The external nose Flashcards
what is the external nose?
a visible component of the face, projecting over and allowing entrance into the nasal cavity
shape of external nose?
pyramidal shape
what is located superiorly on the external nose?
nasal root - continuous with the forehead
apex of external nose?
nose ends inferiorly in a rounded ‘tip’
between root and apex of external nose?
dorsum of the nose
where are nares located?
immediately inferiorly to the apex are the nares
what are nares of the nose?
piriform openings into the vestibule of the nasal cavity
what are nares bounded by medially and laterally?
medially: nasal septum
laterally: the ala nasi (the lateral cartilaginous wings of the nose)
what is the skeleton of the external nose composed of?
both bony and cartilaginous components
bony component of external nose?
located superiorly
comprised of contributions from the nasal bones, maxillae and frontal bone
cartilaginous component of external nose?
located inferiorly
comprised of the two lateral cartilages, two alar cartilages and one septal cartilage
skin overlying nose?
skin over the bony part of the nose is thin
skin overlying the cartilaginous part is thicker with many sebaceous glands
where does skin overlying nose extend?
extends INTO the vestibule of the nose via the nares
there are hairs which function to filter air as it enters the respiratory system
what can trauma to the external nose result in?
saddle nose deformity
what happens in saddle nose deformity?
septal support to the nose is lost
middle part of nose appears sunken
what is saddle nose deformity a result of?
direct damage to septal bone / cartilage
OR
consequence of nasal septal haematoma
how does saddle nose deformity result from nasal septal haematoma?
cartilage has no blood supply of its own, relies on oxygen and nutrients diffusing from blood vessels in surrounding perichondrium
haematoma between cartilage and perichondrium can result in destruction of septum - therefore deformity
where does the skin of the external nose receive its arterial supply from?
branches of the maxillary (V2) and ophthalmic (V1) arteries
where else does the septum and alar cartilages receive additional blood supply from?
the angular artery and lateral nasal artery
what are angular artery and lateral nasal artery branches of?
the facial artery (derived from the external carotid artery)
where does venous drainage of the nose drain into?
into the facial vein, and then in turn into the internal jugular vein
Lymphatic drainage from the external nose is via?
superficial lymphatic vessels accompanying the facial vein
where do superficial lymphatic vessels accompanying the facial vein drain into?
like all lymphatic vessels of the head and neck, ultimately drain into the deep cervical lymph nodes
how is the venous drainage of the nose and surrounding area unique?
result of communication between facial vein and cavernous sinus, via the (superior + inferior) OPHTHALMIC vein
(medial angle of eye)
where does the cavernous sinus lie?
within cranial cavity
small area either side lateral to forebrain
what does communication between facial veins –> ophthalmic veins to cavernous sinus enable?
infections from the nasal area to spread to the brain
what can retrograde spread of infection from the nasal area cause?
cavernous sinus thrombosis,
meningitis,
brain abscess
where is Sensory innervation of the external nose derived from?
the trigeminal nerve (CN V)
what is the external nasal nerve a branch of?
the ophthalmic nerve (CN V1)
what does the external nasal nerve (V1) supply?
the skin of the dorsum of nose, nasal alae and nasal vestibule
what supplies the lateral aspects of the nose?
infrorbital nerve, a branch of the maxillary nerve (CN V2)
what is the motor innervation to the nasal muscles of facial expression?
via the facial nerve (CN VII)
