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
What nerve stimulates lacrimation?
Parasympathetic part of CNVII
What are the four parts of the temporal bone?
Squamous part
Petromastoid part
Tympanic plate
Styloid process
Which parts of the temporal bone would the external acoustic meatus, middle ear and inner ear be found?
Tympanic plate
Petromastoid
Petromastoid
What is the external ear composed of?
Auricle
External acoustic meatus
Which part of the external acoustic meatus are bony and which are cartilaginous
Bony - medial
Cartilage - lateral
What is found within the middle ear?
Ossicles
Eustachian tube opening
Mastoid air cells opening
Oval window
Is the Eustachian tube usually open or closed? What makes it change?
Closed
When swallowing the palate muscles open it
What are the three ossicles and what do they interact with?
Malleus - tympanic membrane and incus
Incus - malleus and stapes
Stapes - incus and inner ear via oval window
Why is the facial nerve easily damaged with middle ear infections?
It lies in the facial canal which only has a very thin bony separation from the middle ear
What is found within the inner ear?
Vestibule - balance
Semicircular ducts/canals
Cochlea - hearing
Spiral organ of corti
What are the functions of the nose?
Olfaction
Respiration
Filter and humidification
Drain and eliminate paranasal sinus/nasalacrimal duct secretions
What arteries supply the nose?
Facial, maxillary and opthalmic
What drains the nose of blood?
Cavernous sinus, facial vein and pterygoid plexus
What is the innervation to the nose?
Olfactory - special sensory
Opthalmic and maxillary (V1 and V2)
Infra orbital and external nasal (V2 and V1)
What are the four paranasal sinuses? Where do they drain?
Maxillary - middle meatus
Frontal - middle meatus
Sphenoid
Ethmoid - middle and superior meatus
How can infections spread to the anterior cranial fossa, middle ear and lacrimal apparatus?
Crib rifle plate
Eustachian tube
Nasolacrimal duct
How is epistaxis treated?
Pressure
Cauterise
Packing
Surgical ligation
What clinical signs will be seen in a patient with oculomotor nerve palsy?
Down and out eye
Upper eyelid ptosis
Possible dilated pupil
Explain harlequin syndrome
Lesion of autonomic fibres of CNV. Lack of sweating and red on half of face
How can the facial nerve be damaged?
Forceps, parotiditis, inflammation
What symptoms are seen with Bell’s palsy?
Ptosis, loss of oral continence
How do you test CNV?
Test sensory in all areas
Test opening and closing the jaw
What are the five branches of the facial nerve?
Temporal, zygomatic, buccal, marginal mandibular, cervical
What are the typical cervical vertebrae and their features?
C3-6 transverse foramen and bifurcated spinous process
What is different about the atypical cervical vertebrae?
C1 - atlas - no body or spinous process
C2 - axis - Odontoid peg
C7 - non bifid spinous process
Explain two types of neck fracture
Burst fracture - fall head first - break atlas
Hangmans - hyperextended - axis break
What are the three main sutures and what bones do they join?
Coronal suture - frontal and parietals
Sagittal - parietals
Lamboid - occipital and parietals
What are the layers of the deep fascia and what do they enclose?
Investing layer - all structures
Pretracheal - trachea, oesophagus, thyroid, infrahyoid
Prevertebral - vertebral column and muscles
Carotid sheath - common, external, internal carotid. Internal jugular vein, vagus nerve and lymph
How can infection spread via fascial planes?
Posterior to prevertebral and enter retropharyngeal space
Investing to pretracheal and enter anterior mediastinum
What are the borders of the anterior triangle?
Superior - mandible
Medial - imaginary midline
Lateral - SCM
What are the borders of the posterior triangle?
Anterior - SCM
Posterior - trapezius
Inferior - clavicle
What are the contents of the anterior triangle?
4 supra hyoid and 4 infrahyoid
CN VIII, IX, X, XI, XII
Carotid arteries and internal jugular vein
What are the contents of the posterior triangle?
Omohyoid, external jugular vein, subclavian artery/vein, CN XI and the cervical and brachial plexuses
List the branches of the external carotid artery
Superior thyroid, lingual, facial, ascending pharyngeal, occipital, posterior auricular, maxillary, superficial temporal
What arteries ascend via the transverse foramina?
Internal carotid
Vertebral
What is in the carotid triangle and what are its borders?
Internal jugular vein, bifurcation of common carotid artery
Posterior - digastric
Lateral - SCM
Medial - omohyoid
What is the arterial blood supply to the scalp? Where are they derived from?
Supra-orbital and supra-trochlear: internal carotid
Superficial temporal, posterior auricular, occipital: external carotid
What are the layers of the scalp?
Skin Connective tissue (loose) Aponeurosis Loose connective tissue Periosteum
How can the middle meningeal artery and what can this cause?
Pterion fracture
Extradural haematoma
