Anatomy - Special Senses Flashcards
Name the three foramina at the apex of the orbit
- Optic foramen
- Superior orbital fissure
- Inferior orbital fissure
What 2 structures transverse through the optic foramen?
Ophthalmic artery and optic nerve
What 5 structures transverse through the superior orbital fissure?
- Oculomotor nerve (CN III)
- Trochlear nerve (CN IV)
- Abducens nerve (CN VI)
- Ophthalmic veins
- Ophthalmic division of trigeminal nerve (CN V1)
What passes through the inferior orbital fissure?
Maxillary division of the trigeminal nerve (CN V2)
What air sinuses lie in close proximity to the walls of the orbit?
Frontal sinus, ethmoid air cells and the maxillary sinus
What are the seven main contents of the orbit?
- Fat
- Extrinsic ocular muscles
- Ligaments supporting eye
- Optic nerve
- Branches of ophthalmic artery
- Lacrimal (tear) apparatus
- Eyeball
What are the parts to the outer fibrous layer of the eye?
Cornea and sclera - complete layer
What are the parts to the middle vascular layer of the eye?
- Iris, ciliary body and choroid
* Incomplete anteriorly - anterior aperture (in iris) is the pupil
What are the parts to the inner sensory layer of the eye?
Retina - present posteriorly and stops just infront of the equator
What two types of fluid are found in the eye and where?
- Aqueous Humor - watery fluid in the anterior segment
* Vitreous Humor - gel in the posterior segment
What is the fovea of the eye?
Sight of maximal vision
What is the optic disc of the eye?
Physical blind spot
What part of the eye produces aqueous humor?
Ciliary Body
Name the intrinsic muscles of the eye
- Ciliaris
- Constrictor pupillae
- Dilator pupillae
Where is the ciliaris and what is its action?
Found in the ciliary body and is responsible for accommodation, innervated by the oculomotor nerve (CN III)
Where is the constrictor pupillae and what is its action?
Pupillary border of iris and constrict the pupil, innervated by the oculomotor nerve (CN III)
Where is the dilator pupillae and what is its action?
Border of the iris and dilates the pupil with sympathetic innervation
What is the benefit of intorsion and extorsion of the eye?
Occur when the head is tilted, to keep the eyeballs focussed on an object the eyes rotate in an opposite direction.
Describe the innervation of the extrinsic muscles of the eye
All oculomotor nerve (CN III) except:
• Lateral rectus - abducens nerve (CN VI)
• Superior oblique - trochlear nerve (CN IV)
What is the action of the medial and lateral rectus?
Adduction and abduction
What are the three movement of the superior rectus muscle?
a. elevation b. adducts c. intorsion
What are the three movement of the inferior rectus muscle?
a. depression b. adducts c. extorts
What are the three movement of the superior oblique muscle?
a. depression b. abducts c. intorsion
What are the three movement of the inferior oblique muscle?
a. elevation b. abducts c. extorsion
What extrinsic muscle is the only one not to arise from the posterior aspect of the orbit?
Inferior oblique
Name the ligaments that prevent over-adduction and over-abduction of the eye
Medial and later check ligaments - lateral ligament prevents the medial rectus from turning too far in and vice versa
What is the function of the suspensory ligament?
Support the eyeball and prevent downwards movements
What branch of the ICA supplies the orbit and the eye?
Ophthalmic artery
Are there any lymphatics in the orbit?
No
Name the three ossicles in the ear
Malleus, incus and stapes
Which ossicle is in contact with the tympanic membrane?
Malleus
Name two muscles related to the ossicles?
Tensor tympani and the stapedius
What is the action of the tensor tympani in the ear?
Pulls malleus medially, tensing tympanic membrane and reducing the amplitude of sound waves
What is the action of stapedius muscle in the ear?
Stabilises stapes when loud noise enters ear
Name two areas with which the cavity of the middle ear communicates
Nasopharynx (via eustacian tube) and mastoid air cells
Within which part of the temporal bone do the middle and inner earl lie?
Petrous part
Name the boney and the membranous chambers in the inner ear
- Bony labyrinth - filled with perilymph fluid
* Membranous labyrinth - filled with endolymph fluid
Which foramen does the facial nerve exit the posterior cranial fossa?
Internal acoustic foramen
What two nerves exit the posterior cranial fossa via the internal acoustic foramen?
Facial and vestibulocochlear (CN VIII)