The spinal cord is a long, thin, tubular bundle of nerves that is an extension of the central nervous system from the brain and is enclosed in and protected by the bony vertebral column. A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons. In Vertebrates the central nervous system ( CNS) is the part of the Nervous system which is enclosed in the Meninges. In Human anatomy, the vertebral column ( backbone or spine) is a column of 34 Vertebrae the Sacrum, Intervertebral The main function of the spinal cord is transmission of neural inputs between the periphery plus the brain. The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain [1]
Contents |
Structure
The spinal cord is the main pathway for information connecting the brain and peripheral nervous system. The length of the spinal cord is much shorter than the length of the bony spinal column. The human spinal cord extends from the medulla oblongata and continues through the conus medullaris near the first or second lumbar vertebrae, terminating in a fibrous extension known as the filum terminale. The medulla oblongata is the lower portion of the Brainstem. It deals with autonomic functions such as breathing and blood pressure The conus medullaris is the terminal end of the Spinal cord. It occurs near Lumbar nerves 1 (L1 and 2 (L2 The lumbar vertebrae are the largest segments of the movable part of the Vertebral column, and are characterized by the absence of the Foramen transversarium within The filum terminale is a delicate filament about 20 cm in length prolonged downward from the apex of the Conus medullaris.
It is about 45 cm long in men and 43 cm long in women, ovoid-shaped, and is enlarged in the cervical and lumbar regions. In cross-section, the peripheral region of the cord contains neuronal white matter tracts containing sensory and motor neurons. White matter is one of the three main solid components of the Central nervous system. Sensory neurons are Neurons that are activated by sensory input (vision touch hearing etc In Vertebrates the term motor neuron (or motoneuron) classically applies to Neurons located in the Central nervous system (or CNS that project Internal to this peripheral region is the gray, butterfly shaped central region made up of nerve cell bodies. Neurons (ˈnjuːɹɒn also known as neurones and nerve cells) are responsive cells in the Nervous system that process and transmit information This central region surrounds the central canal, which is an anatomic extension of the spaces in the brain known as the ventricles and, like the ventricles, contains cerebrospinal fluid. For the engineering project see Indiana Central Canal. The central canal is the Cerebrospinal fluid -filled space that runs longitudinally through the Cerebrospinal fluid ( CSF) Liquor cerebrospinalis, is a clear Bodily fluid that occupies the Subarachnoid space and the Ventricular system
The three meninges that cover the spinal cord -- the outer dura mater, the arachnoid mater, and the innermost pia mater -- are continuous with that in the brainstem and cerebral hemispheres. The meninges (singular meninx) is the system of membranes which envelops the Central nervous system. The dura mater (from the Latin "hard mother" or pachymeninx, is the tough and inflexible outermost of the three layers of the Meninges surrounding the The arachnoid mater is one of the three Meninges, the membranes that cover the Brain and Spinal cord. The pia mater (Latin "tender mother" itself a translation from Arabic) is the delicate innermost layer of the Meninges - the membranes surrounding the Similarly, cerebrospinal fluid is found in the subarachnoid space. Cerebrospinal fluid ( CSF) Liquor cerebrospinalis, is a clear Bodily fluid that occupies the Subarachnoid space and the Ventricular system In the Central nervous system, the subarachnoid cavity ( subarachnoid space) is the interval between the Arachnoid membrane and Pia mater The cord is stabilized within the dura mater by the connecting denticulate ligaments which extend from the enveloping pia mater laterally between the dorsal and ventral roots. The Pia mater of the Spinal cord has 21 pairs of denticulate Ligaments which attach it to the arachnoid and Dura maters Named for their The pia mater (Latin "tender mother" itself a translation from Arabic) is the delicate innermost layer of the Meninges - the membranes surrounding the The dural sac ends at the vertebral level of the second sacral vertebra. The sacrum is a large triangular bone at the base of the spine and at the upper and back part of the Pelvic cavity, where it is inserted like a wedge between
Spinal cord segments
The human spinal cord is divided into 31 different segments, with motor nerve roots exiting in the ventral aspects and sensory nerve roots entering in the dorsal aspects. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species The ventral and dorsal roots later join to form paired spinal nerves, one on each side of the spinal cord. The term spinal nerve generally refers to the mixed spinal Nerve, which is formed from the dorsal and ventral roots that come out of the Spinal cord.
There are 31 spinal cord nerve segments in a human spinal cord:
- 8 cervical segments (cervical nerves exit spinal column above C1 and below C1-C7)
- 12 thoracic segments (thoracic nerves exit spinal column below T1-T12)
- 5 lumbar segments (lumbar nerves exit spinal column below L1-L5)
- 5 sacral segments (sacral nerves exit spinal column below S1-S5)
- 1 coccygeal segment (coccygeal nerves exit spinal column at coccyx)
Because the vertebral column grows longer than the spinal cord, spinal cord segments become higher than the corresponding vertebra, especially in the lower spinal cord segments in adults. The cervical nerves are the Spinal nerves from the Cervical vertebrae. The thoracic nerves are the Spinal nerves emerging from the Thoracic vertebrae. The lumbar nerves are the five Spinal nerves emerging from the Lumbar vertebrae. The five sacral nerves emerge from the Sacrum. Although the vertebral components of the sacrum are fused into a single bone the sacral vertebrae are still used to number the The term spinal nerve generally refers to the mixed spinal Nerve, which is formed from the dorsal and ventral roots that come out of the Spinal cord. A vertebra (plural vertebrae) is an individual Irregular bone in the spinal or Vertebral column ( aka ischis a flexuous and flexible column In a fetus, the vertebral levels originally correspond with the spinal cord segments. In the adult, the cord ends around the L1/L2 vertebral level at the conus medullaris, with all of the spinal cord segments located superiorly to this. The conus medullaris is the terminal end of the Spinal cord. It occurs near Lumbar nerves 1 (L1 and 2 (L2 For example, the segments for the lumbar and sacral regions are found between the vertebral levels of T9 and L2. The S4 spinal nerve roots arise from the cord around the upper lumbar/lower thoracic vertebral region, and descend in the vertebral canal. After they pass the end of the spinal cord, they are considered to be part of the cauda equina. The cauda equina is a structure within the lower end of the spinal column of most vertebrates that consists of nerve roots and rootlets from above The roots for S4 finally leave the vertebral canal in the sacrum. The sacrum is a large triangular bone at the base of the spine and at the upper and back part of the Pelvic cavity, where it is inserted like a wedge between
There are two regions where the spinal cord enlarges:
- Cervical enlargement - corresponds roughly to the brachial plexus nerves, which innervate the upper limb. The cervical enlargement corresponds with the attachments of the large nerves which supply the Upper limbs. The brachial Plexus is an arrangement of nerve fibers running from the spine formed by the Ventral rami of the lower cervical and upper thoracic nerve roots specifically In Human anatomy, the upper limb (also upper extremity) refers to what in common English is known as the arm, that is the region of the shoulder It includes spinal cord segments from about C4 to T1. The vertebral levels of the enlargement are roughly the same (C4 to T1).
- Lumbosacral enlargement - corresponds to the lumbosacral plexus nerves, which innervate the lower limb. The lumbar enlargement (or lumbosacral enlargement) gives attachment to the Nerves which supply the Lower limbs. The anterior divisions of the Lumbar nerve, Sacral nerve, and Coccygeal nerves form the lumbosacral plexus, the first lumbar nerve being frequently joined A leg is a limb on an Animal 's Body that supports the rest of the animal above the ground between the Ankle and the Hip and is used for It comprises the spinal cord segments from L2 to S3, and is found about the vertebral levels of T9 to T12.
Embryology
The spinal cord is made from part of the neural tube during development. In the developing vertebrate the neural tube is the Embryo 's precursor to the Central nervous system, which comprises the Brain and Spinal cord As the neural tube begins to develop, the notochord begins to secrete a factor known as Sonic hedgehog or SHH. Sonic hedgehog homolog (SHH is one of three Proteins in the Mammalian hedgehog family the others being Desert hedgehog (DHH and Indian As a result, the floor plate then also begins to secrete SHH and this will induce the basal plate to develop motor neurons. In the developing Nervous system, the floor plate is a Neural tube structure that separates the left and right components of the basal plate. In Vertebrates the term motor neuron (or motoneuron) classically applies to Neurons located in the Central nervous system (or CNS that project Meanwhile, the overlying ectoderm secretes bone morphogenetic protein (BMP). The ectoderm is the start of a tissue that covers the body surfaces Bone Morphogenetic Proteins ( BMPs) are a group of Growth factors and Cytokines known for their ability to induce the formation of Bone and This will induce the roof plate to begin to also secrete BMP which will induce the alar plate to develop sensory neurons. The alar plate (or alar lamina) is a neural structure in the embryonic nervous system part of the dorsal side of Neural tube, that involves the communication of general The alar plate (or alar lamina) is a neural structure in the embryonic nervous system part of the dorsal side of Neural tube, that involves the communication of general Sensory neurons are Neurons that are activated by sensory input (vision touch hearing etc The alar plate and the basal plate are separated by the sulcus limitans. In the Fourth ventricle, the sulcus limitans forms the lateral boundary of the Medial eminence.
Additionally, the floor plate will also secrete netrins. Netrin is a class of Protein involved in Axon guidance. It is named after the Sanskrit word "netr" which means "one who guides The netrins act as chemoattractants to decussation of pain and temperature sensory neurons in the alar plate across the anterior white commissure where they will then ascend towards the thalamus. Decussation (or decussatio) is used in biological contexts to describe a crossing The thalamus (from Greek θάλαμος = room chamber, IPA= /ˈθæləməs/ is a pair and symmetric part of the brain
Lastly it is important to note that the past studies of Viktor Hamburger and Rita Levi-Montalcini in the chick embryo have been further proven by more recent studies which demonstrated that the elimination of neuronal cells by programmed cell death (PCD) is necessary for the correct assembly of the nervous system.
Overall, spontaneous embryonic activity has been shown to play a role in neuron and muscle development, but is probably not involved in the initial formation of connections between spinal neurons.
Sensory Organization
Somatosensory organization is divided into the dorsal column-medial lemniscus tract (the touch/proprioception/vibration sensory pathway) and the spinothalamic tract (the pain/temperature sensory pathway). The posterior column-medial lemniscus pathway is the sensory pathway responsible for transmitting fine touch, Vibration and Proprioception (ˌproʊpriːəˈsɛpʃən PRO -pree-o-SEP-shun from Latin proprius, meaning "one's own" and perception is the Sense The spinothalamic tract is a sensory pathway originating in the spinal cord
Each of these sensory pathways utilizes three different neurons to get information from the sensory receptors to the cerebral cortex. The cerebral cortex is a structure within the Brain that plays a key role in Memory, Attention, perceptual Awareness, Thought, These neurons are designated primary, secondary and tertiary sensory neurons. The primary neuron has its cell body in the dorsal root ganglia and its axon projects into the spinal cord. In Anatomy and Neurology, the dorsal root Ganglion (or spinal ganglion) is a nodule on a Dorsal root that contains cell bodies of An axon or nerve fiber is a long slender projectionof a nerve cell or Neuron, that conducts electrical impulses away from the neuron's Cell
In the case of the touch/proprioception/vibration sensory pathway, the primary neuron enters the spinal cord and travels in the dorsal column. The posterior column-medial lemniscus pathway is the sensory pathway responsible for transmitting fine touch, Vibration and Below level T6, the neuron travels in the fasciculus gracilis - the most medial part of the column. The fasciculus gracilis ( tract of Goll) is a bundle of Axon fibres in the dorsomedial Spinal cord that carries information about fine touch vibrations Above level T6, the neuron enters the fasciculus cuneatus - lateral to the fasiculus gracilis. The fasciculus cuneatus ( tract of Burdach, named for Karl Friedrich Burdach) is a bundle of nerves in the spinal cord which primarily transmits information from the
As the primary axons reach the caudal medulla, they leave their respective fasiculi and enter and synapse on secondary neurons within the nucleus gracilis and the nucleus cuneatus, respectively. Located in the Medulla oblongata, the gracile nucleus is one of the Dorsal column nuclei that participates in the sensation of fine touch and Proprioception One of the Dorsal column nuclei, the cuneate nucleus is a wedge-shaped nucleus in the closed part of the Medulla oblongata. At this point, the secondary neuronal axons decussate and continue to ascend as the medial leminiscus. Decussation (or decussatio) is used in biological contexts to describe a crossing The medial lemniscus, also known as Reil's band or Reil's ribbon, is a pathway in the Brainstem that carries sensory information from the gracile They run up to the VPL nucleus of the thalamus,and synapse there on the tertiary neurons. The ventral posterolateral nucleus (VPL is a nucleus of the Thalamus. The thalamus (from Greek θάλαμος = room chamber, IPA= /ˈθæləməs/ is a pair and symmetric part of the brain From there, the tertiary neurons ascend via the posterior limb of the internal capsule to the post central gyrus, or Brodmann area 3,1,2. The internal capsule is an area of White matter in the Brain that separates the Caudate nucleus and the Thalamus from the Lenticular nucleus A Brodmann area is a region of the cortex defined based on its Cytoarchitecture, or organization of cells
The pain/temperature sensory pathway differs from that of the touch/proprioception/vibration pathway. The pain neurons enter as primary neurons and ascend 1-2 levels before synapsing in the substantia gelatinosa. The tract that ascends those 1-2 levels before synapsing is known as Lissauer's tract. The posterolateral tract ( fasciculus of Lissauer, Lissauer's tract, tract of Lissauer, dorsolateral fasciculus, zone of Lissauer) After synapsing, the secondary neurons decussate and ascend as the spinothalamic tract in the anterior lateral portion of the spinal cord. The spinothalamic tract is a sensory pathway originating in the spinal cord Hence, the spinothalamic tract is also known as the anterior lateral system (ALS). In the Nervous system, the anterolateral system is an ascending pathway that conveys Pain, Temperature ( Protopathic sensation) and Crude The tract ascends all the way to the VPL of the thalamus where it synapses on the tertiary neurons. The tertiary neuronal axons then project via the posterior limb of the internal capsule to the post-central gyrus or Broadmann area 3,1,2.
It should be noted that the pain fibers in the ALS can also deviate in their pathway towards the VPL. In one pathway, the axons project towards the reticular formation in the midbrain. The reticular formation is a part of the Brain that is involved in actions such as awaking/ sleeping cycle, and lying down The reticular formation then projects to a number of places including the hippocampus (to create memories about the pain), to the centromedian nucleus (to cause diffuse, non-specific pain) and various places in the cortex. The hippocampus is a part of the Forebrain, located in the medial Temporal lobe. In the Anatomy of the brain the centromedian nucleus, also known as the centrum medianum, ( CM or Cm-Pf) is a part of the Intralaminar Additionally, neurons project to the periaqueductal gray in the pons. Periaqueductal gray (PAG also called the "central gray" is the Midbrain Grey matter that is located around the Cerebral aqueduct within the The neurons form the periaqueductal gray then project to the nucleus raphe magnus which projects back down to where the pain signal is coming from and inhibits it. The nucleus raphe magnus, located directly rostral to the Raphe obscurus, is afferently stimulated from axons in the Spinal cord and Cerebellum. This reduces the pain sensation to some degree.
Motor Organization
Upper motor neuronal input comes from the cerebral cortex and from primitive brain stem nuclei. Cortical upper motor neurons originate in Brodmann areas 4, 6, 3, 1 and 2. A Brodmann area is a region of the cortex defined based on its Cytoarchitecture, or organization of cells They then descend through the genu and the posterior limb of the internal capsule. The internal capsule is an area of White matter in the Brain that separates the Caudate nucleus and the Thalamus from the Lenticular nucleus This pathway is known as the corticospinal tract. The corticospinal or pyramidal tract is a massive collection of Axons that travel between the Cerebral cortex of the Brain and the Spinal After passing through the internal capsule, the tract descends through the cerebral peduncles, down through the pons and to the medullary pyramids. The anterior or ventral portion of the Medulla oblongata is named the pyramid and lies between the Anterior median fissure and the Antero-lateral sulcus At this point, ~85% of these upper motor neuronal axons decussate. Decussation (or decussatio) is used in biological contexts to describe a crossing These fibers then descend as the lateral corticospinal tract. The remaining ~15% descend as the anterior corticospinal tract.
The midbrain nuclei include four motor tracts that send upper motor neuronal axons down the spinal cord to lower motor neurons. These are the rubrospinal tract, the vestibulospinal tract, the tectospinal tract and the reticulospinal tract. The rubrospinal tract is a part of the Nervous system. It is a part of the Lateral indirect Extra-pyramidal tract. The vestibulospinal tract is one of the descending spinal tracts of the ventromedial pathway In humans the tectospinal tract (also known as colliculospinal tract) is a nerve pathway which coordinates head and eye movements The reticulospinal tract (or anterior reticulospinal tract) is an Extrapyramidal motor tract which travels from the Reticular formation. The rubrospinal tract descends with the lateral corticospinal tract and the remaining three descend with the anterior corticospinal tract.
The function of lower motor neurons can be divided into two different groups: the lateral corticospinal tract and the anterior cortical spinal tract. The lateral tract contains upper motor neuronal axons which synapse on dorsal lateral (DL) lower motor neurons. An axon or nerve fiber is a long slender projectionof a nerve cell or Neuron, that conducts electrical impulses away from the neuron's Cell The DL neurons are involved in distal limb control. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species Therefore, these DL neurons are found specifically only in the cervical and lumbosaccral enlargements within the spinal cord. There is no decussation in the lateral corticospinal tract after the decussation at the medullary pyramids.
The anterior corticospinal tract descends ipsilaterally in the anterior column where the axons emerge and either synapse on lower ventromedial (VM) motor neurons in the ventral horn ipsilaterally or descussate at the anterior white commissure where they synapse on VM lower motor neurons contralaterally . In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species The anterior (or ventral white commissure also known as the alba anterior medullae spinalis, is a bundle of nerve fibers which cross the midline of the spinal cord just anterior In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species The tectospinal, vestibulospinal and reticulospinal descend ipsilaterally in the anterior column, but do not synapse across the anterior white commissure. Rather, they only synapse on VM lower motor neurons ipsilaterally. The VM lower motor neurons control the large, postural muscles of the axial skeleton. The axial skeleton consists of the 80 bones in the head and trunk of the human body These lower motor neurons, unlike those of the DL, are located in the ventral horn all the way throughout the spinal cord.
Spinocerebellar Tracts
Proprioceptive information in the body travels up the spinal cord via three tracts. Proprioception (ˌproʊpriːəˈsɛpʃən PRO -pree-o-SEP-shun from Latin proprius, meaning "one's own" and perception is the Sense Below L2 the proprioceptive information travels up the spinal cord in the ventral spinocerebellar tract. The ventral spinocerebellar tract conveys proprioceptive information from the body to the Cerebellum. Also known as the anterior spinocerebellar tract, sensory receptors take in the information and travel into the spinal cord. The cell bodies of these primary neurons are located in the dorsal root ganglia. In Anatomy and Neurology, the dorsal root Ganglion (or spinal ganglion) is a nodule on a Dorsal root that contains cell bodies of In the spinal cord, the axons synapse and the secondary neuronal axons decussate and then travel up to the superior cerebellar peduncle where they decussate again. The superior cerebellar peduncles ( brachium conjunctivum) two in number emerge from the upper and medial part of the white substance of the hemispheres and are placed under From here, the information is brought to deep nuclei of the cerebellum including the fastigial and interposed nuclei. The fastigial nucleus or nucleus fastigii refers specifically to the concentration of gray matter nearest to the middle line at the anterior end of the superior Vermis
From the levels of L2 to T1, the proprioceptive information enters the spinal cord and ascends ipsilaterally where it synapses in the Dorsal Nucleus of Clark. The secondary neuronal axons continue to ascend ispilaterally and enter the pass into the cerebellum via the inferior cerebellar peduncle. The upper part of the posterior district of the Medulla oblongata is occupied by the inferior peduncle, a thick rope-like strand situated between the lower part of the Fourth This tract is known as the dorsal spinocerebellar tract and also as the posterior spinocerebellar tract. The dorsal spinocerebellar tract ( posterior spinocerebellar tract, Flechsig's fasciculus, Flechsig's tract) conveys proprioceptive information The dorsal spinocerebellar tract ( posterior spinocerebellar tract, Flechsig's fasciculus, Flechsig's tract) conveys proprioceptive information
From above T1, proprioceptive primary axons enter the spinal cord and ascend ipsilaterally until reaching the accessory cuneate nucleus, where they synapse. The accessory cuneate nucleus is located lateral to the Cuneate nucleus in the Medulla oblongata at the level of the Sensory decussation (the The secondary axons pass into the cerebellum via the inferior cerebellar peduncle where again, these axons synapse on cerebellar deep nuclei. This tract is known as the cuneocerebellar tract. The posterior external arcuate fibers ( dorsal external arcuate fibers) take origin in the Gracile and Cuneate nuclei they pass to the Inferior peduncle
Injury
Spinal cord injuries can be caused by trauma to the spinal column (stretching, bruising, applying pressure, severing, etc. Spinal cord injury causes myelopathy or damage to white matter or myelinated fiber tracts that carry sensation and motor signals to and from the brain . . the spinal cord). The vertebral bones or intervertebral disks can shatter, causing the spinal cord to be punctured by a sharp fragment of bone. Intervertebral discs (or intervertebral fibrocartilage) lie between adjacent vertebrae in the spine. Bones are rigid organs that form part of the Endoskeleton of Vertebrates They function to move support and protect the various organs of the body produce Usually victims of spinal cord injuries will suffer loss of feeling in certain parts of their body. In milder cases a victim might only suffer loss of hand or foot function. The hands ( med / lat: manus pl manūs are the two intricate prehensile multi- Fingered body parts normally located at the end of each arm of a The foot is an Anatomical structure found in many Animals It is the terminal portion of a limb which bears weight and allows Locomotion. More severe injury may result in paraplegia, tetraplegia, or full body paralysis below the site of injury to the spinal cord. Paraplegia is an impairment in motor and/or sensory function of the lower extremities Quadriplegia, also known as tetraplegia, is a Symptom in which a human experiences Paralysis affecting all four limbs although not necessarily total paralysis Paralysed redirects here For other uses see xx Paralysed (disambiguation Paralysis is the complete loss of Muscle function
Damage to upper motor neurons axons in the spinal cord results in a characteristic pattern of ipsilateral deficits. These include hyperreflexia, hypertonia and muscle weakness. Hyperreflexia is defined as overactive or overresponsive Reflexes. Hypertonia is an Upper motor neuron dysfunction marked by an abnormal increase in tightness of Muscle tone and a reduced ability of a muscle to stretch Lower motor neuronal damage results in its own characteristic pattern of deficits. Rather than an entire side of deficits, there is a pattern relating to the myotome affected by the damage. In Vertebrate Embryonic development, a myotome is a group of tissues formed from Somites that develop into the body wall muscle Additionally, lower motor neurons are characterized by muscle weakness, hypotonia, hyporeflexia and muscle atrophy. Hypotonia is a condition of abnormally low Muscle tone (the amount of tension or resistance to movement in a muscle often involving reduced muscle strength Hyporeflexia is the condition of below normal or absent reflexes Muscle atrophy is defined as a decrease in the mass of the muscle it can be a partial or complete wasting away of muscle
The two areas of the spinal cord most commonly injured are the cervical spine (C1-C7) and the lumbar spine (L1-L5). In Vertebrates cervical vertebrae (singular vertebra) are those vertebrae immediately behind (posterior to the Skull. The lumbar vertebrae are the largest segments of the movable part of the Vertebral column, and are characterized by the absence of the Foramen transversarium within (The notation C1, C7, L1, L5 refer to the location of a specific vertebra in either the cervical, thoracic, or lumbar region of the spine. A vertebra (plural vertebrae) is an individual Irregular bone in the spinal or Vertebral column ( aka ischis a flexuous and flexible column )
Additional images
 Diagrams of the spinal cord. |
 Cross-section through the spinal cord at the mid-thoracic level. |
 Cross-sections of the spinal cord at varying levels. |
References
- ^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall, 132-144. ISBN 0-13-981176-1.
See also
External links
- Spinal Cord Histology - A multitude of great Images from the University of Cincinnati
- ACES Ing.- GmbH - Human Spinal Implant
- Spinal Cord Medical Notes - Online medical notes on the Spinal Cord
- eMedicine: Spinal Cord, Topographical and Functional Anatomy
- WebMD. The cauda equina is a structure within the lower end of the spinal column of most vertebrates that consists of nerve roots and rootlets from above The conus medullaris is the terminal end of the Spinal cord. It occurs near Lumbar nerves 1 (L1 and 2 (L2 The meninges (singular meninx) is the system of membranes which envelops the Central nervous system. The term spinal nerve generally refers to the mixed spinal Nerve, which is formed from the dorsal and ventral roots that come out of the Spinal cord. In Medicine, a lumbar puncture (colloquially known as a spinal tap) is a Diagnostic and at times therapeutic procedure that is performed in order A Neutral Spine or "good posture" refers to the "three natural curves are present in a healthy spine The University of Cincinnati is a Coeducational public Research university in Cincinnati, Ohio. May 17, 2005. Events 1521 - Edward Stafford 3rd Duke of Buckingham, is executed for Treason. Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Spina Bifida - Topic Overview Information about Spina Bifida in fetuses and throughout adulthood. WebMD children's health. Retrieved March 19, 2007. Events 1279 - A Mongolian victory in the Battle of Yamen ends the Song Dynasty in China. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.
- Potential for spinal injury repair Retrieved Feb 6, 2008.
Dictionary
spinal cord
-noun
- (anatomy) A thick, whitish cord of nerve tissue which is a major part of the vertebrate central nervous system. It extends from the brain stem down through the spine, with nerves branching off to various parts of the body.
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic