HaN Flashcards
What do the following develop from: facial skeleton, muscles of mastication and muscles of facial expression?
Neural crest cells of 1st pharyngeal arch
Mesoderm of 1st pharyngeal arch
Mesoderm of 2nd pharyngeal arch
What are neural crest cells?
Specialised population of cells from the neuroectoderm
What does the buccopharyngeal membrane become?
Stomatodeum
Outline the development of the nose
Nasal placodes sink to become nasal pits
Medial and lateral prominences form on either side of pits
Maxillary prominences grow and push the nasal prominences towards the midline
Maxillary and medial prominences all fuse in the middle
How can a cleft lip +/- palate occur?
Medial nasal prominence doesn’t fuse with the maxillary prominence
Palatal shelves also don’t fuse
How are the nasal and oral cavities separated?
Palate - maxillary prominence forms two palatal shelves which fuse in the midline
How does the eye develop?
Forebrain out pockets and contacts the ectoderm to become the lens placode which invaginates and pinches off. The retina is formed from the forebrains. Eyes originally on the side but move round to the middle
What makes the external auditory meatus and the auricles
1st cleft
Proliferation if 1st and 2nd arch
Develop in the neck then move up
What cartilage lines the temporomandibular joint?
Fibrocartilage
What ligaments are in the temporomandibular joint?
Lateral ligament - prevent posterior dislocation
Sphenomandibular
Stylomandibular - support weight
What movements can the TMJ do? What muscles do each one?
Protrusion - lateral pterygoid
Retraction - genie hyoid and digastric
Elevation - temporalis, masseter and medial pterygoid
Depression - gravity and if needed, digastric, geniohyoid and mylohyoid
What is the most likely direction for the TMJ to dislocate, why and what can it damage?
Anterior
Posterior protected by lateral ligament
Facial and auriculotemporal nerve
What bones make up the borders of the orbit?
Roof-frontal/sphenoid
Floor-maxilla/zygomatic
Medial-ethmoid/maxilla/lacrimal
Lateral-zygomatic/sphenoid
What is in the superior orbital fissure?
Lacrimal nerve, frontal nerve, trochlear nerve, superior branch of oculomotor nerve, nasociliary nerve, inferior branch of oculomotor, abducens nerve, ophthalmic vein, sympathetic nerve
What is in the optic canal and the infra orbital fissure?
Optic nerve
Infra orbital nerve
Explain the structure of the optic nerve
Covered by pia, arachnoid and dura mater of the meninges
Central artery and vein
Explain orbital fractures
Usually along the sutures
Medial and inferior walls (thinner)
Can involve sinuses
Blow out fracture displaces walls and contents
What are the muscles of eye movement and what directions do they look in?
Superior, inferior, medial and lateral recti - look in direction they say Inferior oblique (up and out) superior oblique (internal rotation, down and in)
What is the nerve supply to the muscles of eye movement?
Lateral rectus - CNVI abducens
Superior oblique - CNIV trochlear
Rest - CNIII oculomotor
What is the blood supply to the eye?
Internal carotid–>opthalmic–>carotid artery of the retina
External carotid–>infra orbital
Superior/inferior opthalmic veins–>cavernous sinus
Central vein of the retina–>cavernous sinus
What is the danger triangle?
There is communication between the facial vein and cavernous sinus so retrograde infections can spread to the brain
Cavernous sinus thrombosis, meningitis, brain abscess
What is the function of the eyelids?
Protect from light and injury
Prevent drying
What is a stye?
Blockage of the ciliary glands
What stimulates the blink reflex?
Dry eyes
Irritated/contact
What muscles open and close the eyelids and what is their respective nerve supply?
Close - orbicularis oculi - CNVII
Open - levator palpebrae superiorid -CNIII
Superior tarsal muscles - sympathetic nerves
What can cause lesions of sympathetic nerve fibres, CNVII and CNIII and how can this affect the eyelids?
CNVII - Bell’s palsy - lose blinking reflex, dry eyes and infection common
CNIII - ptosis, compromise vision
Sympathetic - horners syndrome