Cranial Nerves Flashcards
what do the pyramids contain?
corticospinal axons
which gland produces melatonin?
pineal gland
where does the pituitary stalk lie?
above the mammillary body
where do the cerebral peduncles lie?
lateral on either side of the mammillary body
What are cerebral peduncles?
descending tracts which are corticospinal and corticobulbar
Which nerves emerge or go into in the pons level?
Cranial nerves 5, 6, 7 and 8
how many pairs of peduncles connect the cerebellum to the pons?
3, cerebellar peduncles
which nerves emerge/ go into the medulla?
cranial nerves 9, 10, 11 and 12
Where is the open (upper) medulla?
cerebellar level (after ‘removing’ the cerebellum so that the 4th ventricle is open)
Where are the 4 dorsal columns?
Posterior to central canal
What is the medulla?
rostral continuation of the spinal cord
What does the anterior surface of the medulla have?
pyramids (descending tracts)
What does the posterior surface have?
dorsal columns
How is the posterior surface divided?
Into open and closed
Where are the nuclei of the dorsal columns?
rostral, posterior medula
Which arterial systems does the CNS blood supply come from?
anterior derived from internal carotid arteries, and the posterior is derived from the vertebral-basilar arteries - vertebral arteries which join to form the basilar
Where does the vertebral-basilar system feed?
brainstem
Where do the internal carotid arteries feed?
most of the forebrain/ cerebral hemisphere
From superior to posterior, name the 3 main parts of the brainstem
midbrain, pons, medulla
what are salivatory nuclei and nucleus ambiguus and which nerves bring their effects about?
not associated with a single cranial nerve - salivatory nuclei go to fascial nerve and glossopharangeal nerve if going to the carotid salivary gland
G E S V S
general, efferent, sensory, visceral, somatic
occulomotor nerve
supply motor neurones to skeletal muscle fibres which move the eye, pupil size and length, plus reflexes - P
trochlear nerve
sends motor out to superior oblique
trigeminal nerve
many sensory nuclei, brings sensation back from the face, pain and temperature from the head, and motor nucleus - innervates muscle
facial nerve
salivation, taste, muscles of mastication and sensation around the ear
vestibulocochlear
vestibular and cochlear P
Vagus
Does many things, lots of nuclei; heart, glands P
Hypoglossal
muscles of the tongue only has single nucleus as is a motor nerve only
what is the PNS?
nerves (cranial and spinal) outside brain and spinal cord
what is the CNS?
brain and spinal cord
all ascending and descending pathways pass through where? where do they synapse?
the brainstem, here in relay nuclei or arise directly from or synapse in other brainstem, nuclei
how is the cerebellum connected to the brainstem?
via 3 cerebellar peduncles
what is a cerebellar peduncle?
The cerebellar peduncles contain the afferent and efferent white fibre tracts of the cerebellum.
how many of the 12 cranial nerves have their nuclei in the brainstem? Which are the exceptions?
9 out of 12 I, II and XI
what is the part of the brainstem that sits behind the cerebral aqueduct?
tectum (roof)
what is the largest part of the brainstem called?
what is the anterior part called?
tegmentum
base
which is the only cranial nerve to come out of the dorsal aspect of the brainstem?
IV - the trochlear nerve
what have we removed in this image?
what are the 4 long structures stuck together on the dorsal aspect of the medulla?
what are the enlargements?
the cerebellum and 4th ventricle (diamond shape is where it was removed)
dorsal columns (ascending)
gracile and cuneate pathways at the bottom
enlargements are where these pathways are synapsing onto their nuclei which contain the cell bodies of the second order sensory neurons which cross over to the other side before going up to the brain
(medulla is where second order axons of the dorsal columns cross over)
name what we can see on the anterior aspect of the brainstem, in descending order
cerebral hemispheres removed - we would be seeing olfactory bulbs but they have been removed
we are looking at the ventral surface of the brain
we can see the optic tract on either side of the stalk in the middle (pituitary gland)
the two rounded things below are the mamillary bodies (named as they resemble mammary glands)
next we see cranial nerves III and IV, V , VI, VII, VIII, IX, X XI, XII.
EXPECTED TO BE ABLE TO LABEL THE CRANIAL NERVES
white fibre tracts at the front of the midbrain (cerebral peduncle) bringing information from the cerebral hemispheres to the spinal cord which are continuous with the structures at the front of the the medulla called the pyramids or pyramidal tracts, where we can see some decussation in the middle
The ventral aspect of the brainstem
Key: 1, infundibulum; 2, tuber cinereum; 3, mammillary body; 4, basilar pons; 5, abducens nerve; 6, foramen caecum; 7, olive; 8, glossopharyngeal nerve; 9, vagus nerve; 10, rootlets of hypoglossal nerve; 11, accessory nerve; 12, olfactory tract; 13, optic nerve; 14, optic chiasma; 15, optic tract; 16, oculomotor nerve; 17, uncus; 18, trochlear nerve; 19, trigeminal nerve; 20, facial nerve; 21, vestibulocochlear nerve; 22, flocculus; 23, pyramid; 24, motor decussation (decussation of pyramids).
label the cranial nerves
what is the decussation of the pyramids?
where the corticospinal and some other motor axons cross
I
olfactory
II
optic
III
oculomotor
IV
trochlear
V
trigeminal
- opthalmic division
- maxillary division
- mandibular division
VI
abducent
VII
facial
VIII
vestibulocochlear
IX
glossopharyngeal
X
vagus
XI
accessory
XII
hypoglossal
function of the olfactory nerve
sensory - smell
function of the optic nerve
sensory - vision, pupillary light reflex (afferent limb)
function of the oculomotor
eyelid elevation, eye movements (elevation, abduction, depression in abduction) and pupillary light reflex (efferent limb)
function of the trochlear nerve
intorsion, depression in adduction
function of the trigeminal nerve
motor to muscles of mastication
sensory from face, sinuses, teeth etc
function of the abducens nerve
eye movement - abduction
function of the facial nerve
motor - to muscles of face
sensory - taste (anterior 2/3 of tongue)
- external auditory meatus
- naso-pharynx
function of the vestibulocochlear
sensation of hearing and balance
function of the glossopharyngeal nerve
motor to stylopharyngeus muscle
sensory taste (post 1/3 tongue) and general sensation from tongue
mucosa of nasopharynx and middle ear
function of the vagus nerve
motor to vocal muscles
sensory from pharynx, larynx, and lateral aspect of face
parasympathetic innervation to GI tract, heart and lungs
function of the accessory nerve
motor to sternocleidomastoid and trapezius
function of the hypoglossal nerve
motor to tongue muscle
what does the pineal gland do?
produce melatonin
what are the superior and inferior colliculi?
superior - visual pathway
inferior - auditory
where do optic nerves come from?
where do optic tracts come from?
comes from one eye
comes from both eyes
which cranial nerves emerge at the midbrain level?
3 and 4
which descending tracts make up the cerebral peduncles?
corticospinal and corticobulbar
what is the lower medulla called and why?
closed medulla because the fourth ventricle is completely enclosed by neural tissue
which cranial nerves emerge from the closed medulla?
9, 10 and 12
posterior surface is divided into open and closed, meaning what?
closed has extension of central canal of spinal cord
canal widens to form 4th ventricle in open medulla
dorsal column pathways
gracile -
cuneate -
gracile - legs
cuneate - arms
why do dorsal columns end in rostral medulla but exist in caudal medulla?
they are sensory tracts which synapse onto their nuclei in the dorsal medulla
anterior blood supply is derived from……….. arteries which feed the ……………..
posterior supply is derived from ……….. arteries which feed the …………..
internal carotid - most of cerebral hemispheres
vertebral-basilar - brainstem
label the cranial nerves on this diagram
