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Anatomy of the brain and spinal cord, with special reference to mechanism and function, for students and practitioners online

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Real central termination, terminal nuclei 364

Gray matter of the cord 364-365

Nuclei of medulla oblongata 365

Physiological groups of posterior root-fibers 365

Lesions of posterior roots 365

CHAPTER VII.
TRACING OF IMPULSES.

I. Efferent, or Motor Paths: 366-374

Cerebro-spinal or pyramidal paths 366-369

Through spinal nerves 366

Through cerebral nerves 369

Cerebro-pontal paths 369-37

Fronto-pontal 37






XXIV TABLE OF CONTENTS.

PAGE

Temporo-pontal 370

Intermediate 370

Spinal and cerebral 370

Paths through red nucleus 37~373

Rubro-spinal path, direct 37~373

Indirect via brachium conjunctivum 373

Ponto-spinal paths (Collieri) 373

Medial ponto-spinal tract 373

Lateral ponto-spinal tract 373

Short fiber paths in formatio-reticularis 373~374

II. Afferent, or Sensory Paths, General Sensations: 377-3&3

Tactile, muscular, pain, and temperature sense 377

(I). Muscular and tactile impulses from muscles, skin,

etc 377-38i

Through fasciculi gracilis et cuneati 377~37^

Direct route 378

Indirect route 378

Through cerebral nerves and medial fillet 378-381

(II). Muscular and tactile impulses from viscera 381

Through posterior cerebello-spinal tract 381

(III). Paths for pain, temperature and tactile impulses . . 381-382

Through spino-thalamic tract 381-382

Through ascending anterior cerebello-spinal tract 381-382

Through cerebral nerves and spino-thalamic tract 382

Short fiber paths 382-383

Afferent Paths Special Sensations: 383-390

Olfactory path 383-384

Optic path 384-385

Auditory path 385-389

Cochlear (hearing proper) 386

Vestibular (equilibrium) 386-389

Reflex connections 389

Gustatory path 389

Lesions of special sense paths 389-390

III. Reflex Paths : 390-394

Reflex arcs 390

(1) Spinal reflexes 390-392

Coordinating reflexes 390

Defecation reflexes 39 J -39 2

(2) Cerebral reflexes 39 2 ~393



TABLE OF CONTENTS. XXV



PAGE



(3) Spino-cerebral reflexes 393

(4) Cerebro-spinal reflexes .-. . 393-394

Respiratory reflexes 393

Equilibrium reflexes 393

Pupillary reflexes 394

CHAPTER VIII.
EMBRYOLOGY OF THE BRAIN AND SPINAL CORD.

Medullary plate and ridges 395

Neural Tube: 395-400

Brain vesicles 395 and 402

Ependymal cells 397

Indifferent cells 397~39&

Neuroblasts, neurones 398

Spongioblasts, neuroglia 398-399

Zones, roof -plate and floor-plate 399-400

Neural Crest: 400-401

Cephalic portion 400

Cerebral nerve ganglia 400

Unipolar and bipolar neurones 400-401

Spinal portion of crest 401

THE BRAIN: 401-426

Flexures 402

Table IV. Brain Vesicles and Derivatives 403

Table V. Secondary Brain Vesicles 403-404

Telencephalon (end-brain) 404-415

Table VI. Derivatives of 404-405

Optic vesicle, cup and retina 405

Hemisphere of cerebrum 405-415

Rhinencephalon 406-409

Primary fissures 409-410

Secondary sulci and fissure 410-411

Transverse fissure of cerebrum 411

Cerebral cortex and medulla 411-412

Fornix 412

Stria terminalis 412

Internal capsule 412-413

Anterior commissure : - - . 413-414

Corpus callosum 414



XXVI TABLE OF CONTENTS.

PAGE

Septum pellucidum 415

Bars optica hypothalami 415

Diencephalon (inter-brain) 415-417

Table VII. Derivatives of 415

Roof-plate 416

Dorsal lamina 417

Ventral lamina and floor-plate 417

Mesencephalon (mid-brain) 417-418

Table VIII. Derivatives of 417-418

Metencephalon (hind-brain) 418-424

Table IX. Derivatives of 419

Cerebellum 418-42 1

Vermis and hemispheria 419-420

Sulci 420-421

Cortex and ganglia 421

Corpus restiforme and brachia 42 1

Pons (Varolii) 42 1-422

Myelencephalon (medulla oblongata) 422-426

Internal surface 423

External surface 423-424

Table X. Derivatives of Myelencephalon 424

Ependymal layer 424-425

Mantle layer 425

Neuroglia layer, marginal velum 425-426

THE SPINAL CORD: 426-430

Ventriculus terminalis 426

Filum terminale 426

Cauda equina 426

Meninges 426

Zones, ventral and dorsal 426-427

Histologic layers 427-428

Marginal velum, neuroglia layer 428

Mantle layer 428-429

Ependymal layer 429

Longitudinal tracts 429-430

Order of medullation 429-430

Fissures of cord 430

Posterior median fissure 430

Posterior lateral sulcus 430

Anterior median fissure 430



LIST OF ILLUSTRATIONS.



FIG. PAGE

1. Sagittal section of skull, showing falx cerebri, falx cerebelli,

a part of the tentorium cerebelli and the sinuses of the
dura mater. (After Morris's Anatomy) 3

2. Upper surface of tentorium cerebelli, tentorial notch and cer-

tain sinuses of the dura. (After Morris's Anatomy) . . 4

3. Sinuses of the dura mater in the base of cranium, etc. (After

Morris's Anatomy) 5

4. Coronal section of meninges showing falx cerebri, superior

sagittal sinus and the arachnoid granulations. (Gor-
dinier after Key and Retzius) 6

5. Middle meningeal artery inside the cranium. (After Mor-

ris's Anatomy) 7

6. Diagram of pia mater and arachnoid, showing subarachnoid

spaces. (After Morris's Anatomy) 9

7. Horizontal section of the cerebrum. Fornix turned back to

show the chorioid tela of third ventricle. (Original) . 1 1

8. Roof and lateral walls of fourth yentricle and its chorioid

plexus. (After Morris's Anatomy) 13

9. Arterial circle of Willis and its branches. The base of the

brain. (After Morris's Anatomy) 15

10. Arterial circle (Willisi) and base of the cerebrum. (After

Gordinier from Quain) 19

11. Middle cerebral artery, and its branches. (After Gordinier

from Quain) 22

12 Anterior and posterior cerebral arteries. (After Spalteholz) . . 25

13. Arteries of the medulla oblongata. (Gordinier after Duret) ... 27

14. Median section of embryonic brain of third month. (After

McMurrich from His) 28

15. Divisions of the brain, diagrammatic. (After Morris's Anat-

omy) 3 1

16. Neural tube and brain vesicles. (After Morris's Anatomy). . 35

17. Diagrammatic horizontal section of vertebrate brain, showing

vesicles and ventricles. (After Morris from Huxley) 36
xxvii



XXviii LIST OF ILLUSTRATIONS.

FIG. PAGE

1 8. Diagrammatic median section of vertebrate brain showing

vesicles, ventricles and olfactory diverticulum. (After

Morris from Huxley) 37

19. Antero-superior surface of the brain. (Original) 39

20. The posterior aspect of the brain. (Original) 43

21. The base of brain. (Original) 47

22. Latero-superior aspect of the brain, showing great fissures,

lobes, poles and borders. (Original) 53

23. The convex surface of the cerebrum, showing the fissures and

sulci. (Original) 57

24. Gyri of the convex surface of the cerebrum. (Original) 61

25. Lateral aspect of the brain. Part of frontal and parietal lobes

are cut away to show the island (Reili) and the superior
surface of the temporal lobe, arachnoid granulations,
etc. (Original) 65

26. Base of the fore-brain and cut surface of mid-brain. Right

temporal pole is cut away. (Original) 75

27. The median section of the brain. (Original) 87

28. Medial surface of left cerebral hemisphere, showing lobes and

sulci. (Original) 91

29. Gyri on medial surface of hemisphere. (Original) 95

30. Transverse section of the brain, directed from the pons ob-

liquely upward and forward, showing internal capsule,
corpus callosum, ganglia and ventricles of the fore-
brain. (Original) 101

3 1 . Horizontal section of right cerebral hemisphere cutting corpus

callosum, internal capsule, corpus striatum, thalamus,
and the island. (Original) 105

32. Sagittal section of basal part of right cerebral hemisphere

showing inferior lamina of internal capsule, hippocam-
pus, inferior horn of lateral ventricle. (Original) 113

33. Diagram of internal capsule in colors. (Original) 115

34. Dorsal surface of corpus callosum, cerebral hemisphere cut

away to expose it. (Original) 117

35. Horizontal section of cerebrum, cutting splenium and genu of

corpus callosum, showing lateral ventricles, septum pel-
lucidum, fornix and transverse temporal gyri. (Orig-
inal) 121

36. Horizontal section of cerebrum just below splenium of corpus

callosum, showing commissura hippocampi, fornix, sep-



LIST OF ILLUSTRATIONS Xxix

PIG. PAGE

turn pellucidum, the island and lateral ventricles. (Or-
iginal) 125

37. Horizontal section of cerebrum. Fornix turned back, showing

chorioid tael of third ventricle, and internal cerebral
veins. (Original) 129

38. Transverse section of left cerebral hemisphere cutting the

splenium and showing the posterior horn and the floor
of the inferior horn of the lateral ventricle. (Original) 131

39. The inferior and posterior horns of the lateral ventricle, shown

by removal of their lateral walls. (Original) 133

40. Horizontal section of cerebrum through genu and below sple-

nium of corpus callosum, fornix and chorioid tela turned
back, to show inter-brain and third ventricle. (Or-
iginal) 137

41. Lateral and dorsal view of the ventricles. Diagrammatic.

(Original) 141

42. Transverse section of brain, cutting corpora mammillaria.

(After Told. Morris's Anatomy) 145

43. The region of the mid-brain showing pulvinar of the thalamus,

the geniculate bodies, the corpora quadrigemina and
brachia, the pineal body, the optic tract and the fourth
nerve. (Original) 147

44. The dorsal or posterior aspect of the inter-brain, the mid-brain,

the pons and the medulla. (Original) 149

45. Anterior aspect of the mid-brain, pons, and medulla. (Orig-

inal) 153

46. Transverse section through the corpora mammillaria and the

superior colliculi of the corpora quadrigemina. (Orig-
inal) 157

47. Section of the mid-brain through superior colliculi and the ap-

parent origin of the oculo-motor nerve. (Original) . . 159

48. Section of the mid-brain cutting the inferior colliculi of the cor-

pora quadrigemina. (Original) 161

49. Varieties of neurones in the human nervous system. (After

Morris's Anatomy) 165

50. Motor neurone. (After Barker's Nervous System) 169

51. An efferent neurone and an afferent neurone. (After Bru-

baker's Physiology) 171

52. Diagram showing development of neurones in the spinal cord.

(McMurrich after Schaffer) 172



XXX LIST OF ILLUSTRATIONS.

FIG. PAGE

53. Neuroglia cells and ependyma cells of the spinal cord. (After

Lenhossek, Gordinier's Nervous System) 173

54. Cortical areas on convex surface of cerebral hemisphere. (Or-

iginal} 175

55. Cortical areas on the medial and tentorial surface of the cere-

bral hemisphere. (Original] 179

56. Cortical areas after C. K. Mills. Convex surface of cerebral

hemisphere. (Brubaker's Physiology} 182

57. Cortical areas after C. K. Mills. Medial and tentorial surface

of cerebral hemisphere. (Brubaker's Physiology) 183

58. Cell and fiber lamination in the posterior half of the anterior

central gyrus. The motor area. (After A. W. Camp-
bell) 185

59. Cell and fiber lamination in the anterior half of the posterior

central gyrus. The common sensory area. (After
A. W. Campbell) 189

60. Cell and fiber lamination in the calcarine region. Receptive

visual area. (After A. W. Campbell) 193

61. Cell and fiber lamination in the uncus hippocampi (lobus pyra-

formis). The area of smell. (After A. W. Campbell) 197

62. Transverse section of the hippocampal region. (After Edinger) 201

63. Chief elements of the olfactory bulb. (Gordinier after Van

Gehuchten) 203

64. Horizontal section of the cerebrum through genu and below

splenium of corpus callosum, fornix and chorioid tela
turned back to show inter-brain and third ventricle.
(Original) 205

65. Dissection of brain to show geniculate bodies, optic tract,

nucleus amygdalae, etc. (After Morris's Anatomy) 207

66. Transverse section of the brain in the line of the pyramidal

tracts, showing basal ganglia, internal capsules, corpus
callosum, lateral and third ventricles, etc. Viewed
from front. (Morris's Anatomy after Toldt) 209

67. The optic path. (Original) 213

68. Section of mid-brain through superior colliculi and the appa-

rent origin of the oculomotor nerve. (Original) 215

69. Section of the mid-brain cutting the inferior colliculi of the cor-

pora quadrigemina. (Original) 216

70. Horizontal and sagittal section through internal capsule, much

enlarged. (Original) 226



LIST OF ILLUSTRATIONS. Xxxi

FIG. PAGE

71. Diagram of internal capsule in colors. (Original) 227

72. A diagram showing motor and sensory paths, motor red,

sensory blue. (After Gordinier' s Central Nervous
System) 229

73. Transverse section of cerebrum, cutting corpus callosum,

anterior commissure and optic chiasma. Viewed from
front. Commissural fibers. (Morris's Anatomy after
Toldt) 235

74. Diagram of association fibers in the cerebral hemisphere.

(Gordinier and Quain after Meynert) 237

75. Fasciculus occipito-frontalis. Stria terminalis and fasiculus

uncinatus. (Gordinier after Dejerine) 239

76. Dorsal view of inter-brain, mid-brain and cerebellum. Su-

perior surface of cerebellum. (Original) 243

77. Anterior aspect of cerebellum. (Original) 245

78. Dissection of rhombencephalon to show brachium conjuncti-

vum, brachium pontis and corpus restiforme. (Gor-
dinier, Sappey after Hirschjeld and Leveille) 246

79. Median section of cerebellum, pons and medulla. (Original) 247

80. Inferior surface of cerebellum. (Original) 252

81. Sagittal section of cerebellum, cutting nucleus dentatus. (Or-

iginal) 255

82. Section of cerebellar gyrus made parallel with its free border.

Diagrammatic. (Cunningham after Kolliker) 258

83. Section across a cerebellar gyrus at a right angle to the free

border. Diagrammatic. (Gordinier after Van Gehuch-
ten) 259

84. Horizontal section of cerebellum cutting nuclei and brachia

conjunctiva. (Morris's Anatomy after Toldt) 261

85. Anterior aspect of mid-brain, pons and medulla. (After

Morris's Anatomy) 267

86. Dorsal surface of pons and medulla. (Morris's Anatomy

modified from Spalteholz) 270

87. Superior transverse section of the pons. (Original) 275

88. Inferior transverse section of the pons together with the cere-

bellum. (Original) 277

89. Diagram of the auditory paths in the pons. (After Morris's

Anatomy) - 280

90. Section of embyronic medulla, embryo measuring 9.1 mm. in

length. (Gordinier and Minot after His) 285



XXXil LIST OF ILLUSTRATIONS.

FIG; PAGE

91. Roof and lateral walls of fourth ventricle, and its chorioid

plexuses. (After Morris's Anatomy) 289

92. Section of medulla oblongata near the pons. (Original) . . . 295

93. Section of the medulla oblongata at the middle of olive. (Or-

iginal) 297

94. Section of the medulla oblongata at the fillet decussation. (Or-

iginal) 305

95. Section of the medulla oblongata at the pyramidal decussation.

(Original) 311

96. Nuclei of the cerebral nerves in the medulla, pons, mid-brain,

inter-brain, and olfactory bulb. Motor (or genetic)
nuclei red, terminal (or sensory) nuclei blue. (After
Morris's Anatomy) 315

97. Meninges of the spinal cord. A. Transverse section. (After

Key and Retzius.) B. Anterior view. (After Ellis.)
(Morris's Anatomy) 327

98. Diagrammatic section of the spinal meninges and spinal cord.

(After Morris's Anatomy) 329

99. The arteries and veins in the spinal cord. Diagrammatic.

(After Morris's Anatomy) 331

100. Posterior view of the spinal cord, the dura mater and the arach-

noid being laid open and turned aside. (Bnibaker
after Sappey) 334

1 01. Sections of the spinal cord: A. The cervical. B. The thora-

cic. C. The lumbar, and D. The lower sacral. (Or-
iginal) 335

1 02. Tracts of fibers and columns of cells, in the cervical and thora-

cic regions of the cord. Diagrammatic. (In part after
Bruce and Cunningham} 341

103. Tracts of fibers and columns of cells in the lumbar and sacral

regions of the cord. Diagrammatic. (In part after
Bruce and Cunningham) 345

104. The roots of the spinal nerves. Diagrammatic. (Original) . 349

105. Direct motor paths from cerebral cortex, to cerebral and spi-

nal nerve. Diagrammatic. (Original) 367

106. Indirect motor paths to the spinal nerves. Diagrammatic.

(Original) 371

107. Common sensory paths, muscular and tactile, by way of the

posterior column and (posterior) cerebello-spinal tract.
Diagrammatic. (Original) 375



LIST OF ILLUSTRATIONS. XXxiii

FIG. PAGE

108. Common sensory paths, pain, temperature and touch, by way

of ascending anterior cerebello-spinal and spino-thala-
mic tracts. Diagrammatic. (Original} 379

109. Chief elements of the olfactory bulb. (Gordinier after Van

Gehuchteri} 384

no. The chief retinal elements. (After Brubaker' s Physiology).. 385

in. The optic path. (Original) 387

112. A simple spinal reflex arc. (Brubaker after Morat and

Dayon) 391

113. A more complicated spinal reflex arc, involving the fasciculi

proprii. (Brubaker after Kb'lliker) 392

114. Medullary groove, neural tube, etc. (Gordinier after E. A.

Schajer) 396

115. Two histologic layers in the embryonic spinal cord, embryo

4.25 mm. long. (McMurrich after His) 397

116. Diagram showing development of neurones in the spinal cord.

(McMurrich after Schajer) 398

117. Ventral and dorsal zones of the spinal cord. (Gordinier and

Quain after Kb'lliker) 399

118. Median section of embryonic brain of the third month. (Mc-

Murrich after His) 406

119. Transverse section through the fore-brain of a four and one

half weeks' embryo. (Gordinier and Quain after His) 407

120. Diagrammatic sagittal section of vertebrate brain. (Morris's

Anatomy after Huxley) 409

121. Medial sagittal section through the brain of an embryo of

three months showing the primitive fissures on the
medial surface of the cerebral hemisphere. (McMur-
rich after Mihalkovicz) 4 1 1

122. The fossa cerebri lateralis, in embryonic brain of fourth

month. (After McMurrich' s Development oj the Human
Body) 413

123. Permanent fissures and sulci on the convex surface of the

cerebrum as seen in a seven months' embryo. (Mc-
Murrich after Cunningham) - 4 J 4

124. Dorsal view of an embroynic brain, the roof of the lateral ven-

tricles having been cut away. Embryo of 12.6 mm.
(McMurrich after His) 416

125. Transverse section of medulla from an embryo of 9.1 mm.

(McMurrich after His) ; 422



XXxiv LIST OF ILLUSTRATIONS.

FIG. PAGE

126. Transverse section of 'the medulla from an embryo of eight

weeks. (McMurrich after His) 423

127. Transverse section of the spinal cord, from an embryo of (A)

four and one-half weeks, and (B) of three months.
(McMurrich after His) 427

128. Mode of origin of anterior and posterior roots of spinal

nerves. Diagrammatic. (Brubaker and Edinger after
His) 428



ERRATA.



Page 30. Paragraph two, last line, last word should be brain-
vesicles.

Page 57. Fig. 23. "Intraparietal sulcus," and wherever found
should be written Interparietal sulcus.

Page 1 08. Paragraph four, fourth line, second word is sulcus,
instead of "fissure."

Page 184. Paragraph one, last line and first word is Alfred,
instead of "Arthur."

Page 264. Fourth line, the phrase "anterior ascending cerebello-
spinal tract," and wherever it occurs, should read Ascending an-
terior cerebello-spinal tract.

Page 265. Paragraph two, third line, the phrase "anterior de-
scending cerebello-spinal tract," should stand Descending anterior
cerebello-spinal tract : likewise, wherever the quoted phrase is
found.

Page 277. Third line, last word is (Horsley).

Page 286. Paragraph three, last sentence, the phrase "fasciculus
cerebello-spinalis," and wherever else it occurs should stand thus
fasciculus cerebello-spinalis (posterior).

Page 288. Paragraph three, fifth line, the substantive " cerebello-
spinal fasciculus" should have "posterior" prefixed so as to read
posterior cerebello-spinal fasciculus. This is a necessary varia-
tion from the BNA and applies wherever the phrase is found.

Page 291. Last line, there should be added a fifth item, viz., (e)
the medullarv striae.



ERRATA. XXXV

Page 319. Fifth line, common sensory should be added under
intermediate nerve.

Page 35 ! Paragraph three, third item, (3) should be omitted,
as no posterior root-fibers decussate. Intrinsic fibers only cross
through the gray commissure (Mott and Russell).

Page 358. To the last sentence should be added: and according
to Sir Victor Horsley has to do with locomotion (Brain, 1906).

Page 410. Fourth line, "callosal fissure" should be callosal
sulcus.



BRAIN AND SPINAL CORD.



CHAPTER I.

THE MENINGES OF THE BRAIN.

(Meninges Encephali.)

Three membranes invest the brain and spinal cord. They
are, from without inward, the dura mater, the arachnoid, and
the pia mater. Each membrane forms a protecting sheath for
the cerebral or spinal nerves piercing it.

THE DURA MATER OF THE BRAIN.

(Dura Mater Encephali.)

Structure and Relations. It is a very dense and inelastic
membrane composed of white fibrous and yellow elastic tissue
lined with flat endothelial cells, which constitute its internal
surface. In children it is closely adherent to the cranial bones of
which it forms the real periosteum; but it is attached chiefly at
the foramina and along the sutures in adults. The dura of the
brain is made up of two layers which are separable up to the
eighth or tenth year. The external layer constitutes the endos-
teum of the cranial bones. It is their nutrient membrane.
Through the cranial foramina and sutures it is continuous with
the external periosteum. In the adult the internal layer of the
dura separates from the outer layer only over the apex of the
petrous bone, to form Meckel's space for the semilunar ganglion
(Gasseri); at the foramina, to form sheaths for the nerves; and,
along the sinuses, to form their internal boundary and to produce
the great incomplete partitions, called process.es, which project
centrally into the great fissures of the brain.

Processes. (Processus dura malris). From the inner surface
of the dura the great processes are given off. The falx cerebri



2 THE MENINGES OF THE BRAIN.

and falx cerebelli hang vertically in the longitudinal fissure of
the cerebrum and the posterior notch of the cerebellum; and,
into the transverse fissure of the cerebrum, extends horizontally the
tentorium cerebelli. The falx cerebri (Figs, i, and 4) is attached
in front to the crista galli -and behind to the internal occipital pro-
tuberance and superior surface of the tentorium; the falx cere-
belli (Fig. i) continues from the inferior surface of the tentorium,
along the occipital crest, to the posterior border of the foramen
magnum. The bony attachment of the tentorium cerebelli
(Fig. 2) is to the internal protuberance and the lateral arms of
the crucial ridge forward to the petrous bone; and, then, it is
along the superior border of the petrous bone to the clinoid proc-
esses of the sphenoid. Between its clinoid attachments there is
a deep bay, the incisura tentorii, which transmits the midbrain.
The diaphragma sellae is a small centrally perforated sheet of
dura which covers the hypophyseal fossa.

Sinuses. (Sinus durce matris). Large venous passages lined
with endothelial cells, and called sinuses, are situated between
the layers of the dura (Figs, i, 2, 3 and 4). In the convex and in
the free border of the falx cerebri are, respectively, the superior
sagittal sinus (s. sagittalis superior) and the inferior sagittal
sinus (s. sagittalis inferior). The superior (Fig. i) extends
from the foramen caecum back to the confluens sinuum (torcular
Herophili,) located at the internal occipital protuberance. Having
run through the posterior two-thirds of the concave border of
the falx cerebri, the inferior sagittal sinus joins the great cerebral
vein at the margin of the tentorium and forms the straight sinus
(s. rectus). The latter runs through the middle of the tentorium
to the confluens (Fig. 2). The occipital sinus (s. occi pit alls)
traverses the falx cerebelli from the foramen magnum upward
to the same point. In the confluens sinuum the transverse
sinuses (s. transversi) rise (Fig. 2). Grooving the horizontal
arms of the crucial ridge, each runs outward in the tentorium to
the base of the petrous bone, where it receives the superior petrosal
sinus; it then turns downward through the sigmoid fossa, com-
municates with the occipital sinus and unites with the inferior
petrosal sinus in the jugular foramen. Situated on either side



THE DURA MATER OF THE BRAIN. 3

of the sella Turcica is a continuation of the ophthalmic vein,
the large cavernous sinus (s. cavernosus) (Fig. 3), which receives
at the sphenoidal fissure the spheno-parietal sinus (s. ala> parva),
the course of which is along the posterior border of the lesser



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