Development of the Head and Neck - Topic 9 Flashcards
The posterior (dorsal) surface of the embryo develops a hollow tube called…?
the neural tube
The neural tube of the early embryo is expanded in the head region and eventually forms the _____ and _____. The remainder of the neural tube extends the length of the embryo and ultimately forms the ____ ___.
- brain
- ventricles
- spinal cord
The expanded cranial end of the neural tube initially forms primary vesicles. How many? What are they called?
3
- Prosencephalon (forebrain)
- Mesencephalon (midbrain)
- Rhombencephalon (hindbrain)
The 3 primary vesicles of the developing neural tube give rise to how many secondary vesicles? What are they called?
5
* Telencephalon
* Diencephalon
[from primary vesicle: prosencephalon]
*Mesencephalon [continuation of Mesencephalon, 2nd of the primary vesicles]
*Myelencephalon
*Metencephalon
[From primary vesicle: rhombencephalon]
The 5 secondary vesicles of the developing neural tube give rise to which adult brain structures?
- Telencephalon:
- > L cerebral hemisphere
- > R cerebral hemisphere
- Diencephalon:
- > Hypothalamus
- > Thalamus
- > associated structures
*Mesencephalon: -> Midbrain (uppermost part of adult brainstem) -> Cerebral aqueduct (connecting 3rd and 4th ventricles) in the adult brain arises from the hollow cavity inside the Mesencephalon.
- Metencephalon:
- > Cerebellum
- > Pons
- > 4th ventricle forms from its hollow centre
- Myelencephalon:
- > Medulla oblongata
- > beginning of the central canal of the spinal cord develops from its hollow centre
The lateral ventricles in the brain are derived from which secondary vesicles in the developing neural tube?
Hollow space inside telencephalon.
The third ventricle inside the adult brain (very close to the diencephalon in the adult brain)
Hollow space inside the Diencephalon (secondary vesicle) of the developing neural tube.
Which is the only primary vesicle in the neural tube (‘S’ - same) that does not develop into 2 secondary vesicles.
Mesencephalon
Metencephalon and Myelencephalon develop from the primary vesicle the Rhombencephalong. Which is uppermost out of the two?
‘T’ = ‘top’ -> Metencephalon (develops into Cerebellum, pons and 4th ventricle of adult brain)
When does complete closure of the neural tube usually occur?
30 days after fertilisation
What are 3 common neural tube defects?
- Spina bifida
- anencephaly
- encephalocoele
A birth defect that can occur as a result of developmental abnormalities in the ventricular system:
Hydrocephalus
What is Spina Bifida?
“split spine” - incomplete closure of one or more of the sections of the spinal cord.
Which parts of the spine does spina bifida usually affect?
Lumbar and sacral spine (peripheral nerves supplying lower abdomen, pelvis and lower limbs)
What kinds of problems does Spina Bifida cause?
Loss of urinary and bowel control, ambulatory problems, some loss of sensation below affected spinal cord. Dependent on degree of closure of neural tube and location of lesion. Hydrocephalus and cognative problems may co-occur. (also possible latex allergy)
What causes Hydrocephalus?
Abnormal accumulation of CSF in ventricles of the brain, usually due to blockage in CSF circulation.
What can cause the blockage to CSF circulation that can result in hydrocephalus?
Congenital malformation, tumours, infection, trauma/injury.
What are some symptoms of congenital hydrocephalus?
Enlarged head and relatively small face, bulging fontanels (in babies), fatigue, vomiting, abnormal reflexes.
What are the 5(6) bar-like ridges that appear on the anterolateral surface of the head and neck region in week 4 of embryo development?
Pharyngeal (branchial) arches
Another name for branchial arches
pharyngeal arches
How many pharyngeal arches are there?
5 (or 6 - but 5 blends in with 6 so often counted together)
How are the branchial arches named?
pharyngeal arches are numbered in Roman Numerals from the cranial end of the embryo.
what are inside the pharyngeal arches?
- blood vessels
- muscles
- nerves
- cartilage
Under the headings: Blood vessels, Nerves, Bones, Muscles, list structures derived from Pharyngeal Arch I
Blood vessels:
*Maxillary Artery
Nerves:
- CNV2
- CNV3
Bones:
- Maxilla
- Mandible
- Zygomatic part of temporal bone
Muscles:
- TMJ muscles
- Mylohyoid
- Anterior belly of digastric
- Tensor veli palatini
- Tensor tympani
Under the headings: Blood vessels, Nerves, Bones, Muscles, list structures derived from Pharyngeal Arch II
Blood Vessels: Nil
Nerves:
*CN VII
Bones:
- Stapes
- Styloid process
- part of hyoid
Muscles:
- Facial expression muscles
- Posterior digastric
- stylohyoid
- Stapedius
Under the headings: Blood vessels, Nerves, Bones, Muscles, list structures derived from Pharyngeal Arch III
Blood vessels:
* Carotid arteries
Nerves:
*CN IX
Bones:
*part of Hyoid bone
Muscles:
*stylopharyngeus
Under the headings: Blood vessels, Nerves, Bones, Muscles, list structures derived from Pharyngeal Arch IV
Blood vessels:
- subclavian arteries
- Aortic arch
Nerves:
*superior laryngeal branch of CN X
Cartilages:
- thyroid cartilage
- epiglottis
Muscles:
- cricothyroid
- levator veli palatini
- pharyngeal constrictors
Under the headings: Blood vessels, Nerves, Bones, Muscles, list structures derived from Pharyngeal Arch/es V/VI
Blood vessels:
*pulmonary artery
Nerves:
*recurrent laryngeal branch of CN X
Cartilages:
- arytenoid
- cricoid
- corniculate
Muscles:
*intrinsic laryngeal muscles
What major structure develops from combined tissue originating in pharyngeal arches I-IV in the developing embryo?
the tongue
This structure is initially large and degenerates during embryonic development. Failure of this structure to degenerate causes a condition called ankyloglossia. Name of structure:
the Lingual frenulum
The maxillary artery derives from which pharyngeal arch?
I
The carotid arteries derive from which pharyngeal arch?
III
The subclavian arteries and Aortic arch derive from which pharyngeal arch?
IV
The pulmonary artery derives from which pharyngeal arch?
V/VI
CN V2 maxillary branch and CN V3 mandibular branch of the Trigeminal nerve derive from which pharyngeal arch?
I
CN VII Facial nerve derives from which pharyngeal arch?
II
CN IX Glossopharyngeal nerve derives from which pharyngeal arch?
III
The maxilla, mandible and zygomatic part of the temporal bone derive from which pharyngeal arch?
I
The Recurrent Laryngeal Branch of CNX Vagus nerve derives from which pharyngeal arch?
V/VI
The Superior Laryngeal Branch of CNX Vagus nerve derives from which pharyngeal arch?
IV
Part of the Hyoid bone derives from one pharyngeal arch and part from another. Which ones?
II and
III
The stapes, styloid process and part of the hyoid bone derive from which pharyngeal arch?
II
The only bone deriving from this pharyngeal arch is a part of the Hyoid bone… Which arch?
III
The thyroid cartilage and epiglottis (but no bones) derive from which pharyngeal arch?
IV
The arytenoid cartilages, cricoid cartilage and corniculate cartilages of the larynx (but no bones) derive from which pharyngeal arch?
V/VI
The intrinsic laryngeal muscles derive from which pharyngeal arch?
V/VI
The stylopharyngeus muscle derives from which pharyngeal arch?
III
The cricothyroid muscle, levator veli palatini and all of the pharyngeal constrictor muscles derive from which pharyngeal arch?
IV
The muscles of facial expression, the posterior belly of the digastric muscle, the stylohyoid muscle and the stapedius derive from which pharyngeal arch?
II
The TMJ muscles, mylohyoid, the anterior belly of the digastric muscle, the tensor veli palatini and the tensor tympani derive from which pharyngeal arch?
I
A single frontonasal prominence on the embryo ultimately forms which structures?
- Nose
* forehead
What causes cleft lip?
Failure of the lip and nasal tissue to fuse properly
What causes cleft palate?
failure of the hard palate to fuse in the midline.
The maxillary process (which will give rise to the maxilla) and the mandibular process (which will give rise to the mandible) are part of the bony components of which pharyngeal arch?
I
On an early embryo the top bulge is the _____ _____ and below that is the ____ _____ and below that the _____ _____.
- Frontonasal prominence
- Maxillary process
- Mandibular process
The Frontonasal prominence, maxillary process and mandibular process on further development correspond to the pattern of sensory nerve innervation for which nerve?
CN V Trigeminal
- Frontonasal prominence corresponds to CNV1 Opthalmic branch, Maxillary process to CNV2 Maxillary branch and mandibular process to CNV3 mandibular branch.
What is affected in unilateral cleft lip?
Only one side of the lip.
What is affected in bilateral cleft lip?
Both sides of the lip
Cleft palate can affect the complete palate, or only part of it (called _____ ____ ____).
Partial cleft palate.
Cleft palate leaves a clear opening between the ____ ____ and the _____ ____ which, due to the hard palate’s important function as fixation point for the tongue, has implications for articulation, chewing and swallowing.
- nasal cavity
2. oral cavity
Generally cleft lip and cleft palate will occur together, although they can occur separately. True or false?
True
During the 4th to 10th week the face forms from 5 prominences that grow and fuse. List these prominences:
- frontonasal prominence
- 2 x maxillary prominences
- 2 x mandibular prominences
Why might babies with cleft palate have feeding problems?
food aspirates into the nasal cavity
In an embryo the face forms from which structures?
Pharyngeal arches I and II and the frontonasal prominence.
As different tissue types form on the embryo, the dorsal surface develops a hollow tube called…..?
Neural tube
The neural tube is expanded at the developing head region, and this expansion eventually forms which 2 structures?
- Brain
* Ventricles
The part of the neural tube that is not expanded, and which extends the length of the embryo, will form which structure?
Spinal cord
Most of the structures of the head and neck arise from the _____ _____ of the embryo.
Pharyngeal arches
The expanded cranial end of the neural tube first forms how many primary vesicles? Name them:
3
- Prosencephalon (forebrain)
- Mesencephalon (midbrain)
- Rhombencephalon (hindbrain)
The 3 primary vesicles give rise to how many secondary vesicles?
5
Does the Prosencephalon form one or two secondary vesicles? Name it/them:
2
- Telencephalon
- Diencephalon
Does the Rhombencephalon form one or two secondary vesicles? Name it/them:
2
- Myelencephalon
- Metencephalon
Does the Mesencephalon form one or two secondary vesicles? Name it/them:
1
Mesencephalon - it does not change!
Which secondary vesicle eventually forms the cerebral hemispheres?
Telencephalon
The secondary vesicle called the Diencephalon forms which adult brain structures?
(the Diencephalon!)
- Hypothalamus
- Thalamus
- Associated structures
The Mesencephalon, myelencephalon and metencephalon form which adult brain structures?
- Midbrain
- Pons
- Medulla oblongata
- Cerebellum
The central cavity of the neural tube enlarges in 4 areas to form what?
the Ventricles
Primary vesicles mnemonic?
Pros- Mes- Rhomb-
Secondary vesicles mnemonic?
Tel- Di- Mes- Met- My(el)-
Tel- -> ?
2 cerebral hemispheres
Di- ->?
Hypothalamus and thalamus (diencephalon!)
Mes- Met- My-
Midbrain, pons, medulla oblongata, cerebellum [ie all of Brainstem and Cerebellum]
Pros- TO tel- di-
TO Cerebral hemispheres and diencephalon of adult brain
Mes- TO Mes-
TO with Met- My- form brainstem and cerebellum
Rhomb- TO Met- My-
Mes- Met- My- TO all brainstem and cerebellum
The ____encephalon divides into the telencephalon and diencephalon.
Pros-
The ____encephalon is an example of a primary vesicle:
- Prosencephalon
- Mesencephalon
- Rhombencephalon
The diencephalon forms the ____, _____ and associated structures.
Thalamus
Hypothalamus
The ___encephalon, ____encephalon and ___encephalon form the midbrain, pons, medulla oblongata and cerebellum.
Mes-
Met-
Myel-
The hindbrain is also know as the ___encephalon.
Rhomb-
After the ___encephalon and the ___encephalon develop into the secondary vesicles, the ___encephalon remains.
Pros-
Rhomb-
the mes- encephalon remains.
Another name for the prosencephalon is ____?
Forebrain
The ___encephalon expands to create the cerebral hemispheres.
Tel-
Name the secondary vesicles.
Tel- Di- Mes- Met- Myel-
Which primary vesicle remains after development of the secondary vesicles?
Mesencephalon
The thalamus is formed from the ___encephalon.
Di-
The myelencephalon and metencephalon are formed from which primary vesicle?
Rhombencephalon
When does complete closure of the neural tube occur?
~30 days after fertilisation
Many people with spina bifida also develop an allergy to what?
latex
This neural tube defect results in incomplete closure of one or more of the sections of the spinal cord:
Spina Bifida
This neural tube defect can cause loss of urinary and bowel control, ambulatory problems and some loss of sensation below level of spinal cord affected. Hydrocephalus and some cognitive problems can occur in some people:
Spina bifida
This condition results from abnormal accumulation of CSF in the ventricles of the brain, most commonly due to a blockage in CSF circulation.
Hydrocephalus
How can hydrocephalus be caused?
- congenital
- result of tumors
- result of infection
- result of trauma/injury
5-6 bar like ridges appear on the anterolateral surface of the head and neck region of the embryo during which week?
Week 4 of development
When do the pharyngeal arches first appear?
week 4
Another name for pharyngeal arches?
Branchial arches
What are inside the embryonic pharyngeal arches?
- Blood vessels
- muscles
- nerves
- cartilage
How are the pharyngeal arches numbered?
Roman numerals I-V starting from the cranial end.
The muscles innervated by CN V3 Mandibular branch of the Trigeminal nerve, are the SAME muscles that derive from the 1st Pharyngeal arch during development. Name them:
- TMJ muscles - Temporalis, Masseter, Medial and Lateral Pterygoids
- Tensor Veli Palatini
- Tensor Tympani
- Anterior belly of Digastric
- Mylohyoid
The muscles that derive from the 2nd pharyngeal arch during embryonic development are the SAME ones innervated by CN VII Facial nerve in the adult. Name them:
- Muscles of Facial expression
- Posterior digastric muscle
- Stylohyoid
- Stapedius
(Chant while contorting facial muscles Pos di-, Stylohy-, Stapedius)
The only muscle innervated by CN IX Glossopharyngeal nerve derives from the same pharyngeal arch that CN IX develops from. Blood vessels that CN IX innervated for VS also come from this pharyngeal arch. Name muscle and blood vessels:
- Stylopharyngeus muscle
- Carotid Arteries
- Pharyngeal Arch III
Name the bones that originate from cartilages in Pharyngeal arch II:
- Stapes
- Styloid process
- Part of hyoid bone
Which Pharyngeal arch does the tongue develop from?
From combined tissues from arches I-IV.
What is initially quite large and degenerates with development. A condition called Ankyloglossia occurs if it fails to degenerate.
Lingual frenulum
A singular frontonasal prominence in the embryo, ultimately forms which structures?
- Nose
* Forehead
Maxillary, mandibular and nasal prominences form on either side and fuse in the midline and with the frontonasal prominence to form which structures?
- Palate
- Oral cavity
- lips
Failure of the lip and nasal tissue to fuse properly causes what condition?
Cleft lip
Failure of the hard palate to fuse in the midline causes what?
Cleft palate