Central Nervous System

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Central Nervous System
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Central Nervous System

• Central nervous system (CNS) includes the brain
  and spinal cord
• Peripheral nervous system (PNS) composed of the
  cranial and spinal nerves
• Autonomic system comprises the sympathetic and
  parasympathetic system (controls smooth muscle
  action)

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Central nervous system

• Comprised of the brain and the spinal cord
  together with the nerve trunks and fibers
  connected to them.
• Referred to as the cerebrospinal system.

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Divisions of the Brain

• Forebrain cerebrum and diencephalon
• Midbrain mesencephalon
• Hindbrain cerebellum,pons and the medulla
  oblongata (sometimes called the brain stem)

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Forebrain

• Divided into two hemispheres
• Each hemisphere is divided into four lobes

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Midbrain

• The upper part of the brain stem
• Connects the lower brain centers to the higher
  brain centers

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Hindbrain

• Cerebellum (called little brain)
• Pons
• Medulla oblongata (Brain stem)
• The most posterior portion of the brain
• Extension of the spinal canal

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Peripheral Nervous System

• 31 pairs of spinal nerves
• Attached to spinal cord
• 8 cervical
• 12 thoracic
• 5 lumbar
• 1 coccygeal
• The rest control the lower extremities and extend
  below the level of the spinal cord
• 12 pairs of cranial nerves
• Attached to brain

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Autonomic Nervous System

• Sympathetic system
• Arises from all the thoracic and first 3 lumbar
  segments of the spinal cord
• Parasympathetic system
• Arises from the 3rd, 7th, 9th, and 10th cranial
  nerves and from the 2nd, 3rd, and 4th sacral
  segments of the spinal cord.

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Special Imaging Procedures

• CT best demonstrates ventricular size or
  infarcts as well as the presence of blood. It is
  also good for bony abnormalities.
• MRI best demonstrates soft tissue abnormalities
  such as ruptured disk or spinal cord defects

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Special Imaging Procedures Cont.

• Nuclear Medicine best demonstrates pathologic
  processes which involve the blood brain barrier.
• Angiography locates and evaluates aneurysms,
  intracranial mass, abnormal cranial vessels,
  hemorrhages and malformations.

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Special Imaging ProceduresCont.

• Myelography confirms or excludes the presence
  of an intraspinal lesion such as a herniated
  disc.
• Discography demonstrates individual disc by
  injecting contrast.

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Congenital Abnormalities

• Anencephaly the cranial vault is absent and the
  cerebral hemispheres are either missing or
  markedly reduce in size.

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Congenital Abnormalities

• Microcephaly the infant is born with an
  exceedingly small head.
• Usually related with the cerebrum failing to
  develop properly

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Congenital Abnormalities

• Hydrocephaly (water brain) the ventricles
  enlarge as a result of a block in the flow of
  cerebrospinal fluid at some level.
• Usually diagnosed with ultrasound or MRI

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Congenital Abnormalities

• Spina Bifita characterized by an opening in the
  spine, the result of a defect in the neural tube
  in which the posterior arches and spines of some
  vertebrae fail to close or are absent.

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Inflammatory Processes

• Abscesses an accumulation of puss on the brain
• Epidural abscess collection of puss is between
  the skull and the underlying dura
• Brain abscess all other abscesses

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Inflammatory Processes

• Aneurysms a weakening of the vessel wall which
  allows that wall to protrude outward and
  eventually rupture.
• The most common type is a berry aneurysm.

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Inflammatory Processes

• Cerebrovascular accidents (CVA) also called
  strokes
• Possible causes are thrombosis (blood clot),
  embolism (moving blood clot) and hemorrhage.

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Inflammatory Processes

• Transient Ischemic Attacks (TIAs) often called
  mini strokes because they proceed CVAs.
• They are the warning sign that a stroke is eminent

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Inflammatory Processes

• Subdural empyema a pus forming process in the
  space between the dura mater and the arachnoid
  space.
• Most commonly caused by spread of infection from
  the frontal or ethmoid sinuses.

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Inflammatory Processes

• Encephalitis inflammation of the brain
• Caused from a virus usually but can be caused
  from a hemorrhage.

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Inflammatory Processes

• Cerebral hemorrhage (also known as hematoma) is
  the escape of blood from the vessels into the
  cerebrum.
• Subarachnoid hemorrhage caused from a ruptured
  berry aneurysm in the circle of Willis
• Intracerebral or intraparenchymal hypertensive
  vascular disease is the main cause

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Inflammatory Processes

• Meningitis inflammation of the leptomeniges
• Streptococcal meningitis arises from the nose
  or throat area
• Pneumococcal meningitis arises from the lungs.

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Head injuries

• Concussion when the brain strikes the opposite
  side of the head during a violent blow or jar.
• Contusion bruises on the surface of the brain

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Head injuries cont

• Fractures break in the skull
• Linear irregular or jagged radiolucent line
• Comminuted a break of three or more pieces
• Depressed when the fragments are depressed into
  the cranial cavity.
• Basilar skull fractures breaks into the base of
  the skull

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Head injuries

• Epidural hemorrhage (extradural hematoma)
  caused by a tear in the middle menigeal vessels,
  which causes bleeding between the bone and the
  dura mater.

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Head injuries

• Subdural hematoma a tear of the veins between
  the dura mater and the arachnoid.

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Head injuries

• Intracerebral Hematoma traumatic hemorrhage
  into the brain parenchyma

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Degenerative Diseases

• Alzheimers Disease (pre-senile dementia)
  progressive cerebral atrophy that develops at an
  earlier age than the senile period.

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Degenerative Diseases

• Huntingtons Disease an inherited condition
  that predominantly involves men in early to
  middle age. It presents as dementia and
  choreiform movements (involuntary movements that
  are rapid, jerky, and without stop.)

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Degenerative Diseases

• Parkinsons Disease (shaky palsy) progressive
  degenerative disease characterized by stooped
  posture, stiffness and slowness of movement,
  fixed facial expression, and involuntary rhythmic
  tremor of the limbs that disappears with
  voluntary movement.

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Neoplasms

• Glioma originate in the cerebral hemispheres
  and the posterior fossa
• Astrocytomas benign form
• Glioblastoma multiforme malignant form

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Neoplasms

• Medulloblastoma occurs in the roof of the
  fourth ventricle in the midline of the
  cerebellum.
• Effects children between ages 9 and 12
• Rapidly growing and usually result in death.

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Neoplasms

• Meningiomas slow growing benign tumor arising
  in the meninges particularly the arachnoid and
  dura mater.
• The most common brain tumor.

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Neoplasms

• Pituitary adenomas a tumor that grows within
  the sellae turcica where the pituitary gland is
  located

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Neoplasms

• Craniopharyngioma originates above the sellae
  turcica
• Found in children between ages of 5 and 18

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Neoplasms

• Tumors of the pineal gland cause a compression
  of the ventricular system causing hydrocephalus
  and an enlarged ventricular system.
• Teratomas
• Germinomas

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Metastatic tumors

• Chordoma located at the clivus of the skull
• Radiographically reveals destruction of the
  dorsum sellae and clivus along with cloud like
  calcifications.

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Metastatic Tumors

• Acoustic neuromas the origin at the 8th cranial
  nerve causes the tumor to destroy the internal
  auditory meatus
• Usually associated with deafness.

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Spinal Cord Disease

• Neurofibromas may occur any where in the spinal
  canal and are hallmarked by a foraminal widening

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Spinal Cord Disease

• Slipped disc the most common abnormality of the
  spinal
• When an intervertebral disc protrudes or
  herniates into the vertebral canal and presses on
  the spinal cord or stretch the nerves.

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THE END