Neuroanatomy chap 6 : blood supply of brain

Arterial supply of brain/ spinal cord (2 pairs of vessels)

Carotid & Vertebral arteries

Internal carotid artery proceeds superiorly along optic chiasm and forks (bifurcates) into

middle and anterior cerebral arteries

2 smaller branches

Anterior choroidal artery and posterior communicating artery

Anterior choroidal artery (long and thin) -

Frequently involved in cerebrovascular accidents. Supplies the optic tract; chroid plexus of the inferior horn of the lateral ventricle ; and some so,e deep brain structures

Posterior communicating artery passes posteriorly, inferiorly-

To the optic tract and towards the cerebral penduncle and joins the posterior cerebral artery.

Anterior cerebral artery-

Runs medially, superiorly to the optic nerve and enters the longitudinal fissure

Carotid arteries

Provide about 80 % of blood supply. most to the telencephalon and much of the deincephalon

Vertebral system

Provides 20% supply to the brain stem and cerebellum, as well as parts of the diencephalon, spinal cord, occipital and temporal lobe.

Ophthalmic artery

First divisions of the internal carotid arteries. Travels along the optic nerve to the orbit, where it supplies the eyes orbital contents.

Conduit

All the ascending and descending pathway fibers have to pass through here to get to the brain

Cranial nerves

10 of the 12 cranial nerves are attached to the brainstem

Integration

Respiration, cardiovascular control, consciousness, sleep

Midbrain

Includes cerebral penduncle, superior and inferior colliculus, and aqueduct

Pons “bridge”

Basal pons and fourth ventricle

Medulla

Contain pyramids, a part of the fourth ventricle, part of the central canal and flows with the spinal cord

Obex

Where 4th ventricle becomes continuous with central canal

10 seconds without blood/oxygen (ischemia) -

Loss of consciousness

20 seconds without blood/oxygen -

Electrical activity in brain stops

Anterior system

Carotid

Posterior system

Vertebral-basilar

Anterior cerebral=

Medial wall of frontal and parietal

Midbrain

Cerebral penducle, superior/inferior collicus, aqueduct

Pons “bridge”

Basal pons, 4th ventricle

Medulla

Pyramids, part of 4th ventricle, central canal/ spinal cord

The brainstem-

Keeps us alive

Ventral view (pyramids)

Descending/ ascending motor cortocospinal tract fibers

Olives (ventral view)

Contain inferior olivary nuclei (motor coordination)

Pons (ventral view)

Dominated by transverse fibers —> contralateral cerebral hemispheres

Posterior view

Floor of 4th ventricle

Obex

“V” where the vent becomes central canal

Corticospinal tract

1. Motor cortex 2. Internal capsule 3. Cerebral penducles 4. Basal pons 5. Medullary pyramids 6. Crosses at pyramidal decussation (medulla) 7. Lateral corticospinal tract = voluntary movement