NB1-3 - General Morphology and Surface Structures of the CNS and DLAs Flashcards
What are the peaks and valleys of the brain called?
The bumps are called gyri and the valleys are called sulci
Important note about the parietooccipital sulcus
It’s not a real sulcus. Its an imaginary line drawn from the preoccipital notch to form a boundary for the occipital lobe.
Label image and say what the radiographs are highlighting.
The insular lobe
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On a mid-sagital section of the brain, how do you locate the central sulcus?
You follow the cingulate sulcus to the surface of the brain, the next most rostral sulcus is the central sulcus.
What is the clinical significance of the calcarine sulcus?
Everything you see below your visual focus is represented above the calcarine sulcus and vice versa.
List the parts of the corpus callosum and their functions
- Splenium - connects occipital lobes
- Genu - connects frontal lobes
- Body - connects parietal lobes and connects frontal lobes
- Rostrum - connects frontal lobes
What is the purpose of the septum pellucidum?
To separate the lateral ventricles from one another
What is a commissure?
A place where two structures are joined
What does the anterior commisure do?
It joins the tips of the temporal lobes and the olfactory bulb
What does the posterior commissure do?
It is involved with certain aspects of eye movements and pupilary responses
What is highlighted in this image?
The fornix
What is the optic chiasm and where is it located?
It is where the CN2 fibers decussate to form an “X” shape. It is located just inferior and anterior to the hypothalamus.
What is the clinical significance of the mamillary bodies?
They appear to have a role in the formation of memories which makes sense since they are very closely related to the hippocampus
What is the significance of the interventricular foramen?
It is the passageway through which CSF from the lateral ventricles enter the 3rd ventricle
What is the function of the massa intermedia?
It is the commissure of the thalamus
What does the middle cranial fossa cradle? What will the anterior cranial fossa cradle? Why is this clinicaly significant?
The inferior pole of the temporal lobes
The orbital gyri
If someone hits their head very hard, these two areas of the brain are most likely to be damaged.
What is this a zoomed in image of? What is the arrow pointing to? What is this structure a part of? What is the clinical significance of this structure?
This is the inferior surface of the brain zoomed in on the brain stem. The arrow is pointing to the uncus which is a part of the parahippocampal gyrus. In the event of a brain herniation, the uncus can compress CN3 which will cause the eyes to be dilated. Therefore, a simple way to check for brain herniation is to check the pupils of the patient.
List the sections of the inferior frontal gyrus and their functions.
- Pars opercularis
- Pars triangularis
Both of these function in formulating fluid speech
- Pars orbitalis (don’t need to know function)
What does the inferior parietal lobe consist of?
The supramarginal and angular gyri
List the Brodman areas we need to know, the areas of the brain they correspond to, and their clinical significance.
Brodman 1,2, & 3 - postcentral gyrus - damage to this causes somatosensory loss
Brodman 4 - precentral gyrus - damage to this causes muscle weakness
Brodman 17 - occipital lobe - damage to this causes blindness
Brodman 44 and 45 - pars opercularis and pars triangularis, respectively - damage to this causes speech problems
Brodman 22 - Wernicke’s area - damage to this causes language comprehension problems
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List the important motor and sensory pathways.
- Corticospinal - motor
- Corticobulbar - motor
- Vestibulospinal (lateral & medial) - motor
- Reticulospinal (lateral & medial) - motor
- Rubrospinal - motor
- Dorsal Column (medial lemniscus) - sensory
- Anterolateral System (spinothalamic tract) - sensory
In which region of the brain is the motor homunculus?
The primary motor cortex which is layer 5 (pyramidal cell) of the precentral gyrus
Describe the origin, route, and end of teh corticospinal tract.
Origin - the primary motor cortex
Route - corona radiata > internal capsule > crus cerebri > basilar pons > pyramids of medulla > decussation at caudal end of medulla > lateral corticospinal tract in spinal cord
End - the ventral motor nuclei of the spinal cord
How do you distinguish a lower motor neuron from an upper motor neuron?
If a neuron synapses directly on a muscle then it is always considered to be a lower motor neuron.
What are the mnemonics to remember the cranial nerves and whether they are sensory, motor, or both.
Oh, Oh, Oh, to touch and feel very good velvet. Such Heaven!
Olfactory (I), Optic (II), Oculomotor (III), Trochlear (IV), Trigeminal (V), Abducens (VI), Facial (VII), Vestibulocochlear (VIII), Glossopharyngeal (IX), Vagus (X), Spinal Accessory (XI), Hypoglossal (XII)
Some say marry money but my brother says big brains matter most
s = sensory, m = motor, b = both
In general, what does each cranial nerve do?
- CN I - Olfactory - Sense of smell
- CN II - Optic - Vision
- CN III - Oculomotor - superior, inferior, and medial rectus and inferior oblique muscles (elevation, depression, adduction, extortion); levator palpebrae (eyelid retraction), and iris constrictors.
- CN IV - Trochlear - superior oblique muscles (intortion, depression, abduction)
- CN V - Trigeminal - Chewing muscles and some facial sensation
- CN VI - Abucens - lateral rectus muscles (abduct)
- CN VII - Facial - Facial muscles (including eyelid closure), some salivation, and taste from anterior two-thirds of tongue
- CN VIII - Vestibulocochlear - senses sound, rotation, and gravity
- CN IX - Glossopharyngeal - motor to stylopharyngeas and parotid gland, taste from posterior one-third of tongue, and sensory from upper pharynx
- CN X - Vagus - Motor to swallowing muscles (including one tongue muscles) and nearly all thoracoabdominal viscera up to splenic flexure, some sensation from ear
- CN XI - Spinal Accessory - Motor to SCM and Trapezius
- CN XII - Hypoglossal - Motor to tongue
Label all of the cranial nerves. Include name and number
Describe where the anterior and posterior commisures are located
The AC is located about where the septum pellucidum and hypothalmus touch
The PC is located near the most superior part of the tectum
