Week 1 Flashcards
what is mesenchyme?
- mesenchyme is embryonic connective tissue.
- it has the same properties as a connective tissue and develops into bone, cartilage, blood vessels etc.
what is the embryological origin of the neck?
branchial/pharyngeal arches
what is the embryological origin of the face?
develops from 5 mesenchymal processes/prominences.
what is the embryological origin of the skull?
develops from the mesenchyme in the head region of developing embryo.
how is the neural tube formed and what does it give rise to?
- some of the ectoderm in the midline of an embryo folds down o form neural tube > brain + spinal cord.
what is the role of somites in the future head region of an embryo?
they help in cranial skeleton development.
what are pharyngeal/branchial arches?
series of arches which develop around the future mouth and pharynx.
how many branchial arches develop in humans?
5
- 6 arches start to develop but number 5 disappears so we are left with 1,2,3,4 and 6.
when do branchial arches begin developing?
late week 4 of gestation
what embryological tissues make up branchial arches? give detail
- ectoderm lines the outside > also forms clefts in between the arches.
- mesoderm in the middle (+ neural crest cells) > cartilage, muscles.
- endoderm on the inside > also forms pouches between arches.
which nerve is derived from the 1st branchial arch?
mandibular branch of trigeminal nerve (V).
what nerve is derived from the 2nd branchial arch?
facial nerve (VII).
which nerve is derived from the 3rd branchial arch?
glossopharyngeal nerve (IX).
which nerve is derived from the 4th branchial arch?
superior laryngeal branch of vagus (X).
which nerve is derived from the 6th branchial arch (no 5th arch)?
recurrent laryngeal branch of vagus (X).
which nerve innervates the muscles of the face?
facial nerve (VII).
which branchial arch are the facial muscles derived from?
2nd branchial arch
- remember because facial nerve is derived from this arch and this nerve innervated the facial muscles.
the anterior belly of the digastric muscle is innervated by which nerve?
- mandibular division of trigeminar nerve (V3).
the posterior belly of the digastric muscle is innervated by which nerve?
- facial nerve (VII).
the anterior belly of the digastric muscle is derived from which branchial arch?
1st
the posterior belly of the digastric muscle is derived from which branchial arch?
2nd
label this
The Meckel’s cartilage, Malleus and Incus are derived from which branchial arch?
1st
The Stapes, Styloid process, Stylohyoid ligament and Lesser horn of hyoid bone are derived from which branchial arch?
2nd
The greater horn and body of the hyoid bone are derived fromk which branchial arch?
3rd
The thyroid cartilage is derived from which branchial arch?
4th
The cricoid cartilage is derived from which branchial arch?
6th
which other important structures develop from the branchial arches?
tongue
thyroid gland
parathyroid gland
part of the pituitary gland
list the 5 processes/prominences which the fave develops from?
- one frontonasal process (from mesenchyme superior to future mouth).
- two maxillary processes (from maxillary part of 1st branchial arch mesoderm).
- two mandibular processes (also 1st arch mesoderm).
how is the philtrum formed?
when the medial nasal process further grows down downwards and laterally to form a philtrum.
label this
describe the development of the palate
what causes a cleft lip/palate?
when the palatine shelves fail to meet in the midline to form the secondary palate.
describe the bones composing the cranial vault
flat, membranous bones formed by membranous ossification calvaria.
describe the bones composing the base of the skull
irregular bones formed by endochondrial ossification.
how are the viscerocranuim > bones forming skeleton of face, formed?
partly from branches, and partly from sensory (special sense) capsules.
at which age does the anterior fontanelle close?
1.5 years old
why is the skull/cranial vault not fully formed at birth?
- sutures between them soft > allow deformation during passage through birth canal.
what is craniosynostosis?
Craniosynostosis is a birth defect in which the bones in a baby’s skull join together too early. This happens before the baby’s brain is fully formed. As the baby’s brain grows, the skull can become more misshapen.
what are sensory capsules and what is their function?
- derived from mesoderm of somites in head and neck region.
- preform in cartilage and ossify to form bones around the sense organs i.e. nose, eye and ear.
- they form partly base of skull and partly viscerocranium.
what is treacher collins syndrome caused by?
1st pharyngeal/branchial arch abnormality.
how is an auricular/pinna haematoma managed?
- incision and drainage.
- pressure dressing.
- antibiotics.
what is a complication of auricular haematoma?
‘cauliflower ear’
what is the definition of otitis externa?
inflammation of external auditory meatus.
what is the management of otitis externa?
- antibiotic/steroid ear drops.
- +/- suction under microscope.
how can otitis externa be prevented?
no water or cotton buds in the ear
what is the definition of ‘malignant’ otitis externa?
- osteomyelitis of temporal bone.
what are the most common causative organisms in otitis externa?
- pseudomonas
- staphylococcus aureus
what is the usual presentation of ‘malignant’ otitis externa?
- elderly diabetic patient.
- severe pain.
- granulations in external auditory meatus.
- +/- cranial nerve palsies.
what is the management of ‘malignant’ otitis externa?
antibiotics for weeks or months
what is ‘glue ear’/otitis media with effusion?
Otitis media with effusion (OME) is a condition in which there is fluid in the middle ear but no signs of acute infection.
- sterile fluid.
what is the management of otitis media with effusion ‘glue ear’?
- observation for 3 months.
- otovent.
- Grommets are tiny tubes inserted into the eardrum. They allow air to pass through the eardrum, keeping the air pressure on either side equal.
what is the definition of acute supparitive otitis media?
pus in middle ear
presentation of acute suppurative otitis media?
otalgia +/- otorrhoea (pus coming out of ear due to perforation of eardrum).
management of acute supparitive otitis media
observation
paracetamol/ibuprofen
+/- antibiotics
what is the definition of tympanosclerosis?
calcification in tympanic membrane +/- middle ear.
what is the presentation of chronic suppurative otitis media?
- persistent purulent drainage through the perforated tympanic membrane.
or - A cholesteatoma is an abnormal collection of skin cells deep inside your ear. > skin in middle ear +/- mastoid bone.
what are complication of chronic suppurative otitis media?
‘dead ear’
facial palsy
meningitis
brain abscess
what is the management of a perforated tympanic membrane?
water precautions
+/- myringoplasty
what is the presentation of cholesteatoma?
- persistent offensive otorrohoea.
- headache.
- otalgia.
what is the management of cholesteatoma?
mastoidectomy
what is the definition of otosclerosis?
- abnormal bone growth occurs around the stapes bone in the middle ear, impeding its function as a piston onto the cochlea.
- this can result in progressive conductive hearing loss.
aetiology of otosclerosis?
- autosomal dominant condition, significant family history of disease.
management of otosclerosis?
hearing aid
stapedectomy