Brain Flashcards
What does each cranial nerve do primarily? (Sensory, motor, or both)
Some say marry money but my brother says big brains matter more
Olfactory (CNI): sensory Optic (CNII): sensory Occulomotor (CNIII): motor Trochlear (CNIV): motor Trigeminal (CNV): both Abducent (CNVI): motor Facial (CNVII): both Vestibulocochlear (CNVIII): sensory Glossopharyngeal (CNIX): both Vagus (CNX): both Spinal accessory (CNXI): motor Hypoglossal (CNXII): motor
List the cranial nerves by number
Oh oh oh to touch and feel very good velvet, such heaven
CNI: olfactory CNII: optic CNIII: oculomotor CNIV: trochlear CNV: trigeminal CNVI: abducens CNVII: facial CNVIII: vestibulocochlear CNIX: glossopharyngeal CNX: vagus CNXI: spinal accessory CNXII: hypoglossal
List sinuses where CSF a travels from arachnoid granulations to the internal jugular vein
Superior (saggital) dural sinuses
Transverse sinus or superior/inferior petrosal sinus
Cavernous sinus
Sphenoparietal sinus
Sigmoid sinus
Internal jugular vein
What separates the cerebral hemispheres?
Right and left hemispheres separated by longitudinal cerebral fissure
Also falx cerebri, part of dura mater that extends into the longitudinal fissure
What separates the frontal and parietal lobes?
Central sulcus (in the coronal plane)
What separates the parietal and temporal lobes?
Lateral sulcus (transverse plane)
What separates the parietal and occipital lobes?
Parieto-occipital sulcus (on medial surface of cerebrum)
Sulcus, gyri, and fissures: which is very conserved?
Sulcus: grooves (variable)
Gyri: folds (variable)
Fissures/clefts: predictable and conserved
What structures of the brain compose the diencephalon?
Central core of the brain: epithalamus, dorsal thalamus, hypothalamus
What separates parts of the cerebellum?
Tentorium cerebelli = separates cerebellum from cerebrum
Vermis = lies between the two cerebellar hemisphere
What structures form the brain stem?
Midbrain (most superior part)
Pons (between midbrain and medulla oblongata), associated with CNV (trigeminal)
Medulla oblogata (most caudal) and continuos with spinal cord
Where is CNI located and what is its modality?
Special sensory: SVA (visceral afferent bc smell is through a mucous membrane in the nose)
Nerve cells are in the cribiform plate of ethmoid
Olfactory nerves (cell bodies in olfactory epithelium) project superiorly to the olfactory bulb
Bulb is connected to olfactory tract
Describe the flow of CSF through the ventricles in the brains
Choroid plexus (vascular pia mater) produces about 0.5L/day CSF in the lateral, 3rd and 4th ventricles
Lateral ventricle through interventricular foramen to the 3rd ventricle
3rd ventricle through cerebral aqueduct to the 4th ventricle
4th ventricle continues to central canal
4th ventricle median and lateral apertures allow CSF out to cisterna magna (around the brain)
How does CNII send visual stimuli to be processed in the brain?
SSA: special somatic afferent (sensory but NOT through mucous membrane)
Optic disc is where the retinal ganglia cells form nerves that exit eye (no rods or cones here = blind spot)
Nasal fibers and temporal fibers converge at optic chiasm, the decussation/crossing of nerve fibers through optic tract allows binocular vision
Relay to lateral geniculate of thalamus
Processed in visual cortex of occipital lobe
What does CNIII innervate and what is the modality?
GSE bc the muscles are voluntary, also GVE
For 5 out of 7 skeletal muscles of the eye
- levator palpebrae superioris (elevates eyelid)
- superior rectus (elevates eyelids, upward gaze)
- inferior oblique (upward gaze, external rotation, with some abduction)
- medial rectus (adducts gaze)
- inferior rectus (downward gaze)
Where are the nerve cell bodies for CNIII and how do they travel to their innervation site?
Cell bodies for GVE component are in the midbrain for presynaptic neurons (postsynaptic cell bodies in the ciliary ganglia)
GSE cell bodies in the midbrain
All parasympathetic innervation transverses the ciliary ganglion, only some of the sympathetic and sensory nerves transverse here too
Postganglionic parasympathetic fibers run through the ganglia, postsynaptic SYMPATHETIC ones follow carotid plexus vessels and hop onto ciliary ganglia and adjacent long ciliary nerve fibers to eye
Why is CNIII also GVE (in addition to GSE)?
Also has parasympathetic function
Has visceral motor nucleus with cell bodies of presynaptic neurons that synapse at ciliary ganglia
The postsynaptic neurons there innervate the sphincter pupillae (pupil constriction)
And the ciliary muscles (controls lens shape)
What does CNIV do and what’s its modality?
Trochlear nerve is GSE only
Innervates the superior oblique eye muscle
Each eye will be innervated by the CONTRALATERAL trochlear nucleus
What does CNV do, its modality, and what are its branches?
Mixed sensory and motor innervation:
GSA to cornea, forehead skin, scalp, eyelids, nose, nasal mucosa, maxillary teeth
GSE to masticating muscles and suprahyoid muscles
Ophthalmic, maxillary, and mandibular branches
What does CNVI do and what is its modality?
GSE skeletal muscle
Abducens innervates the lateral rectus eye muscle to abduct the eye (lateral movement)
What does CNVII do and what is its modality?
Mixed sensory and motor GSE, GVE, SSA
GSE: scalp, facial expression, stapedius of middle ear, and suprahyoid muscles
GVE: preganglionic parasympathetic neurons from pons to submandibular or pterygopalatine ganglia…postganglionic from ganglia to submandibular/sublingual salivary glands, lacrimal and nasal glands
SSA: special sensory for taste (anterior 2/3 of tongue and palate)
What does CNVIII do and its modality?
SSA sensory only
Vestibulocochlear is for hearing and balance
Has cell bodies in the vestibular ganglia to form vestibular nerve for position, balance and head movement
Also in spiral ganglia to form cochlear nerve for hearing
What does CNIX do and its modality?
Mixed sensory and motor
GSE to stylopharyngeus muscle for swallowing
GSA for cutaneous sensation from external ear
GVE parasympathetic: presynaptic neurons from medulla to otic ganglion, postsynaptic neurons to parotid gland
GVA: sensations from parotid gland, carotid body+sinus, pharynx and middle ear
SSA: taste for posterior 1/3 of tongue
What does CNX do and its modality?
Mixed sensory and motor
GSE: innervates pharyngeal muscles EXCEPT stylopharyngeus, larynx, palate, superior 2/3 of esophagus
GSA: cutaneous sensation from external auricle, external acoustic meatus, dura mater of posterior cranial fossa
GVE parasympathetic: presynaptic neurons from medulla travel to near viscera, postsynaptic neurons are near viscera and go to trachea, bronchi, digestive tract, coronary arteries, and conduction nodes of the heart
GVA: sensation from base of tongue, pharynx, larynx, trachea, bronchi, heart, esophagus, stomach and intestine up to left colic flexure
SVA: special sensory (visceral bc goes through mucous membrane) taste from epiglottis and palate
What does CNXI do and its modality?
GSE motor only
Innervates SCM and trapezius
What does CNXII do and its modality?
GSE motor only
Innervates muscles of the tongue
How does the olfactory nerve CNI exit the cranium?
Cranial roots in forebrain and cerebral hemispheres
Cell bodies in olfactory epithelium
Exit via olfactory foramina in cribiform plate
How does the optic nerve CNII exit the cranium?
Cranial root in the forebrain
Cell bodies in retina ganglia cells
Exits through optic canal
Where does oculomotor nerve CNIII exit the cranium?
Cranial roots in midbrain (also visceral motor nucleus cell bodies here) for both GSE and GVE (presynaptic)
GVE also has its postsynaptic component in ciliary ganglion
Exits via superior orbital fissure
Where does the trochlear nerve CNIV exit from the cranium?
Cranial root and cell bodies in midbrain
Exits via superior orbital fissure
Where does the trigeminal nerve CNV exit the cranium?
GSA cell bodies in the trigeminal ganglion
GSE cell bodies in the pons
Different exits for the 3 branches:
CNV1 exits via superior orbital fissure
CNV2 exits via foramen rotundum
CNV3 exits via foramen ovale
Where does the abducens CNVI exit the cranium?
Cranial root in brain stem
Cell bodies in pons
Exits via superior orbital fissure
Where does the facial nerve CNVII exit the cranium?
Cranial roots in brain stem
Cell bodies in:
Geniculate ganglion for SSA
Pons for GSE + presynaptic parasympathetic GVE
Pterygopalatine ganglion and submandibular ganglion for postsynaptic parasympathetic GVE
Exits via internal acoustic meatus, facial canal, and stylomastoid foramen
Where does vestibulocochlear nerve CNVIII exit the cranium?
Cranial roots in brain stem
Cell bodies in vestibular ganglia and spiral ganglia
Exits via internal acoustic meatus
Where does glossopharyngeal nerve CNIX exit the cranium?
Cranial roots in brain stem
Cell bodies:
Medulla contains GSE and GVE presynaptic parasympathetic
Otic ganglion has GVE postsynaptic parasympathetic
Inferior ganglion has GSA and SSA
Superior ganglion has GVA
Exits via jugular foramen
Where does the vagus nerve CNX exit the cranium?
Cranial roots in brain stem
Cell bodies:
- Medulla contains GSE and presynaptic parasympathetic GVE
- Neurons near or on viscera are GVE postsynaptic parasympathetic
- Inferior ganglion has GVA and SSA
- Superior ganglion has GSA
Exits via jugular foramen
Where does the spinal accessory CNXI exit the cranium?
Cranial root is in spinal cord
Exits via spinal cord through foramen magnum
Where does the hypoglossal nerve CNXII exit the cranium?
Cranial roots in brain stem
Cell bodies in the medulla
Exits via hypoglossal canal
