Brain ventricle

• The thrid ventricle is one of the 4 interconnected fluid-filled cavities within the brain, part of ventricular system which is responsible for production of cerebrospinal fluid.
• Third ventricle is a narrow, vertically oriented cavity located between the. 2 halves of thalamus and hypothalamus
• Ventricular system

  
• Thrid ventricle

  
• The third ventricle extend from lamina terminalis anterior and up to the cerebral aqueduct posterior
• It communicates

  • Anterosuperiorly: with the lateral ventricles throught the intraventricular foramen of monro
  • Posteroinferiorly: with the 4 ventricle through the cerebral aqueduct of silvius.
• Boundaries of 3 ventricle:

  • Anterior wall: Lamina terminalis and anterior comissure
  • Posterior wall: pineal body, Posterior comissure, habenular comissure
  • Lateral wall: medial surface of right and left thalamus and hypothalmanys. The 2 lateral walls are joined by interthalamic adherence
• Roof of third ventricle if formed by:

  • fornix and ependyma lining the under suf of tela choroideia of 3 ventricle
• Floor of 3 ventricle is formed by:

  • Optic chiasma
  • tuber cinerum
  • infundibulum + pituitary stalk
  • mamillary bodies
  • posterior perforated substance and tegmentum of midbrain
• The recesses of third ventricle of extensions of the ventricle into the surrounding structure. These are:

  • infundibular recess
  • Supraotic recess
  • Suprapineal recess: sup to pineal gland
  • pineal recess: btw the 2 diverging layers of pineal gland
• Tela choroidea is a double layer of pia matter and modified ependyma cells that lines the third ventricle cavity. They are responsible for o CSF.

  Within the tela choroidea is a network of capillaries covered by choroidal epithelial cells known as choroid plexus. These are branches if the posterior cerebral arteries. The choroid plexus filters blood to produce CSF actively secreting ions and nutrients into the 3 ventricle
• Lateral ventricle

  • Pair C-shaped cavities present on each side of cerebral hemispheres
  • Lined with ependyma and filled with CSF
  • Each lateral ventricle communicated wuth 3 ventricle via interventricular foramen of monro

  
• Each lateral ventricles consists of 4 parts:

  Body and 3 horns

  • Body: extends from foramen of monro to splenium of corpus callosum.
  • Roof: body corpus callosum
  • Floor: body of caudate nucleus, stria terminalis, thalamostriated vein and thalamus
  • Medial wall: septum pellucidum, body of fornix.

  
• Anterior horn of lateral ventricle

  • Lies in front of foramen of monro
  • Extends into frontal lobe

  Boundaries:

  Anterior: genu + rostrum of corpus callosum.

  Roof: trunk of corpus callosum

  Floor: head of caudate nucleus

  Medial: septum pellucidum + column of fornix

  
• Posterior horn of lateral ventricle

  • Lies behind splenium of corpus callosum
  • Extends into occupital lobe

  Boundaries: floor + medial wall: shows 2 elevations: bulb of posterior horn (raised by forceps major) + calcar avis (raised by calcarine sulcus)

  Roof + lateral wall: tapenum

  
• Inferior horn of lateral ventricle

  • largest horn
  • extends into temporal lobe

  Boundaries:

  • roof: tail of caudate nucleus, stria terminalis, tapenum, amygdaloid body
  • Floor: collateral eminence + hippocampus

  
• Boundaries of body of lateral ventricle

  
• Boundary of posterior horn

  
• Boundaries pf anterior horn

  
• Boundaries pf inferior horn

  
• • Choroidal plexus are supplied by branches of anterior and posterior choroidal arteries→enter ventricles through choroidal fissure→ runs along superior aspect of each lateral ventricle and communicated with third ventricle through interventricular foramen.
  • The ventricles produce CSF through process of filtration, secretion and selective transport of molecules from plasma into interventricular space
  • Once produce, CSF circulates through ventricular system, bathing brain + spinal cord before being reabsorbed into blood stream by arachnoid villi and granulations.

  
• Functions of CSF include: Cushioning effect on brain, protection against trauma, removal of waste products, regulation of temperature, distribution of nutrients to nervous tissue, facilitation of movement of cerebral spinal fluid within subarachnoid spaces, and maintenance of normal pressure within cranial vault.
• CSF is composed of water (98%), glucose, proteins, electrolytes, urea, lactate, carbon dioxide, hormones, enzymes, antibodies, etc.
• Forth ventricle

  • Dimond shaped cavity in hindbrain located just in front of cerebellum and behind pons and upper medulla.
  • Connected to third ventricle via cerebral aqueduct of silvius.
  • Has a floor, roof, lateral boundaries and a cavity.

  Boundaries:

  Superiolaterall: superior cerebellar peduncle

  Inferiolaterally: gracillis + cuneate tubercles + inferior cerebellar peduncle

  
• Floor of fourth ventricle

  • Known as rhomboid fossa, formed by dorsal suf of lower pons and dorsal suf of upper medulla

  Parts:

  1. Upper triangular: formed by dorsal suf of pons (closed)
  2. Lower triangular: formed by dorsal suf of medulla (open)
  3. Intermediate part: at junction btw pons ans medulka. Prolonged lat over inf cerebellar peduncles as floor of lat recess. Marked by transversely running fibers of stria medullaris

  
• Floor of 4th ventricle

  • Dorsal median sulcus: divides floor into 2 symmetrical halves
  • Median eminence: on each side of median sulcus. Presents facial colliculi just opposite to a depression superior fovea
  • Sulcus limitans: limits median eminence on lateral sides. In uppermost part overloes locus coerulus (Substancia ferruginea)
  • Upper part of sulcus limitans there is sup fovea and in medullary part there is inf fovea. Descending from inf fovea there is a sulcus that runs obliquely through midline dividing median eminence into 2 traingles
  • Vagal triangle: overlies vagal nucleus and hypoglossal triangle overlies hypoglossal nucleis
  • Btw vagal triangle above and graciles tubercle bellow there is area posterma that function as chemireceptor (vomiting center)
  • Vestibular area: lies lat to inf fovea. Overlies vestibular nucleus
• roof of 4 ventricle

  • diamond shaped

  Divided into:

  Superior part: formed by superior cerebellar peduncle and superior medullary vellum (thin sheet of white matter)

  Inferior part: formed by inferior medullary velym (non nervous tissues) formed by combined portions of ependyma and pia matter of tela choroidea.

  • Roof has 2 openings: foramen of magendie + foramen of lushka through which CSF drain into cerebellomedullary system.

  
• Forth ventricle communicates inferiorly with central canal and superiorly with cerebral aqueduct.

  
• The fourth ventricle drains excess CSF through two foramina: the foramen of Magendie and the foramen of Luschka.
• Third ventricle

  
• CSF flow

  
• Brain ventricles