TOPIC 9 Flashcards
What is a neural tube?
Some of the neural tube develops on the posterior (dorsal) side of the embryo and eventually forms the brain and ventricles. The remainder develops down the length of the embryo and will eventually form the spinal cord.
The extended cranial end of the neural tube forms 3 primary vesicles. What are they?
1) Forebrain (Prosencephalon)
2) Midbrain (mesencephalon)
3) Hindbrain (rhombencephelon)
What are the five secondary vesicles that the 3 primary vesicles give rise to?
1) The Prosencephalon (forebrain) divides into the telencephalon and diencephalon
2) The mesencephalon (midbrain) remains the same.
3) The rhombencephalon constricts to form: the mylencephelon and the metencephelon
What adult brain structures do the five secondary vesicles give rise to?
1) Telencephalon: expands into two parts and forms the cerebrum (2 hemispheres of)
2) Diencephalon: the thalamus, hypothalamus and associated structures.
3) The mylencephelon and metencephalon and the mesencephalon give rise to the midbrain, the pons, the medulla oblongata and the cerebellum.
What is spina bifida?
Spina bifida means split spine. It can mean one or more incomplete closures of the spinal cord.
The peripheral nerves of the lower spine are often affected (supply lower abdomen, pelvis, lower limb).
the neural tube is meant to fuse and close up approx 30 days after fertilisation. If it doesn’t it can cause abnormalities such as spina bifida.
What is hydrocephalus?
Means ‘water - head’.
This is usually caused by an abnormal accumulation of CSF due to a blockage (tumor or infection or injury). It can also be congenital.
SYMPTOMS: enlarged head, bulging eyes and fontanels fatigue, vomiting and abnormal reflexes.
What are the pharyngeal arches and when do they develop?
The brachial or pharyngeal arches develop during week 4 of development on the anterolateral part of the head and neck region. Inside are blood vessels, muscles, nerves and cartilage.
Name 2 structures that develop from each arch?
I: Cranial nerve V1, V2: muscles of mastication TMJ
II: CNVII: muscles of facial expression
III: CNIX: Glossopharyngeal: Stylopharyngeus
CNX: superior branch of the vagus: pharyngeal constrictors
CNX: recurrent branch of vagus: intrinsic laryngeal
What causes cleft lip?
Failure of lip and nasal tissue to fuse properly
What causes a cleft palate?
Failure of the hard palate (horizontal processes of the palatine bones and the palatine processes of the maxillary bones) to fuse in the midline.
What is ankyglossia?
A failure of the lingual frenulum to degenerate. If it doesn’t degenerate it extends the length of the tongue and cause ‘tongue tie’,
