27 Head and Neck Flashcards
most of the head and face develop from WHAT
PHARYNGEAL APPARATUS which is a series of bulges and internal pouches that appear week 4
bulges covered with ectoderm externally, endoderm internally, and filled with mesenchyme (mesoderm and neural crest)
eventually FIVE PAIRS develop
each has CAN: Cartilage Bar, Artery and Nerve
PHARYNGEAL ARCHES
these are external grooves that separate each pharyngeal arch
PHARYNGEAL CLEFTS (GROOVES)
these are INTERNAL ooutpocketings of the endoderm lined foregut (pharynx)
PHARYNGEAL POUCHES
Skeletal elements found in arch 1 (I’M)
Maxilla, Mandible, Incus, Malleus
Skeletal elements found in arch 2 (S)
Stapes, Styloid Process
Skeletal elements found in arch 3 (H)
Hyoid (lower body) and Greater Horn
Skeletal elements found in arch 4 (T)
Thyroid Cartilage
a cranial nerve grows into each arch and INNERVATES what
mucosa and muscles that form them
each arch is supplied by what artery
a SEPERATE artery
outpocketings of the endoderm lined foregut (pharynx) give rise to the epithelial of auditory tube, middle ear, inner lining of tympanic membrane and the palatine tonsils
PHARYNGEAL Pouches
Only CLEFT 1 gives rise to a permanent structure which is
EXTERNAL AUDITORY MEATUS and the outer lining of the tympanic membrane
When do the other clefts disapper
when ARCH 2 OVERGROWS the other clefts leaving a small cervical sinus which is eventually lost
If persistence of a cervical sinus occurs it can cause formation of what
a FISTULAR or CYST on the side of the neck
Where does most of the glandular tissue of the thyroid orginiate from
MIDLINE GROWTH from the endoderm in the floor of the future pharynx
primordial thyroid cells descends through the developing tongue at a small pit known as
FORAMEN CECUM
Failure of the thyroid tissue to migrate results in what
LINGUAL THYROID GLAND
remenants of the thyroglossal duct can result in what
CYST or FISTULA along the midline of the front of neck
how does tongue development begin
swellings appear on the endoderm on the floor of the mouth (intially from arches 1-4) but eventually arch 2 is overgrown
(Tongue Tie ) – the tip of the tongue is tethered to the floor of the mouth by a thick band of tissue “anchored tongue”
ANKYLOGLOSSIA
when does salivary gland development begin and what do they initally form as
SOLID EPITHELIAL BUDS beginning in weeks 6 and 7
Parotid develops first from oral ectoderm
Submandibular and sublingual glands develop from endoderm lined portion of oral cavity
The arches that make up the tongue are:
One arch is lost
Arches 1, 3 and 4
Arch 2 is LOSt
Anterior 2/3rd of the tongue is made up of Arch __ innervated by __
Posterior 1/3 of the tongue is made of arch ___ innervated by
Epiglottis and way post tongue = Arch ___ innervated by ___
Arch 1 – CN 5 = Trigeminal Nerve
Arch 3 – CN 9 = Glossopharyngeal Nerve
Arch 4 – CN 10 = vagus nerve
Development of face is made up of two parts
Frontonasal (FN) prominence : Medial and Lateral Nasal prominence
Pharyngeal Arch 1 : Maxillary and Mandibular Prominence (2 each)
The maxillary prominences grow towards each other trapping:
stupid MEDIAL nasal prominences in the middle
The upper lip is formed from which two prominences
MAXILLARY prominecnces and stupid medial nasal prominences
The frontonasal prominence forms what at week 10
Forehead
Medial Nasal and Lateral Prominences Form:
Medial – middle of nose and philtrum of upper lip
Lateral – sides of the nose
The Mandibular prominences form
LOWER LIP and FACE
How is the PALATE formed?
Maxillary prominences grow together from both sides, trapping the inside part of medial nasal prominences
This palate forms when the inner portions of the two MEDIAL nasal prominences = INTERMAXILLARY segment merges together at the midline forming a cute triangle
PRIMARY PALATE
This palate forms when the inner portions of the MAXILLARY prominences = PALATINE SHELVES grow together and fuse in the midline
SECONDARY PALATE
What happens when the maxillary prominence fails to fuse with the medial nasal prominence
occurs during weeks 7-8
CLEFT LIP
What happens when the maxillary prominence fails to fuse with the lateral nasal prominence
The nasolacrimal duct = exposed
OBLIQUE FACIAL CLEFT
When the maxillary prominence fails to fuse with each other and or with the primary or anterior palate during weeks 8-10
CLEFT PALATE
many craniofacial defects are due to abnormalities in the migration or proliferation of what cells in the phayngeal arches
Neural Crestrs
In this syndrome, the infant has a small, underdeveloped mandible and cheek bones. External ears are malformed and hearing defects are common.
External features on eyes = abnormal and are described as downward slanting eyes
First Arch Syndrome – TREACHER COLLINS SYNDROME
In this syndrome, the infant has a small, underdeveloped mandible. Tongue is posteriorly placed with a tendency to ball up at the back of the mouth and fall into throat
Experience feeding and breathing problems
First ARCH syndrome: PIERRE ROBIN SEQUENCE
This defect has a complete or partial absence of thymus and parathyroid glands due to failure of third and fourth pharyngeal pouches to differntiate properly.
DIGEORGE ANOMALY
