Impaired Cerebro-Cerebellar White Matter Connectivity and Its
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DR. Sanaa Alshaarawy
By DR. Sanaa Alshaarawy 1 By the end of the lecture, students will be able to : Distinguish the internal structure of the components of the brain stem in different levels and the specific criteria of each level. 1. Medulla oblongata (closed, mid and open medulla) 2. Pons (caudal, mid “Trigeminal level” and rostral). 3. Mid brain ( superior and inferior colliculi). Describe the Reticular formation (structure, function and pathway) being an important content of the brain stem. 2 1. Traversed by the Central Canal. Motor Decussation*. Spinal Nucleus of Trigeminal (Trigeminal sensory nucleus)* : ➢ It is a larger sensory T.S of Caudal part of M.O. nucleus. ➢ It is the brain stem continuation of the Substantia Gelatinosa of spinal cord 3 The Nucleus Extends : Through the whole length of the brain stem and upper segments of spinal cord. It lies in all levels of M.O, medial to the spinal tract of the trigeminal. It receives pain and temperature from face, forehead. Its tract present in all levels of M.O. is formed of descending fibers that terminate in the trigeminal nucleus. 4 It is Motor Decussation. Formed by pyramidal fibers, (75-90%) cross to the opposite side They descend in the Decuss- = crossing lateral white column of the spinal cord as the lateral corticospinal tract. The uncrossed fibers form the ventral corticospinal tract. 5 Traversed by Central Canal. Larger size Gracile & Cuneate nuclei, concerned with proprioceptive deep sensations of the body. Axons of Gracile & Cuneate nuclei form the internal arcuate fibers; decussating forming Sensory Decussation. Pyramids are prominent ventrally. 6 Formed by the crossed internal arcuate fibers Medial Leminiscus: Composed of the ascending internal arcuate fibers after their crossing. -
Brainstem and Its Associated Cranial Nerves
Brainstem and its Associated Cranial Nerves Anatomical and Physiological Review By Sara Alenezy With appreciation to Noura AlTawil’s significant efforts Midbrain (Mesencephalon) External Anatomy of Midbrain 1. Crus Cerebri (Also known as Basis Pedunculi or Cerebral Peduncles): Large column of descending “Upper Motor Neuron” fibers that is responsible for movement coordination, which are: a. Frontopontine fibers b. Corticospinal fibers Ventral Surface c. Corticobulbar fibers d. Temporo-pontine fibers 2. Interpeduncular Fossa: Separates the Crus Cerebri from the middle. 3. Nerve: 3rd Cranial Nerve (Oculomotor) emerges from the Interpeduncular fossa. 1. Superior Colliculus: Involved with visual reflexes. Dorsal Surface 2. Inferior Colliculus: Involved with auditory reflexes. 3. Nerve: 4th Cranial Nerve (Trochlear) emerges caudally to the Inferior Colliculus after decussating in the superior medullary velum. Internal Anatomy of Midbrain 1. Superior Colliculus: Nucleus of grey matter that is associated with the Tectospinal Tract (descending) and the Spinotectal Tract (ascending). a. Tectospinal Pathway: turning the head, neck and eyeballs in response to a visual stimuli.1 Level of b. Spinotectal Pathway: turning the head, neck and eyeballs in response to a cutaneous stimuli.2 Superior 2. Oculomotor Nucleus: Situated in the periaqueductal grey matter. Colliculus 3. Red Nucleus: Red mass3 of grey matter situated centrally in the Tegmentum. Involved in motor control (Rubrospinal Tract). 1. Inferior Colliculus: Nucleus of grey matter that is associated with the Tectospinal Tract (descending) and the Spinotectal Tract (ascending). Tectospinal Pathway: turning the head, neck and eyeballs in response to a auditory stimuli. 2. Trochlear Nucleus: Situated in the periaqueductal grey matter. Level of Inferior 3. -
ON-LINE FIG 1. Selected Images of the Caudal Midbrain (Upper Row
ON-LINE FIG 1. Selected images of the caudal midbrain (upper row) and middle pons (lower row) from 4 of 13 total postmortem brains illustrate excellent anatomic contrast reproducibility across individual datasets. Subtle variations are present. Note differences in the shape of cerebral peduncles (24), decussation of superior cerebellar peduncles (25), and spinothalamic tract (12) in the midbrain of subject D (top right). These can be attributed to individual anatomic variation, some mild distortion of the brain stem during procurement at postmortem examination, and/or differences in the axial imaging plane not easily discernable during its prescription parallel to the anterior/posterior commissure plane. The numbers in parentheses in the on-line legends refer to structures in the On-line Table. AJNR Am J Neuroradiol ●:●●2019 www.ajnr.org E1 ON-LINE FIG 3. Demonstration of the dentatorubrothalamic tract within the superior cerebellar peduncle (asterisk) and rostral brain stem. A, Axial caudal midbrain image angled 10° anterosuperior to posteroinferior relative to the ACPC plane demonstrates the tract traveling the midbrain to reach the decussation (25). B, Coronal oblique image that is perpendicular to the long axis of the hippocam- pus (structure not shown) at the level of the ventral superior cerebel- lar decussation shows a component of the dentatorubrothalamic tract arising from the cerebellar dentate nucleus (63), ascending via the superior cerebellar peduncle to the decussation (25), and then enveloping the contralateral red nucleus (3). C, Parasagittal image shows the relatively long anteroposterior dimension of this tract, which becomes less compact and distinct as it ascends toward the thalamus. ON-LINE FIG 2. -
Chapter 3: Internal Anatomy of the Central Nervous System
10353-03_CH03.qxd 8/30/07 1:12 PM Page 82 3 Internal Anatomy of the Central Nervous System LEARNING OBJECTIVES Nuclear structures and fiber tracts related to various functional systems exist side by side at each level of the After studying this chapter, students should be able to: nervous system. Because disease processes in the brain • Identify the shapes of corticospinal fibers at different rarely strike only one anatomic structure or pathway, there neuraxial levels is a tendency for a series of related and unrelated clinical symptoms to emerge after a brain injury. A thorough knowl- • Recognize the ventricular cavity at various neuroaxial edge of the internal brain structures, including their shape, levels size, location, and proximity, makes it easier to understand • Recognize major internal anatomic structures of the their functional significance. In addition, the proximity of spinal cord and describe their functions nuclear structures and fiber tracts explains multiple symp- toms that may develop from a single lesion site. • Recognize important internal anatomic structures of the medulla and explain their functions • Recognize important internal anatomic structures of the ANATOMIC ORIENTATION pons and describe their functions LANDMARKS • Identify important internal anatomic structures of the midbrain and discuss their functions Two distinct anatomic landmarks used for visual orientation to the internal anatomy of the brain are the shapes of the • Recognize important internal anatomic structures of the descending corticospinal fibers and the ventricular cavity forebrain (diencephalon, basal ganglia, and limbic (Fig. 3-1). Both are present throughout the brain, although structures) and describe their functions their shape and size vary as one progresses caudally from the • Follow the continuation of major anatomic structures rostral forebrain (telencephalon) to the caudal brainstem. -
The Long Journey of Pontine Nuclei Neurons : from Rhombic Lip To
REVIEW Erschienen in: Frontiers in Neural Circuits ; 11 (2017). - 33 published: 17 May 2017 http://dx.doi.org/10.3389/fncir.2017.00033 doi: 10.3389/fncir.2017.00033 The Long Journey of Pontine Nuclei Neurons: From Rhombic Lip to Cortico-Ponto-Cerebellar Circuitry Claudius F. Kratochwil 1,2, Upasana Maheshwari 3,4 and Filippo M. Rijli 3,4* 1Chair in Zoology and Evolutionary Biology, Department of Biology, University of Konstanz, Konstanz, Germany, 2Zukunftskolleg, University of Konstanz, Konstanz, Germany, 3Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland, 4University of Basel, Basel, Switzerland The pontine nuclei (PN) are the largest of the precerebellar nuclei, neuronal assemblies in the hindbrain providing principal input to the cerebellum. The PN are predominantly innervated by the cerebral cortex and project as mossy fibers to the cerebellar hemispheres. Here, we comprehensively review the development of the PN from specification to migration, nucleogenesis and circuit formation. PN neurons originate at the posterior rhombic lip and migrate tangentially crossing several rhombomere derived territories to reach their final position in ventral part of the pons. The developing PN provide a classical example of tangential neuronal migration and a study system for understanding its molecular underpinnings. We anticipate that understanding the mechanisms of PN migration and assembly will also permit a deeper understanding of the molecular and cellular basis of cortico-cerebellar circuit formation and function. Keywords: pontine gray nuclei, reticulotegmental nuclei, precerebellar system, cortico-ponto-cerebellar circuitry, Hox genes Edited by: Takao K. Hensch, INTRODUCTION Harvard University, United States Reviewed by: The basal pontine nuclei (BPN) (also known as basilar pons, pontine gray nuclei or pontine nuclei Masahiko Takada, (PN)) and the reticulotegmental nuclei (RTN) (also known as nucleus reticularis tegmenti pontis) Kyoto University, Japan are located within the ventral portion of the pons. -
Anatomyguy Brainstem Sections
Brain Stem Sections Handout 6/8/12 Midbrain Pons Rostral Medulla Middle Rostral Caudal Laurie L. Wellman Ph.D. Sean M. Dawson MD2014 Caudal Theodore Tzavaras MD2015 Caudal Rachel Seaman Eastern Virginia Medical School Dr. Craig Goodmurphy Anatomy Guy Review Review ■ Corticospinal tract Caudal Medulla ■ CN XII nucleus ■ Corticospinal tract Rostral Medulla Decussation of pyrimids ■ ■ Medial longitudinal fasiculus (MLF) ■ Internal arcuate fibers ■ Medullary motor area (MMA) ■ Gracile fasciculus ■ Spinal trigeminal tract Nucleus gracilis ■ Spinal trigeminal nucleus ■ ■ Spinothalamic tract (ALQ) ■ Cuneate fasciculus ■ Medial lemniscus ■ Nucleus cuneatus ■ Spinocuneocerebellar fibers ■ Accessory cuneate nucleus ■ Vestibular complex ■ Dorsal & ventral cochlear nerves ■ Medial lemniscus ■ Dorsal vagal nerve ■ Spinothalamic tract (ALQ) ■ Solitary tract & nucleus ■ Spinocerebellar tract ■ Ambiguous nucleus Descending ANS control Spinal trigeminal tract and ■ ■ ■ Pressor area nucleus (STT/n) ■ Post. Respiratory group ■ Depressor area ■ Lateral aperture ■ Anterior respiratory group ■ Olivocerebellar fibers ■ Inferior olivary nucleus ■ Pericentral grey ■ Olive ■ Central canal ■ Post- olivary fissure ■ Pre- olivary fissure AnatomyGuy.com 1 Brain Stem Sections Handout 6/8/12 Review Review ■ CN VII motor nucleus ■ CN V motor nucleus ■ CN VII axons Caudal Pons Pyramid (Corticospinal) Mid Pons ■ CN VI nucleus ■ ■ CN VI axons ■ Medial longitudinal ■ Pyrimidal system (corticospinal) fasciculus (MLF) ■ MLF & PPRF (lateral gaze center) ■ Pontine motor area -
The Pons Neurological System > Brainstem & Cranial Nerve Anatomy > Brainstem & Cranial Nerve Anatomy
The Pons Neurological System > Brainstem & Cranial Nerve Anatomy > Brainstem & Cranial Nerve Anatomy THE PONS OVERVIEW Here, we'll learn about the pons. • Start a table. • Denote that, from a clinician's perspective, the pons is, most notably, the neurobiological site of injury that produces locked-in syndrome. • Start a mid-sagittal section. First, draw the different brainstem levels, from superior to inferior: • Midbrain • Pons • Medulla KEY SURROUNDING STRUCTRES Label the anterior/posterior orientational plane of our diagram. • Include the key structures that border the brainstem: • The hyopthalamus, superiorly. • The cerebellum, posteriorly. • The cervical spinal cord, inferiorly. • And the temporal lobe, laterally. • Now, point out the pontine basis, which comprises pontine nuclei and pontocerebellar fiber tracts. • Shade in the CSF and indicate that the 4th ventricle lies at the level of the pons. RADIOGRAPHIC AXIAL SECTION • Before we draw a detailed anatomical section, let's review an axial section in radiographic perspective, which is the 1 / 4 common clinical perspective. • Show its anterior/posterior orientational plane. • Draw the pons. • Demarcate the pontine basis, anteriorly. • In this view, show its representative pontine nuclei. • And show its pontocerebellar fibers, which cross the pons and pass into the middle cerebellar peduncle as an important step in the corticopontocerebellar pathway. Clinical Correlation: central pontine myelinolysis ANATOMIC AXIAL SECTION Now, let's draw an anatomic axial outline of the pons. • Indicate the anterior–posterior axis of our diagram. • Label the left side of the page as nuclei and the right side as tracts. • Then, label the fourth ventricle — the cerebrospinal fluid space of the pons. • Next, distinguish the large basis from the comparatively small tegmentum. -
Cerebellum(Small Brain)
Cerebellum (Small brain) • Posterior part of hind brain • In adult it weighs around150 gm • Situated in posterior cranial fossa behind the pons &medulla separated from them by fourth ventricle • From the cerebrum it is separated by tentorium cerebelli Subdivisions Cerebellum consist of a part lying near the midline called the vermis & two lateral hemisphere •Two surfaces superior inferior •On superior surface there is no distinction between vermis & hemisphere •On inferior surface vermis lies in depth of vallecula •Vermis is separated from corresponding hemisphere by paramedian surface • Surface of cerebellum is marked by parallel running fissures • They divide the surface into narrow Folia • Section of the cerebellum cut at right angle to the folia axis has the appearance of tree so given the name of Arbor vitae • Some of the fissures are deep. They divide the cerebellum into lobes which is constituted by smaller lobules • Like cerbrum it also has a superficial layer of grey matter the cerebellar cortex • Because numerous fissures are present the actual cerebellar cortex is much more then what is seen on surface • Cerebellar notches Anterior Posterior Fissures- primary fissure Horizontal fissure posterolateral fissure Lobes- anterior lobe Middle lobe Posterior lobe • Functional areas of cerebellar cortex Vermis- Movement of the long axis of the body namely neck, shoulders, thorax, abdomen & hips • Paravermal areas- control the muscles of distal pert of the limbs especially the hands & feet • Lateral zone is concerned with the planning of sequential movements of the entire body & is involved with the conscious assessment of movement errors Morphological & functional divisions – Archicerebellum- flocculonodular lobe & lingula Oldest part. -
Assessment of Fetal Midbrain and Hindbrain in Mid-Sagittal Cranial Plane by Three-Dimensional Multiplanar Sonography
Ultrasound Obstet Gynecol 2014; 44: 581–587 Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/uog.13312 Assessment of fetal midbrain and hindbrain in mid-sagittal cranial plane by three-dimensional multiplanar sonography. Part 2: application of nomograms to fetuses with posterior fossa malformations Z. LEIBOVITZ*†, C. SHKOLNIK‡, K. KRAJDEN HARATZ*, G. MALINGER§, I. SHAPIRO† and T. LERMAN-SAGIE*¶ *Unit of Fetal Neurology and Prenatal Diagnosis, Department of Obstetrics and Gynecology, Wolfson Medical Center, Holon, Israel, affiliated with the Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel; †Department of Obstetrics and Gynecology, Bnai Zion Medical Center, Haifa, Israel; ‡Carmel Medical Center, Haifa, Israel; §Ob-Gyn Ultrasound Unit, Lis Maternity Hospital, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel; ¶Pediatric Neurology Unit, Wolfson Medical Center, Holon, affiliated with the Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel KEYWORDS: 3D ultrasound; CNS malformations; hindbrain; midbrain; nomogram; pons; posterior fossa malformations; vermis ABSTRACT those with isolated enlarged posterior fossa cerebrospinal fluid spaces. Use of the nomograms enabled detection Objectives To apply fetal midbrain (MB) and hindbrain of an elongated tectum in fetuses with CMC, C-II and (HB) nomograms, developed using three-dimensional RES, and a flattened pontine belly in cases of CMC, PCH multiplanar sonographic reconstruction (3D-MPR) in the and VD. In the fetuses with VD, the nomograms enabled mid-sagittal cranial plane, to fetuses with known posterior division into three distinctive groups: (1) those with small fossa malformations. SIVD and APVD, (2) those with normal SIVD but small Methods In this retrospective study we examined sono- APVD, and (3) those with small SIVD but normal APVD. -
Lab 3. Pons & Midbrain
Lab 3. Pons & Midbrain Lesion Lessons Lesion 4.1 Anne T. Pasta i) Location ii) Signs/symptoms (Slice of Brain © 993 Univs. of Utah and Washington; E.C. Alvord, Jr., Univ. of Washington) iii) Cause: Lesion 4.2 Colin S. Terase i) Location ii) Signs/symptoms (Slice of Brain © 993 Univs. of Utah and Washington; M.Z. Jones, Michigan St. Univ.) iii) Cause: Medical Neuroscience 4– Pontine Level of the Facial Genu Locate and note the following: Basilar pons – massive ventral structure provides the most obvious change from previous med- ullary levels. Question classic • pontine gray - large nuclear groups in the basilar pons. Is the middle cerebellar peduncle composed – origin of the middle cerebellar peduncle of climbing or mossy • pontocerebellar axons - originate from pontine gray neurons and cross to form the fibers? middle cerebellar peduncle. • corticopontine axons- huge projection that terminates in the basilar pontine gray. • corticospinal tract axons – large bundles of axons surrounded by the basilar pontine gray. – course caudally to form the pyramids in the medulla. Pontine tegmentum • medial lemniscus - has now assumed a “horizontal” position and forms part of the border between the basilar pons and pontine tegmentum. Question classic • central tegmental tract - located just dorsally to the medial lemniscus. What sensory modali- – descends from the midbrain to the inferior olive. ties are carried by the • superior olivary nucleus - pale staining area lateral to the central tegmental tract. medial and lateral – gives rise to the efferent olivocochlear projection to the inner ear. lemnisci? • lateral lemniscus - lateral to the medial lemniscus. – composed of secondary auditory projections from the cochlear nuclei. -
Basic Functional Neuroanatomy
Basic functional neuroanatomy J. A. Kiernan Department of Anatomy and Cell Biology The University of Western Ontario London, Canada Address for correspondence: Dr J. A. Kiernan Department of Anatomy and Cell Biology Medical Sciences Building The University of Western Ontario LONDON, Canada N6A 5C1 Copyright © J. A. Kiernan, 2005, 2009 - 1 - The nervous system is used by everyone to feel, move and think, to experience every symptom and to communicate with every physician. It is a remarkably resilient system, but its importance to the body's economy is so great that the effects of disease can be devastating. Importance of neuroanatomy for diagnosis Some diseases simultaneously affect many parts of the central or peripheral nervous system, causing such symptoms as a reduced level of consciousness, mental impairment, or multiple motor or sensory deficits. Other disorders are due to circumscribed lesions, which include vascular occlusions, localized infections, some tumours, and the changes brought about by some injuries. When neurological symptoms and signs result from a circumscribed lesion, an accurate diagnosis may often be made on the basis of the physician's knowledge of the normal anatomy and connectivity of the nervous system. There are two approaches to the analysis of a clinical problem when involvement of the nervous system is suspected: 1. Functions attributed to a particular part of the brain or spinal cord are found to be disordered, thereby indicating the site of an irritating or a destructive lesion. In many cases the functions of these regions have been deduced principally from correlation of clinical conditions with pathological findings, either after death or in images of the living brain. -
Focal Pontine Lesions Provide Evidence That Intrinsic Functional Connectivity Reflects Polysynaptic Anatomical Pathways
The Journal of Neuroscience, October 19, 2011 • 31(42):15065–15071 • 15065 Behavioral/Systems/Cognitive Focal Pontine Lesions Provide Evidence That Intrinsic Functional Connectivity Reflects Polysynaptic Anatomical Pathways Jie Lu,1* Hesheng Liu,3* Miao Zhang,1 Danhong Wang,3 Yanxiang Cao,1 Qingfeng Ma,2 Dongdong Rong,1 Xiaoyi Wang,1 Randy L. Buckner,3,4,5,6 and Kuncheng Li1 Departments of 1Radiology and 2Neurology, Xuanwu Hospital of Capital Medical University, Beijing 100053, China, 3Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology and 4Department of Psychiatry, Massachusetts General Hospital, Charlestown, Massachusetts 02129, 5Psychology and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138, and 6Howard Hughes Medical Institute, Cambridge, Massachusetts 02138 Intrinsic functional connectivity detected by functional MRI (fMRI) provides a useful but indirect approach to study the organization of human brain systems. An unresolved question is whether functional connectivity measured by resting-state fMRI reflects anatomical connections. In this study, we used the well-characterized anatomy of cerebrocerebellar circuits to directly test whether intrinsic func- tional connectivity is associated with an anatomic pathway. Eleven first-episode stroke patients were scanned five times during a period of 6 months, and 11 healthy control subjects were scanned three times within 1 month. In patients with right pontine strokes, the functional connectivity between the right motor cortex and the left cerebellum was selectively reduced. This connectivity pattern was reversed in patients with left pontine strokes. Although factors beyond anatomical connectivity contribute to fMRI measures of func- tional correlation, these results provide direct evidence that functional connectivity depends on intact connections within a specific polysynaptic pathway.