C1 - Meninges of the brain and spinal cord, blood supply of the brain

Question 1

Meninges of the brain

Answer 1

• The CNS is enclosed by soft tissue membranes, called meninges

Divided into 3 different layers:

1. Dura mater
   
   • Outer most layer, fused with inner periosteum
   • ​Separated form the periosteum linging of the vertebral canal by the epidural space
     
     • Epidural space: Fat, fluid and internal venous system
   • Splits from hemispheres at for. magnum
   • 3 meninges converge caudal in filum terminale
   • Falix cerebri: Extension form dorsal and rostral. DN in between 2 hemispheres
   • Diaphragma sellae: Horizontal extension, separat of hypopyses form brain
2. Arachnoidea
   
   • ​Between dura mater and pia mater
   • Has 2 layers
     
     • Each layer is fused to one of the former parts
   • Subarachnoid space: Between the two membranes
     
     • Filled with cerebrospinal fluid
   • At certain sites, this space is enlarge to form cisternae, which can be used for the extraction of CSF or for injection
     
     • Cerebellomedullary cistern: Where caudal surface of cerebellum meets the dorsal surface of medulla oblongata
3. Pia mater
   
   • ​In direct contact with glia limiting membrane of neural tissue
   • Lig. denticulate: bilaterally thickening alont the lateral surface of the spinal cord
     
     • Tranverese the subarachnoid space and attaches to dura mater

• Dura mater encephali
  
  • Falix cerebri
  • Tentorium cerebelli membranaceum (separating the two hemisphers from cerebellum)
  • Diaphragma sellae (partly separating hypophysis from brain)
  • Incisura tentorii (tentorial notch from the passage of the brainstem)
  • Cavum trigeminale (pouch for ggl. trigeminale)
  • Cavum subdurale (subdural cavity)
• Dura mater spinalis (separated from the wall of vertebral canal by cavum epidurale)
  
  • Filum durae matris spinalis (caudal end of dura mater spinalis)
  • Cavum epidurale (epidural space, between dura mater spinalis and periosteum of canalis vertebralis)
  • Cavum subdurale
• Arachnoidea encephali (connected by trabeculae with pia)
  
  • Cavum subarachnoidale (filled with liqour cerebrospinalis)
• Arachnoidea spinalis
  
  • ​Cavum subarachnoidale​ (filled with liqour cerebrospinalis)
    
    • Cisternae subarachnoidales (enlargement of cavum subarachnoidale​)
  • Cisterna cerebellomedullaris (enlargement of subarachnoid space between cerebellum and medulla oblogata)
  • Cisternae valleculae lateralis (enlargement of subarachnoid space in vallecula lateralis cerebri)
  • Cisterna chiasmatis (around chiasma opticum)
  • Cisterna interpeduncularis (within fossa interpeduncularis)
  • Granulationes arachnoideales (evaginations of arachnoidea through dura mater into sinus dura matirs)
• Pia mater encephali
  
  • ​Tela choridea ventriculi quarti
  • Plexus choroideus ventricul quarti
  • Tela choridea ventriculi tertii
  • Plexus choroideus ventricul lateralis
  • Glomus choroideum
• Pia mater spinalis
  
  • ​Lig. denticulatum (fibrous anchors of medulla spinalis to dura)
  • Septum intermedium (connective tissue separating faciculus gracilis from faciculus cuneatus in the cervical part of spinal cord)

Question 2

Blood supply of the brain

Arterial

Answer 2

• Ca, eq: blood supply to brain form paired a. carotis interna
• Fe, Ru: a. maxillaris → a. carotis cerebri (cerebral carotid artery)
• A. carotis interna / a. carotis cerebri penetrated the dura mater at the diaphragmatica sellae → cerebral arterial circle ventral to hypothalamus
• Branches:
  
  • A. cerebri rostralis
  • A. cerebri media
  • A. cerebri caudalis
  • A. cerebellaris rostralis
  • A. cerebellaris caudalis

Question 3

Blood supply of the brain

The venous drainage

Answer 3

• Complicated system of venous sinuses which are enclosed in dura mater
• Divided into dorsal and ventral system

Dorsal system:

• Sinus saggitalis dorsalis
• SInus rectus
• Sinus transversus
  
  • ​Sinus temporalis
  • SInus sigmoideus

Ventral system:

• Sinus cavernosus
• Sinus basilaris
• Sinus petrosus ventralis
• Sinus intercavernosus
• Flow of blood into crania cavity:
  
  • Spreading of infections
  • Cooling the arterial blood supply to hypothalamus