Anatomy - Important Reflexes of the Orbital Region Flashcards
where does the suspensory ligament of the eye attach between?
the zygoma and the lacrimal bone
what is the function of the suspensory ligament of the eye?
holds the eye just above the floor of the orbit
in which direction does a fractured zygoma tend to rotate?
medially towards the floor of the orbit
how can a fractured zygoma cause double vision?
the suspensory ligament attaches laterally to the zygoma so if they zygoma is fractured it tends to rotate medially towards the floor of the orbit and the ligament cannot do its job so the eye can be lowered to towards the orbital floor, which causes the eyes to no longer be on the same vertical position
what else can be injured, other than the suspensory ligament, in a fractured zygoma?
the infraorbital neurovascular bundle
if there is damage to the infraorbital NVB, what does this result in?
general sensory deficit of the facial skin
what does CN V1 supply?
the upper eyelid, the cornea, all the conjuctiva, the skin of the root/bridge/tip of the nose
what does CN V2 supply?
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 does CN V3 supply?
the skin over the mandible and TMJ joint
what area of the mandible is not supplied by CN V3? and what does supply it?
the angle of the mandible- supplied by C2,3 spinal nerves
what is the name of the branch that supplies the angle of the mandible?
great oricular nerve
what are the 2 components of the blink reflex?
the afferent (sensory) limb and the efferent (motor) lim
how do you assess the blink reflex in clinical practice?
use a sterile point of cotton wool and gently touch the cornea
when the cotton wool touches the cornea, what is the pathway in which AP are conducted to the brain?
via CN V1 to the trigeminal ganglion then in the trigeminal nerve (CN V) to the pons
once the APs reach the pons, how is the motor limb of the blink reflex brought about?
there is CNS connections between CN V and CN VII, action potentials are conducted to the eyelid part of orbicularis oculi to bring about the blink
where do presynaptic sympathetic axons from the CNS (to supply the head and neck) exit the spinal cord?
in T1 spinal nerve
after a presynaptic sympathetic axon exits the spinal cord in T1 spinal nerve, what does it ascend within and where does it synapse?
ascends within sympathetic trunk and then synapses in the superior cervical sympathetic ganglion
when a presynpatic sympathetic axon synapses at the superior cervical ganglion, what does it release?
acetylcholine
where do the postsynaptic sympathetic axons enter after synapsing in the superior cervical ganglion?
the internal carotid nerve and external carotid nerve
once the postsynaptic sympathetic axons have entered the internal and external carotid nerve, what do they do?
pass onto the surface of the internal and external carotid arteries to be carried to organs of the head
what artery carries sympathetic axons into the orbit?
the ophthalmic artery - branch of internal carotid
what forms the stellate ganglion?
the inferior cervical and 1st thoracic ganglia often fuse to form the stellate ganglion
what does the postsynaptic sympathetic axon release to stimulate the target organ?
noradrenaline
where are the ganglions for parasympathetic axons?
located within the organ
