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RM2ANEE1Y–Human anatomy, including structure and development and practical considerations . ng betweenthe usual larger clear ele-ments and the basementmembrane ; these are thecrescents of Giannzi, or demilunes of Heidenhain, the interpretation of which hascaused much discussion. The older view regarded the crescents as groujw of cellsdiffering from the surrounding ones only in their stage of actiity and not in theiressential characters, all the cells within the alveolus being of the same nature. Theopposite view, advanced by Ebner over a quarter of a century ago, has receied suji-port from more recent
RM2ANAKJ4–Human anatomy, including structure and development and practical considerations . relations to the mesogastrium of three branches of its artery, the coeliac axis, are asfollows. The splenic artery, in the adult condition, lies entirely behind the perma-nent peritoneum to near the hilum of the spleen, where the mesogastrium is nolonger attached to the wall. It then sends its terminal branches to the spleen, thegastro-epiploica sinistra to the greater curvature of the stomach, and the vasa breviato the fundus. The gastric artery, originally in the mesenterv of the duodenum,reaches the cardiac en
RM2AWDB87–Human anatomy, including structure and development and practical considerations . the rhinencephalon, but the lines of itsgrowtii are particularly backward and downward, in coiiseiiuence of which, in addition tothe production of a temporal and the distinctive occipital lobe, the other brain-segmentsbecome gradually covered over and deposed from their original sujierior position tcjward thebasal surface of the brain. This process is already marked during the third nu^nth (Fig. 1031),by the end of which period the pallium covers the diencephalon. By the beginning of the fifthmonth the mid-brain
![Human anatomy, including structure and development and practical considerations . of the colon, page 1670. ) The breadth of the transverse mesocolon is from12-15 cm. (5-6 in. ). In the adult it is fused with the greater omentum, as alreadydescribetl. The sviperior mesenteric artery enters this mesentery under the pancreas,and gies from its left or conxex side the branches for the small intestine. Fromits right, just after its origin, it gives oft the inferior ])ancreatico-duodenal and thebranches for the ciecum and the ascending and transverse colon. In the adult theright colic artery runs ln Stock Photo](https://c8.alamy.com/comp/2ANAJ8T/human-anatomy-including-structure-and-development-and-practical-considerations-of-the-colon-page-1670-the-breadth-of-the-transverse-mesocolon-is-from12-15-cm-5-6-in-in-the-adult-it-is-fused-with-the-greater-omentum-as-alreadydescribetl-the-sviperior-mesenteric-artery-enters-this-mesentery-under-the-pancreasand-gies-from-its-left-or-conxex-side-the-branches-for-the-small-intestine-fromits-right-just-after-its-origin-it-gives-oft-the-inferior-ancreatico-duodenal-and-thebranches-for-the-ciecum-and-the-ascending-and-transverse-colon-in-the-adult-theright-colic-artery-runs-ln-2ANAJ8T.jpg "Human anatomy, including structure and development and practical considerations . of the colon, page 1670. ) The breadth of the transverse mesocolon is from12-15 cm. (5-6 in. ). In the adult it is fused with the greater omentum, as alreadydescribetl. The sviperior mesenteric artery enters this mesentery under the pancreas,and gies from its left or conxex side the branches for the small intestine. Fromits right, just after its origin, it gives oft the inferior ])ancreatico-duodenal and thebranches for the ciecum and the ascending and transverse colon. In the adult theright colic artery runs ln Stock Photo")
RM2ANAJ8T–Human anatomy, including structure and development and practical considerations . of the colon, page 1670. ) The breadth of the transverse mesocolon is from12-15 cm. (5-6 in. ). In the adult it is fused with the greater omentum, as alreadydescribetl. The sviperior mesenteric artery enters this mesentery under the pancreas,and gies from its left or conxex side the branches for the small intestine. Fromits right, just after its origin, it gives oft the inferior ])ancreatico-duodenal and thebranches for the ciecum and the ascending and transverse colon. In the adult theright colic artery runs ln
RM2ANAAT1–Human anatomy, including structure and development and practical considerations . ed and protruding parietalperitoneum, and subdivided into (a) the month,the aperture corresponding to the internal her-nial orifice ; (<^) the body, the expanded pro-truding portion, the lowest portion of which iscalled iQ fundus; and (c) the 7ieck, the constricted portion connecting the bodyand mouth ; and (2) the contents, which in the order of frequency are ileum, omen-tum, jejunum, sigmoid, caecum, and transverse colon. More rarely the ascendingand descending colon, the bladder, the ovary, and the variou
RM2AWG8GY–Human anatomy, including structure and development and practical considerations . size, each corpuscle is sup-plied by one or more nerve-fibres which enter inthe vicinity of the base, as the deeper end iscalled, and, on piercing the capsule and losingthe medullary sheath, divide into a number ofnaked axis-cylinders. These pass across thecorpuscle in parallel or spiral windings and arebeset with fusiform and pyriform varicosities,similar enlargements marking the ends of theterminal threads. The entire fibrillar interlace-ment is embedded within a semifluid substanceand enclosed bv a thin nuclea
RM2AWF7Y7–Human anatomy, including structure and development and practical considerations . alcells. The Purkinje cells, the most distinctive nerous elements of the cerebellum,occupy the deepest part of the molecular layer, where they are disposed in a singlerow along the outer boundarv of the subjacent granular layer. The cells are mostnumerous and more closely placed upon the summit of the folium and fewer andmore scattered along the fissures, in which situation they are also often of less typicalpyriform shape. They possess a large flask-like body, about .060 mm. in diameter,from the pointed and out
RM2ANJ8PG–Human anatomy, including structure and development and practical considerations . first the sui)eri()r and then the posteriormediastinum, its course differing widely on the two sides. The right vagus (Fig. 1090), after pa.ssing in front of the first portion of thesubclaian artery and behind the right innominate vein and the superior vena cava,descends along the right side of the trachea to reach the posterior aspect of the rootof the lung. Here the entire nerve breaks up to form the posterior pulniouaryplexus^ which assembles at its lower border to form two cords. These pass inwardacross the
RM2AWECGY–Human anatomy, including structure and development and practical considerations . iaphragmasellce, through an opening in which the infundibulum passes to the mushroom-shapedorgan. The pituitary body consists of two distinct parts, of which the so-calledanterior lobe is much the larger and of a darker grayish red color. Its posteriorsurface is concae and receies the small posterior lobe, which is partially embracedat the sides by the e.xpanded lateral margins of the anterior division. Although thetwo lobes are closely bound together by connective tissue, they are not only distinctas to struct
RM2ANE1WH–Human anatomy, including structure and development and practical considerations . theground-substance which they have formed. The de-mands made upon the odontoblasts during their active role as dentine producers aremet by the nutrition supplied by the rich vascular supply of the dentinal papilla, sothat for a time the cells are enabled not only to increase the dentinal matrix, but alsoto extend their processes, which they send into the tubules of the dentine as the den-tinal fibres, without diminution in size. With the completion of dentine production,and the consequent decrease in the area up
RM2AWDN75–Human anatomy, including structure and development and practical considerations . rly in the paracentrallobule, this increa.ses to over 5 mm.,whilst over the frontal and occipital polesthe thickness of the cortex is reduced toalmost 2 mm. The entire superficialextent of the cortex of the two hemi-spheres has been estimated to be about ^^2000 sq. cm., of which scarcely one- -^third is exposed surface, the remainder Caicarine fissure being sunken. Frontal section of hemisphere including cortex sur- On examining sections of the fresh rouncllng caicarine fissure; stripe of Gennari (outer stripe. =
RM2ANGBCF–Human anatomy, including structure and development and practical considerations . remains of their shrunken nuclei. These cornified scales are disposed in lamellae,which, in transverse section, pursue a course in general parallel with the dorsal sur-face. In nails which possess the longitudinal ridges, however, the latter coincidewith an upward arching of the lamellae dependent upon the conformation of thenail matrix (Brunn). In longitudinal section the lamellation is oblique, extending 1396 HUMAN AN ATOM . from aboe downward and forward, parallel to the shelving under surface beneath thewhi
RM2ANJDY9–Human anatomy, including structure and development and practical considerations . MMandibular Mandibular SC. iL ,i; Vlaxillary .//f ^?. ^ r- Cervical plexus ^ / / ^ .^?—, Occipitalis -Afe>/ major I f Cervical plexus
RM2ANHF26–Human anatomy, including structure and development and practical considerations . branch tothe rectus femoris. Thosewhich aid in the innervationof the knee arise from the in-ternal saphenous and fromthe nerves to the vasti exter-nus and internus and thecrureus. cc. The internal or longsaphenous nerve ( n. saphenus)(Fig. 1109) is the continuationof the posterior division ofthe anterior crural nerve. Itcourses down the thighfirst lateral to and then an-terior to the superficial femoral artery under cover of the sartorius muscle. At the apexof Scarpas triangle it enters Hunters canal and accompan
![Human anatomy, including structure and development and practical considerations . nch of tlieabdominal aorta to the ihaphravjni, tlie rii^ht being larjjer than the left. AftersupplviniLj^ scjme tilanienls to the siijjrarenal body, it enters the musculature of thedia])hras4in and there unites with the phn-nic nerve from the cervical sjjinal plexus.At the point of inosculation, on the rij^ht side only, near the suprarenal body and onthe under surface of the diaphrajrm, is a small j^anj^lion called the phrenic ganglion(«. phrenicuin). From it are given off branches to the suprarenal b(Kly, the in Stock Photo](https://c8.alamy.com/comp/2ANGY9G/human-anatomy-including-structure-and-development-and-practical-considerations-nch-of-tlieabdominal-aorta-to-the-ihaphravjni-tlie-riiht-being-larjjer-than-the-left-aftersupplvinilj-scjme-tilanienls-to-the-siijjrarenal-body-it-enters-the-musculature-of-thedia-hras4in-and-there-unites-with-the-phn-nic-nerve-from-the-cervical-sjjinal-plexusat-the-point-of-inosculation-on-the-rijht-side-only-near-the-suprarenal-body-and-onthe-under-surface-of-the-diaphrajrm-is-a-small-janjlion-called-the-phrenic-ganglion-phrenicuin-from-it-are-given-off-branches-to-the-suprarenal-bkly-the-in-2ANGY9G.jpg "Human anatomy, including structure and development and practical considerations . nch of tlieabdominal aorta to the ihaphravjni, tlie rii^ht being larjjer than the left. AftersupplviniLj^ scjme tilanienls to the siijjrarenal body, it enters the musculature of thedia])hras4in and there unites with the phn-nic nerve from the cervical sjjinal plexus.At the point of inosculation, on the rij^ht side only, near the suprarenal body and onthe under surface of the diaphrajrm, is a small j^anj^lion called the phrenic ganglion(«. phrenicuin). From it are given off branches to the suprarenal b(Kly, the in Stock Photo")
RM2ANGY9G–Human anatomy, including structure and development and practical considerations . nch of tlieabdominal aorta to the ihaphravjni, tlie rii^ht being larjjer than the left. AftersupplviniLj^ scjme tilanienls to the siijjrarenal body, it enters the musculature of thedia])hras4in and there unites with the phn-nic nerve from the cervical sjjinal plexus.At the point of inosculation, on the rij^ht side only, near the suprarenal body and onthe under surface of the diaphrajrm, is a small j^anj^lion called the phrenic ganglion(«. phrenicuin). From it are given off branches to the suprarenal b(Kly, the in
RM2ANCY0A–Human anatomy, including structure and development and practical considerations . , and contain i)oth medullated and nonmedullated fibres, the latter predominating. On Fig. i?8i. reaching the organ, the stems pierce the exter-nal longitudinal muscu-lar layer, between whichand the circular layerthey fo-m eplexus ofAuerbach. The pointsof juncture in this net-work are marked by mi-croscopic sympatheticganglia, from whichnon-medullated fibressupply the involuntarymuscle. Leaving theintramuscular plexus,twigs pass obliquelythrough the circularmuscular tunic, and ongaining the submucouscoat form
RM2AWEGGJ–Human anatomy, including structure and development and practical considerations . ridi^e and the divernini>; mesial border of the upper surface of the thalamus, isincluded a narrow depressed trianirular area, known as the trigonum habenulae.It lies on a distinctly lower level than the adjoining conex upjjer surface of thethalamus. Since it contains a special nucleus and belongs to the eiMthalamus, itsdescription will be deferred until that region is considered (yd^(j: 1123). The upijersurface is not quite even, but subdixided by a shallow oblique furrow, which runsfrom before backward and
RM2AWD0W4–Human anatomy, including structure and development and practical considerations . Olfactory nerve-fibres An upper ant. nasal br.Meckels ganKlion Ipper jx)st. nasal brs.Meckels ganglion Naso-palatine nerve (Sup. ant. nasal br. ofMeckels ^anKl. andinf. ant. nasal br. ofant. descendingpalatine nerveA i)osterior nasal br.Meckels ganglion Ant. descending palatine nerve, the middle palatine appearing posteriorly Right nasal fossa showing distribution of olfactory and nasal nerves on lateral wall; mucous membrane has been partly removed to expose nerves. whose fibres are nonmedullated, exhibit a ple.
RM2ANJFAW–Human anatomy, including structure and development and practical considerations . e l)ranches of distribution from the otic gang-lion, secretory fibres are carried along with those ul the auriculo-teniporal (page1244) to the parotid gland. The small superficial petrosal nerve also contains taste-fibres, which pass either tt) the petrous ganglion of the ninth or to the geniculateganglion of the seventh, and thence centralward to the reception-nuclei in themedulla. The motor root is a branch from the internal pterygoid nerve. The syvipatheticroot is represented Iiy one or two nerve-filaments fro
RM2ANHTRY–Human anatomy, including structure and development and practical considerations . mary artery, is distributed to the medias-tinal pleura. d. The pericardiac branch (r. pericardinciis) is a tiny filament which is usually given offopposite the lower mariL^in of tiie thirtl costal cartilage. It is sometimes absent on the left side. r. The terminal branches arise uiukr cover of the pleura anti differ to some e.xtent onthe two sides. The riffht phrenic divides antero-lateral to the opening for the inferioivena cava into (aa)an anterior and (bb) a posterior branch. aa. The anterior branch l)reaks up
RM2ANG8PC–Human anatomy, including structure and development and practical considerations . ules ofkeratohyalin, so that on reaching thelevel of the summit of the papilla theprocess of cornification has been estab-lished. This is especially marked inthe elements of Henles layer, in whichthe deposit takes the form of a longi-tudinal fibrillation. The growth of the hair takesjilace exclusively at the lower end ofits bulb, Mhere, so long as the hairgrows, the conversion of the matrix-cells into the substance of the hair iscontinuously progressing. By this pro-cess the substance already differentiatedis pus
RM2AWFH13–Human anatomy, including structure and development and practical considerations . l) the ijara-median furrow, extends a second longitudinal tract, the funiculus cuneatus, whichat the lower end of the medulla receives the column of Hurdach. Slightly above thelower level of the clava, the cuneate strand also exhibits an expansion, the cuneatetubercle (tuberculiMU cincreum), that is less circumscribed, but extends farther upwardthan the median elevation. Beneath this prominence lies an elongated mass of gravmatter, the nucleus cuneatus( nucleus funiculi cuncati), around whose cells the Ionsensor
RM2ANF3PX–Human anatomy, including structure and development and practical considerations . rs ciliaris retinae in the vicinity of the ora serrata. The investigationsof Retzius, Salzmann and others indicate that some fibres arise also from the mem-brana limitans interna of the pars optica retina;, whilst others pass into and endwithin the vitreous body. The greater number of the fibres pass forward chiefly inthe depressions between the ciliary processes, and along the sides of the latter, closelyapplied to the surface ; they then proceed outward across the circumlental space tobe attached to the capsule
RM2ANAX62–Human anatomy, including structure and development and practical considerations . Pouparts ligament. A slight fold,caused by the vas deferens or the round ligament, is described as running downwardfrom the ring into the pelvis ; the fact is, however, that the structure can be onlyindistinctly seen through the peritoneum, and a raised fold is rare. It forms theouter border of the slightly markedyrw^ra/ depression (fovea femoralisj opposite thefemoral ring (annulus cruralis), between the pubes and Pouparts ligament. Theperitoneum is continued laterally on either side without presenting any featu
RM2AWD5Y0–Human anatomy, including structure and development and practical considerations . en traversing the cortex, to whichthey contribute but few twigs, to gain the white matter within which they find theirdistribution. The contrast in richness between the supj)ly of the gray substance andthat of the adjoining white matter is not limited to the cerebral cortex, but is alsowell shown when the internal nuclei are examined (Fig. 1036). The veins emergefrom the surface of the brain, but do not retain a definite relation to the arteries, since,instead of following the latter to their points of entrance,
RM2ANC4HB–Human anatomy, including structure and development and practical considerations . into the two bands already mentioned, of which the posterior is thelarger and the more concerned in bridging over the folds. The internal sphincter isbut an hypertrophy of the circular muscles, while the external sphincter is a muscleof the perineum. It has been thought advisable to here describe together themuscles and some of the fasciae of the rectum and anus, including some that arelargely extrinsic. THE MUSCLES AND FASCIA OF THE RECTUM AND ANUS. TliLlevator ani( Figs. 1423, 1424) arises from the back of the
RM2AWFY12–Human anatomy, including structure and development and practical considerations . o be composetl of iniuunerable, closely set, small cells, heldtoii^ether by delicate supportniii;- tissue. These ai)j)arent cells are the niedullatcdnerve-fibres cut transversely, in which the sectioned axis-cylinders show as deeplystained dots, that commonly lie somewhat eccentrically and are surrounded by deli-cate irrei^ularly annular striations representing the framework of the medullary c<xat.The ncrve-tibres of the cerebro-spinal axis are without neurilemma, the lack of thissheath beiuir compensated l)y
RM2AWG53Y–Human anatomy, including structure and development and practical considerations . Edge ot cut dural shealh .Spinal cord I L Pedicles 5/« Posterior > divisions of /sacral nerves s: Cu -. -End of conns medullaris Filuni lerminale Desiendinjt nerves End of dtiralshealh J Sll Iiliiin ixterniini— Cn End of fihnnCoccyx Posterior wall of vertebral canal has been removed anddural sheath opene<l to expose spinal cord and dorsal rootsof attache/, I C. first cervical ner-e and vertebrarespectively; O/, coccygeal ner>es. which may transmit blood-vessels, isimperfect or alto).jcthcr absent. Ast
![Human anatomy, including structure and development and practical considerations . ; taken by llie lateral ciilaiiei)USbranch of the twcltlli tlioiacic nerve. Tiie liypoj^astric branch may inosculate with the twelfththoracic ant! may su|ii)ly llu- pyramidalis muscle. V Till-; 1 i.i()-I.(;uiN.i. Nkrvk. The ilid-iiii^uinal nerve (n. ili(iin<;uinalis) (lio-. 1107) is the secxmd branch ofthe hnnbar i)K-.us and is soniewliat smaller than the ili()-hy])().uastric. Its fibresusually arise from the first luinl)ar nerve, with accessions from the twelfth thoracic. Fig. 1107. Xll. libXII. thoracic i Stock Photo](https://c8.alamy.com/comp/2ANHJ2M/human-anatomy-including-structure-and-development-and-practical-considerations-taken-by-llie-lateral-ciilaiieiusbranch-of-the-twcltlli-tlioiacic-nerve-tiie-liypojastric-branch-may-inosculate-with-the-twelfththoracic-ant!-may-suiily-llu-pyramidalis-muscle-v-till-1-ii-iuini-nkrvk-the-ilid-iiiiuinal-nerve-n-iliiinltuinalis-lio-1107-is-the-secxmd-branch-ofthe-hnnbar-ik-us-and-is-soniewliat-smaller-than-the-ili-hy-uastric-its-fibresusually-arise-from-the-first-luinlar-nerve-with-accessions-from-the-twelfth-thoracic-fig-1107-xll-libxii-thoracic-i-2ANHJ2M.jpg "Human anatomy, including structure and development and practical considerations . ; taken by llie lateral ciilaiiei)USbranch of the twcltlli tlioiacic nerve. Tiie liypoj^astric branch may inosculate with the twelfththoracic ant! may su|ii)ly llu- pyramidalis muscle. V Till-; 1 i.i()-I.(;uiN.i. Nkrvk. The ilid-iiii^uinal nerve (n. ili(iin<;uinalis) (lio-. 1107) is the secxmd branch ofthe hnnbar i)K-.us and is soniewliat smaller than the ili()-hy])().uastric. Its fibresusually arise from the first luinl)ar nerve, with accessions from the twelfth thoracic. Fig. 1107. Xll. libXII. thoracic i Stock Photo")
RM2ANHJ2M–Human anatomy, including structure and development and practical considerations . ; taken by llie lateral ciilaiiei)USbranch of the twcltlli tlioiacic nerve. Tiie liypoj^astric branch may inosculate with the twelfththoracic ant! may su|ii)ly llu- pyramidalis muscle. V Till-; 1 i.i()-I.(;uiN.i. Nkrvk. The ilid-iiii^uinal nerve (n. ili(iin<;uinalis) (lio-. 1107) is the secxmd branch ofthe hnnbar i)K-.us and is soniewliat smaller than the ili()-hy])().uastric. Its fibresusually arise from the first luinl)ar nerve, with accessions from the twelfth thoracic. Fig. 1107. Xll. libXII. thoracic i
RM2ANJDHR–Human anatomy, including structure and development and practical considerations . ^ r- Cervical plexus ^ / / ^ .^?—, Occipitalis -Afe>/ major I f Cervical plexus. Diagrams showing distribution of cutaneous branches of trigeminal and cervical spinal nerves. to the chorda tympani and {c) another to the buccal nerve, {d) a branch to theinternal pterygoid nerve, and {e) and (/) branches to the nerves supplying thetensor palati and tensor tympani muscles. The Submaxillary Ganglion.—The submaxillary ganglion (g. siibmnxillare)(Fig. 1063) is a reddish triangular or fusiform body, measuring from 2-
RM2ANE2E1–Human anatomy, including structure and development and practical considerations . Mesoblast Oral epithelium.
RM2ANG0PC–Human anatomy, including structure and development and practical considerations . )fli^yjm^:i Section of human olfactory mucousmembrane, silver preparation; twoolfactory cells are seen, one of whichsends nerve-fibre towards brain. X 335-(/>» linn.). Isolated elements of epithelium of olfactorymucous membrane; a, olfactory cells; b, sup-porting cells. X 1000. {Bruiiii.) processes of the olfactory cells, much more delicate than the peripheral, are directlycontinued, as the axis-cylinders, into the subjacent nonmedullated nerve-fibres withinthe tunica propria, from which they pass through the
RM2AWFNCX–Human anatomy, including structure and development and practical considerations . Fig. 911. Fore-brain(thalamic region > Pallium Mid-brain Hind-brain. Reconstruction of b-ain of human embryo of about two weeks (3.2 mm.); ./4, outer surface; B^ inner surface;np, neural pore, where fore-brain is still open ; cs, anlage of corpus striatum ; o> optic recess leading into opticvesicle; A/, hypothalamic region. {His.) evagination is attached by a hollow stem, the optic stalk, which later takes part inthe formation of the optic nere that connects the eye with the brain, the vesicleitself givin
RM2AWD3T5–Human anatomy, including structure and development and practical considerations . losi), and on either sidealong the stem of the Sylvian fissure (cisterna fissurae lateralis). Within the medianregion of the cisterna basalis lie the large arterial trunks forming the circle of Willis.These vessels are invested with delicate sheaths of arachnoid, which accompany thesmaller branches until they enter the vascular membrane to become pial vessels. The arachnoid also contributes sheaths to the cranial nerves as they pass fromtheir superficial origins to the points where they pierce the dura, these she
RM2AWD1DC–Human anatomy, including structure and development and practical considerations . by the posterior part of the rij^ht third frontal conxolution, l)ut in the left-lianded it is probably the chief centre. In the first left temporal conxolution is the aiuiiiorv ccnlrc for speech, a lesicjiiof which leads to a loss of memory for word-sounds, though the hearings may beundisturbed. The centre for memory of pri)ited -cords is probably in the left an i,^ular i^yrus ;and a lesion tliere probably causes a loss of the ability to read or tf) understandwritten lanouatie, though ordinary sij^ht is undisturb
RM2ANCD6M–Human anatomy, including structure and development and practical considerations . embling adenoid tissue,covered by a single layer of columnar epithelium exhibiting a cuticular border. Thechief difference, on the other hand, is the absence of villi, in consequence of whichthe velvety appearance imparted by the latter is not seen in the large intestine.Valvulae conniventes are also wanting, although there are projections into the largegut involving all or a part of the coats internal to the serous tunic. The muscularismucosae is less regular in its development, being feebly represented in the c
RM2ANEPYP–Human anatomy, including structure and development and practical considerations . er with the fibres of the anterior iij^anieiit iyin.^ in the same plane, form the axis-ligament of the malleus, since the axis on wiiich the malleus turns passes through the attach-ment of these two fibrous structures. 4. The posterior ligament of the incus extends from tlie apex of the short process of theincus to the tympanic wall at the lower part of the mouth of the antrum. It is fan-shaped, theincudal attachment being less extensive than that of the tympanic. The superior ligamentof the incus is variable and
RM2AWFJ4J–Human anatomy, including structure and development and practical considerations . shed backward towards the mid-lineby the appearance of the inferior olive and the mesial fillet until, finally, it iscontinued as the posterior longitudinal fasciculus at the side of the median raphebeneath the gray matter covering the floor of the fourth ventricle. The proportion of the pyramidal fibres taking part in the motor decussation isnot always the same, from 80-90 i)er cent, being the usual number. ary rarely allthe fibres cross, with suppression of the direct pyramidal tracts—an arrangementfound norma
RM2ANC2FT–Human anatomy, including structure and development and practical considerations . above theboundary line. Vessels may be receied also from the sacra media. The middlehemorrhoidal arteries, of uncertain origin and distribution, rarely give any consider-able supply to the gut. The inferior hemorrhoidals—two or three small branchesfrom the internal pudic—supply chiefly the external sphincter, but also form a num-ber of fine anastomoses with the superior hemorrhoidal artery. The general dis-tribution of the veiiis is not very different from that of the arteries. The superiorhemorrhoidal veins, tr
RM2AWDGGM–Human anatomy, including structure and development and practical considerations . Frontal section of brain passing through hemispheres infront of cf>rpus callosum ; core of white matter is everywhereenclosed by cortical gray matter. THK TELENCEPHALON. 1183 Fk;. 1021.. Diagram showitiR association fibres, lateral surface;part of left lu-mispliere removed to expose sliort fibres;loiiK fibres arc supposed to show throuj^h tratisparctilhemisphere; S/,/- superior lonjjiludinal fasciculus; (/?,uncinate fasciculus. Within the early months after birth, liowcver, the myehnation of these, as well as
RM2ANFGNM–Human anatomy, including structure and development and practical considerations . omthe fasciie coxerinj;^ the inferior and internal recti and the inferior ()bli(|ue, is attachedto the lower and median orl)ital wall. These fascial extensicjns, i)assin^ as they dofrom the tendons of the eye-muscles to the orbital wall, restrain excessive muscularaction and hence the name, c/iec^ //Q-amen/s, has been applied, especially to thoselimiting the action of the internal and external recti. The processes also materiallyassist in maintaining the position of the eyeball within the orbit. This function isp
RM2AWEGTD–Human anatomy, including structure and development and practical considerations . uadrigemina, the red nucleus and thecerebellum.. Diaijram sbdwinj^ chief coiistiluetilsof posterior longitudinal fasciculus. III.I, VI, II, XII, nuclei of respectivenerves; DN, vestibular (Deiters) nu-cleus; CN, common nucleus of posteriorcommissure and posterior longitudinalfasciculus. DEVELOPMENT OF THE MESENCEPHALON. Of the three primary cerebral vesicles, the mid-brain undergoes least change. Althoughmuch smaller than either of the other segments of the brain-tube, its prominent position, lyingas it does at
RM2ANC5FW–Human anatomy, including structure and development and practical considerations . ay measure 25 cm. (9>4 in.), oreven more, in circumference. The saccules are separated by deep creases, passingabout two-thirds around the gut, caused by a folding in of all the coats internal to thetwo bands of longitudinal muscular fibres. The folds form the valves of the rectum,to be describctl with its interior. In the male the ampulla extends against the backof the prostate and the lower part of the seminal vesicles and the terminal parts ofthe vasa deferentia, to all of which it is connected by areolar t
RM2AWFBAR–Human anatomy, including structure and development and practical considerations . sray matter that collectively constitutes the reception-nucleus of the cochlear division ofthe auditory nerve. This j^anglion is subdivided into a superior and an inferior portion, thesebein^ the dorsa/ corh/tar iiiu/ius and the ventral lOihltar nin/tus resiK-ctively. They bothreceive the fibres of the cochlear or lateral division of the auditory nerve. The ventral cochkarnucleus is the startin.n point of a tract of transverse fibres, that pass horizontally inward, manytraversing the fillet and crossing the raphe
RM2ANDRYC–Human anatomy, including structure and development and practical considerations . rejections of tunica pro-pria constituting basis ofpapilla e-tissue stroma ofmembrane •-T—fi^J--. ^^ Muscular tissue of f^Jj tongue Section of lingual mucous membrane, showing filiform and fungiform papillae. X 75. organs, or taste-buds, which lie embedded within the epithelium lining the grooveencircling the central elevation. A detailed description of the taste-buds is givenwith the organs of special sense (page 1433). The surface of the vertical posterior third of the tongue is smooth, in the sensethat there a
RM2AWFX78–Human anatomy, including structure and development and practical considerations . rior horn ; S. C, spinal ganglion. WHITE MATTER OF THE SPINAL CORD. 1041 sections of the cord in the cervical reg-ion the hjiiy lil^res entering;- by the lowernere-roots occupy the inner part of Golls column, but are excludetl from the medianseptum, except behind, by a narrow hemielliptical area, which with its mate of theop{)osite side forms the oval field ol hlechsig. The fibres entering by the lowerthoracic nerves lie more laterally, while those entering by the upper thoracic andcerical nerves appropriate th
RM2AWFBEA–Human anatomy, including structure and development and practical considerations . ,^ Section of inferior olivary nucleus, showinj; plicated sheet of gray substancetraversed by strands of cerebello-olivary fibres. X loo. THE MEDULLA OBLONGATA. 1073 which the lower and middle are continuous and the upper is unconnected, and foursmall isolated masses of j^ray matter alonj^ the dorsal border of the nucleus. Theinferior or spinal end of the nucleus is thickened and bent outward, so that its planeis oblique and parallel with the ventral surface of the chief olive. Higher, when thelatter is well esta
RM2AWGEWE–Human anatomy, including structure and development and practical considerations . nes ofmotor neurones whose cell-bodies are situated within the s[)inal cord or brain ; (2) theafferent dendrites of sensory neurones within the spinal and other sensory ganglia ;and (3) the efferent axones of neurones within the sympathetic ganglia that accompanythe spinal fibres to the periphery and serve for the innervation of the involuntarymuscle of the blood-vessels and of the skin and the glands. The nerve-fibres, the various kinds usually more or less intermingled, aregrouped into bundles, the funiculi, wh
RM2AWD338–Human anatomy, including structure and development and practical considerations . aths by whichthis is accomplished include : (i) theextension of the subarachnoid spacealong the nerve-trunks, and (2) thevillous projections of arachnoid tissue,the Pacchionian bodies, along thecourse of the dural blood-sinuses. The Pacchionian bodies (gran-iilati(>nes arachnoidales) are numerouscauliflower-like excrescences of thearachnoid, for the most part small butoccasionally reaching a diameter of5 mm. or over, w^hich lie on the outersurface of the membrane along thecourse of the dural venous sinuses.The
RM2ANF416–Human anatomy, including structure and development and practical considerations . e at sometimepartial, and they are called according to their location, anterior polar or capsular,posterior polar or capsular, central or nuclear, lamellar, perinuclear and cortical.Cataract occurs sometimes in the young, and is then soft; that is, the lens has nonucleus. The Vitreous Body. The vitreous body (corpus vitreum) fills the space between the lens and theretina, being in close contact with the retina and acting as a support to it as farforward as the ora serrata. Here it becomes separated from the retin
RM2AWE8C0–Human anatomy, including structure and development and practical considerations . vian fissure, which intervenesbetween it and the temporal lobe. ()n the mesial surface the frontal lobe includesan irregular -), marked ofT by the calloso-marji^inal sulcus, the l(jnj:(er upper limbendinj^ behind the central fissure. On the inferior surface of the hemisphere, thefrontal lol)e includes the concave orbital area, bounded behind by the transverselydirected stem of the .SyKian fissure, which sulcus thus separates it from the temporallobe. Tile princii:)al fissures on the dorso-lateral surface of the f
RM2ANF3MG–Human anatomy, including structure and development and practical considerations . nfuse, and in this manner form a closed sac, the lens-vesicle. This remains for a time connected with thesurface ectoblast, but later becomes separated fromit and forms an isolated sac of epidermal tissue, which,by the proliferation of its cells, becomes converted into a solid structure and constitutes thecrystalline lens. At first the lens-vesicle fills the cavity of the optic cup completely, but withthe deepening of the latter, a space appears between its anterior wall and the lens-vesicle,which gradually widen
RM2ANBA9D–Human anatomy, including structure and development and practical considerations . ser or gastro-hepatic omentiuii is a foldenclosing the vessels in the porttU fissure and passing to the lesser curvature of thestomach and the first part of the duodenum. A secondary fcjld containing thecystic duct, the duodeno-eystic fold, joins it on the right. Near this it presents afree border forming the ft^^^i of the foramen of Winslow. On the left it runs alongthe fissure of the ductus venosus to the notch in the lier made by the passage ofthe oesophagus. There its left layer is reflected as the under one
RM2ANCAMK–Human anatomy, including structure and development and practical considerations . Portion of descending colon, somewhat distended, show-ing sacculations, taenia, and epiploic appendages. quent in the colon, but are again numer-ous in the rectum. They are generallyof larger size than in the small intestine,measuring from 1.5-3 mm. in diameter,and are situated at the bottom of pit-likedepressions on the mucous surface intowhich the nodules project. The submucous coat closely cor-responds with the similar areolar tunic ofthe small intestine, allowing of fairly free Fig. 140Q.. --- *I».*r- • Mucos
RM2ANER8C–Human anatomy, including structure and development and practical considerations . t of the stapes, are cov-ered with a layer of hyaline cartilage.The cartilage of the foot-plate and thatof the window are connected by a liga-ment of elastic fibres, forming a .syn-chondrosis. In addition to the ligaments con-cerned in the foregoing articulations,four bands attach the ossicles to the tym-panic walls and prevent their excessivemovement ; of these, three connect themalleus and one the incus. 1. The superior ligament of the malleus extends from the tegmen tympani to the head ofthe malleus. (Figs. 12
RM2ANF9YY–Human anatomy, including structure and development and practical considerations . ed as to be indistinguishable without bleaching the tissue. The dilatatormuscle is developed from the outer layer of fusiform cells, so that it represents anepithelial Cectoblastic) muscle. The inner cells are larger polygonal elements, whichgradually lose their pigment as they approach the ciliary processes. Over the latterthey contain no pigment, whereas the outer cells remain pigmented. The blood-vessels of the iris pass radially inward from the circulus arteriosus iridismajor at the periphery. Near the pupill
![Human anatomy, including structure and development and practical considerations . littleinformation as to its true form. Indeed, it is only in the jjresent generation, sincethe introduction of adequate methods of hardening in situ, that this has beenlearned. The liver in general may be described as an ovoid mass which in the youngftttus nearly tills the abdomen, l)ut in the adult has the appearance of having had atleast a third of its substance scoo])ed out from below, the back haing been left intactat the right end only. The organ is therefore a thick mass in the right hypochon-drium, growin Stock Photo](https://c8.alamy.com/comp/2ANBPTR/human-anatomy-including-structure-and-development-and-practical-considerations-littleinformation-as-to-its-true-form-indeed-it-is-only-in-the-jjresent-generation-sincethe-introduction-of-adequate-methods-of-hardening-in-situ-that-this-has-beenlearned-the-liver-in-general-may-be-described-as-an-ovoid-mass-which-in-the-youngftttus-nearly-tills-the-abdomen-lut-in-the-adult-has-the-appearance-of-having-had-atleast-a-third-of-its-substance-scoo-ed-out-from-below-the-back-haing-been-left-intactat-the-right-end-only-the-organ-is-therefore-a-thick-mass-in-the-right-hypochon-drium-growin-2ANBPTR.jpg "Human anatomy, including structure and development and practical considerations . littleinformation as to its true form. Indeed, it is only in the jjresent generation, sincethe introduction of adequate methods of hardening in situ, that this has beenlearned. The liver in general may be described as an ovoid mass which in the youngftttus nearly tills the abdomen, l)ut in the adult has the appearance of having had atleast a third of its substance scoo])ed out from below, the back haing been left intactat the right end only. The organ is therefore a thick mass in the right hypochon-drium, growin Stock Photo")
RM2ANBPTR–Human anatomy, including structure and development and practical considerations . littleinformation as to its true form. Indeed, it is only in the jjresent generation, sincethe introduction of adequate methods of hardening in situ, that this has beenlearned. The liver in general may be described as an ovoid mass which in the youngftttus nearly tills the abdomen, l)ut in the adult has the appearance of having had atleast a third of its substance scoo])ed out from below, the back haing been left intactat the right end only. The organ is therefore a thick mass in the right hypochon-drium, growin
RM2ANJA4J–Human anatomy, including structure and development and practical considerations . lar fibres, and {b) a smallermass of cells which lies above the larger one and partly to the inner and partly to the outer sideof the tract of the vestibular fibres. The apex of the large triangular mass approaches themid-line and its superior and inferior basal angles are prolonged upward and downward alongthe vestibular tract. When examined microscopically the large mass is found to include three subdivisions : (a)a tapering caudally directed nucleus which continues the inferior angle along the descendingvestib
RM2AWGME1–Human anatomy, including structure and development and practical considerations . Multipolar nerve-cells of various forms; .1, from spinal cord ; B. from cerebral cortex; C, from cerebellar cortex(Purkinje cell) ; ii, axone; r, ini|)lantation cone. the multipolar neurones of Golgis type II, whose axones almost immediatelyundergo elaborate branching within the gray matter to which they are confined.The Nerve-Fibres.—From the foregoing considerations it is evident that thenerve-fibres are not independent elements, but that all are the processes of neurones—either the axones of those that are pro
RM2AWD193–Human anatomy, including structure and development and practical considerations . lel to the longitudinal fissure to within i8mm. (^ ;?4 in.; of the fissure of Rolando. Tlie inferior frontal sulcus is represented,appro.ximately, by the anterior end of the temporal ridge. In the parietal lobe the most imjjortant sulcus is the intraparietal. It beginsnear the horizontal limb of the fissure of Sylvius, and passes upward and backwardabout midway between the fissure of Rolando and the parietal eminence. It thenturns backward, running about midway to the longitudinal fissure and the centreof the par
![Human anatomy, including structure and development and practical considerations . f/i^-JM^^^. Epidermis of drum-headSub(.])idcrmal layerExtt-rual auditory canal Epidermis of canal Corium of skin liningcanal Epidermis passing ontodrum-head rO-Qi-- Bone Radial fibres of annulusfibrosus Section through attached margin of tympanic membrane, showing continuation of skin and mucous membraneover its outer and inner surfaces respectively. X 75- Drawn from preparation made by Dr. Ralph Butler. The nerves supplying the tympanic membrane are derived chiefly from the auriculo-tem-poral branch of the trige Stock Photo](https://c8.alamy.com/comp/2ANETTD/human-anatomy-including-structure-and-development-and-practical-considerations-fi-jm-epidermis-of-drum-headsub-idcrmal-layerextt-rual-auditory-canal-epidermis-of-canal-corium-of-skin-liningcanal-epidermis-passing-ontodrum-head-ro-qi-bone-radial-fibres-of-annulusfibrosus-section-through-attached-margin-of-tympanic-membrane-showing-continuation-of-skin-and-mucous-membraneover-its-outer-and-inner-surfaces-respectively-x-75-drawn-from-preparation-made-by-dr-ralph-butler-the-nerves-supplying-the-tympanic-membrane-are-derived-chiefly-from-the-auriculo-tem-poral-branch-of-the-trige-2ANETTD.jpg "Human anatomy, including structure and development and practical considerations . f/i^-JM^^^. Epidermis of drum-headSub(.])idcrmal layerExtt-rual auditory canal Epidermis of canal Corium of skin liningcanal Epidermis passing ontodrum-head rO-Qi-- Bone Radial fibres of annulusfibrosus Section through attached margin of tympanic membrane, showing continuation of skin and mucous membraneover its outer and inner surfaces respectively. X 75- Drawn from preparation made by Dr. Ralph Butler. The nerves supplying the tympanic membrane are derived chiefly from the auriculo-tem-poral branch of the trige Stock Photo")
RM2ANETTD–Human anatomy, including structure and development and practical considerations . f/i^-JM^^^. Epidermis of drum-headSub(.])idcrmal layerExtt-rual auditory canal Epidermis of canal Corium of skin liningcanal Epidermis passing ontodrum-head rO-Qi-- Bone Radial fibres of annulusfibrosus Section through attached margin of tympanic membrane, showing continuation of skin and mucous membraneover its outer and inner surfaces respectively. X 75- Drawn from preparation made by Dr. Ralph Butler. The nerves supplying the tympanic membrane are derived chiefly from the auriculo-tem-poral branch of the trige
RM2ANDPFP–Human anatomy, including structure and development and practical considerations . hat it is not easy to recognize them. The foliate pai)ilke are also relativelyxmdeveloped. On the other hand, the fungiform papilla- are j^roportionately bothlarger and more numerous than in the adult. The development of the adenoid tissueat the back of the tongue occurs during the last tv(j mcjnths of fcetal life. In jjlacesthe connective tissue surrounding the ducts of the mucous glands becomes infiltratedwith leucocytes and is transformed into lymjjhoid tissue (Stohr). THE SUBLINGUAL SPACE. This space is betw
RM2ANEE45–Human anatomy, including structure and development and practical considerations . pending upon the number of those associated to compose the gland.These units correspond to the groups of terminal compartments, or alveoli, con-nected with a single ultimate division of the duct-system. The alveoli or acini containthe secreting cells, and are limited externally by a basement membrane, often welldeveloped, which supports the glandular epithelium and separates the latter from theblood- and lymph-vessels that surround the acinus. The alveoli belonging to the same intermediate duct, held together by
RM2ANHGB3–Human anatomy, including structure and development and practical considerations . rural or of either branch may occur, the fibres of the genital branch being contained in the ilio-inguinal and those of the crural in the external cutaneous or the anterior crural. The genitalbranch may replace or reinforce the ilio-inguinal nerve; the crural branch may act similarlytoward the external or the middle cutaneous nerve. A specimen found in the anatomical labo-ratorj of the University- of Pennsylvania showed unusually extensive distribution of the crural THE LUMBAR PLEXUS. 1323 branch. It was larji^er
RM2ANDRK8–Human anatomy, including structure and development and practical considerations . Interlacing fibrous andmuscular bundles Section from posterior third of childs tongue, showing lymph-nodes constituting a part of lingual tonsil. X 30. tinued backward by additional collections of mucous glands along the edges of thetongue. The ducts—five or six in number—open on the folds occupying the undersurface of the tongue near the frenulum. Muscles of the Tongue.—These include two groups, the extrinsic and theiyitrinsic muscles. The former pass from the skull or hyoid bone to the tongue ; thelatter compri
RM2AWD1GB–Human anatomy, including structure and development and practical considerations . lesions of the motor zonemay therefore produce a paralysis limited to one part controlled by the affected por-tion of the cortex, as of the face, arm or leg (monoplegia). The lesion is muchmore likely to involve two adjacent areas, as of the face and arm, or of the armand leg, giving rise to a combined paralysis ; but no single lesion, unless it werecrescentic in form, could involve at the same time the leg and face areas withoutincluding the intervening arm area. Within each of the larger areas a more specialize
RM2ANFXAK–Human anatomy, including structure and development and practical considerations . rtain of the nasal lymphatics emj)ty, may result in a retropharyngeal ab-scess ; or (/i) infection (pyogenic or tuberculous) of the submaxillary, preauricular,or deep cervical nodes may follow nose diseases. The graver of these complicationsare, of course, associated with the severer infective forms of rhinitis. Malignantgrowths—commonly sarcomatous—may begin in the nasal chambers and may extendin any of the directions above mentioned. THE ACCESSORY AIR-SPACES. The nasal fossae communicate with a number of remark
RM2ANJ9W3–Human anatomy, including structure and development and practical considerations . the correspondingnucleus of the trigeminus. Thespinal nucleus is closely associatedwith a conspicuous longitudinaltract of caudally directed fibres,the fasciculus solitarius(tractus solitarius), so called on account of the apparent isolation of the bundle whenviewed in transverse sections (Fig. 927). That such, however, is not the case isevident when the fact is recalled that the fibres which turn downward to form the tractare accompanied by the spinal nucleus of reception, around whose cells they end. Thefascicu
