Cerebellum: Anatomy

Overview and Features

• Cerebellum is Latin for “little brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification” and is involved in several functions:
  • Modification of motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology output
  • Maintenance of balance and posture
  • Coordination Coordination Cerebellar Disorders of voluntary movements
  • Motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology learning
  • Cognitive functions
• Located dorsal to the pons Pons The front part of the hindbrain (rhombencephalon) that lies between the medulla and the midbrain (mesencephalon) ventral to the cerebellum. It is composed of two parts, the dorsal and the ventral. The pons serves as a relay station for neural pathways between the cerebellum to the cerebrum. Brain Stem: Anatomy and medulla in the posterior cranial fossa Posterior cranial fossa The infratentorial compartment that contains the cerebellum and brain stem. It is formed by the posterior third of the superior surface of the body of the sphenoid (sphenoid bone), by the occipital, the petrous, and mastoid portions of the temporal bone, and the posterior inferior angle of the parietal bone. Skull: Anatomy
• Forms the roof of the 4th ventricle
• Each hemisphere consists of 3 lobes:
  • Anterior lobe: input primarily from the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy:
    • Separated from the posterior lobe by the primary fissure Fissure A crack or split that extends into the dermis Generalized and Localized Rashes
    • United with the contralateral anterior lobe by the midline vermis
  • Posterior lobe: input from the brainstem and cerebral cortex Cerebral cortex The cerebral cortex is the largest and most developed part of the human brain and CNS. Occupying the upper part of the cranial cavity, the cerebral cortex has 4 lobes and is divided into 2 hemispheres that are joined centrally by the corpus callosum. Cerebral Cortex: Anatomy:
    • Separated from the flocculonodular lobe by the posterolateral fissure Fissure A crack or split that extends into the dermis Generalized and Localized Rashes
    • United with the contralateral posterior lobe by the midline vermis
  • Flocculonodular lobe: input from the vestibular nuclei Vestibular nuclei The four cellular masses in the floor of the fourth ventricle giving rise to a widely dispersed special sensory system. Included is the superior, medial, inferior, and lateral vestibular nucleus. Vertigo:
    • Smallest of the 3 lobes, lies superior to the anterior aspect of the posterior lobe, inferior to the anterior lobe, and posterior to the brainstem
    • United with the contralateral flocculonodular lobe by the midline vermis
• Cerebellum is joined to the brainstem by 3 peduncles that are paired bilaterally:
  • Middle cerebellar peduncle:
    • Conveys information about voluntary motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology activities
    • Connects cerebellar cortex to the contralateral basal pontine nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles
    • Located laterally
    • Largest of the 3 peduncles
  • Inferior cerebellar peduncle:
    • Consists of afferent Afferent Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology and efferent Efferent Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology fibers that carry proprioceptive information to and from the body and vestibular system
    • Connects cerebellum to the medulla oblongata Medulla Oblongata The lower portion of the brain stem. It is inferior to the pons and anterior to the cerebellum. Medulla oblongata serves as a relay station between the brain and the spinal cord, and contains centers for regulating respiratory, vasomotor, cardiac, and reflex activities. Brain Stem: Anatomy and the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy
    • Located medially to the middle peduncle
  • Superior cerebellar peduncle:
    • Afferent Afferent Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology and efferent Efferent Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology fibers are engaged in motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology control.
    • Connects cerebellum to the midbrain Midbrain The middle of the three primitive cerebral vesicles of the embryonic brain. Without further subdivision, midbrain develops into a short, constricted portion connecting the pons and the diencephalon. Midbrain contains two major parts, the dorsal tectum mesencephali and the ventral tegmentum mesencephali, housing components of auditory, visual, and other sensorimotor systems. Brain Stem: Anatomy and thalamus Thalamus The thalamus is a large, ovoid structure in the dorsal part of the diencephalon that is located between the cerebral cortex and midbrain. It consists of several interconnected nuclei of grey matter separated by the laminae of white matter. The thalamus is the main conductor of information that passes between the cerebral cortex and the periphery, spinal cord, or brain stem. Thalamus: Anatomy
    • Located superior to the other peduncles
• Cerebellar blood supply is via 3 bilateral arterial vessels:
  • Superior cerebellar artery Superior cerebellar artery Cerebrovascular System: Anatomy (SCA)
  • Anterior inferior cerebellar artery Anterior inferior cerebellar artery Cerebrovascular System: Anatomy (AICA)
  • Posterior inferior cerebellar artery Posterior inferior cerebellar artery Cerebrovascular System: Anatomy ( PICA Pica Pica is an eating disorder characterized by a desire or recurrent compulsion to eat substances that are nonnutritive and not food. These compulsions and ingested substances are inappropriate for age or culture. Pica)
• Cerebellar embryology: dorsal surface ectoderm Ectoderm The outer of the three germ layers of an embryo. Gastrulation and Neurulation → neural tube Neural tube A tube of ectodermal tissue in an embryo that will give rise to the central nervous system, including the spinal cord and the brain. Lumen within the neural tube is called neural canal which gives rise to the central canal of the spinal cord and the ventricles of the brain. Gastrulation and Neurulation → rhombencephalon Rhombencephalon The posterior of the three primitive cerebral vesicles of an embryonic brain. It consists of myelencephalon, metencephalon, and isthmus rhombencephalon from which develop the major brain stem components, such as medulla oblongata from the myelencephalon, cerebellum and pons from the metencephalon, with the expanded cavity forming the fourth ventricle. Development of the Nervous System and Face → metencephalon Metencephalon The anterior portion of the developing hindbrain. It gives rise to the cerebellum and the pons. Development of the Nervous System and Face → cerebellum

Cerebellar peduncles and their connections:

• Midbrain Midbrain The middle of the three primitive cerebral vesicles of the embryonic brain. Without further subdivision, midbrain develops into a short, constricted portion connecting the pons and the diencephalon. Midbrain contains two major parts, the dorsal tectum mesencephali and the ventral tegmentum mesencephali, housing components of auditory, visual, and other sensorimotor systems. Brain Stem: Anatomy/ thalamus Thalamus The thalamus is a large, ovoid structure in the dorsal part of the diencephalon that is located between the cerebral cortex and midbrain. It consists of several interconnected nuclei of grey matter separated by the laminae of white matter. The thalamus is the main conductor of information that passes between the cerebral cortex and the periphery, spinal cord, or brain stem. Thalamus: Anatomy ↔ superior cerebellar peduncle ↔ cerebellum
• Basal pons Pons The front part of the hindbrain (rhombencephalon) that lies between the medulla and the midbrain (mesencephalon) ventral to the cerebellum. It is composed of two parts, the dorsal and the ventral. The pons serves as a relay station for neural pathways between the cerebellum to the cerebrum. Brain Stem: Anatomy → middle cerebellar peduncle → cerebellum
• Medulla ↔ inferior cerebellar peduncle ↔ cerebellum

Internal Circuitry and Organization

Cerebellar cortex

The majority of neuronal cell bodies are located in the cortex, which can be divided into 3 layers:

Granular cell layer:

• Innermost layer
• Consists primarily of 2 cell types:
  • Granule cells:
    • Excitatory cells
    • Glutamate Glutamate Derivatives of glutamic acid. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the 2-aminopentanedioic acid structure. Synthesis of Nonessential Amino Acids is the key neurotransmitter.
    • Axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology of granule cells are parallel fibers that stimulate Purkinje cells.
  • Golgi cells:
    • Inhibitory cortical interneurons
    • Glycine Glycine A non-essential amino acid. It is found primarily in gelatin and silk fibroin and used therapeutically as a nutrient. It is also a fast inhibitory neurotransmitter. Synthesis of Nonessential Amino Acids is the key neurotransmitter.
    • Axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology terminate on dendrites Dendrites Extensions of the nerve cell body. They are short and branched and receive stimuli from other neurons. Nervous System: Histology of granule cells.

Purkinje cell layer:

• Middle layer
• Consists of 2 cell types:
  • Purkinje cells:
    • Largest cells in the cerebellar cortex
    • Inhibitory and GABAergic: inhibit neurons Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the nervous system. Nervous System: Histology in the deep cerebellar nuclei
    • Only output neurons Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the nervous system. Nervous System: Histology of the cerebellar cortex
    • Arranged in a monolayer
    • Axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology advance to cerebellar nuclei and the molecular layer.
  • Bergmann glia:
    • Specialized astrocytes Astrocytes A class of large neuroglial (macroglial) cells in the central nervous system – the largest and most numerous neuroglial cells in the brain and spinal cord. Astrocytes (from ‘star’ cells) are irregularly shaped with many long processes, including those with ‘end feet’ which form the glial (limiting) membrane and directly and indirectly contribute to the blood-brain barrier. They regulate the extracellular ionic and chemical environment, and ‘reactive astrocytes’ (along with microglia) respond to injury. Nervous System: Histology
    • Closely associated with Purkinje cells

Molecular layer:

• Outermost layer of the cerebellar cortex
• Location of stellate and basket cells, which are important cortical interneurons

Cortical interneurons

Cortical interneurons can be divided into 2 categories:

• Inhibitory glycinergic cells from the granular layer:
  • Golgi cells:
    • Located primarily in the granular layer
    • Axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology terminate on dendrites Dendrites Extensions of the nerve cell body. They are short and branched and receive stimuli from other neurons. Nervous System: Histology of granule cells.
• Inhibitory GABAergic cells from the molecular layer:
  • Stellate cells:
    • Located in the upper molecular layer
    • Axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology terminate on the dendrites Dendrites Extensions of the nerve cell body. They are short and branched and receive stimuli from other neurons. Nervous System: Histology of Purkinje cells.
  • Basket cells:
    • Located in the deep molecular layer
    • Axons Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Nervous System: Histology terminate on the dendrites Dendrites Extensions of the nerve cell body. They are short and branched and receive stimuli from other neurons. Nervous System: Histology of Purkinje cells.

Cerebellar nuclei

Cerebellar nuclei consist of 4 pairs of areas:

• Nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles dentatus:
  • Most lateral of the nuclei
  • Most prominent nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles
  • Efferent Efferent Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology → ventral anterior ( VA VA Ventilation: Mechanics of Breathing) and ventral lateral (VL) nuclei of the thalamus Thalamus The thalamus is a large, ovoid structure in the dorsal part of the diencephalon that is located between the cerebral cortex and midbrain. It consists of several interconnected nuclei of grey matter separated by the laminae of white matter. The thalamus is the main conductor of information that passes between the cerebral cortex and the periphery, spinal cord, or brain stem. Thalamus: Anatomy
• Nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles interpositus:
  • Consists of 2 nuclei:
    • Nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles emboliform: located medial to the nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles dentatus
    • Nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles globosus: located medial to the nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles emboliform
  • Efferent Efferent Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology → red nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles of the midbrain Midbrain The middle of the three primitive cerebral vesicles of the embryonic brain. Without further subdivision, midbrain develops into a short, constricted portion connecting the pons and the diencephalon. Midbrain contains two major parts, the dorsal tectum mesencephali and the ventral tegmentum mesencephali, housing components of auditory, visual, and other sensorimotor systems. Brain Stem: Anatomy and reticular formation Reticular Formation A region extending from the pons and medulla oblongata through the mesencephalon, characterized by a diversity of neurons of various sizes and shapes, arranged in different aggregations and enmeshed in a complicated fiber network. Brain Stem: Anatomy
• Nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles fastigii:
  • Located most medially
  • Efferent Efferent Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology → vestibular nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles
• Primary output is to the glutamatergic relay neurons Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the nervous system. Nervous System: Histology.
• Primary input:
  • Inhibition from Purkinje cells
  • Excitation from mossy and climbing fibers

Cerebellar Connections

Cerebellar afferent Afferent Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology pathways

Many afferents pass through the 3 cerebellar peduncles to the cerebellar cortex. There are 2 extracerebellar excitatory glutamatergic afferent Afferent Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology systems:

• Mossy fibers:
  • Originate in the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy and brainstem
  • Synapse Synapse The junction between 2 neurons is called a synapse. The synapse allows a neuron to pass an electrical or chemical signal to another neuron or target effector cell. Synapses and Neurotransmission on Purkinje cells
• Climbing fibers:
  • Originate in the contralateral inferior olivary nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles within the medulla
  • Synapse Synapse The junction between 2 neurons is called a synapse. The synapse allows a neuron to pass an electrical or chemical signal to another neuron or target effector cell. Synapses and Neurotransmission on Purkinje cells

Cerebellar efferent Efferent Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology pathways

Efferent Efferent Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology pathways of the cerebellum pass from the cerebellar nuclei to the following:

• Thalamus Thalamus The thalamus is a large, ovoid structure in the dorsal part of the diencephalon that is located between the cerebral cortex and midbrain. It consists of several interconnected nuclei of grey matter separated by the laminae of white matter. The thalamus is the main conductor of information that passes between the cerebral cortex and the periphery, spinal cord, or brain stem. Thalamus: Anatomy
• Vestibular nuclei Vestibular nuclei The four cellular masses in the floor of the fourth ventricle giving rise to a widely dispersed special sensory system. Included is the superior, medial, inferior, and lateral vestibular nucleus. Vertigo
• Red nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles
• Reticular formation Reticular Formation A region extending from the pons and medulla oblongata through the mesencephalon, characterized by a diversity of neurons of various sizes and shapes, arranged in different aggregations and enmeshed in a complicated fiber network. Brain Stem: Anatomy

Cerebellar regions

The cerebellum can also be divided into 3 regions based on connections:

• Vestibulocerebellum:
  • Function: maintenance of posture and vestibular reflexes
  • Inputs: vestibular nerve
  • Outputs:
    • Cerebellovestibular tract
    • Vestibular nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles
    • Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy
• Spinocerebellum:
  • Function:
    • Integration of sensory Sensory Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology input with motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology output
    • Adaptive coordination Coordination Cerebellar Disorders of muscle movements
  • Input: spinocerebellar tract
  • Outputs:
    • Reticular formation Reticular Formation A region extending from the pons and medulla oblongata through the mesencephalon, characterized by a diversity of neurons of various sizes and shapes, arranged in different aggregations and enmeshed in a complicated fiber network. Brain Stem: Anatomy
    • Red nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles
    • Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy
• Pontocerebellum:
  • Function:
    • Timing and planning of movements
    • Cognition
  • Input: pontocerebellar tract
  • Output:
    • Thalamic nuclei Thalamic nuclei Several groups of nuclei in the thalamus that serve as the major relay centers for sensory impulses in the brain. Thalamus: Anatomy ( VA VA Ventilation: Mechanics of Breathing and VL)
    • Cortex
    • Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy

Clinical Relevance

• Brainstem: consists of the midbrain Midbrain The middle of the three primitive cerebral vesicles of the embryonic brain. Without further subdivision, midbrain develops into a short, constricted portion connecting the pons and the diencephalon. Midbrain contains two major parts, the dorsal tectum mesencephali and the ventral tegmentum mesencephali, housing components of auditory, visual, and other sensorimotor systems. Brain Stem: Anatomy, pons Pons The front part of the hindbrain (rhombencephalon) that lies between the medulla and the midbrain (mesencephalon) ventral to the cerebellum. It is composed of two parts, the dorsal and the ventral. The pons serves as a relay station for neural pathways between the cerebellum to the cerebrum. Brain Stem: Anatomy, and medulla oblongata Medulla Oblongata The lower portion of the brain stem. It is inferior to the pons and anterior to the cerebellum. Medulla oblongata serves as a relay station between the brain and the spinal cord, and contains centers for regulating respiratory, vasomotor, cardiac, and reflex activities. Brain Stem: Anatomy. The brainstem is a stalk-like structure that connects the cerebrum with the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy and is a major relay station for sensory Sensory Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology, motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology, and autonomic information. All cranial nerves Cranial nerves There are 12 pairs of cranial nerves (CNs), which run from the brain to various parts of the head, neck, and trunk. The CNs can be sensory or motor or both. The CNs are named and numbered in Roman numerals according to their location, from the front to the back of the brain. The 12 Cranial Nerves: Overview and Functions except I and II are found in the brainstem and are topographically arranged so that motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology nuclei are medial to the sensory Sensory Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology nuclei. The brainstem also plays a critical role in the control of cardiac and respiratory function, consciousness, and the sleep Sleep A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility. Physiology of Sleep cycle.
• Chiari malformation: Arnold-Chiari malformations Arnold-Chiari malformations A group of congenital malformations involving the brainstem, cerebellum, upper spinal cord, and surrounding bony structures. Type II is the most common, and features compression of the medulla and cerebellar tonsils into the upper cervical spinal canal and an associated meningomyelocele. Type I features similar, but less severe malformations and is without an associated meningomyelocele. Type III has the features of type II with an additional herniation of the entire cerebellum through the bony defect involving the foramen magnum, forming an encephalocele. Type IV is a form a cerebellar hypoplasia. Clinical manifestations of types i-iii include torticollis; opisthotonus; headache; vertigo; vocal cord paralysis; apnea; nystagmus, congenital; swallowing difficulties; and ataxia. Development of the Nervous System and Face are a group of congenital abnormalities Congenital Abnormalities Malformations of organs or body parts during development in utero. Omphalocele that are associated with a bony base of the cranium Cranium The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy causing limitation of space in the posterior fossa, thus affecting the cerebellum, brainstem, and upper spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy.
• Embryologic development: Before the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification reaches the phase when it looks like the organ, there are several complex processes that occur. Beginning with neurulation Neurulation An early embryonic developmental process of chordates that is characterized by morphogenic movements of ectoderm resulting in the formation of the neural plate; the neural crest; and the neural tube. Improper closure of the neural groove results in congenital neural tube defects. Gastrulation and Neurulation, the neural tube Neural tube A tube of ectodermal tissue in an embryo that will give rise to the central nervous system, including the spinal cord and the brain. Lumen within the neural tube is called neural canal which gives rise to the central canal of the spinal cord and the ventricles of the brain. Gastrulation and Neurulation and neural crest cells Neural crest cells Gastrulation and Neurulation allow the developing embryo Embryo The entity of a developing mammal, generally from the cleavage of a zygote to the end of embryonic differentiation of basic structures. For the human embryo, this represents the first two months of intrauterine development preceding the stages of the fetus. Fertilization and First Week to form the central and peripheral nervous systems. The face starts to develop from the 4th week. A recognizable face can be seen from the 14th week due to the formation of the frontonasal, medial, lateral, and mandibular prominences.
• Friedreich ataxia Ataxia Impairment of the ability to perform smoothly coordinated voluntary movements. This condition may affect the limbs, trunk, eyes, pharynx, larynx, and other structures. Ataxia may result from impaired sensory or motor function. Sensory ataxia may result from posterior column injury or peripheral nerve diseases. Motor ataxia may be associated with cerebellar diseases; cerebral cortex diseases; thalamic diseases; basal ganglia diseases; injury to the red nucleus; and other conditions. Ataxia-telangiectasia: occurs due to the expansion of the GAA repeat in the FXN gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics. Affected individuals present with ataxia Ataxia Impairment of the ability to perform smoothly coordinated voluntary movements. This condition may affect the limbs, trunk, eyes, pharynx, larynx, and other structures. Ataxia may result from impaired sensory or motor function. Sensory ataxia may result from posterior column injury or peripheral nerve diseases. Motor ataxia may be associated with cerebellar diseases; cerebral cortex diseases; thalamic diseases; basal ganglia diseases; injury to the red nucleus; and other conditions. Ataxia-telangiectasia, weakness, absent reflexes, and dorsiflexion of the toes. Late atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation of the cerebellum and a thin cervical spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy can be seen on MRI.