Anatomy 2- Orbital Autonomics Flashcards
Where does CNV1 supply?
Upper eyelid, cornea, conjunctiva, skin of the root/bridge, tip of nose
Where does CNV2 supply?
Skin of the lower eyelid, maxilla, ala of nose, upper lip
Where does CNV3 supply?
Skin over the mandible and TMJ joint
What supplies the angle of the mandible?
C2/3 spinal nerves
The supra/infraorbital nerves are branches of what?
Supraorbital- CNV1, infraorbital- CNV2
In the blink reflex, something touches the cornea, and APs are conducted via what nerves to where?
From the cornea to the trigeminal ganglion via CNV1 branches. Then along CNV to the pons.
In the blink reflex, central connections are made at the CNS between what two nerves?
CNV and CNVII
In the blink reflex, what happens after connections have been made at the CNS?
APs are conducted via CNVII to the palpebral part of orbicularis oculi
In the skin, what type of innervation is found in the arterioles, sweat glands and arrestor muscles?
Sympathetic
Does the brain have motor function?
No
The anterior surface of the eyes are sensitive to touch. What nerve is responsible for this?
CNV1
Where do sympathetic axons originate from and where do they pass to?
Originate from autonomic centres in the brain and pass down the spinal cord
Where do sympathetic axons exit the spinal cord and where do they pass to?
They exit at T1-L2 spinal nerves (thoracolumbar outflow) and pass into the sympathetic chain
Where do sympathetic axons pass into from the sympathetic chain?
All spinal nerves (anterior and posterior rami) and then into splanchnic nerves to supply all organs
All anterior and posterior rami will have what 3 types of innervation?
Somatic motor, somatic sensory and sympathetics
Where do presynaptic sympathetic axons from the CNS synapse? What do they then become?
They synapse at the superior cervical ganglion to become postsynaptic sympathetic axons
How do postsynaptic sympathetic axons get to the orbit?
They enter the internal/external carotid nerves and then pass onto the internal/external carotid arteries where they are carried to the organs of the head. The ophthalmic artery carries them into the orbit.
Where do parasympathetic axons leave the CNS?
Cranial nerves III, VII, IX and X and via sacral spinal nerves (craniosacral outflow)
What do parasympathetics supply?
Internal organs
Where in the head receives parasympathetic supply?
Eye, lacrimal gland and salivary glands
What does the vagus nerve supply?
Organs of the neck, chest and abdomen as far as the midgut
Sacral spinal nerves carry parasympathetic nerves to where?
Hindgut, pelvis and perineum
What is CNIII?
Oculomotor nerve
Where does CNIII attach with the CNS?
The junction between the midline and pons and passes through the cavernous sinus
Where does CNIII exit the skull?
Superior orbital fissure
The oculomotor nerve supplies somatic motor supply to where?
Superior, medial, inferior rectus muscles, inferior oblique and LPS
The oculomotor nerve supplies presynaptic parasympathetic axons to where?
Ciliary ganglion
Where does the superior division of CNIII supply?
SR and LPS
Where does the inferior division of CNIII supply?
MR, IR, IO and ciliary ganglion
Ciliary nerves supply autonomic axons to do what?
Control the diameter of the iris and refractive shape of the lens
What fibres do long ciliary nerves contain?
Sympathetic, somatic sensory
What fibres do short ciliary nerves contain?
Sympathetic and parasympathetic
What is the accommodation reflex?
Focussing the lens on near and far
Describe the vestibulo-ocular reflex? It involves CNS connections between where?
Turns the eyes in the opposite direction to a head movement. Involves CNS connections between CNVIII and CNs III, IV and VI
Describe the oculocardiac reflex? It involves CNS connections between where?
Reflex bradycardia in response to tension on extra ocular muscles or pressure on the eye. Involves CNS connections between CNV1 and CNX
What nerve fibres are involved in opening the eyes really wide?
Sympathetic
What nerve fibres focus on far objects? (dilate pupil)
Sympathetic
What nerve fibres focus on near objects? (constrict pupil)
Parasympathetic
What nerve fibres are involved in reflex lacrimation?
Parasympathetic
What muscle is involved in opening the eyes in fight or flight response?
Smooth muscle part of the LPS
What is a mydriatic pupil?
A non-physiologically enlarged pupil e.g. due to mydriatic drugs
What muscle is responsible for dilating the pupil?
Dilator pupillae
Where does the dilator pupillae muscle originate and insert?
Originates around the external surface of iris (fixed) and insert around the internal surface of the iris (mobile)
What is a mitotic pupil? Give an example of a syndrome where this is seen.
A non-physiologically constricted pupil- can be seen in Horner’s Syndrome
A fixed pin point pupil can be a serious pathological sign of what?
Opiate drug use
A fixed dilated ‘blown’ pupil can be a serious pathological sign. It can indicate pathology in what cranial nerve?
CNIII
In the pupillary light reflex, what is the sensory afferent limb?
Ipsilateral optic nerve
In the pupillary light reflex, where do CNS connections occur?
Midbrain
In the pupillary light reflex, what is the motor efferent limb?
Bilateral oculomotor nerve
In the pupillary light reflex, a direct light reflex occurs in which eye?
Stimulated eye
In the pupillary light reflex, a consensual light reflex occurs in which eye?
Non-stimulated eye
The pupillary light reflex involves a how many neurone chain?
4
What are the 1st neurones involved in the pupillary light reflex?
Retinal ganglion cells
The 2nd neurones in the pupillary light reflex are located entirely within where?
The midbrain
The 3rd neurones in the pupillary light reflex exit the midbrain to synapse where?
Ciliary ganglion
The 4th neurones in the pupillary light reflex have a course in the short ciliary nerves to act on which muscles?
Sphincter pupillae muscles
The suspensory ligament of the lens connects what?
The circumference of the lens and ciliary body
What type of muscle is the ciliary body?
Smooth
What happens to the ciliary muscles, suspensory ligament and lens in far vision?
Ciliary muscles relax, the ligament tighten and the lens flattens
What happens to ciliary muscles in near vision? What nerve fibres are responsible for this?
The contract- parasympathetics
What happens to the suspensory ligament and lens in near vision?
Ligament relaxes and the lens becomes spherical
What does lysozyme do?
Hydrolyses bacterial cell walls
What is the afferent limb in reflex tears?
CNV1 from cornea/conjunctiva
What is the efferent limb in reflex tears?
CNVII
What are the main symptoms of Horner’s syndrome?
Ipsilateral mitosis, ptosis, anhydrosis, increased warmth and redness
What causes Horner’s syndrome?
Impaired sympathetic innervation to the head and neck from compression of the cervical sympathetic trunk
Name 5 causes of Horner’s syndrome?
Root of neck trauma, carotid dissection, internal jugular vein engorgement, deep cervical node metastases, pancoast tumour
