clinical neuroanatomy test - wordpress.com

TESTKhaleel Alyahya, PhD, MEdwww.khaleelalyahya.net

CLINICAL NEUROANATOMY Khaleel Alyahya, PhD, MEdwww.khaleelalyahya.net

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Resources

Clinical Neuroanatomy

Richard Snell

Essential of Human Anatomy & Physiology

Elaine Marieb

Gray’s Anatomy

Richard Drake, Wayne Vogl & Adam Mitchell

Atlas of Human Anatomy

Frank Netter

KENHUB

www.kenhub.com

2

INTRODUCTION

The nervous system is arguably the most complex system in thebody.

It facilitates internal communication within the body by integratingand controlling the various functions of the body.

The nervous system is responsible for sending, receiving andprocessing nerve impulses, while the sense organs detect thevarious stimuli in the external environment that humans react to.

Sense organs provide the nervous system with information aboutthe environment by means of such senses as sight, hearing, smell,taste and touch.

The activities that keep the body operating, such as respiration,digestion, heart pumping, movement, all the senses, and the uniqueprocesses that make us human such as thinking, dreaming, laughingand memory, are not possible without a properly functioningnervous system.

3 Khaleel Alyahya, PhD, MEd

FUNCTIONS

Sensory Input - collect

information

Integration

Motor Output – send

feedback


STRUCTURAL CLASSIFICATION

Central Nervous System

Peripheral Nervous System

STRUCTURAL ORGANIZATION

Central Nervous System (CNS)

• Organs

o Brain.

o Spinal cord.

• Functions:

o Integration; command center.

o Interprets incoming sensory information.

o Issues outgoing instructions.

Peripheral Nervous System (PNS)

• Nerves extending from the brain and spinal cord.

o Spinal nerves—carry impulses to and from the spinal cord.

o Cranial nerves—carry impulses to and from the brain.

• Functions:

o Serve as communication lines among sensory organs, the brain and spinalcord, and glands or muscles.


FUNCTIONAL CLASSIFICATION

Sensory (Afferent)

Motor (Efferent)

FUNCTIONAL ORGANIZATION

Sensory (afferent) division

• Nerve fibers that carry information to the central nervous system.

o Somatic sensory (afferent) fibers carry information from the skin, skeletal muscles,and joints.

o Visceral sensory (afferent) fibers carry information from visceral organs.

Motor (efferent) division

• Nerve fibers that carry impulses away from the central nervous system organs toeffector organs (muscles and glands).

• Two subdivisions:

o Somatic nervous system = voluntary.

• Consciously (voluntarily) controls skeletal muscles.

o Autonomic nervous system = involuntary.

• Automatically controls smooth and cardiac muscles and glands.

• Further divided into the sympathetic and parasympathetic nervous systems.

Interneurons (association neurons)

• Cell bodies located in the CNS

• Connect sensory and motor neurons


NEURONS

Cells specialized to transmit messages (nerve impulses).

Major regions of all neurons:

• Cell body—nucleus and metabolic center of the cell.

• Processes—fibers that extend from the cell body.

Processes (fibers)

• Dendrites—conduct impulses toward the cell body.

o Neurons may have hundreds of dendrites.

• Axons—conduct impulses away from the cell body.

o Neurons have only one axon arising from the cell body at the axon hillock.

o End in axon terminals, which contain vesicles with neurotransmitters.

o Axon terminals are separated from the next neuron by a gap.

• Synaptic cleft—gap between axon terminals and the next neuron.

• Synapse—functional junction between nerves where a nerve impulse istransmitted.


CEREBRUM

Cerebral areas involved in special senses

• Visual area (occipital lobe)• Auditory area (temporal lobe)• Olfactory area (temporal lobe)• Primary motor area

o Located anterior to the central sulcus in the frontal lobeo Allows us to consciously move skeletal muscleso Motor neurons form pyramidal (corticospinal) tract, which descends to spinal cord.

• Broca’s area (motor speech area)o Speech Productiono Involved in our ability to speako Usually in left hemisphere

• Other specialized areaso Anterior association area (frontal lobe)o Posterior association area (posterior cortex)o Speech area (Wernicke’s area) (for comprehension of written and spoken language)

Cerebral white matter

• Composed of fiber tracts deep to the gray mattero Corpus callosum connects hemisphereso Tracts, such as the corpus callosum, are known as commissureso Association fiber tracts connect areas within a hemisphereo Projection fiber tracts connect the cerebrum with lower CNS centers


DIENCEPHALON

Sits on top of the brain stem.

Made of three structures:

• Thalamus• Hypothalamus• Epithalamus

Thalamus

• Encloses the third ventricle• Relay station for sensory impulses passing upward to the cerebral cortex• Transfers impulses to the correct part of the cortex for localization and

interpretation

Hypothalamus

• Makes up the floor of the diencephalon• Important autonomic nervous system center

o Regulates body temperature

o Regulates water balance

o Regulates metabolism

• Houses the limbic center for emotions• Regulates the nearby pituitary gland• Houses mammillary bodies for olfaction (smell)

Epithalamus

• Forms the roof of the third ventricle• Houses the pineal body (an endocrine gland)• Includes the choroid plexus—forms cerebrospinal fluid


BRAINSTEM

Midbrain

• Extends from the mammillary bodies to the pons inferiorly

• Cerebral aqueduct (tiny canal) connects the third and fourth ventricles

• Two bulging fiber tracts, cerebral peduncles, convey ascending anddescending impulses

• Four rounded protrusions, corpora quadrigemina, are visual and auditoryreflex centers

Pons

• The rounded structure protruding just below the midbrain

• Mostly composed of fiber tracts

• Includes nuclei involved in the control of breathing

Medulla Oblongata

• The most inferior part of the brain stem that merges into the spinal cord

• Includes important fiber tracts

• Contains important centers that control:

o Heart rate and Blood pressure

o Breathing, Swallowing and Vomiting

• Fourth ventricle lies posterior to pons and medulla


CEREBELLUM

Two hemispheres with convoluted surfaces.

Outer cortex of gray matter and inner region of white matter.

Control balance.

Provides precise timing for skeletal muscle activity and coordinationof body movements.


SPINAL CORD

Extends from the foramenmagnum of the skull to the first or second lumbar vertebra

Cauda equina is a collection of spinal nerves at the inferior end

Provides a two-way conduction pathway to and from the brain

31 pairs of spinal nerves arise from the spinal cord

Gray matter of the spinal cord and spinal roots

• Internal gray matter is mostly cell bodies

• Dorsal (posterior) horns house interneurons

o Receive information from sensory neurons in the dorsal root; cell bodies housed in dorsal root ganglion

• Anterior (ventral) horns house motor neurons of the somatic (voluntary) nervous system

o Send information out ventral root

• Gray matter surrounds the central canal, which is filled with cerebrospinal fluid

White matter of the spinal cord

• Composed of myelinated fiber tracts

• Three regions: dorsal, lateral, ventral columns

• Sensory (afferent) tracts conduct impulses toward brain

• Motor (efferent) tracts carry impulses from brain to skeletal muscles14 Khaleel Alyahya, PhD, MEd

MENINGES

Dura mater

• Outermost leathery layer

Arachnoid mater

• Middle layer

• Weblike extensions span the subarachnoid space to attach it tothe pia mater

• Subarachnoid space is filled with cerebrospinal fluid

Pia mater

• Internal layer

• Clings to the surface of the brain and spinal cord


CEREBROSPINAL FLUID

Similar to blood plasma in composition.

Formed continually by the choroid plexuses.

• Choroid plexuses—capillaries in the ventricles of the brain.

CSF forms a watery cushion to protect the brain and spinal cord.

Flows through the ventricles and into the subarachnoid space via themedian and lateral apertures. Some CSF flows through the central canalof the spinal cord.

CSF flows through the subarachnoid space.

CSF is absorbed into the dural venous sinuses via the arachnoid villi.


BLOOD SUPPLY

The cerebral arterial supply is provided by two systems:

• Carotid System

o Supply anterior portion of the brain.

• Vertebro-Basilar System

o Supply posterior portion of the brain.

Anterior Cerebral Arteries

o Supplies orbital and medial surfaces of frontal and parietal lobes

Posterior Cerebral Arteries

o Anterior and inferior temporal lobes.

o Inferior and Medial Occipital lobe.

Middle Cerebral Arteries

o Somatosensory Cortex

o Motor Cortex

o Broca’s and Wernicke’s Areas

o Area

o Heschl’s Gyrus


OCCLUSION OF CEREBRAL ARTERIES

Occlusion of anterior cerebral artery

• Motor disturbance in contralateral distal leg• Difficulty in prefrontal lobe functions:

o Cognitive thinking

o Judgment

o Motor initiation

o Self monitoring

Occlusion of posterior cerebral artery

• Visual disturbanceso Contralateral homonymous hemianopsia

o Bilateral lesions: cortical blindness

• Memory impairmento If temporal lobe is affected

Occlusion ofmiddle cerebral artery

• Contralateral weakness of:o face, arm, and hand more than legs

• Contralateral sensory loss of:o face, arm, and hand more than legs

o visual field cut (damage to optic radiation)

• Aphasia: language disturbanceso Broca's: production

o Wernicke's: comprehension18 Khaleel Alyahya, PhD, MEd

ANGIOMA

An angioma is a benign growth that consists of small blood vessels.

These tumors can be located anywhere on the body.

Some of the different types include spider angiomas andcherry angiomas.

The cause of most types of angiomas is not known.

Cherry angiomas are due to aging and do not have any knownsignificance.

Surgical procedure is the most common option to treat angioma.


ANEURYSM

An aneurysm is a localized dilation or ballooning of an arterial wall due toweakness in the wall of the blood vessel.

The aorta, cerebral and mesenteric arteries are most commonly affected.

If the aneurysm ruptures it becomes a life-threatening emergency.

Surgery may be performed to repair the defect or minimally invasivetreatment involving placement of coils or stents introduced through otherarteries of the body or neck and guided into the affected vessel may beperformed.


STROKE

A stroke occurs when part of the brain loses its blood supply and stopsworking.

This causes the part of the body that the injured brain controls to stopworking.

A stroke also is called a cerebrovascular accident, CVA, or brain attack.

Caused by sudden occlusion or hemorrhage


SINUS THROMBOSIS

Superior sagittal sinus thrombosis

• Can complicates ear infection.

Cavernous Sinus thrombosis

• As a complication of infection in the dangerous area of the face.

Obstruction of venous drainage of the brain leads to Cerebralswelling (edema) and raised Intracranial Pressure.


ALZHEIMER’S DISEASE

Alzheimer’s disease (dementia) also known as Alzheimer’s dementia, isan irreversible, progressive brain disorder of deteriorating mentalcapacity.

It is characterized by confusion, memory loss, other cognitive defectsand eventually even the inability to carry out the simplest tasks oractivities of daily living.

The Alzheimer’s brain is characterized by the deposit of amyloid plaquesand atrophy.

Alzheimer’s disease is the most common cause of dementia amongolder people.


PARKINSON’S DISEASE

Parkinson’s disease is a slowly progressive, degenerative neurologicdisorder.

Nerve cells in the brain deteriorate causing a deficiency of theneurotransmitter dopamine.

Parkinson’s disease is characterized by:

• Rhythmic fine tremors or trembling in the hands, arms, legs, jaw and face.

• Stiffness of the limbs and joints.

• Bradykinesia.

• Impaired balance and coordination.

It causes weakness and stiffness of the muscles and interferes withspeech, walking and daily tasks.

There is no cure for Parkinson’s disease, therefore treatment is aimed atimproving the symptoms.


EPILEPSY

Epilepsy is an episodic neurological disorder characterized by recurrent,transient abnormal electrical activity in the brain.

The normal pattern of neuronal activity becomes disturbed, causing aperiod of confusion, sensory disturbances, a staring spell, convulsions,muscle spasms and/or loss of consciousness.

Epilepsy has many possible causes, including illness, an imbalance ofneurotransmitters, brain injury and abnormal brain development.

In many cases, the cause is unknown.

Epilepsy is classified by the type of seizure; partial or focal andgeneralised.

In partial seizures, there is no loss of consciousness rather the patient mayappear to be daydreaming with only mild symptoms.

Generalised seizures include a loss of consciousness with possible musclespasm.

Epilepsy can usually be controlled by anticonvulsant medications.


MENINGITIS

Meningitis is an inflammation in the meninges.

Most cases are due to a bacterial or viral infection.

Meningitis usually has a sudden onset and is characterized by a severeheadache, neck stiffness, irritability, fever, nausea, vomiting and delirium.

A particular type of meningitis, meningococcal meningitis, is characterizedby a rapidly spreading rash.

Meningitis can be life threatening because of the proximity to the brainand spinal cord; therefore, the condition is classified as a medicalemergency.

A lumbar puncture is performed to diagnose the condition.

Treatment is with specific antibiotics.


PARALYSIS

Paralysis is loss of the ability to move one or more muscles.

It may be associated with loss of feeling and other bodily functions.

Paralysis may be partial or complete, and temporary or permanent.

It is not usually caused by problems with the muscles, but by problemswith the spinal cord or nerves that control muscles.

A person with paralysis will usually have some form of nerve damage.

Most paralysis results from cerebrovascular accidents and spinal cordinjuries.

Other causes of paralysis include Bell’s palsy, multiple sclerosis, andGuillain-Barré syndrome.


CEREBRAL PALSY

It refers to a variety of neurological conditions that manifest as disordersof movement or posture.

Body movement and muscle coordination are permanently affected.

While it may appear to be a muscular disorder, cerebral palsy isactually due to damage to the part of the brain that controls musclemovements.


BELL’S PALSY

Bell’s palsy is a condition that causes a temporary weakness or paralysis ofthe muscles in the face.

It can occur when the nerve that controls your facial muscles becomesinflamed, swollen, or compressed.

The condition causes one side of your face to droop or become stiff.

You may have difficulty smiling or closing your eye on the affected side.

In most cases, Bell’s palsy is temporary and symptoms usually go awayafter a few weeks.

Although Bell’s palsy can occur at any age, the condition is more commonamong people between ages 16 and 60.

Bell’s palsy is named after the Scottish anatomist Charles Bell, who was thefirst to describe the condition.


MULTIPLE SCLEROSIS

It is a progressive degenerative neurological disease with scatteredpatches of demyelination of nerve fibres of the brain and spinal cord.

Common symptoms include tingling, numbness, muscle weakness orspasm, ataxia, dysarthria, dysphagia, visual problems (such as diplopia),fatigue, pain and bladder and bowel incontinence.


HYDROCEPHALUS

It is an increased amount of cerebrospinal fluid (CSF) within the ventricles ofthe brain.

It results in an abnormal widening of the ventricles.

This widening creates a potentially harmful increase in pressure on thecerebral tissues.


CAUDA EQUINA SYNDROME

The cauda equina is a bundle of spinal nerves that arise from the distalend of the spinal cord.

They run in the subarachnoid space, before exiting at their appropriatevertebral level.

Compression of these nerves produces a range of signs and symptomscollectively termed cauda equina syndrome.

There are many causes of compression, including intervertebral discprolapse, extrinsic or primary cord tumours, spinal stenosis, trauma andabscess formation.

Suspected cauda equina patients should be assessed with a full lowerlimb neurological assessment.

If sufficient clinical evidence exists, an MRI is required immediately fordiagnosis.

Any confirmed case must be sent for surgery within 36 hours of firstpresentation of the symptoms for surgical decompression.


GLAUCOMA

Glaucoma is an eye disease in which the optic nerve at the back of theeye atrophies.

In most people this damage is due to raised intraocular pressure dueto problems with the drainage of the aqueous humor.

Chronic (primary open-angle) glaucoma is the most common type.

Damage progresses very slowly and destroys vision gradually, startingwith peripheral vision.

It has no real symptoms until eyesight is lost at a late stage.

It can lead to blindness if not treated.


CEREBRAL ANGIOGRAPHY

Cerebral angiography is a procedure which uses radio-opaque contrastto record x-ray images of the blood vessels in the brain to identifyconditions such as aneurysms, occlusion and haemorrhage in the brain.


CEREBRAL FLUID ANALYSIS

Cerebrospinal fluid (CSF) analysis is a test that is undertaken todiagnose a range of diseases and conditions affecting the CNS.

Conditions include infectious diseases such as meningitis andencephalitis, haemorrhaging from the brain and tumours within theCNS.


LUMBAR PUNCTURE

It is a medical procedure in which a needle is inserted into the spinalcanal, most commonly to collect cerebrospinal fluid (CSF) for diagnostictesting.

The patient lies on one side, curled forward to open the interspinousspaces of the lumbar region.

The spine of vertebra L4 is identified in the intercristal (supracristal) planeat the level of the tops of the iliac crests.

Under aseptic conditions, a lumbar puncture needle is introducedobliquely above the spine of vertebra L4, parallel to the plane of thespine.

The needle is passed through the interspinous ligament.

A slight give is perceived when the needle pierces the dura–arachnoidmater and enters the subarachnoid space.

Transverse section showing the cauda equina floating in the subarachnoidspace.

The anterior and posterior roots of spinal nerve L3 are coming together asthey leave the lumbar cistern.


COMPUTED TOMOGRAPHY

A CT is a diagnostic test that can be used to identify disorders of thebrain and spinal cord.


MAGNETIC RESONANCE IMAGING

MRI is a process of diagnostic testing to create images of the brainusing radio waves and a magnetic field to identify lesions that cannotbe easily noted on x-ray


DOPPLER ULTRASOUND STUDY

A Doppler ultrasound study is a test using ultrasound technology toanalyze the speed of blood flow in the carotid and intracranial arteriesby measuring echoes from the blood vessel


Thank YouJens Martensson

+1 23 987 6554

[email protected]

http://www.fabrikam.com/

Questions?Jens Martensson

+1 23 987 6554

[email protected]


Questions? Khaleel Alyahya

+966 11 4670811

[email protected]

www.khaleelalyahya.net



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