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133 Cards in this Set
- Front
- Back
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Where does the transition between the brain stem and spinal cord occur?
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Foramen magnum
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What is the significance of the tonsil?
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The tonsil sits right above the foramen magnum and will herniate through the foramen magnum with increased intracranial pressure, compressing the brain stem and causing loss of consciousness and death.
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What is the difference between gray matter and white matter?
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Gray matter is composed of cell bodies, and white matter is composed of myelinated axons.
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What are fasciculi and funiculi?
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Fasciculi are tracts of bundled axons, which are further bundled into columns/funiculi.
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What is the only part of the brain that can activate voluntary motor activity?
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Motor cortex
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What are the three parts of the brain stem?
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1. Midbrain (adjacent to diencephalon)
2. Pons 3. Medulla oblongata |
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What are the four parts of the diencephalon?
Why is it called the diencephalon? |
1. Thalamus
2. Hypothalamus- sensory and motor processing 3. Epithalamus- pituitary regulation 4. Subthalamus It is called the diencephalon because it is tucked between the two large hemispheres of the cerebrum. |
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What does the cerebellum do?
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The cerebellum coordinates motor activity and is involved in motor learning.
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What happens if the cerebellum is damaged?
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Ataxia/incoordination
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How is the cerebrum organized?
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The cerebrum is divided into two hemispheres. Gray matter is on the outside, white on the inside. There are many ventricles.
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What are the four lobes of the cerebrum?
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1. Occipital
2. Parietal 3. Frontal 4. Temporal |
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What connects the two cerebral hemispheres?
Is it composed of gray or white matter? |
Corpus callosum
White matter |
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What are the two cerebral speech centers?
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Anterior- Broca's (expression of language)
Posterior- Wernicke (understanding of and response to language) |
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What are the two functions that are not symmetrically represented in the cortex?
How is this related to right/left handedness? |
Language- left
Spatial function- right Right handed people tend to follow these divisions. Left handed people may be right dominant for speech or have bilateral representation of speech. |
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How are cerebral ventricles related to the neural tube?
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Ventricles are the developed lumen of the neural tube.
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In general, what in the head and neck is innervated by somatosensory nerve components?
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Anything of ectodermal derivation (ie. skin, cornea, some mucosal surfaces)
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From where do sympathetics to head and neck structures originate?
Where do they synapse? |
Sympathetics to the head and neck originate in the T1-T5 spinal cord segments.
They synapse in the superior cervical sympathetic ganglion. |
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What four functions do sympathetics perform in the head and neck region?
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1. Sweating of the face
2. Constricting arteries in the face 3. Pupil dilation 4. Eyelid elevation (superior tarsal muscle) |
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Which three cranial nerves have only special sensory components?
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Olfactory (I)- smell
Optic (II)- vision Vestibulocochlear (VIII)- Hearing/balance |
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Which four cranial nerves contain only somatomotor components?
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1. Trochlear (IV)- eye muscle
2. Abducent (VI)- eye muscle 3. Accessory (XI)- trapezius and SCM 4. Hypoglossal (XII)- tongue muscles There are no somatosensory or symp/post components in these nerves! |
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Which cranial nerve has only two components?
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Oculomotor (III)- somatomotor, para/pre
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What are the nerve components of the root of the trigeminal?
What are the components of its three branches? |
Trigeminal (V)- somatosensory, somatomotor
Ophthalmic (V1)- somatosensory Maxillary (V2)- somatosensory Mandibular (V3)- somatosensory, somatomotor |
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What are the nerve components of the facial nerve?
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Facial (VII)- somatosensory, somatomotor, taste, parasympathetic
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What are the nerve components of the glossopharyngeal nerve?
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Glossopharyngeal (IX)- viscerosensory, somatomotor, taste, parasympathetic
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What are the nerve components of the vagus nerve?
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Vagus (X)- viscerosensory, somatomotor, taste, parasympathetic
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Which cranial nerves have pharyngeal arch association? With which arches are they associated? What are the four components found within a pharyngeal arch?
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Trigeminal- mandibular (V3): 1st pharyngeal arch
Facial (VII): 2nd pharyngeal arch Glossopharyngeal (IX): 3rd pharyngeal arch Vagus- superior laryngeal branch (X): 4th pharyngeal arch Vagus- recurrent laryngeal branch (X): 6th pharyngeal arch 1. Mesenchyme 2. Cartilage 3. Aortic arch 4. Cranial nerve |
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Defects in what embryonic structure result in hemifacial microsomia?
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1st (mandibular) pharyngeal arch
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What is the significance of the former location of the buccopharyngeal membrane?
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Everything in front of it has somatosensory innervation and everything behind it has viscerosensory innervation.
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What are the two layers of the dura in the cranial cavity?
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Periostial layer and meningeal layer. They may separate to form venous sinuses.
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Where is the anterior attachment of the falx cerebri? Posterior?
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Anterior:Crista galli
Posterior: Tentorium cerebelli |
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What is the anterior attachment of the tentorium cerebelli?
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Petrosal ridge
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What is a reason that tentorial herniations are dangerous, in relation to a meningeal layer?
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When a tentorial herniation occurs, the temporal lobe is pushed down over the sharp edge of the tentorium cerebelli and can be cut.
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In what direction does blood flow within dural venous sinuses?
Name the seven dural sinuses. Through what structure do the dural sinuses ultimately drain? |
Anterior to posterior
1.Superior sagittal sinus 2. Inferior sagittal sinus 3. Straight sinus 4. Confluence of sinuses 5. Transverse sinuses 6. Sigmoid sinuses 7. Cavernous sinuses Internal jugular veins |
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What are the two types of veins that drain into the superior sagittal sinus?
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1. Cerebral/bridging vein- drains cerebral hemispheres
2. Emissary vein- drains from outside of skull |
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What are the three types of vascular accidents that may occur within the cranial cavity? Describe their vascular origin, causes, and location within the cranial cavity.
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1. Subdural hematoma- Occurs as a result of head trauma that causes rupture of a cerebral vein. Blood accumulates between dura and arachnoid.
2. Epidural hematoma- Occurs as a result of head trauma that causes rupture of middle meningeal arteries. Blood accumulates between dura and cranium. 3. Subarachnoid hematoma- Occurs as a result of a stroke, causing rupture of cerebral artery and resulting in accumulation of blood between arachnoid and pia. |
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Why is infection a danger in the cavernous sinus?
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Infection is a danger in the cavernous sinus because blood flow is slow due to the presence of trabeculae. Infection may occur as a result of a pimple being squeezed and inoculating the facial nerve.
Blindness may result. |
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What is the only location in the body where an artery runs within a vein? Name the two vessels.
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The internal carotid artery runs within the cavernous sinus.
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Why is the interior of a cell negatively charged?
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Potassium is leaving more rapidly than sodium is entering, and there are a few more chloride ions inside.
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What are the three states in which one might find a voltage-gated ion channel?
Why is this important? |
Closed-open-inactive. Channels can move freely between closed and open, but conversion to inactive is reversible.
Many diseases are due to alterations in rate constants for conversion between these states. |
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How does the relationship between K efflux and Na influx change at threshold?
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At threshold a number of sodium channels opens that allows Na influx to exceed K efflux.
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What are the three types of neuroglia in the CNS?
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1. Oligodendrocytes
2. Astrocytes 3. Microglia |
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What are the CNS equivalents of the epineurium, perineurium, and endoneurium?
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Epineurium- dura mater
Perineurium- arachnoid Endoneurium- pia mater |
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Between which meningeal layers is CSF found?
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Between the pia and the arachnoid, in the subarachnoid space.
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What microanatomical structures help the arachnoid keep CSF from leaking?
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Tight junctions and desmosomes
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Which meningeal layer is epithelioid?
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Arachnoid
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What type of cells lines the central canal of the spinal cord?
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Ependymal cells
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How is the blood-brain barrier maintained?
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Endothelial cells of vessels within the CNS are continuous, allowing no gaps between cells. Endfeet of astrocytes surround the vessels and help maintain the endothelial phenotype.
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What cells in the CNS produce myelin?
Is myelin secreted? |
Oligodendrocytes
No, it is the oligodendrocyte membrane wrapped around the axon. |
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What protein is responsible for linking membranes of myelin?
What happens when this protein is mutated? |
P0
Mutation causes demyelination disease. |
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What is the astrocyte-comprised membrane that maintains capillary phenotype called?
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Glia limitans
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What is the cellular origin of microglia?
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Most likely monocytes
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Name four functions/features of microglial cells.
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1. Secretion of growth factors during development
2. Reaction to injury, including cytokine and protease release 3. Vulnerable to HIV infection 4. Beta-amyloid production in Alzheimer's |
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What muscle attaches to the epicranial aponeurosis and subcutaneous tissue of the eyebrows?
What movement is it responsible for? |
Frontalis
Lift the eyebrows (ie, in surprise) |
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What muscle is responsible for closing the eye, blinking, and winking?
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Orbicularis oculi
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What is the sphincter muscle around the mouth?
For what is this muscle used? |
Orbicularis oris
Pursing lips, whistling, kissing |
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Name the muscle running from the base of the mandible to the subclavicular region?
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Platysma
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What muscle is responsible for compressing the cheeks to the teeth, blowing up balloons, blowing into instruments?
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Buccinator
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How many peripheral somatomotor branches does the facial nerve have?
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5
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Which nerves pass through the internal auditory meatus?
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CN VII and VIII
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What nerve innervates the frontalis and orbicularis oculi?
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Temporal and zygomatic branches of the facial nerve
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What nerve innervates the orbicularis oris and the buccinator?
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Buccal branch of the facial nerve
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What nerve innervates the orbicularis orbis alone?
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Mandibular branch of the facial nerve
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What nerve innervates the platysma?
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Cervical branch of the facial nerve
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What is the landmark above and below which the buccal branches of the facial nerve lie?
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Parotid duct
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Bell's palsy is caused by paralysis of which cranial nerve?
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Cranial nerve VII, the facial nerve
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Describe some of the visible effects of Bell's palsy.
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Unilateral drooping mouth corner, inability to close eye, smoothing of forehead
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What causes Bell's palsy?
What is the prognosis? |
Unknown.
Irritated facial nerve becomes swollen due to inflammation. May be caused by HSV1, Lyme disease, metabolic issues. Spontaneous recovery within 3-4 months. |
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What is the largest salivary gland?
Where is it in relation to the ear? the masseter muscle? |
Parotid gland
Anterior and inferior to the ear, superior to the masseter muscle |
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Name the two smaller salivary glands.
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Sublingual and submandibular
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Describe the relationship of the parotid duct to the masseter and buccinator muscles.
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The parotid duct runs superficially along the masseter muscle and pierces the buccinator muscle.
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What is the relationship of the retromandibular vein to the parotid gland, external carotid artery, and facial nerve?
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Through the parotid, superficial to the external carotid artery, deep to the facial nerve
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Name the two branches of the external carotid artery.
What is the relationship of the external carotid artery to the retromandibular vein? |
Superficial temporal artery and maxillary artery
The external carotid artery is deep to the retromandibular vein. |
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Describe the gross effects of mumps.
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Swelling and inflammation of the salivary glands, particularly the parotid. Swollen glands make it painful to chew, swallow and talk.
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Through which foramen does V1 (ophthalmic division) exit?
What does it innervate? |
Superior orbital fissure
Upper eyelid, skin of forehead.... |
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Through which foramen does V2 (maxillary division) exit?
What does it innervate? |
Foramen rotundum
Lower eyelid...... |
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Through which foramen does V3 (mandibular division) exit?
What does it innervate? |
Foramen ovale
Lower lip, skin of chin, mandible, anterior external ear |
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Trigeminal cutaneous branches
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Look at the slide and make some questions
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Describe trigeminal neuralgia/tic douloureux.
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Sudden attack of stabbing, shock-like pain on one side, usually with one division of the trigeminal nerve. It has an increased incidence in individuals with a pierced tongue. It is thought to be a neurovascular problem. It is treated by either placing a pad between the trigeminal nerve and adjacent blood vessels, or by percutanous stereotactic radiofrequency lesion procedure (RFL), which basically zaps the affected nerve.
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From which artery does the facial artery arise?
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External carotid artery
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Which is more tortuous- the facial vein or facial artery? Which is more superficial?
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Artery and artery
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Does the brain itself hurt?
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No, the blood vessels and meninges hurt.
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What is a secondary headache?
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A secondary headache is a sign of serious problems which need to be immediately treated, such as a subarachnoid hemorrhage, trauma, substance abuse, metabolic disorders, infections, head or neck pathology, cranial neuralgias, psychiatric disorders.
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Are primary headaches serious?
Name three types of primary headaches. |
No
Migraine, cluster, tension |
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What headaches are the most concerning, as described by the patient?
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First or worst
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How would you work up a first or worst headache?
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Do a CT scan to look for blood in the brain. If that is negative, do an LP to look for infection or blood. If that is negative, do an MRI to look for aneurisms.
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As time from headache onset increases, which becomes the more reliable test out of CT and LP?
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LP stays at 100% sensitivity until week 3.
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What are the red flag symptoms for headaches?
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SNOOP
Systemic symptoms Neurologic symptoms Onset (sudden) Older (50+ yrs.) Previous headache history |
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What are some signs of a secondary headache?
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Tinnitus, blurred vision, double vision, stiff neck, nerve palsies
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What are the criteria for a migraine?
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5+ episodes lasting 4-72 hours with:
2 of the following: unilateral throbbing worsened by movement moderate-severe PLUS 1 of the following: nausea/vomiting photophobia phonophobia |
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Describe a migraine with aura.
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2+ attacks with 3 of the following:
Fully reversible Evolves over 4 minutes Lasts less than 60 minutes Headache onset within an hour |
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How does a migraine work?
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Neurons of the occipital cortex are hyperexcitable. This can be triggered by light, too much or too little of just about anything (exercise, emotion, sleep). Theories for the cause of hyperexcitability include mutation in Ca channels, brain mitochondrial dysfunction, and low magnesium levels.
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Describe the pathogenesis of aura.
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There is a depression of brain activity, perhaps due to hyperexcitability or increase in blood supply. An area of the pons is the primary generator of stimulation of the hyperexcitable neurons.
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When should a migraine be treated?
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When the pain is mild, within 15 minutes of onset.
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What is the major contraindication for the use of triptans for migraine?
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Cardiovascular disease
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What type of headache is more common in men?
Where is the pain located? Describe the headache. What is the part of the brain associated with this type of headache? |
Cluster headaches
Located behind the eye Unilateral, unique time pattern, red eye, nasal signs, lasts 15-180 minutes, excruciating, restless Hypothalamus |
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What are the four components of the light sensing system?
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1. Rods- seeing in the dark
2. Cones 3. Pineal- not really used by humans 4. ipRGC- Circadian rhythm maintenance |
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What are the three types of chemical sensing?
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1. Olfaction
2. Taste 3. Pheromones- not well understood in humans |
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What are the four types of mechanical sensing?
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1. Hearing
2. Touch 3. Vibration 4. Muscle sense |
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What are the four somatosensory receptors?
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1. Pain
2. Noxious 3. Hot 4. Cold |
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What is the general organization of the sensory receptor neuron?
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Specialized area for reception at one pole, cell body, synaptic terminal at other pole.
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How is a stimulus translated into a signal in the body?
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The stimulus generates a graded membrane potential proportional to its strength. When the graded membrane potential reaches the threshold for action potential, an action potential is generated to signal the next neuron. The strength of the stimulus is proportional to the number of action potentials that are generated.
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Describe the idea of sensory adaptation.
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Adaptation is the process by which the sensory system is adjusted to adapt to the ambient baseline for a stimulus, so the system doesn't saturate.
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What sensation do Meissner's corpuscles translate?
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Light touch
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What sensation do Merkel's corpuscles translate?
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Touch
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What sensation do free terminals translate?
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Pain
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What sensation do Pacinian corpuscles translate?
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Deep pressure
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What sensation do Puffini corpuscles translate?
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Warmth
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How can large receptive fields still convey very particular information?
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Large receptive fields may overlap with one another, allowing the body to triangulate the position of the stimulus based on the relative signal strength from different neurons.
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How does the body focus its transmission of sensory signals?
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When a peripheral neuron receives a signal, it signals to its central neuron, while inhibiting its adjacent central neurons, in order to dampen the weaker signal that they are transmitting and elaborate the difference in stimulus. The adjacent peripheral neurons also inhibit the main central neuron, but to a lesser extent.
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How are the edges of stimulus detected?
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The neurons at the edge of a stimulus are only inhibited by the adjacent neurons that are receiving a stimulus, but not by the adjacent neurons that are not receiving a stimulus, so there is greater stimulus detection around the edges.
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An increase in what ion is required for release of ACh from a presynaptic neuron?
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Calcium
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How does a presynaptic neuron cause muscle contraction?
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Acetylcholine is released from the neuron in a calcium-dependent manner. ACh binds to the nicotinic acetylcholine receptor on the muscle cell which causes a post-synaptic membrane potential change, resulting in an action potential.
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What step of neurotransmitter release does Botox inhibit?
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Fusion of synaptic vesicles with the plasma membrane
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What is the post-synaptic potential called in a muscle cell?
In another neuron? |
Endplate potential
Inhibitory post-synaptic potential or excitatory post-synaptic potential |
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What is the difference between nicotinic and muscarinic ACh receptors?
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Nicotinic ACh receptors are Na/K channels and can be agonized by nicotine. Muscarinic ACh receptors are coupled to ion cannels and cannot be agonized by nicotine.
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What does curare do?
What does alpha bungarotoxin do? |
Curare blocks the binding of ACh to the nicotinic receptor, causing paralysis.
Alpha bungarotoxin prevents the opening of the Na/K channel of the nicotinic receptor. |
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What is the difference between the nicotinic receptor in the CNS and that in the neuromuscular junction?
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In the CNS, the nicotinic receptor is composed only of alpha and beta subunits, while that in the neuromuscular junction is composed of 2 alpha, 1 beta, 1 delta, and 1 epsilon subunit.
In the CNS, different alpha and beta subunits are used at different locations. This allows for different sensitivities to ACh, different kinetics, single channel conductance, Ca permeability, and affinity for drugs. |
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What receptor mediates nicotine addiction?
Which receptor subunits are involved? |
nAChR (neuronal nicotinic acetylcholine receptor)
Alpha4, beta2 |
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What are the different kinds of neurotransmitters in neuron-neuron synapses?
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ACh
Amino acids: glutamate, aspartate (excitatory), glycine, GABA (inhibatory) Peptides: endorphins, enkephalines, substance P Biogenic amines: norepinephrine, dopamine, serotonin |
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How is synaptic transmission terminated?
Name two drugs that inhibit this. |
Cleavage of ACh by acetylcholinesterase.
Reuptake of transmitter into glial cells or presynaptic neuron. Cocain inhibits reuptake of dopamine. Fluoxetine inhibits reuptake of serotonin. |
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What is the difference between ionotropic and metabotropic receptors?
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Ionotropic receptors are also ion channels. Metabotropic receptors are G-protein coupled receptors that are coupled to ion channels.
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How do excitatory post-synaptic potentials work?
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An excitatory neurotransmitter causes a 1-2 mV depolarization event by increasing sodium conductance or decreasing potassium conductance.
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How do inhibitory post-synaptic potentials work?
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An inhibitory neurotransmitter causes a 1-2 mV hyperpolarization event by increasing potassium or chloride conductance.
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How are competing inhibitory and excitatory signals interpreted by a post-synaptic cell?
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Competing excitatory and inhibitory signals are essentially interpreted by algebraic summation of the signals.
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Describe the concept of synaptic plasticity.
Which type is associated with learning? |
With increased frequency of stimulation of a synapse, there may be either an increase or decrease in magnitude of post-synaptic response. When the frequency of stimulation is returned to normal, the magnitude of the post-synaptic response will return to baseline with different kinetics (facilitation- instantaneous, potentiation- slow, depression). The exception is habituation, which over time depresses its magnitude of response, regardless of frequency.
Potentiation is associated with learning. |
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What course does CN VII take to exit the cranium?
What two muscles does it innervate upon exiting the skull? |
It enters the internal acoustic meatus and exits through the stylomastoid foramen.
1. Posterior belly of digastric 2. Stylohyoid (Posterior auricular nerve) |
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What are the six terminal motor branches of CN VII?
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1. Posterior auricular
2. Buccal 3. Temporal 4. Zygomatic 5. Marginal mandibular 6. Cervical |
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How does V1 (ophthalmic division) exit the skull?
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Through the superior orbital fissure
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How does V2 (maxillary division) exit the skull?
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Through the foramen rotundum/pterygopalatine fossa
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How does V3 (mandibular division) exit the skull?
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Through the foramen ovale
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Which branch of the trigeminal nerve has both sensory and motor components?
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V3/mandibular branch
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What innervates the lacrimal and nasal glands?
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Facial nerve- greater petrosal branch
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What are the three scalp arteries and from which arteries do they arise?
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1. Supraorbital- arises from ophthalmic, which comes from the internal carotid
2. Superficial temporal- arises from external carotid 3. Occipital- arises from external carotid |
