Module 3 - Support Systems (CSF and blood supply)

What makes up the CSF system?

Ventricles, meninges, and CSF

What makes up the vascular system?

Arterial supply, veins and venous sinuses, and mechanisms to regulate blood flow

What is the role of CSF?

Nourishes the CNS and protects

Where is CSF produced and where is it located?

It is produced in the choroid plexus, and it is primarily in the lateral ventricles

What are ventricles?

Interconnected cavities in the brain that are filled with CSF

What are the characteristics of the lateral ventricle?

• One lateral ventricle in each hemisphere

• 3 horns

• Anterior horn projects into the frontal lobe, posterior horn projects into the occipital lobe, and the inferior horn projects into the temporal lobe

What are the characteristics in the third ventricle?

• Located between the anterior and posterior horns

• Connected by the inter ventricular foramen to the lateral ventricles

What are the characteristics of the fourth ventricle?

• Lies at the brain stem near the pons and medulla

• Diamond shaped

• Connected by the cerebral aqueduct to the third ventricle

How do the ventricles protect the brain and spinal cord?

CSF is produced in the lateral ventricles and then it flows through the third ventricle to the fourth ventricle. The combination of CSF produced flows out into the subarachnoid space to serve a cushion

What are the Meninges?

Dura matter, arachnoid matter, subarachnoid space, and Pia matter

What is dura matter?

Outermost layer, toughest, and most durable

Where is Pia matter located?

Directly on the surface of the brain

How does blood get to the brain?

Through 2 arteries: carotid artery and vertebral artery

What is the Circle of Willis?

A ring of interconnecting arteries at the base of the brain and it connects anterior and posterior blood supplies from the internal carotids and cerebral arteries

What is the purpose of the Circle of Willis?

It serves as a safety mechanism to prevent loss of blood flow to the brain; if one part of the brain’s blood supply is blocked, the circle of willis can provide an alternative route for the blood to continue to flow through

What are the cerebral arteries?

Anterior, middle, and posterior cerebral arteries

Where is the anterior cerebral artery?

Superior and medial areas of frontal and parietal lobes

Where is the middle cerebral artery?

Lateral surfaces of frontal, temporal, and parietal lobes; parts of internal capsule and basal ganglia

The most common artery affected from stroke

Where is the posterior cerebral artery?

Medial and inferior surfaces of temporal lobes

What is the anatomy of the cerebrum?

Cerebral cortex, white and grey matter, basal ganglia, amygdala, and diencephalon

Where is the primary motor cortex?

It is the most posterior portion of the frontal lobe (area 4)

What is the function of the primary motor cortex?

Controls voluntary movement on opposite (contralateral) side of the body

AKA the motor homunculus

What does damage to the primary motor cortex cause?

Contralateral paralysis, loss of fraction movement (impaired fine motor control), and dysarthria (speech disorder caused by muscle weakness)

What are the functions of the premotor area?

Guides body movements and regulate posture by integrating sensory information. It also controls the muscles closest to the body’s main axis

What does damage to the premotor area cause?

Loss of ability to plan and execute movement even though muscles are intact, AKA motor apraxia

What are the functions of the supplementary motor area?

Planning and initiation of movements based on past experiences. Also coordinating bimanual and complex sequential movements 

What does damage to the supplemental motor area cause?

Loss of ability to plan and execute movement even though muscles are intact, AKA motor apraxia 

What is praxis?

The ability to plan and execute movements cognitively and physically; neurological process which means cognition guides movement

What are the different components of praxis?

Ideation, motor organization, execution, feedback and adaption

What is apraxia?

The inability to perform purposeful movements; they have the physical ability to complete the task but they understand the commands of completing the task

What is motor apraxia?

Difficulty with movements and/or use of objects to perform meaningful activities; Damage to the supplementary motor area and premotor area; contributes to clumsiness

What is ideational apraxia?

Impaired cognitive understanding of motor demands for a task; Damage to the prefrontal cortex; inability to conceptualize, plan, or understand steps needed to perform task

Where is Broca’s area?

In the inferior frontal gyrus

What is Broca’s areas function?

Plan speech production and grammatical aspects of language

What does damage to Broca’s area cause?

Broca’s aphasia (expressive aphasia); speech is coherent but lacks fluidity

What is perception?

The activation of the brain, body, and environment to interpret sensation into meaningful forms

What does perception involve?

Memory, motivation, expectations, and selective of sensory information

What is important to know about perception?

It requires input from many different areas of the cerebrum, including secondary sensory and cortical association areas

Where is the primary somatosensory area located?

Anterior portion of the parietal lobe

What is the function of the primary somatosensory area?

Localize touch and proprioceptive input from opposite side of the body including shape, texture, size

What does damage of the primary somatosensory area cause?

Contralateral sensory loss

Where is the secondary somatosensory area located?

Posterior portion of parietal lobe

What is the function of the secondary somatosensory area?

Stereognosis: the ability to identify objects based on touch alone

Where is the primary visual cortex located?

Posterior region of the occipital lobe

What is the function of the primary visual cortex?

To detect visual input like size, shape, texture

Where is the secondary visual area?

The remainder of the occipital lobe

What is the function of the secondary occipital lobe?

To interpret visual data and attach meaning to an object: color, shape, pattern, motion

What is the dorsal stream of the secondary visual areas purpose?

Analysis of motion and action

Ex: when to reach out to catch a ball

What is the ventral stream of the secondary visual areas purpose?

Perception and object recognition

What does damage of the secondary visual area cause?

Visual agnosia and optic ataxia

What is visual agnosia?

The ability to describe an objects shape and size, but cannot identify its name using only vision

Ex: describing the characteristics of an apple, but cannot remember its called apple

What is optic ataxia?

The inability to use visual information to adjust movement

Ex: inability to pick up an object even though they can see it

Where is the primary auditory cortex?

Temporal lobe

What is the function of the primary auditory area?

Conscious awareness and recognition of sounds from the environment

What does damage to the primary auditory area cause?

Single hemisphere damage causes unilateral deafness and bilateral deafness if both hemispheres are involved

Where is the secondary auditory area located?

Temporal lobe

What is the function of the secondary auditory area?

Categorization and interpretation of sounds; compares sounds with other memories of sounds

Ex: different animal sounds, language

Where is Wernicke’s area?

Left temporoparietal junction

What is the function of Wernicke’s area?

Comprehension of spoken words and language

What does damage to Wernicke’s area cause?

Wernicke’s aphasia (receptive language): inability to understand language or add meaning to spoken language

Ex: sentences do not make sense; the man went to the dirt to feed ice cream

Where is the primary vestibular cortex?

Parietal and temporal lobe

What is the function of the primary vestibular area?

Perception of head orientation and movement; up, down, right, left

What is the primary vestibular cortex responsible for?

Vestibular system functions, eye movements, postural adjustments, and autonomic functions and consciousness

What is ataxia?

Impaired balance from the cerebellum