Head and Neck / Craniofacial; both including embryology Flashcards
Describe gustatory sweating
- Also called Frey’s syndrome
- sweating while eating
- during parotid gland surgery, can get abnormaly reinnervation betwee sympathetics to sweat glands and parasympathetic to the parotid gland from the auriculotemporal nerve,
- as well as parasympathetics crossing to facial sweat glands when raw parotid gland is opposed to skin
- therefore eating which should stimlate the parotid gland actually stimulates sweat glands
describe relationship between arteries in neck, and cranial nerves
- facial artery, at origin at facial-lingual trunk from external carotid, travels UNDER cranial nerve XI (hypoglossal; injury results in ipsilateral tongue paralysis)
- facial artery at lateral mandible is related to the marginal mandibular branch of CN VII
- superior laryngeal artery is related to recurrent laryngeal nerve (vocal cord paralysis)
- common carotid artery is related to vagus nerve (vocal cord paralysis, other)
- occipital artery is related to SAN
describe type of anatomy/joint of the TMJ
- ginglymoarthroidal joint, which means there is sliding component (superior portion - glenoid to disc) and hinge component (inferior portion - disc to condyle)
- early mouth opening is hinge (20mm), from inferior portion
- late / wide mouth opening is helped by translation / sliding forward, from superior portion
List ways to identify the facial nerve as it emerges from the styloid foramen
- If the tragal cartilage is followed to its deep end, it terminates in a point. The nerve is 1 cm deep and inferior to this “tragal pointer”. There is an avascular plane right on the anterior surface of the tragus that allows a safe and quick dissection to this tragal pointer.
- By following the posterior belly of the digastric posteriorly, the nerve is found passing laterally immediately deep to the upper border of the posterior end of the muscle.
- If the anterior border of the mastoid process is traced superiorly, if forms an angle with the tympanic bone. The nerve bisects the angle formed between these two bones (at the tympanomastoid suture).
- By feeling the styloid process in between the mastoid bone and the posterior border of the mandible. The nerve is just lateral to this process.
- By following the terminal branches of the nerve proximally
How many bones are there in the skull? List them
- 22 bones
- Neurocranium
- Occipital (1)
- Parietal (2)
- Temporal (2)
- Frontal (1); orbit
- Sphenoid (1); orbit
- Ethmoid (1); orbit
- Viscerocranium (face)
- Lacrimal (2); orbit
- Zygoma (2); orbit
- Maxilla (2); orbit
- Palatine bone (2); orbit
- Nasal bones (2)
- Inferior nasal concha (2)
- Vomer (1)
- Mandible (1)
what types of structures are derived from ectoderm, mesoderm and endoderm?
- Ectoderm: Nervous system, skin (epidermis and appendages), and neural crest cells and derivatives
- Mesoderm: Bone, cartilage, muscles, connective tissue (dermis), dura mater, heart, vessels, blood, reproductive organs, and genitourinary system
- Endoderm: Gastrointestinal and respiratory lining and digestive organ parenchyma
what are the Carnegie stages?
· based on development; from gestation to birth; standardized system of 23 stages
· defined by morphology, age, somites, length
What is a somite?
- segmental mesodermal swelling around neural tube
- 42 to 44 pairs are present at end of 5th week (# used to date embryo); 3 subtypes:
- myotome (tendon and bone)
- dermotoma (dermis of neck and trunk)
- sclerotome (vertebrae, base of skull and ribs)
what are neural crest cells?
- pluripotent cells of ectodermal origin
- form at jxn of neural tube and surface ectoderm
how do the pharyngeal (branchial) arches form?
- form from migrating NCC & surrounding pharyngeal mesoderm and endoderm
describe the components of each of the branchial arches
Arch
Muscle
Cartilage
Artery
Nerve
I - mandibular
(MxP, MdP)
Mastication
Mylohyoid
Anterior digastric
TVP
tensor tympani
Meckel’s: all disappear except Md condyle and malleus
Also: maxilla, incus, greater wing sphenoid
maxillary
V
II - hyoid
Facial expression
posterior digastric
stylohyoid, stapedius
Reichert’s: lesser horn and upper body hyoid
also: stapes, styloid process, stylohyoid ligament,
stapedial
VII
III - pharyngeal
stylopharyngeus
greater horn and lower body hyoid
carotid
IX
IV - laryngeal
velar: LVP, PP, PG, sup constrictor (ie not TVP)
pharyngeal contricters
laryngeal muscles
thyroid cartilage
aortic arch, R subclavian
X
V
(sometimes grouped w/ IV)
intrinsic laryngeal muscles except cricothyroid
cricoid, arytenoid, corniculate
L pulmonary and DA, R subclavian
recurrent
laryngeal
VI
SCM, trapezius
/
/
XI
describe the branchial pouches and their derivatives
Pouch
Derivative
I
middle ear, internal auditory canal
II
palatine tonsil
III
inferior parathyroid, thymus
IV
superior parathyroid (IV migrates above III)
V
ultimobranchial body (C cells)
briefly define 2 methods of bone formation
- ntramembranous ossification: Cartilaginous precursors resorb; mesenchymal cells directly differentiate into osteoblasts without a cartilaginous intermediate
- Endochondral ossification: A cartilaginous template is directly and gradually replaced with a bony matrix
describe components of the skull that develop from intramembranous ossification compared to endochronral ossification
- Neurocranium - encasing, protecting the brain
- Membranous neurocranium - cranial vault; via IMO of NCCs
- paired frontal, squamosal, pareital, and upper occipital
- Cartilaginous neurocranium - cranial base
- via EO of mesodermal origin
- sphenoid and ethmoid, mastoid and petrous temporal bone, base of occipital bone
- Membranous neurocranium - cranial vault; via IMO of NCCs
- Viscerocranium - bones of facial skeleton
- Membranous viscerocranium; via IMO
- derived from the MxP of the 1st branchial arch: squamous temporal, maxilla, zygoma, palatine, vomer and palatine bone
- derived from MdP of 1st branchial arch: mandible (except condyles)
- Cartilaginous viscerocranium
- 1st arch - meckel’s - condyle of mandible, malleus
- 2nd arch - reichert’s - stapes
- Membranous viscerocranium; via IMO
discuss the embryological facial prominences, and what the derive to become
Prominence
Gives Rise to
FNP
Forehead, nasal dorsum
MNP, LNP
(from ventral, caudal movement)
MNP
central nose and nasal septum, pre-maxilla, primary palate, philtral column and midlip
(from fusion of bilateral MNP)
LNP
nasal ala (incl cartilages)
MxP
secondary palate, lateral lip (lat to philtral column), lateral maxilla, nasolacrimal duct, cheeks, zygoma
(MxP first meets/fuses with LNP then MNP; fusion leads to contuity between lip, nose, palate)
MdP
Lower lip, meckel’s cartilage (mandible, malleolus), lower face
mandible from intramembranous ossification of meckel’s; exception are condyles by endochondral ossification
discuss the embrylogical development of the facial promenences, and specifically the perioral and palate development, as it relates to cleft lip and palate formation
Week
Occurrence
Formation
4
MNP, LNP form from the FNP
Nares
4-6
Maxillary prominence grows medially to merge with MNP; paired MNP in midline
Upper lip and primary palate (paired MNP in midline = medial palatine process)
6
Paired vertical projections of maxillary prominences from either side of the tongue
Lateral palatal shelves (lateral palatine processes)
7
Tongue withdraws, palatine processes “swing” into a horizontal position (R before L)
Secondary hard palate
8
Intramembranous ossification of hard palate
Lateral palatal shelves and premaxilla
7-12
Growth centres in the caudal end of the palatal shelves sequentially merge and remodel
Soft palate
describe the general pathogenesis of clefts of face, lip, palate
- Cleft lip: failure of fusion between the MxP and the MNP, mesenchymal tissue fails to merge
- midline cleft lip: failure of fusion of paired MNP
- Cleft of primary palate: failure of fusion of medial and lateral palatine processes
- Cleft of secondary palate: Failure of elevation/contact/adhesion or failure of fusion of lateral palatine processes to each other / nasal septum
describe innervation of tongue
- anterior 2/3 from 1st branchial arch; innervated by CN V (sensation) and CN VII (taste)
- posterior 2/3 from 3rd branchial arch; innvervated by CN IX for sensation and taste
- motor to tongue from CN XII for all muscles except palatoglossus (CN X)
What is the blood supply to the hard palate?
- Primary hard palate (anterior to incisive foramen)
- nasopalatine
- anterior and posteiror superior alveolar
- Secondary hard palate
- major: greater palatine
- minor: nasopalatine, ant/post superior alveolar
Which muscles contribute the most to velopharyngeal function?
- Levator veli palatini
- Musculus uvulus
- Superior pharyngeal constrictor
Describe the innervation to muscles that contribute to the soft palate / velopharyngeal function
- All muscles are innervated by the pharyngeal plexus CN X (CN IX): LVP, PP, PG, SPC, musculus uvulus EXCEPT:
- TVP - by CN V
