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Anatomy of the Brain

Arteries The Cerebral Circulation
The Cerebral Circulation, Arteries The Arterial Circle (circulus Arteriosis, Willisi).—the Arteries Which Supply The Cerebrum Freely Communicate In The Arterial Circle, Which Is Really A Heptagon Extending From A Point In The Longitudinal Fissure Anterior To The Optic Chiasma, Back To The Pons (fig. 9). It Is About An Inch ...

Association Fibers
Association Fibers These Fibers Remain On The Same Side And Connect Parts Of The Same Hemisphere. They Are Situated Within Or Beneath The Cor Tex, The Various Parts Of Which They Serve To Unite. Associa Tion Fibers Become Medullated And Actively Functional Only As Mental Effort And Education Gradually Develop ...

Blood Supply Of The
Blood Supply Of The Spinal Cord The Vessels Supplying The Cord Are The Anterior Spinal Artery And The Two Posterior Spinal Arteries Which Rise At The Foramen Magnum From The Vertebral Arteries And Are Reinforced By Cervical, Intercostal And Lumbar Arteries. The Anterior Spinal Artery (a. Spinalis Anterior) Descends Along ...

Brain Measurements And Weights
Brain Measurements And Weights Ethnologic Investigations Of Cranial Capacity And Brain Weight Reveal Two Important General Facts: First, The Cultured And Aggressive Races Possess The Larger Brains; And, Second, The Cranial Capacity Increases During The Rise From Barbarism To Culture And Power And, Conversely, Decreases With The Decline Of A ...

Central Or Ventricular Gray
Central Or Ventricular Gray Matter It Is Located (i) In The Floor And Walls Of The Third Ventricle, The Hypothalamus; (2) In The Middle Commissure Of That Ven Tricle, The Massa Intermedia; And (3) Around The Cerebral Aqueduct, The Stratum Griseum Centrale. 1. The Hypothalamus, Pars Optica.—the Lamina Cinerea Terminalis ...

Cerebrum Surfaces
Cerebrum Surfaces The Mid-brain Has Four Surfaces, Viz., The Anterior And Pos Terior, Which Are Free, And The Superior And Inferior, Representing The Ends Of The Cylinder, Which Are Attached. The Two Latter Are Nearly Parallel With Each Other And Are Formed By Section. The Superior Surface, Sloping Downward And ...

Commissural Fibers
Commissural Fibers They Connect Opposite Sides Of The Cerebrum And, Like The Pro Jection Fibers, Are Continuous With The Radiations Of Meynert. They Are Contained Chiefly In The Corpus Callosum, The Anterior Commissure, And The Commissura Hippocampi; But Are Also Found In The Posterior Commissure, Commissura Habenularum, Inferior (gudden's) And ...

Cortical Gray Matter
Cortical Gray Matter The Cerebellar Cortex Is Inexcitable (horsley And Clarke). It Originates No Fibers That Pass Out Of The Cerebellum, Only Cortico-nuclear Fibers; But, With Very Few Exceptions, It Receives All Fibers That Enter The Cerebellum. The Cerebellar Cortex Is A Great Receptive Organ Which Correlates Afferent Impulses. The ...

Fissures And Sulci Of
Fissures And Sulci Of Convex Surface The Convex Surface Of The Cerebral Hemisphere (fades Convexa Cerebri) Is Related To Two Very Extensive Fissures, Viz., The Longi Tudinal And The Transverse. The Longitudinal Fissure Of The Cerebrum (fissura Longitudinalis Cerebri) Is The Vertical Median Cleft Between The Hemispheres Of The Cerebrum ...

Fissures Of The Medial
Fissures Of The Medial And Tentorial Surface To Expose The Medial Surface Of The Cerebral Hemispheres, A Median Sagittal Section Must Be Made Through The Connecting Links Of The Hemispheres And The Inter-brain, Dividing The Fore Brain Into Lateral Halves. Separate The Lips Of The Longitudinal Fissure Of The Cerebrum; ...

General Considerations Of The
General Considerations Of The Brain Or Encephalon Before Taking Up The Special Study Of The Cerebrum The Student Should Notice Certain Prominent Features Of The Entire Brain. To Do This The Arachnoid And Pia Mater Must Be Re Moved, And Great Care And Patience Should Be Exercised To Preserve The ...

Gray Matter Of Medulla
Gray Matter Of Medulla The Gray Matter Of The Medulla Is Composed (i) Of That Con Tinuous With The Nucleus Pontis, Called The Arcuate Nucleus And The Ponto-bulbar Nucleus; (2) Of The Sheet Of Gelatinous Gray Substance Next The Ventricle And The Nuclei Of The Reticular Substance Continuous With The ...

Gray Matter Of The
Gray Matter Of The Pons In The Pons Gray Matter Is Found In Two Situations: (1) In The Interstices Between The Transverse And Longitudinal Fibers Of The Pars Basilaris Pontis, The Nuclei Pontis; And (2) In The Pars Dorsalis Pontis, Where We Find The Gelatinous Gray Sheet Im Mediately Beneath ...

Inferior Surface Of The
Inferior Surface Of The Cerebellum The Inferior Surface Of The Cerebellum (facies Cerebelli Inferior) Is Prominent Laterally And Depressed Centrally (as The Organ Is Viewed Inverted), The Hemispheres Being Separated By The Antero Posterior Groove, Called The Vallecula Cerebelli (figs. 102 And 1o6). The Vallecula (little Valley) Is Occupied By ...

Its Gray And White
Its Gray And White Matter We Have Noticed That Nerve Tissue In A Mass Is Made Up Of Gray And White Substance. The Gray Substance Contains The Bodies Of The Nerve Cells And Certain Nerve Processes, Which For The Most Part Are Non-medullated; The White Substance Con Tains The Medullated ...

Lobes And Gyri Of
Lobes And Gyri Of The Convex Surface I. The Frontal Lobe (lobus Frontalis) Comprises The Anterior Polar Region Of The Hemisphere And Forms A Part Of All Three Sur Faces (figs. 26, 31 And 34). On The Convex Surface, It Extends As Far Back As The Central Sulcus And The ...

Longitudinal Fibers Of Pons
Longitudinal Fibers Of Pons The Longitudinal Fibers Of The Pons Are Arranged In Two Dis Tinct Groups, Viz., The Basilar Or Anterior And The Dorsal Or Posterior (figs. 113-118). The Basilar Longitudinal Fibers Are Situated In The Pars Basilaris Pontis (figs. 113-118). Four Fasciculi Make Them Up. They Are The ...

Medula Oblongata Surfaces
Medula Oblongata Surfaces The Medulla Oblongata Presents Four Surfaces: The Anterior, Posterior And Two Lateral, Separated By The Anterior Lateral And Posterior Lateral Grooves. In The Upper Medulla The Surfaces Are Clearly Defined, But They Become Less Distinct As They De Scend To The Inferior And Nearly Circular Extremity (figs. ...

Membranes Of The Spinal
Membranes Of The Spinal Cord Dura Mater.—through The Foramen Magnum The Membranes Of The Brain Are Continuous With Those Of The Cord With Which They Are Very Similar In Structure. The Dura Mater Spinalis Is Attached To The Margin Of The Great Foramen And To The Bodies Of The First ...

Nuclear Or Ganglionar Gray
Nuclear Or Ganglionar Gray Matter The Nuclei Of The Cerebellum Are The Nucleus Dentatus, Nucleus Emboliformis, Nucleus Globosus And Nucleus Fastigii (figs. 107 And Io). All These Nuclei Are Made Up Of Stellate Cell-bodies, Which Vary In Size From 20-8o Microns. They Form Relay Stations In The Paths Going Out ...

Or Ganglionar Gray Matter
Or Ganglionar Gray Matter The Substantia Grisea Ganglionaris Is Found In The Basal Gan Glia Which, In Their Situation And Relations, Have Already Been Considered. They Should Be Re-studied In This Connection. They Are As Follows: 1. In The Hemisphere: The Corpus Striatum, Composed Of The Caudate And The Lentiform ...

Origin Of Cerebral Or
Origin Of Cerebral Or Cranial Nerves According To Sommering There Are Twelve Pairs Of Cerebral Nerves (nervi Cerebrales), But To This Must Be Added The Nervus Intermedius (pars Intermedia) Which, Though Associated With The Facial Nerve In The Facial Canal, Is.of Itself A True Mixed Nerve. The Remnant Of A ...

Projection Fibers
Projection Fibers All Fibers That Leave The Cerebellum, Or Enter It, Do So Through The Brachia, The Restiform Bodies And The Superior Medullary Velum, Hence These Are Composed Of Projection Fibers. At A Higher Level The Projection Fibers Are Contained In The Corpus Medullare. Brachium Conjunctivum (figs. 56, 102 And ...

Reflex Paths
. Reflex Paths There Is No Visible Limit To The Number Of Reflex Paths. Hence No Attempt Will Be Made To Give Them Completely, But A Few Examples Of Various Kinds Will Be Given Which May Assist The Student To Trace Others And Be Suggestive Of Their Great Multi Plicity ...

Roots Of The Spinal
Roots Of The Spinal Nerves Thirty-one Pairs Of Spinal Nerves Connect The Cord With The Periphery. Each Nerve Is Joined To The Cord By Two Roots: An Anterior, Efferent Or Motor Root And Aposterior, Afferent Or Sensory Root (figs. 138 And 146). These Roots Descend More Or Less From Their ...

Or Motor Paths Efferent
Efferent, Or Motor Paths The Cerebrospinal Or Pyramidal Paths (fig. 147) Are Direct, As They Do Not Pass Through The Cerebellum. Their Impulses Ultimately Run Either Through The Spinal Or The Cerebral Nerves, And Are Both Motor And Inhibitory. Hence The Increased Reflexes And Spastic Contractions Of Lateral Sclerosis In ...

Or Motor Projection Fibers
Corticifugal, Or Motor Projection Fibers The Most Important Tracts Of Corticifugal Or Motor Projection Fibers Are The Following, Namely, The Strio-fugal Fibers, The Fronto Pontal Tract, The Pyramidal Tract And The Temporo-pontal Tract. The Strio-fugal Fasciculi Are Formed By Axones Of Cell-bodies In The Globus Pallidus Which Terminate In The ...

Or Sensory Paths Afferent
Afferent, Or Sensory Paths The Sensory Paths Conduct Two Varieties Of Impulses, Viz., General And Special. The Impulses Originate In The End-organs Of The Cerebral And Spinal Nerves And By Those Nerves Are Con Veyed To The Cerebrospinal Axis Through Which They Reach The Proper Cortical Area In The Cerebrum. ...