Brain Blood Supply Flashcards
Vascular components of brain and brainstem
Internal carotid arteries, maxillary artery and basil are artery
Vertebral to brainstem
Circle of Willis
Surrounds pituitary
Provide all blood to the brain
Rostral, middle and caudal cerebral arteries from here
Internal carotid
Main supply in dog and horse
Rudimentary in car and cow, have rete mirabile system, room smaller vasculature
Rete mirabile
Vascular redundancy or collateral paths of blood to the brain
Can compensate for carotid blockage and avoid brain damage
Cow
Circle of Willis makeup
Basilar supplies majority of blood to the brain
Cerebral hemispheres supplied by 3 cerebral arteries
Cerebellum by 2 pairs of arteries
Left and right internal carotids feed the circle
Dog/horse/human
In dogs maxillary artery is a significant contribution to the internal carotid
Dogs can have rudimentary rete
Pharyngeal arteries can also anastomose along with external ophthalmic and ethmoidal arteries
Vertebrobasilar system supplies blood to cerebral hemispheres via caudal cerebral arteries
Cat/small ruminants
Internal carotid A regress after birth
Blood supply to circle via numerous small dorsal branches of maxillary arteries
Rostral epidural rete mirabile which coalesce into intracranial carotid arteries supplying cerebral arteries
Vertebrobasilar arteries though present have reduced contribution to the brain
Blood flow directed caudal in basilar artery so cerebral hemispheres sourced room intracranial internal carotid
Cow
Internal carotid regress and replaced by maxillary arteries which supply rete mirabile and intracranial off of here
Caudal rete connects to rostral
Vertebral arteries and spinal branches contribute to caudal rete which connects to rostral rete so the vertebrobasilar system contributes to whole Brain
Cetaceans
After exiting heart supply complex anastomoses
Almost all blood to circle of Willis supplied by epidural retia rather than carotid branches
Dog anastomoses
5 can contribute to brain supply so can avoid defects when carotid and vertebral arteries are blocked
Occipital and vertebral
Ascending pharyngeal and internal carotid
Intracranial and maxillary
Maxillary and internal carotid
Ophthalmic and carotid
Venous drainage
Internal and external jugular veins and vertebrobasilar veins
Internal jugular vein
Begins as sigmoid and ventral petrodollars sinuses which join the vertebral vein
Maxillary vein
Branch of external jugular
Retroarticular vein connection from the temporal Dural sinus
Vertebral veins
Bilateral, receive blood from Brain through sigmoid sinus and vein of the hypoglossal canal
Internal vertebral venous plexus
Basilar sinuses
Numerous anastomoses connect to the external vertebral plexus that surrounds cervical and cranial thoracic vertebrae
Emissary vein
Join with ophthalmic, pterygoid and palatine plexus
Also connect cavernous sinuses and maxillary vein
Intracranial veins
Directly drain the brain
Plain veins draining parts of the surface of the brain
Dural veins/ sinuses within subarachnoid and intradural spaces
Dural veins and sinuses
Receive the blood draining into the cerebral veins
Intracranial vein drainage
Cortical and central veins which have different draining
Cortical veins turn to dorsal and ventral cerebral which drain into dorsal Sagittal and petrosal sinuses
Central veins drain into great cerebral
Cortical veins
Dorsal and ventral cerebral veins which drain the cortex and nearly the whole cerebrum
Central veins
Drain the great cerebral vein, corpus callosal, basal , internal cerebral and thalamostriate veins
Brainstem veins
Medullary and pontine veins
Dog cavernous sinuses
Significant portion of blood from Dural sinuses also drains into neural canal of the vertebral column
Vertebral plexus receive large volume of the blood draining from the CNS
Species variation in venous drainage
Aquatic mammals have an increased dependence on epidural venous drainage of blood from the brain
Brain cooling and pulse dampening
Sensitive to temperature changes
Veins regulate temperature and cool arteries to prevent dysfunction
Lack of carotid rete precludes cooling
Carotid rete and epidural retia have pulse dampening effect
Extracranial veins
Jugular veins and vertebral veins
Internal and external vertebral venous plexus
Internal within neural canal, external around vertebral column
Spinal cord arterial supply
Cervical- vertebral arteries
Thoracic spinal cord- dorsal and supreme intercostal arteries
Lumbar spinal cord- lumbar dorsal segmental arteries
Pia network
Anastomoses between dorsal and ventral root arteries and ventral spinal artery
White matter supplied by Pial network, and gray matter by ventral spinal artery
Spinal cord venous drainage
- Central veins, radial veins and coronal plexus (pial)
- Ventral median and dorsal spinal veins
- Radicular and medullary veins
- Internal and external vertebral plexus
- Intervertebral veins
CNS components
Blood, neural tissue and cerebrospinal fluid
Increase in volume increases pressure
Internal and external carotid brain supply
Internal to external
Horse, dog, cat then cow
3 main paths of blood to the brain
Internal And external carotid and vertebral artery
3 main blood drainage from the Brain
Internal and external jugular and vertebrobasilar/ epidural veins
Internal and external jugs in soft tissue so can have pressure increase
Collateral epidural venous system protected inside neural canal
Blood supply to spinal cord review
Begins in aorta and moves up segmental arteries which give off spinal Ramus which enters neural canal and divides into dorsal and ventral root arteries
Ventral medullary artery enters the median ventral spinal artery and dorsal medullary artery enters one of the dorsal spinal arteries
