Basic Neuroanatomy - Blood supply to the brain & the cerebellum

circle of willis

central location of major arteries creating redundancies to ensure constant blood supply to the brain

-if one part/artery is blocked or narrowed, blood flow from the other blood vessel can often preserve cerebral perfusion

Anterior cerebral artery

supplies blood to frontal, parietal, and corpus collosum

middle cerebral artery

supplies blood to the brocas, wernikes, temporal, and primary motor cortex

posterior cerebral artery

supplies blood to the cerebellum and occipital lobe

veins

system of blood vessels that provide means of draining carbon dioxide-laden blood to the lungs from reoxygenation

obstruction in the cerebrovascular supply typically occurs as

-thrombus

-embolism

thrombus

a foreign body (blood clot) that obstructs blood vessel

embolism

when a thrombus breaks loose from its site of formation and floats through bloodstream and causes occlusion

Cerebellum "little brain"

-Responsible for coordinating motor commands with sensory inputs to control movement

-plays significant role as memory for motor functions and cognitive processes

cerebellum communicates with

brainstem, spinal cord, and cerebral cortex by means of superior, middle and inferior peduncles

vermis

separates the two lobes of the cerebellum

Motor functions of cerebellum

-Helps in planning, monitoring, and correction of motor movement using sensory feedback

-Coordinates fine motor activity

Linguistic function of cerebellum

Perception of speech/language, verbal working memory, verbal fluency, grammar processing, writing, and reading

Testing the Cerebellum

-Finger to nose test

-Diadochokinesia test (pa-ta-ka)

-Uncoordinated, sloppy movement may indicate cerebellar damage

Cerebellar Damage Symptoms

ataxia, dysmetria, dysdiadochokinesia, nystagmus, ataxic dysarthria, hypotonia

cerebellar disorders

- Cerebellar Hemispheral syndrome

- Friedreich ataxia

Anatomy of the brainstem

-medulla, pons, midbrain

-Cranial Nerves and their nuclei arise from here and basic bodily functions of life are maintained here

medulla oblongata

portion of the hindbrain that controls autonomic functions

-digestion, heart and blood vessel function, swallowing, sneezing

Medulla oblongata continues

-Motor and sensory neurons from midbrain and forebrain

-Relay of nerve signals between the brain and spinal cord

-Coordination of body movements

Pons

-Connects the cerebral cortex with the medulla oblongata

-Communication and coordination center between the two cerebral hemispheres

-Helps in transferring of messages between brain and spinal cord

pons function

-Arousal

-Controlling autonomic functions

-Relaying sensory information between cerebrum and cerebellum

-Sleep

Midbrain

-makes up brainstem with hindbrain

-connects the hindbrain and the forebrain

-involved in auditory and visual responses as well as motor function

reticular formation function

-arousal

-attention

-cardiac reflexes

-motor functions

-regulates awareness

-relays nerve signals to the cerebral cortex

-sleep

reticular formation location

a group of nerve fibers located inside the brainstem (spans the medulla, pons and midbrain)

spinal cord

-the information lifeline to an from the periphery of the body

-made up of long mass of neurons, with both cell bodies and projections from those neurons

grey portion of spinal cord

neuron cell bodies

white portion of spinal cord

myelinated fibers of tracts that communicate info to and from brain

efferent (motor) tracts

such as corticospinal tract, transmit information from brain to spinal nerves

afferent (sensory) tracts

such as spinothalmic tract, transmit info concerning the physical state of limbs and trunk to higher brain centers

spinal cord begins

-at foramen magnum of skull and courses through the vertebral canal

spinal cord is safely protected by

long tube made up of connective tissue (the meningeal linings)

Spinal nerves

31 pairs of nerves arising from regions related to vertebra

-8 cervical

-12 thoracic

-5 lumbar and sacral

-1 coccygeal