Anatomy 19 (Neuro 2) Flashcards
What is raised intracranial pressure caused by?
Space occupying lesions (SOLs)
Idiopathic intracranial hypertension (IIH)
What are signs and symptoms of raised intracranial pressure?
Headaches
Nausea
Visual disturbance
Later, altered consciousness
Papilledema
Increased blind-spot on visual field testing
Where is the trochlear nerve located?
At the medial edge of the superior orbital fissure
Where does the trochlear nerve terminate?
On the superior oblique muscle
Where is the lateral rectus muscle located?
Runs along the length of the lateral walls of the orbit on a deeper plane to the lacrimal gland
Where is the oculomotor nerve located?
Deep to levator palpebrae superioris
Where does the superior oblique originate?
At the posterior of the orbit
What does the superior oblique insert onto?
The posterior part of the eyeball
Where is the medial rectus muscle located?
Runs along the length of the medial aspect of the orbit on a deeper plane than the superior oblique muscle
What does the inferior oblique muscle insert onto?
The sclera behind the equator of the eyeball
What is the lacrimal puncti?
Small medial holes in the upper and lower eyelids
Which cranial nerves are involved in the parasympathetic outflow from the CNS?
Occulomotor
Facial
Glossopharyngeal
Vagus
Which sacral spinal segments are involved in the parasympathetic outflow from the CNS?
Sacral spinal segments 2,3 and 4
Where do the parasympathetic fibres in the oculomotor nerve originate from?
Edinger-Westphal nucleus in the mid brain
Where do the parasympathetic fibres in the oculomotor nerve travel into?
Branch to the inferior oblique muscle
What does the ciliary ganglion do?
Gives fibres that innervate the ciliary muscle (accommodation) and the sphincter pupillae
What do the parasympathetic fibres in the facial nerve do?
Leave the nerve in the middle ear to synapse in a ganglion in the pterygopalatine fossa
What do the parasympathetic fibres in the facial nerve supply?
Lacrimal gland
What spinal segments is the sympathetic outflow from the CNS from?
Spinal segments thoracic 1 to lumbar 2 (T1 - L2)
Where do the sympathetic trunks run from?
Base of the skull to the bottom of the sacrum
Where do sympathetic fibres to the orbit arise from?
Segment T1
Where do sympathetic fibres to the orbit pass through before entering the base of the skull?
Stellate ganglion
What do the sympathetic fibres to the orbit supply?
The dilator pupillae muscle, and blood vessels
What nerve innervates the medial rectus?
Oculomotor nerve (Cn3)
What movement does the medial rectus cause?
Moves the eye inward, toward the nose (adduction)
What nerve innervates the lateral rectus?
Abducens nerve (Cn6)
What movement does the lateral rectus cause?
Moves the eye outward, away from the nose (abduction)
What nerve innervates the superior rectus?
Oculomotor nerve (Cn3)
What movement does the superior rectus cause primarily?
Primarily moves the eye upward (elevation).
What movement does the superior rectus cause secondarily?
Secondarily rotates the top of the eye toward the nose (intorsion)
What movement does the superior rectus cause tertiarily?
Tertiarily moves the eye inward (adduction)
What nerve innervates the inferior rectus?
Oculomotor nerve (Cn3)
What movement does the inferior rectus cause primarily?
Primarily moves the eye downward (depression)
What movement does the inferior rectus cause secondarily?
Secondarily rotates the top of the eye away from the nose (extorsion)
What movement does the inferior rectus cause tertiarily?
Tertiarily moves the eye inward (adduction)
What nerve innervates the superior oblique?
Trochlear nerve (Cn4)
What movement does the superior oblique cause primarily?
Primarily rotates the top of the eye toward the nose (intorsion)
What movement does the superior oblique cause secondarily?
Secondarily moves the eye downward (depression)
What movement does the superior oblique cause tertiarily?
Tertiarily moves the eye outward (abduction)
What nerve innervates the inferior oblique?
Oculomotor nerve (Cn3)
What movement does the inferior oblique cause primarily?
Primarily rotates the top of the eye away from the nose (extorsion)
What movement does the inferior oblique cause secondarily?
Secondarily moves the eye upward (elevation)
What movement does the inferior oblique cause tertiarily?
Tertiarily moves the eye outward (abduction)
What is the mnemonic used to explain the actions of the superior and inferior muscles of the eye?
RAD SIN
Rectus ADducts (therefore oblique abducts)
Superior INtorts (inferior extorts)
What is the mnemonic used to explain the innervation of the extraocular muscle?
LR6 SO4 3
Lateral rectus (LR) innervated by the abducens nerve (Cn6) Superior oblique (SO) innervated by trochlear nerve (Cn6) All other extraocular muscles are innervated by the oculomotor nerve (Cn3)
Where is the retina located?
Posterior of the eyeball
Where does the optic disc lie?
Lies level with the point of attachment of the optic nerve
Where are the retinal arteries and veins found?
Radiating from the optic disc
Where is the macula lutea located?
Lateral to the optic disc
Where are the lens located?
In the anterior part of the eyeball
Where are the ciliary processes found?
Radiate from the lens
Where is the iris located?
Within the anterior chamber, visible after detachment of the lens
What is the jugular foramen syndrome?
Compression of multiple lower cranial nerves
(Glossopharyngeal (Cn9), Vagus (Cn10) and
Accessory (Cn11)
What are the signs and symptoms of jugular foramen syndrome?
Dysphonia
Loss of gag reflex
Unilateral wasting of sternocleidomastoid and trapezius muscles
What is the foramen magnum syndrome?
Compression of the spinal cord, lower brain stem or part of the cerebellum
What are signs and symptoms of foramen magnum syndrome?
Pain in head, neck, limbs, trunk made worse by straining
Cerebellar symptoms e.g., vertigo, gait disturbance
Decerebrate posture
Cardiorespiratory failure
Pyramidal signs
Death
What is arnold-chiari malformation?
Congenital malformation
Displacement of the cerebellar tonsils down through the foramen magnum
Sometimes blocks CSF flow causing hydrocephalus
What are signs and symptoms of arnold-chiari malformation?
Headaches
Fatigue
Muscle weakness in the head and face
Difficulty swallowing
Dizziness
Nausea
Impaired coordination
Patients may also develop syringomyelia
Where is the petrous temporal bone located?
In the floor of the middle cranial fossa
What is the greater petrosal nerve?
Parasympathetic branch of the facial nerve (Cn7), emerges from the petrous temporal bone and passes anteromedially
Where is the tegmen tympani located?
Lies lateral and posterior to the greater petrosal nerve
What are the 3 ear ossicles in the middle ear?
Stapes
Malleus
Incus
What ear ossicle is attached to the tympanic membrane?
Malleus
What ear ossicle does the tympanic membrane articulate with?
Incus
What is the chorda tympani nerve?
Branch of the facial nerve (Cn7), crossing the tympanic membrane
What is the function of the internal acoustic meatus?
Transmits the facial (Cn7) and vestibulocochlear (Cn8) nerves
What is acoustic neuroma?
A benign tumour of myelin sheath of the vestibulocochlear nerve (Cn8)
What are the signs and symptoms of acoustic neuroma?
Unilateral deafness
Dizziness
Fullness in the ear and tinnitus
If undetected what can an acoustic neuroma progress to?
It progresses to include ataxia and paralysis of the facial (Cn7) and trigeminal (Cn5) cranial nerves.
This is termed cerebellopontine angle syndrome
