AUDI 402 - Midterm 1

Contralateral

opposite side

ipsilateral

same side

unilateral

one-sided

rostral

towards the nose

caudal

towards the tail

dorsal / posterior

towards the back

ventral / anterior

towards the abdomen

inferior

below

superior

above

3 major structures of the brain

-Cerebrum

-Brainstem

-Cerebellum

Cerebrum

Left and right hemispheres

each hemisphere contains:

4 lobes

frontal lobe

cognitive functions

parietal lobe

memory, emotions

occipital lobe

visual

temporal lobe

audition

Broca's area

verbal expression

wernicke's area

language comprehension

Thalamus

Sensory station

Hypothalamus

body temperature, sleep, appetite, emotions, control of the pituitary gland

limbic lobe

motivation, emotion

basal ganglia

regulates motor movements

Brainstem

Contains Pons, Medulla, and Midbrain

What does the medulla control?

-heartbeat and breathing

What does the midbrain control?

-auditory and visual reflexes

Nervous system is composed of:

-Spinal cord

-brainstem

-cerebellum

-cerebrum

Central nervous system (CNS)

brain and spinal cord

Peripheral nervous system (PNS) consists of:

-spinal nerves and cranial nerves

Afferent

Info that travels towards the CNS, usually sensory

Efferent

Info that travels away from the CNS, usually motor

Peripheral nerves are:

both motor and sensory fibres

PNS divided into two systems

somatic and autonomic

autonomic nervous system

Part of the PNS, contains sympathetic and parasympathetic systems

Sympathetic system

fight or flight

Parasympathetic system

restores energy

ganglia

collection of nerve cell bodies

neurons

excitable cells that communicate with each other

Glial Cells

non-excitable cells, support neurons

apoptosis

cell death

myelination

insulation of the axon

junction formation

attaches to other cells or adheres to the extracellular matrix

Gyrus

ridges in the brain

sulcus

valleys of the brain

Longitudinal fissure

divides the two hemispheres

What is the corpus callosum?

band of fibres connecting left and right hemispheres

gray matter

cell bodies

What is white matter?

-myelinated axons

What do association fibers do?

they connect areas in the same lobe

projection fibers

communicate cerebral cortex and lower centres in brainstem

What do commissural fibers do?

-connect centres in hemispheres

What is a synapse?

-the space between 2 nerve cells

-allows messages to pass

What is the Excitatory Post Synaptic Potential (EPSP, positive)?

-When the membrane of receiving neuron becomes depolarized

-likely to fire

What is an Inhibitory Post Synaptic Potential (ISPS, negative)?

-When a Singal is hyperpolarized/inhibitory

-less likely to fire

-More negative signals

3 Meninges

dura mater, arachnoid mater, pia mater

What is Dura mater?

-The tough outer layer of the meninges

-Aluminum foil

Arachnoid mater

seals like plastic wrap

pia mater

follows all infoldings, permeable

What are the blood vessels entering and exiting the skull?

-Internal carotid arteries

-Vertebral arteries

epidural space

space between skull and dura mater

What is subdural space?

-space between dura mater and arachnoid mater

Describe the ventricular system

-source of CSF to cushion the brain

-Consists of 4 Ventricles:

Lateral Ventricles (2 of these)

3rd Ventricle

4th Ventricle

What is CSF?

CSF: Cerebrospinal Fluid

-Fluid that surrounds & protects the brain

-Produced by Epithelial cells

What are the 4 ways a lesion occurs in the ventricular system:

-excess fluid production

-tumours blocking a space

-blockage of cerebral aqueduct

-diminished absorption

What is an aneurysm?

-A large defect in blood vessel that bulges -Space-occupying lesion

Which arteries supply blood to the brain? (2)

-Internal carotid arteries (2)

-Vertebral arteries (2)

What areas of the brain do the internal carotid arteries supply?

-lateral

- anterior

-medial areas

Which areas do the vertebral arteries supply in the brain?

-posterior & inferior surfaces

-cerebellum

-brainstem

Purpose of the Circle of Willis?

-Link anterior and posterior arteries

-Provides blood supply to brain

What are the 7 Venous Sinuses?

-Superior sagittal sinus

-Inferior sagittal sinus

-Straight sinus

-Cavernous sinus

-Confluence of sinuses

-Transverse sinus

-Sigmoid sinus

What is a Hematoma vs. a Hemorrhage?

Hematoma: Slow pooling of blood; venous injury

Hemorrhage: Rapid, high pressure bleeding; arterial blood

List the various hemorrhages (3) and hematoma (1)

-Epidural Hemorrhage

-Subarachnoid hemorrhage

-Intracranial hemorrhage

-Subdural hematoma

What is an Epidural hemorrhage?

-Bleeding occurs between skull and dura mater;

-Occurs from blow to the side of the head

What is a Subdural Hematoma?

-Venous bleed, occurs between dura and arachnoid mater

What is a Subarachnoid hemorrhage?

-Rapid bleeding in the subarachnoid space

-blood mixes with CSF

What is an Intracerebral Hemorrhage?

-Bleeding within the brain tissue;

-Occurs from traumatic brain injury or a hemorrhagic stroke

What is a non-vascular injury?

-trauma to blood vessels in the skull

-cause a space-occupying lesion

-Hematoma

What is a vascular injury?

-Damage to blood vessels in skull AND loss of circulation

-hemorrhagic or ischemic strokes

What are capillaries?

Small blood vessels

What are Cerebrovascular accidents (CVA/stroke)?

-Occurs from insufficient oxygen to brain tissue;

-Can be occlusive or hemorrhagic

Types of occlusive vascular pathology:

-Thrombosis

-Embolism

What is Atherosclerosis?

-hardening of the arteries

-type of occlusive vascular pathology

what is a Transient Ischemic Attack (TIA)?

-when blood circulation to the brain stops temporarily

What is a monosynaptic reflex?

-the simplest reflex

-1 sensory neuron synapses onto 1 motor neuron

What is a complex reflex?

-Involves 1 or more interneuron

-may stimulate complex motor responses

What is an action potential?

-A nerve impulse caused by a change in the electrical charge in an axon

What is the purpose of a Schwann cell?

To cover axons of peripheral nerves

What are central pattern generators?

Constantly active special neurons

What does "Viscera" refer to?

-internal organs

List the neurons involved in Sensory Pathways:

-Primary neuron

-secondary (second order) neuron

-Tertiary/third neuron

Where does the primary neuron begin?

At a sensory receptor in the dorsal root ganglion

Where does the secondary neuron begin & end?

-begins in dorsal horn of the spinal cord

-ends in thalamus

Where does the third neuron begin & end?

-begins in thalamus

-ends in cerebral cortex

Name the types of injury of the PNS (3)

-Neurapraxia

-Axonotmesis

-Neurotmesis

What is Neurapraxia?

-light compression

-hitting your funny bone

What is axonotmesis?

-heavier compression

-axon may be severed while coverings remain intact

-stretching injury

What is neurotmesis?

-complete severance of the axon and its coverings

-from a laceration

What is Wallerian degeneration?

-Severe injury

-Part of the axon is disconnect from its cell body

-remaining debris is cleared by glial cells

What is regeneration?

regrowth from the point of injury

What is Polio?

-A viral infection of the alpha motor neuron cell body

What is Myasthenia Gravis?

-lower motor lesion

-not a peripheral nerve injury