NS Embryology Flashcards
From what germ layer is the nervous system derived from?
Ectoderm
What is a chordoma?
A slow growing tumor from cellular remnants of notochord in adults
What parts of the NS are derived from the surface neuroectoderm?
Anterior pituitary
Lens and cornea
What parts of the NS are derived from the neural tube?
Brain
Spinal cord
Posterior pituitary
Retina and optic N
Skeletal motor neurons
Axons of preganglionic ANS
Oligodendrocytes
What parts of the NS are derived from neural crest cells?
CN ganglia
Spinal/dorsal root ganglia
SyNS chain and pre-aortic ganglia
Sensory N
PsNS ganglia of GI tract
Postganglionic ANS
Schwann cells
Glial cells
Pia and arachnoid mater
Around what day does the cranial neuropore close?
Day 25
Around what day does the caudal neuropore close?
Day 27 or 28
What are the 3 primary brain vesicles developed from neural tube?
Forebrain vesicle - prosencephalon
Midbrain vesicle - mesencephalon
Hindbrain vesicle - rhombencephalon
What are characteristics of spina bifida occulta?
Failure of caudal neuropore to close
Normal spinal cord
Skin over affected area contains tufts of hair
Vertebral arches fail to fuse around spinal cord
Maternal AFP does not increase
What are characteristics of meningocele/spina bifida cystica?
Failure of caudal neuropore to close
Arachnoid and pia maters protrude through the spines to form cystic swelling
Maternal AFP increases
What are characteristics of a meningomyelocele?
Cystic sac contains the spinal cord and nerves
Covered by a thin, friable vascular membrane
Failure of caudal neuropore to close
What are characteristics of anencephaly?
Failure of cranial neuropore to close
Increased maternal AFP
Polyhydramnios
Incompatible with life
What are the parts of the prosencephalon by week 5?
Telencephalon
Diencephlon
What are the parts of the rhombencephalon by week 5?
Metencephalon
Myelencephalon
What develops from the telencephalon?
Cerebral hemispheres
Interventricular foramen
Lateral ventricle
What develops from the diencephalon?
Thalamus
Hypothalamus
Posterior pituitary
Optic vesicle
Third ventricle
What develops from the mesencephalon?
Midbrain
Cerebral aqueduct
What develops from the metencephalon?
Cerebellum
Pons
Fourth ventricle
What develops from the myelencephalon?
Medulla oblongata
What are the three horns that develop into spinal cord?
Ventral motor horn
Dorsal sensory horn
Intermediate horn
What is contained in the intermediate horn of the spinal cord?
Sympathetic neurons of ANS
Only present between T1 to L3
What are the three groups of motor nuclei in the basal plate of the medulla?
Medial somatic efferent - hypoglossal nucleus
Intermediate special visceral efferent - neurons of CN XI, X, and IX
Lateral general visceral efferent - motor neurons to viscera
What are the three groups of sensory nuclei in the alar plate of the medulla?
Lateral somatic afferent - general sensory - related to CN IX
Intermediate afferent - special - nucleus tractus solitarius
Medial visceral afferent - general from vagus
What are the 3 groups of motor neurons in the pons?
Medial somatic efferent - abducens N
Special visceral efferent - trigeminal and facial Ns
General visceral efferent - supply submandibular and sublingual glands via facial N
What are the 3 groups of sensory relay nuclei in the pons?
Lateral somatic afferent - trigeminal N
Special afferent
General visceral afferent
What are the 2 groups of motor nuclei in the midbrain?
Medial somatic efferent - oculomotor and trochlear Ns
Small general visceral efferent group - Edinger Westphal nucleus - innervates sphincter pupillae
What are the 2 colliculi of the alar plate of the midbrain?
Posterior colliculi - synaptic relay for auditory reflexes
Anterior colliculi - correlation and reflex centers for visual impulses
What is the most common cause of hydrocephalus in a newborn?
Obstruction of aqueduct of Sylvius/cerebral aqueduct
