The orbit and nasal cavity Flashcards
Nose function
To filter dust entering the respiratory system
Warm and moisten air
Hairs trap large particles of dust
Nose bones
Paired nasal bones
Maxillae
Frontal bone
Septum
Cartilages
3 main lateral, major alar and septal
Septal cartilage divides nasal cavity into left and right side
Septum
Divides the chamber into two cavities
Internal surface of the nose
Lateral wall has three projections
- superior conchae
- middle conchae
- inferior conchae
Nose blood supply
Branches from opthalmic and maxillary arteries
Nerve supply of nose
From olfactory nerve (V1)
Opthalmic nerve (maxillary V2)
Cranial nerve 1
Olfactory
Type: special afferent- sensory
Exit: cribriform plate
Olfaction
Aided by air flow through the nasal cavity
Conchae help warm and moisten the air
Receptors are in the epithelium lining the roof and walls
Epithelium secretes mucus fluid, odoriferous gases are dissolved into the fluid then detected by the olfactory nerves
Paranasal sinuses
Air filled extensions of the nasal cavity
Paired frontal sinuses in frontal bone that drain through frontonasal duct
Ethmoidal cells
Invaginations in the ethmoid bone and drain into middle meatus (if anterior or middle) or superior meatus (if posterior)
Sphenoidal sinuses
In sphenoid bone
Drain into spheno-ethmoidal recess
Maxillary sinuses
Paired maxillary sinuses in maxilla
Drain into middle meatus
Start growing at about age 2
Orbit bones
Frontal
Maxilla
Ethmoidal
Lacrimal
Sphenoidal
Temporal- zygomatic
Nasal
Eye
Contains optical apparatus for visual system
Located in orbit, suspended by muscles
Outer fibrous later- sclera and cornea
Vascular- iris
Inner- retina
Divided into anterior and posterior chambers
Optic nerve comes in with central artery
Cranial nerve 2
Optic nerve
Type: special afferent- sensory
Exit: optic canal
Special embryology: optic stalk grows out and lens vesicle grows in
Movement of the eye
7 extraocular muscles surrounding globe of the eye responsible for moving it
Extraocular muscles
Levator palpebrae
Superior oblique
Superior rectus
Medial rectus
Lateral rectus
Inferior rectus
Inferior oblique
Attached to eye and bones around it
Movements if the eyeball
Vertical
Transverse
Anteroposterior
Cranial nerve 3
Oculomotor nerve
Doesn’t supply superior oblique or lateral rectus
Type: somatic motor to extra-ocular muscles and via short ciliary nerves to ciliary body and sphincter pupillae
Exit: superior orbital fissure
Parasympathetic means less light going into the eye
Cranial nerve 4
Trochlear nerve
Type: somatic motor to superior oblique
Exit: superior orbital fissure
Cranial nerve 6
Abducent nerve
Type: somatic motor to lateral rectus
Exit: superior orbital fissure
Orbit nerve supply
CN 2, 3, 4, 5(1), 6, 7
Sympathetic
- stimulates dilator pupillae to let more light in
Parasympathetic
- stimulates constrictor pupillae to let less light in
Orbit blood supply
Opthalmic artery
Infra orbital artery
Central artery
Clinical considerations
Inability of specific eye movements (CN 3,4,6), dilated pupil (CN 3), ptosis (CN 3), abnormal pupil reflex (CN 3)
- CN 3: aneurysm of cerebral artery
- CN 4: orbital fracture
- CN 6: cavernous sinus lesion
Lacrimal apparatus consists of
Lacrimal gland which secretes lacrimal fluid
Passes across eye and into lacrimal papilla, sac and inferior meatus via nasolacrimal duct
Nerve supply for crying
Parasympathetic: secretomotor (via facial VII)
Sympathetic: vasoconstrictive ( superior cervical ganglion, via internal carotid)
Conchae
Lined with epithelium
Help direct flow of air
Warm and moisten air
Temporary anosmia
Due to mucus build up
Permanent anosmia
Trauma to face
Abscess
Parkinson’s
Levator palpebrae
Lifts the eyelid
Superior rectus
At the top of the eye
Active in elevation
Adduction
Inferior rectus
At the bottom of the eye
Active in depression
Adduction
Medial rectus
Adduction
Lateral rectus
Abduction
Superior oblique
At the top
Active in depression
Abduction
Inferior oblique
At the bottom
Active in elevation
Abduction
