Functionality

Ppt 1 and 2

Superior colliculi

Superior colliculi

Process visual information

Inferior colliculi

Process auditory information

Tectum

Superior and inferior colliculi make it up.

Substantial nigra

Contains neurons that release dopamine

Red nucleus

Communicates with motor neurons in the spinal cord.

Reticular formation

Involved with sleep and arousal, temperature control, and motor control. The mid brain also gives rise to several cranial nerves.

Pons

Attached to the cerebellum and contains motor control and Sensory nuclei and gives rise to cranial nerves.

Medulla

Contains cranial nerves nuclei and marks the transition brain to spinal cord.

Nuclei regulates breathing and heart rate.

All axons from the to the spinal cord run through the medulla.

Brainstem

Contains pons,medulla and cerebellum.

Cerebellum"the little brain”

Elaborated convoluted and densely packed structure involved in motor coordination and learning.

Three developmental parts of medulla

Archicerebellum

Paleocerebellum

Neocerebellum

Main components of neocerebellum.

Purkinje cell, granule cell, and parallel fibres.

Purkinje cell

The middle layer, it's large cells form a single row.

Granule cell

Layer composed of small neurons whose axons form the third layer.

Parallel fibres

Makes up the third outermost layer(also called molecular)

Cortical regions

Communicate via tract of axons(fascicles)

Short-to nearby cortical regions

Longer-to other parts of cortex

Connection between hemispheres via the corpus callosum.

Long multisynaptic chains through subcortical regions.

Support systems of the brain

1 Arterial circulation

2.venous drainage

Arterial Circulation

Carotid arteries are the major arteries to the brain.

The internal carotid artery branches into anterior and middle cerebral arteries.

Vertebral arteries enter the skull and form the basilar artery,which gives rise to the posterior cerebral arteries.

Circle of willis

Is a structure formed by the major cerebral arteries.

Support drainage system of the brain.

Haemorrhagic stroke

When a rupture in an artery allows blood to leak into the brain (15%)

Mass lesions can displace nervous system structures so severely that they are shifted from one compartment to another. A situation called herniation.

Is Ischemic stroke(brain infarct)

When clots or other debris prevent blood from reaching a region of the brain, causing it to die. 85%

Ventricular system

A series of chambers fills with CSF.

CSF(cerebrospinal fluid) has 2 main functions:

1.Acts as a shock absorber

2.provides an exchange medium between blood and brain.

Choroid plexus

Membrane which produces csf.

Flow of csf

From third ventricle to the fourth ventricle whre it exists to circulate in the brain and spinal cord.

Brain barrier

See figure

Visualising gross brain anatomy.

Usr ct scans,mri,dti,physiology( PET,fMRI)

fMRI

Functional MRI detects small changes in brain metabolism such as oxygen use, in active brain areas.

Limitations of brain imaging

Speed accuracy trade off

MEG/EEG milliseconds

fMRI- sec or min

PET- hours or days.