr CSulIn GyLon TLob 2-46 Lateral view of the left cerebral hemisphere with the cortex overlying the insula removed. Structures characteristic of the insular cortex, and immediately adjacent areas, are clearly seen in the two MRIs in the sagittal plane through lateral portions of the hemisphere (inversion recovery—upper; T1-weighted image—lower). Chronic subdural Bacterial infections of the meninges (bacterial meningitis) are hematomas, usually seen in the elderly, are frequently of unknown ori- commonly called leptomeningitis because the causative organisms are gin; may take days or weeks to become symptomatic; and cause a pro- usually found in the subarachnoid space and involve the pia and arach- gressive change in mental status of the patient. The organism seen in about one-half of adult cases is Streptococcus “long and thin,” compared to an epidural hematoma, follows the sur- pneumoniae, while in neonates and children up to about 1 year it is Es- face of the brain, and may extend for considerable distances (see Fig. Treatment is surgical evacua- neck, stupor), may have generalized or focal signs/symptoms, and, if tion (for larger or acute lesions) or close monitoring for small, asymp- not treated rapidly, will likely die. Patients with viral meningitis may become ill over a period The most common cause of subarachnoid hemorrhage is trauma. Symptomatic bleeding from an arteriove- The most common cause of an epidural (extradural) hematoma nous malformation occurs in approximately 5% of cases. Blood collects is a skull fracture that results in a laceration of a major dural vessel, such in, and percolates through, the subarachnoid space and cisterns (see as the middle meningeal artery. Sometimes, the deﬁcits seen (assuming the pa- ing may come from a venous sinus. The extravasated blood dissects the tient is not in coma) may be a clue as to location, especially if cranial dura mater off the inner table of the skull; there is no preexisting (ex- nerves are nearby. Onset is sudden; the patient complains of an excru- tradural) space for the blood to enter. These lesions are frequently ciating headache and may remain conscious, become lethargic and dis- large, lens (lenticular) shaped, may appear loculated, and are “short oriented, or may be comatose. Treatment of an aneurysm is to surgi- and thick” compared to subdural hematomas (see Fig. The patient may lapse into a coma and, if the lesion is left un- development of vasospasm. In some cases, the patient may initially be arachnoid space and cisterns may be removed. These tumors grow Tearing of bridging veins (veins passing from the brain outward slowly (symptoms may develop almost imperceptibly over years), are through the arachnoid and dura), usually the result of trauma, is a com- histologically benign, may result in hyperostosis of the overlying skull, mon cause of subdural hematoma. In decreasing order, menin- misnomer because the extravasated blood actually dissects through a giomas are found in the following locations: parasagittal area falx specialized, yet structurally weak, cell layer at the dura-arachnoid in- (together 29%), convexity 15%, sella 13%, sphenoid ridge 12%, and terface; this is the dural border cell layer. Treatment is primarily by surgical removal, al- dural space” in the normal brain. Acute subdural hematomas, more though some meningiomas are treated by radiotherapy. The Meninges, Cisterns, and Meningeal and Cisternal Hemorrhages 47 Superior sagittal sinus Arachnoid villus Skull Lateral lacunae Cerebrum Dura mater Arachnoid mater Arachnoid trabeculae Pia mater Transverse sinus Falx cerebri Tentorium cerebelli Cerebellum Cistern Skull Dura mater Subarachnoid space Arachnoid mater Cerebral vessel and branch Pia mater Arachnoid trabeculae Vertebrae Spinal nerves Spinal vessel Dura mater Dura mater Intervertebral ligament Epidural space Conus medullaris Vertebra Cauda equina Lumbar cistern Arachnoid mater Filum terminale (interum) Denticulate ligament Pia mater Coccygeal ligament (filum terminale externum) Coccyx 2-47 Semidiagrammatic representation of the central nervous sys- fourth ventricles. It circulates through the ventricular system (small ar- tem and its associated meninges. The details show the relationships of rows) and enters the subarachnoid space via the medial foramen of Ma- the meninges in the area of the superior sagittal sinus, on the lateral as- gendie and the two lateral foramen of Luschka.
Basic Elements of the Nervous System The Nerve Cell 18 The Synapse 24 Neuronal Systems 32 The Nerve Fiber 36 Neuroglia 42 Blood Vessels 44 Kahle order clarinex 5mg with amex food allergy symptoms quiz, Color Atlas of Human Anatomy 5mg clarinex visa allergy symptoms in 8 month old, Vol. Some have short axons (interneurons), others have axons more than 1 m long (pro- The nervous tissue consists of nerve cells jection neurons). Blood vessels and meninges do different methods yield only partial images not belong to the nervous tissue; they are of of neurons. The nerve cell (gan- method) shows nucleus and perikaryon glion cell or neuron) is the functional unit (B –D). In its mature state, it dendrites, is filled with clumps (Nissl sub- is no longer able to divide, thus making pro- stance, tigroid bodies) and may contain pig- liferation and the replacement of old cells ments (melanin, lipofuscin) (D11). Motor neurons possess a large peri- and one main process, the axon or neurite karyon with coarse Nissl bodies, while (A–D3). The perikaryon is the trophic center of the cell, and processes that become separated Impregnation with silver (Golgi’s from it degenerate. It contains the cell nu- method) stains the entire cell including all cleus (A4) with a large, chromatin-rich neuronal processes; the cell appears as a nucleolus (A5) to which the Barr body (sex brown-black silhouette (B–D). The processes of other neurons often end at small dendritic appendices, spines (thorns), which give the dendrites a rough appearance (D). The axon conducts the nerve impulse and begins with the axon hillock (AD7), the site wherenerveimpulsesaregenerated. Atacer- tain distance from the perikaryon (initial segment) it becomes covered by the myelin sheath (A8), which consists of a lipid-con- taining substance (myelin). The axon gives off branches (axon collaterals) (A9) and fi- nally ramifies in the terminal area (A10) to end with small end-feet (axon terminals, or boutons) on nerve cells or muscle cells. The bouton forms a synapse with the surface membrane of the next cell in line; it is here that impulse transmission to the other cell takes place. Depending on the number of processes, we distinguish between unipolar, bipolar, or multipolar neurons. The Nerve Cell: Structure and Staining Patterns 19 2 6 1 5 4 E Impregnation of F Impregnation of 2 boutons (synapses) neurofibrils 7 3 3 8 B Nerve cell in the 3 brain stem 9 3 3 C Nerve cell in the anterior horn of the spinal cord 9 A Neuron, diagram D Pyramidal cell in the cerebral cortex 11 7 3 10 B–D Equivalent images of nerve cells: cellular stain (Nissl) and silver impregnation (Golgi) Kahle, Color Atlas of Human Anatomy, Vol. The availability of methods for studying the structure and function of cells, tissues, and The longest processes of nerve cells, the organs is often the limiting factor in ex- axons (which can be up to 1m long in panding our knowledge. Certain terms and humans), cannot be traced to their target interpretations can only be understood if area in histological sections. In order to the background of the method used is demonstrate the axonal projections of neu- known. Therefore, the methods commonly rons to different brain regions, axonal trans- used in neuroanatomy are presented here port (p. The Nissl Very long fiber connections can be visual- method has proven helpful because of excel- ized (C–E) by means of tracers (e. However, the different types of taining the cell bodies of the corresponding nerve cells are essentially characterized by population of neurons; the tracers are then their long processes, the dendrites and the taken up by the axon terminals or by the cell axon, which are not stained by the Nissl bodies of the projection neurons, respec- method. When using retrograde transport (C), these processes as possible, thick sections the tracer is injected into the assumed tar- (200µm) are required. By means of retrograde transport can be demonstrated in such thick sections. When it is now possible to stain individual nerve using anterograde transport (E), the tracer is cells by filling them with a dye using rec- injected into the region of the cell bodies of ordingelectrodes(A). Labeled axon terminals technique is that electrical signals can be will be visible in the assumed target zone if recorded from the neuron in question at the the labeled neurons indeed project to this same time. An important characteristic of nerve cells is their specific neurotransmitter or messenger substance by which communication with other nerve cells is achieved. By means of immunocytochemistry and the use of anti- bodies against the messenger substances themselves, or against neurotransmitter- synthesizing enzymes, it is possible to visual- ize nerve cells that produce a specific trans- mitter (B). Again, these immunocytochemi- cally stained nerve cells and their processes Kahle, Color Atlas of Human Anatomy, Vol. Methods in Neuroanatomy 21 C–E Visualization of projections by means of retrograde and an- terograde axonal transport of tracers C Retrograde transport A Visualization of a neuron by means of an intracellularly in- jected marker D Retrograde transport from differ- ent projection zones of a neuron E Anterograde transport to different projection zones of a neuron B Immunocytochemical visualization of a cholinergic neuron using an antibody against choline acetyltransferase Kahle, Color Atlas of Human Anatomy, Vol. The mitochondria are the site (A–C) of cellular respiration and, hence, of energy generation.
There is a geniculate neu- loculated (have some sort of internal structure) cheap clarinex 5mg visa allergy treatment at home in hindi. The structure ralgia (related to the ear) and a glossopharyngeal neuralgia (related (shape) of this lesion does not conform to hemorrhage into the to the throat or palate) clarinex 5mg visa allergy juice, but neither of these originates from the substance of the brain (brain parenchyma), into the subarachnoid surface of the face near the oral cavity. The hypoglossal nerve is space (or cisterns), and certainly not to hemorrhage into the ven- the motor for the tongue and the vagus is the motor for most of tricles. Answer A: The only portion of the ventricular system that does not contain choroid plexus is the cerebral aqueduct. Answer A: In most cases (85–100%), the labyrinthine artery, plexus in the lateral ventricle is continuous from the inferior horn also called the internal auditory artery, originates from the ante- into the atrium and into the body of the ventricle, and through the rior inferior cerebellar artery. It enters the internal acoustic mea- interventricular foramen with the choroid plexus located along tus, serves bone and dura of the canal, the nerves of the canal, and the roof of the third ventricle. There is a tuft of choroid plexus in vestibular and cochlear structures. In a few cases (15% or less), the fourth ventricle, a small part of which extends into the lateral this artery originates from the basilar artery. None of the other recess and through the lateral foramen (of Luschka) into the sub- choices gives rise to vessels that serve the inner ear. Answer E: Branches of the superior cerebellar artery are most ply to the superior and inferior colliculi: this vessel originates from frequently involved in cases of trigeminal neuralgia that are pre- P1. The geniculate bodies receive their blood supply from the thal- sumably of vascular origin. The posterior cerebral artery and its amogeniculate arteries, and the pineal and habenula from the pos- larger branches serve the midbrain-diencephalic junction or join terior medial choroidal artery. The basilar artery serves the receives its blood supply via the medial branch of the superior basilar pons and the anterior inferior cerebellar artery serves the cerebellar artery, and branches of the cerebral circle (of Willis) caudal midbrain, inner ear, and the inferior surface of the cere- serve the mammillary bodies. The basal vein drains the medial portions of the hemisphere and passes through the ambient cistern to enter the 5. Answer C: The afferent limb of the corneal reﬂex is via the oph- are not seen in these patients, diplopia (involvement of oculomotor, thalmic division of the trigeminal nerve (V); the cell body of ori- abducens or trochlear nerves, singularly or in combination) may be gin is in the trigeminal ganglion and the central terminations in the present, but in fewer than 10% of these individuals. The efferent limb originates in the motor nucleus of the facial nerve (VII) and dis- 6. Answer B: The internal acoustic meatus contains the vestibulo- tributes to the facial muscles around the eye. None of the other cochlear nerve, the facial nerve, and the labyrinthine artery, a choices contains ﬁbers related to the corneal reﬂex. A vestibular schwannoma located in the meatus would likely affect the facial 13. Answer B: The callosomarginal artery, a branch of the anterior nerve and result in facial weakness. The vagus and glossopharyn- cerebral artery, serves the medial aspect of the superior frontal geal nerves exit the skull via the jugular foramen (along with the gyrus and that portion of this gyrus on the superior and lateral as- accessory nerve). The cerebellar arteries originate within the skull pects of the hemisphere. M4 segments of the middle cerebral and distribute to structures within the skull. Answer C: The lingual gyrus is the lower bank of the calcarine sul- sphere caudal to the parietoccipital sulcus, and the angular artery cus; the upper (cuneus) and lower banks of this sulcus are the loca- (an M4 branch) serves the angular gyrus of the inferior parietal lob- tion of the primary visual cortex. The lenticulostriate arteries are branches of M1 that serve in- of the parietal lobe, and the angular gyrus is a portion of the inferior ternal structures of the hemisphere. The cingu- late and parahippocampal gyri are located on the medial aspect of the 14. Answer B: The limbic lobe, consisting primarily of the cingu- hemisphere and are parts of the limbic lobe. None of the other The internal cerebral vein (to the great cerebral vein) drains the lobes of the cerebral cortex borders directly on the corpus callo- internal parts of the hemisphere; the ophthalmic vein connects the sum. Answer B: The inferior frontal gyrus consists of the pars or- with the transverse sinus.
Sacral Plexus 93 1 L 4 L 5 S 1 S 2 2 1 3 6 2 6 6 7 4 11 5 12 14 4 5 11 9 15 12 8 13 19 6 8 10 B Skin supplied by the 13 common peroneal nerve 9 17 (according to Lanz-Wachsmuth) 13 10 12 11 C Sequence of branches 16 18 A Muscles supplied by the common peroneal nerve (according to Lanz-Wachsmuth) Kahle buy clarinex 5mg cheap allergy shots safe during pregnancy, Color Atlas of Human Anatomy clarinex 5mg lowest price quick allergy treatment, Vol. Before the nerve trunk branches (AC1) originate from the tibial por- ramifies into terminal branches, it sends off tion of the sciatic nerve, namely, those for the medialcalcanealbranches (B19) to the me- the proximal and distal parts of the semi- dial skin area of the heel. Finally, it divides into the three com- tibial nerve descends vertically through the mon plantar digital nerves (BC24), which middle of the popliteal fossa and under- supply lumbrical muscles 1 and 2 (D25) and neath the gastrocnemius muscle. It then lies divide further into the proper plantar digital under the tendinous arch of the soleus nerves(BC26 ) for theskin oftheinterdigital muscle and, further distal, between the long spaces from the great toe up to the fourth flexor muscle of the great toe and the long toe. It extends between The second terminal branch, lateral plantar the tendons of both muscles to the back of nerve (CD27), divides into a superficialbranch the medial ankle and winds around it. D34, short flexor muscle of the municating branch of the peroneal nerve to little toe. The latter extends laterally from the Achilles tendon behind Clinical Note: Injury of the tibial nerve leads the lateral ankle and around it to the lateral to paralysis of the flexor muscles of toes and foot. It gives off the lateral cal- The foot can no longer be moved in plantar direc- tion: tiptoeing becomes impossible. Autonomic cutaneousnerve (BC9) to the lateral aspect of zone (dark blue) and maximum zone (light the foot. Also in the popliteal fossa, motor branches (AC10) go off to the flexor muscles of the lower leg, namely, to the two heads of the gastrocnemius muscle (A11), to the soleus muscle (A12), to the plantar muscle and the popliteal muscle (A13). The popliteal branch gives rise to the interosseous nerve of the leg (C14),whichrunsalongthedorsalsurfaceof the interosseous membrane and provides sensory innervation to the periosteum of the tibia, the upper ankle joint, and the tib- iofibular joint. Sacral Plexus 95 L 4 L 5 S 1 1 S 2 7 5 S 3 3 8 2 19 9 19 4 24 30 1 26 3 B Skin supplied by the tibial nerve (according to Lanz-Wachsmuth) 10 10 11 6 14 13 12 15 22 17 16 18 21 27 20 28 11 7 31 12 8 25 34 19 9 32 20 27 33 28 23 29 24 31 26 30 C Sequence of branches D Foot muscles supplied by the ti- bial nerve (according to Lanz- A Muscles supplied by the tibial nerve Wachsmuth) (according to Lanz-Wachsmuth) Kahle, Color Atlas of Human Anatomy, Vol. Infemales,itsuppliessensory Pudendal Nerve (S2–S4) (A, B) fibers to the clitoris including the glans. The pudendal nerve (AB1) leaves the pelvis through the infrapiriform foramen (AB2), Muscular Branches (S3, S4) extends dorsally around the sciatic spine The levator ani muscle and the coccygeal (AB3) and passes through the lesser sciatic muscle are supplied directly by nerve foramen (AB4) into the ischioanal fossa. The anococcygeal nerves originate dendal canal; the inferior rectal nerves from here; they supply sensory fibers to the (A–C5), which may also originate directly skin over the coccyx and between coccyx from the second to fourth sacral nerves, and anus (C14). The deep the obturator nerve (C17), the posterior cu- branches participate in the innervation of taneous nerve of the thigh (C18), the inferior the external sphincter muscle of the anus. The superficial branches rectum are border areas between involun- supplysensoryfiberstotheposteriorpartof tary smooth intestinal muscles and volun- the scrotum (posterior scrotal nerves) (AC8) tary striated muscles. Accordingly, auto- in males and to the labia majora (posterior nomic and somatomotor fibers are here in- labial nerves) (BC9) in females. The pudendal nerve contains, supply the mucosa of the urethra and the apart from sensory, somatomotor, and sym- bulb of penis in males, and the external pathetic fibers, also parasympathetic fibers urethral opening and the vestibule of vagina from the sacral spinal cord. After passing through the urogenital diaphragm (AB13), it gives off a branch to the cavernous body of the penis in males, and to the cavernous body of the cli- toris in females. In males, the nerve runs along the dorsum of the penis and gives off Kahle, Color Atlas of Human Anatomy, Vol. Sacral Plexus 97 22 33 11 1414 44 A Pudendal nerve in the male 1010 55 66 1515 1515 77 1313 88 99 1717 88 1515 1414 1919 1818 2020 1616 C Sensory innervation of the per- ineum (according to Haymaker and Woodhall) 22 33 11 1414 44 55 1212 1111 B Pudendal nerve in the female 1313 77 44 66 99 Kahle, Color Atlas of Human Anatomy, Vol. Brain Stem and Cranial Nerves Overview 100 Cranial Nerve Nuclei 106 Medulla Oblongata 108 Pons 110 Cranial Nerves (V, VII – XII) 112 Parasympathetic Ganglia 128 Midbrain 132 Eye–Muscle Nerves (Cranial Nerves III, IV, VI) 138 Long Pathways 140 Reticular Formation 146 Histochemistry of the Brain Stem 148 Kahle, Color Atlas of Human Anatomy, Vol. An unpaired embryonic development and from where opening lies below the inferior medullary ten pairs of genuine peripheral nerves velum, the median aperture (foramen of (cranial nerves III – XII) emerge. The floor of the lum, which in ontogenetic terms also rhomboid fossa shows bulges near the me- belongs to it, will be discussed separately dian sulcus (B21); they are caused by cranial because of its special structure (p. The anterior median myelinated nerve fibers, the medullary fissure, which is interrupted by the pyra- striae (B27). The pigmented nerve cells of midal decussation (A4), and the antero- the locus ceruleus (B28) shine blueish lateral sulcus (AD5) on each side extend up through the floor of the rhomboid fossa. The anterior funiculi thicken They are mostly noradrenergic and project below the pons to form the pyramids (A6). Here, de- The anterior surface of the midbrain, or scending pathways from the brain are re- mesencephalon, is formed by the cerebral layed to neurons extending to the cerebel- peduncles (A29) (descending cerebral path- lum. Between them lies the interpeduncu- The posterior surface of the brain stem is lar fossa (A30); its floor is perforated by covered by the cerebellum (C8).