Anatomy 4 - Orbital Autonomics Flashcards
In what direction does a fractures zygoma tend to rotate?
Medially towards the floor of the orbit
What is the name of the thick facial sling that holds the eye just above the floor of the orbit?
Suspensory ligament of the eye
Where does the suspensory ligament of the eye attach?
To the zygoma laterally and the lacrimal medially
What is the purpose of the suspensory ligament?
To support both the eyes in the same vertical position within the orbit
What symptom may a patient experience if they fracture their zygoma (medially rotating it)?
Why?
Diplopia
Due to the suspensory ligament being loosened lowering one eye towards the floor of the orbit
What lies within the infraorbital canal of the maxillary bone?
The infraorbital NVB (infraorbital nerve, artery and vein)
What symptom may a patient present with due to damage of the infraorbital canal?
general sensory deficit of the facial skin
Name of CN V1?
Ophthalmic nerve
Name of CN V2?
Maxillary nerve
Name of CN v3?
Mandibular nerve
What structures of the face does the ophthalmic nerve (CN V1) provide general sensation to? (4)
the upper eyelid
The cornea
All the conjunctiva
The skin of the root/ bridge/ tip of the nose
What structures of the face does the maxillary nerve (CN V2) provide general sensation to? (4)
The skin of the lower eyelid
The skin over the maxilla
The skin of the ala of the nose
The skin/ mucosa of the upper lip
What structures of the face does the mandibular nerve (CN V3) provide general sensory supply to? (2)
The skin over the mandible and temporomandibular joint (apart from the angle of the mandible)
What nerve(s) supply the angle of the mandible?
C2,3 spinal nerves
What is the infraorbital nerve a branch of?
CN V2
What does afferent and efferent mean?
Afferent = sensory Efferent = motor
Why is the blink (corneal) reflex important?
Prevents the eye from becoming extremely dry and prevents damage to the anterior surface of the eye
What is a ganglion?
A group of nerve cell bodies located in the autonomic nervous system
What is the name of the big sensory ganglion of CN V?
Trigeminal ganglion
What makes the afferent limb of the blink reflex?
CN V1 to trigeminal ganglion then in CN V to the pons
What makes the efferent limb of the blink reflex?
CN VII to the eyelid part of obicularis oculi
Where is the ganglion of sympathetic axons located?
Sympathetic trunk (for the organs of the head region = cervical part of sympathetic trunk)
What is the neurotransmitter used between the presynaptic and postsynaptic axons in the sympathetic nervous system?
Acetylcholine
What is the neurotransmitter used between the postsynaptic axon and the organ in the sympathetic nervous system?
Noradrenaline
What are the names of the 3 cervical sympathetic ganglia?
Superior, middle and inferior sympathetic ganglia
What is the route of the presynaptic sympathetic axons from the CNS which are going to innervate the eye?
Descend in the spinal cord and then exit the spinal cord in T1 spinal nerve
Then ascend within the sympathetic trunk and then synapse in the superior cervical sympathetic ganglion
Where does the post-synaptic sympathetic axons which are going to innervate the eyes pass?
Enter the internal carotid nerve and external carotid nerve and pass onto the surface of the internal and external carotid arteries respectively to be carried to the organs of the head on the surface of the branches of these arteries
The ophthalmic artery (an intracranial branch of the internal carotid artery) carries sympathetic axons into the orbit)
What does the inferior cervical and 1st thoracic ganglia often fuse to form?
The stellate ganglion
What are the parasympathetic cranial nerves?
CN III, VII, IX or X
Where is the ganglion of the parasympathetic axons located?
Within the organ
What neurotransmitter does the presynaptic axon of parasympathetic nerves release?
Acetylcholine
What neurotransmitter does the post-synaptic axon of the parasympathetic nerves release?
Acetylcholine
Where does the parasympathetic axons in CN III pass?
To the eye
Where does the parasympathetic axons in CN VII pass?
2 branches - 1 to lacrimal gland and one to the submandibular and sublingual salivary galnds
Where does the parasympathetics from CN IX pass?
To the parotid salivary gland
What is the name of the parasympathetic ganglion of CN III?
Where is this located?
Ciliary ganglion
In the orbit
What supplies the parasympathetic axons to the organs of the neck/ chest and abdomen as far as the midgut?
The vagus nerves
What carries the parasympathetic axons to the hindgut, pelvis and perineum?
The sacral spinal nerves
What does the oculomotor nerve supply? (3)
Somatic motor to SR, MR, IR and IO extraocular muscles
Somatic motor to levator palpebrae superioris
Presynaptic parasympathetic axons to the ciliary ganglion
What nerves pass through the superior orbital fissure from superior to inferior?
CN III
CN IV
CN V1
CN VI
What are the names of the 2 branches of CN III?
SUperior and inferior branch
What does the superior branch of CN III supply?
Superior rectus
Levator palpabae superioris
What does the inferior branch of CN III supply?
Medial rectus
Inferior rectus
Inferior oblique
Ciliary ganglion
Where does CN III connect to the CNS?
Near the midline at the junction between the midbrain and the pons
What does the ciliary nerves supply?
The autonomic axons to control the diameter of the iris and the refractive shape of the lens
What type of innervation does the long ciliary nerve contain?
Sympathetic (from the sympathetic axons from the surface of the ophthalmic artery)
Somatic sensory from the cornea and conjunctiva
What type of innervation does the short ciliary nerve contain?
Somatic sensory
Parasympathetic (from the sensory ganglion)
Sympathetic (from superior cervical ganglion)
What 3 types of axons pass through the ciliary ganglion?
What synapses?
General sensory
Sympathetic
Parasympathetic -> only one to synapse (between pre-synaptic fibres from CN III and post-synpatic fibres)
What are the 6 autonomic reflexes of the eye?
Maximal eyelid elevation (wide eye opening of fight or flight) Pupillary (light) reflex The accommodation reflex Lacrimation reflex Vestibulo-ocular reflex Oculocardiac reflex
What CNs are the CNS connections between for the vestibulo-ocular reflex?
CN VIII & CNs III, IV and VI
What is the oculocardiac reflex?
Reflex bradycardia in response to tension on the extra ocular muscles or pressure on the eye
What CNs are the CNS connections between for the oculocardiac reflex?
CN V1 and CN X
Sympathetic effects on eyelid elevation?
Opens eyes wider
Parasympatehtic functions on eyelid elevation?
Allows obicularis oculi to work
Sympathetic functions on pupillary reflex?
Allow more light into the eyes
Parasympathetic functions on pupillary reflex?
Get less light into eyes (to protect the retina from bright light or when asleep)
Sympathetic effect on accommodation reflex?
Focus on far objects
Parasympathetic effect on accommodation reflex?
Focus on near objects
Sympathetic effect on lacrimation reflex?
Emotional lacrimation
Parasympathetic effect on lacrimal reflex?
Reflex lacrimation (to wash away the stimulant foreign body and clean the cornea)
What type of muscle is the elevator palpebrae superiors?
Skeletal plus smooth muscle
How do postsynaptic sympathetic fires reach elevator palpebrae superioris?
Via the superior cervical sympathetic ganglion
The internal carotid nerve
The internal carotid plexus
Axons carried on the ophthalmic artery and on its branches to the orbital structures
Name of a non-physiologically enlarged pupil?
A mydriatic pupil
What kind of drugs induce dilation of the pupil?
mydriatic drugs
Is the insertion of the dilator papillae fibres fixed or mobile?
Mobile
Is the origin of the dilator papillae fibres fixed or mobile?
Fixed
Name for a non-physiologically constricted pupil?
A miotic pupil
Name for a fixed-dilated pupil?
A blown pupil
What is a blown pupil often a sign of?
CN III pathology (inhibiting the pupillary constricting action of parasympathetic axons in the ciliary nerves)
What is the afferent limb of the pupillary reflex?
CN II (on ipsilateral side)
Name of the light reflex in the stimulate eye?
Direct light reflex
Name of the light reflex in the non-stimulate eye?
Consensual light reflex
Where is the CNS connections in the light reflex?
In the thalamus
What is the motor limb of the light reflex?
Bilateral via CNs III
How many neurones does the pupillary light reflex contain?
4
Describe the route of the 1st neurone in the light reflex?
The retinal ganglion cells pass via the ipsilateral optic nerve to cross over in the optic chiasm
Where does the first and second neurones in the pupillary reflex synapse?
In the pretectal nucleus in the midbrian
What is the route of the 2nd neurone in the light reflex?
Located entirely in the midbrain and connects the pretectal nucleus to the next synpase
Where does the 2nd and 3rd neurone in the light reflex synapse?
In the Edinger Westphal nucleus (location of the cell bodies of the parasympathetic axons of CN III)
Describe the route of the 3rd neurone in the light reflex?
Passes from the Edinger Westphal nucleus, via CN III then its inferior division to synapse with the 4th neuorne
Where does the 3rd and 4th neurone of the light reflex synapse?
In the ciliary ganglion
Describe the course of the 4th neurone in the light reflex?
Course in the short ciliary nerves to the sphincter papillae muscles
What type of nerve controls the lens shape?
Parasympathetic
What are the 3 components of the accommodation reflex?
What nerve controls this?
Bilateral pupillary constriction
Bilateral convergence (medial rotation of both eyes)
Bilateral relaxation of the lens
All of these are controlled by CN III
What are the 3 types of tears?
Basal tears
Reflex tears
Emotional tears
What is the purpose of basal tears?
Important in corneal health -> clean, nourish and hydrate the avascular cornea, contain lysozyme
Afferent and efferent limb of reflex tears?
Afferent = CN V1 Efferent = CN VII
What nerve is the chorda tympani a branch of?
CN VII
What does the chorda tympani branch of CN VII contain?
The presynaptic parasympathetic axons for the submandibular and sublingual glands
What carries the branch of CN VII supplying the lacrimal gland to the gland?
Branches of V2 then V1