S2 Anatomy Exam 3: Head & Neck Development

Front 1

Obj.
List the sources of mesenchyme in the head

Back 1

-paraxial mesoderm
-lateral plate mesoderm
-neural crest ectomesenchyme
-ectodermal placodes

Front 2

Obj.
role of neural crest cells in forming skeletal tissues in the mesenchyme of the head

Back 2

form pharyngeal arch & facial skeletal tissues & CT

Front 3

Obj.
Neural crest cells also form the sensory ganglia of nerves by joining with __________

What nerves?

Back 3

ectodermal placodes


trigeminal, facial, glossopharyngeal, & vagus nerves

Front 4

The _____________ forms the laryngeal cartilages

Back 4

lateral plate mesoderm

Front 5

Obj.
The ______________ becomes segmented into somitomeres & somites

What does it form?

Back 5

paraxial mesoderm

forms:
-cranial base & cranial vault
-skeletal muscles of craniofacial region
-dermis, meninges, & other CT of dorsal head

Front 6

Obj.
List the head and neck muscles that develop from somites/somitomeres and their innervations.

Back 6

somites 1-2-->sup, med, vent recti-->oculomotor
somites 1-2-->intrinsic laryngeal--> vagus
somites 2-5--> tongue muscles-> hypoglossal
somite 3--> superior oblique--> trochlear
somite 4--> jaw closing--> trigeminal
somite 5--> lateral rectus--> abducens
somite 6--> jaw open/2nd arch--> facial
somite 7--> stylopharyngeus--> glossopharyngeal

Front 7

Obj.
List which cranial nerves contain general somatic efferent (GSE) nerve fibers and the muscles innervated by each cranial nerve.

Back 7

trigeminal (3)- jaw closing muscles
trochlear (4)- superior oblique
abducens (6)- lateral rectus
glossopharyngeal (9)- stylopharyngeus
hypoglossal (12)- tongue muscles

Front 8

Obj
Pharyngeal arch 1:
skeletal component-
muscle component-
SVE nervous component-

Back 8

skeletal component-
middle ear (malleus, incus, ant ligament malleus)
maxillary process (maxilla, premaxilla)
mandibular process (sphenomandibular ligament)
frontonasal prominence (zygomatic & temporal)

muscle component-
masseter, temporalis, lat & med pterygoid
mylohyoid & anterior belly of digastric
tensor veli palatini (soft palate)
tensor tympani (middle ear)

SVE nervous component-
trigeminal nerve via mandibular (V3)

Front 9

Obj
Pharyngeal arch 2:
skeletal component-
muscle component-
SVE nervous component-

Back 9

skeletal component-
stapes
styloid process
stylohyoid ligament
lesser horn & upper body of hyoid

muscle component-
buccinator, auricularis, frontalis (facial expression)
platysma, orbicularis oris & orbicularis oculi
stylohyoid & post belly digastric
stapedius

SVE nervous component-
facial

Front 10

Obj
Pharyngeal arch 3:
skeletal component-
muscle component-
SVE nervous component-

Back 10

skeletal component-
greater horn & lower body of hyoid

muscle component-
stylopharyngeus

SVE nervous component-
glossopharyngeal

Front 11

Obj
Pharyngeal arch 4 & 6:
skeletal component-
muscle component-
SVE nervous component-

Back 11

skeletal component-
thyroid, cricoid, arytenoid, corniculate, cuneiform (larynx cartilage)

muscle component-
soft palate & pharynx (4)
cricothyroid (4)
intrinsic larynx (6)

SVE nervous component-
vagus via pharyngeal branch (4), external laryngeal (4), recurrent laryngeal (6)

Front 12

The first pharyngeal arch--> _____________ cartilage--> malleus, incus, ant ligament of malleus, & sphenomandibular ligament

Back 12

meckel's cartilage

Front 13

The second pharyngeal arch--> ___________cartilage-->
stapes, styloid process of temporal bone, stylohyoid ligament, lesser horn & upper body hyoid bone

Back 13

Reichert's cartilage

Front 14

Obj.
Describe the development of adult derivatives of the pharyngeal pouches.

Back 14

1st- tubotympanic recess--> tympanic cavity , auditory (Eustachian) tube, tympanic membrane

2nd- palatine tonsil, tonsillar fossa

3rd- inferior parathyroid gland & thymus

4th- superior parathyroid gland & ultimobranchial body--> parafollicular (C) cells of thyroid

Front 15

Obj.
Describe the development of adult derivatives of the 1st pharyngeal cleft

Back 15

forms external auditory meatus
--> plugged by meatal plug during development
(if persists= deafness)

-contributes also to tympanic membrane (eardrum)

Front 16

Obj
Desribe the development of adult derivatives of 2nd, 3rd, & 4th pharyngeal clefts

Back 16

temporarily form cervical sinus-->
2nd pharyngeal arch over grows 3rd & 4th-->
fuses w/ epicardial ridge

Front 17

Obj.
Discuss the embryological basis for the variability in location of the parathyroid glands.

Back 17

-during development, the thymus migrates caudally into the thorax, pulling the inferior parathyroid (from 3rd pouch) part of the way with it
-superior parathyroid (4th pouch) also migrates caudally w/ thyroid
= variable position
(inferior parathyroid usually more variable)

Front 18

Obj.
Discuss the development of lateral cervical and thyroglossal duct cysts and how they differ in their clinical presentations.

Back 18

lateral cervical cyst= remnant of cervical sinus
*located laterally along ant border of SCM, may be present w/ external/internal fistula

thyroglossal duct cyst= remnant of thyroid tissue
*located in or near midline , may be the ONLY thyroid tissue present

Front 19

The face develops from five facial primordia. List them

Back 19

(1) frontonasal prominence
(2) maxillary prominences
(2) mandibular prominences

*development begins 4th wk

Front 20

Medial & lateral nasal prominences develop from the ______________, which invaginates to form the nasal pit

The 2 medial nasal prominences merge to from what?

Back 20

nasal placode


the intermaxillary segment

Front 21

Obj.
List the derivatives of the intermaxillary segment.

Back 21

Philtrim of upper lip
Maxillary alveolar process w/ 4 incisor teeth
Primary palate

(primary palate + maxillary alveolar--> premaxilla)

Front 22

The nasal pit (future cavity) is initially separated from the oral cavity by the ___________ membrane

What does this membrane break down to form?

Back 22

oronasal membrane


primitive choanae (at future site of incisive canals)

Front 23

The medial nasal & maxillary prominences fuse to form the _____________

Back 23

upper lip

Front 24

The lateral nasal & maxillary prominences are initially separated by the ____________, where the nasolacrimal duct will later form & connect the __________ & ____________

Back 24

nasolacrimal groove


lacrimal sac & inferior meatus

Front 25

What is the dorsum of the nose formed by?

Back 25

frontonasal prominence
lateral nasal prominences (sides of nose)
medial nasal prominences (crest & tip)

Front 26

The mandibular prominences merge to form the ______

Back 26

lower lip (& jaw)

Front 27

Outgrowths from the maxillary prominences, palatal shelves, fuse together to form the _________

Back 27

secondary palate

Front 28

Palatal shelves also fuse superiorly w/ the __________
& anteriorly w/ the _____________

Back 28

nasal septum

incisive fossa (containing incisive canals)

Front 29

Obj.
Facial clefts are caused by what?

Back 29

multifactorial*
-deficient neural crest migration & proliferation

Front 30

Obj.
Discuss the embryological basis for cleft lip and cleft palate and the different types of facial clefts.

Back 30

cleft lip = failure of maxillary & medial nasal prominences to fuse (lip only or lip & maxillary alveolar process)

cleft palate= cleft lip w/ cleft of primary palate (hard & soft palates BOTH or only soft palate)

Front 31

Obj.
Discuss the embryological basis for the differences in sensory innervation of the mucosa of the anterior 2/3 and posterior 1/3 of the tongue.

Back 31

ant 2/3- from 1st pharyngeal arch
lateral lingual swellings overgrow tuberculumimpar
GSA from trigeminal nerve

post 1/3- from 3rd pharyngeal arch
copula (hypobranchial eminence)
GVA from glossopharyngeal nerve

Front 32

The extreme posterior part of the tongue is from what arch?
innervated by what?

Back 32

4th arch (epiglottic swelling)

internal laryngeal branch of vagus nerve

Front 33

Obj.
Describe the development of the muscles of the tongue

Back 33

develop from myoblasts from occipital somites
--> carry nerve supply w/ (hypoglossal nerve)

Front 34

Obj.
Describe the development of the thyroid gland

Back 34

begins development as an endodermal proliferation btwn tuberculum impar & coplua
(^site = foramen cecum on developed tongue)

descends along midline anterior to hyoid bone & laryngeal cartilages

reaches final position in front of trachea

Front 35

Obj.
Basis for and potential clinical importance of aberrant thyroid tissue.

Back 35

As thyroid migrates, it remains connected to foramen cecum of tongue by thyroglossal duct

--> thyroglossal cyst or aberrant thyroid tissue may be anywhere along this path

Front 36

Obj.
Describe normal development of the skull

Back 36

Hypophyseal fossa divides skull developmentally:
-Front half of of skull from paraxial mesoderm
-Back half of skull from neural crest cells

Front 37

2 parts of the skull

Back 37

viscerocranium- facial skeleton (from paraxial)

neurocranium- encloses & supports/protects brain

Front 38

2 parts of neurocranium

Back 38

cranial base (floor)

cranial vault (sides & roof/skullcap (calvaria))

Front 39

Intramembranous ossification of the cranial vault forms_________________

Endochondral ossification in cranial base forms ____________

Back 39

desmocranium


chondrocranium

Front 40

Obj.
Role of sutures & synchrondroses in skull development

Back 40

synchondroses= cartilaginous joints
sutures= fibrous joints (btwn adjacent bones)
^allow for growth of skull

*important bc bone can grow only on surface

Front 41

Obj.
Define “craniosynostosis” and discuss the different malformations that may result.

Back 41

= sutures fuse prematurely

-growth is restricted to perpendicular fused sutures & compensatory overgrowth occurs:
sagittal suture-->scaphocephally (long, narrow)
metopic suture--> trigoncephally (triangle/wedge)
bilateral coronal--> oxycephaly (tall "tower", wide)
unilateral coronal/lamboidal--> plagiocephally (facial asymmetry)

Front 42

Obj.
Distinguish between occipital plagiocephaly and deformational plagiocephaly

Back 42

occipital plagiocephaly- unilateral flattening due to ipsilateral fusion of the lambdoid suture, contralateral side buldges

deformational plagiocephaly- due to supine sleep position