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