Stages in Neural Tube Development
1st. Neural Plate 2nd. Neural folds 3rd. Neural tube
Time line for the formation of nervous system occurs during what embryonic stage:
End of second week to end of eighth week
What are the subdivisions of cranial end of neural tube?
pentapartite brain and tripartite brain
tripartite brain is made up of
Prosencephalon Mesencephalon and Rhombencephalon
What do the three parts of the growing pentapartite brain divide into?
Prosencephalon into->telencephalon (most anterior) and diencephalon mesencephalon: does not divide rhombosephlon divides into -> metencephalon and myelencephalon
Where is the cerebral aquaduct?
between the third and fourth ventricle
What are the parts of the Telencephalon Primordia?
Lumina-Lateral Ventricles I and II Floor-Basal ganglia (nuclei) and olfactory lobes and nerves- tracts Roof-cerebral hemispheres
What are the parts of the diencephalon primorida?
lumen... third ventricle roof...epithalamus walls... thalamus floor... hypothalamus and infundibulum
What are the parts of the mesencephalon primordia?
lumen... cerebral aqueduct (of Sylvius) roof=tectum: superior and inferior colliculi floor...tegmentum
What are the parts of the metencephalon primorida?
lumen- part of forth ventricle roof- cerebellum floor- pons
What are the parts of the myelencephalon primorida?
lumen- rest of fourth ventricle main part- medulla oblongata roof- posterior choroid plexus
What is the Myelencephalon's main part, the Medulla oblongata, composed of?
nuclei Pyramids Olives Vital reflex centers Various nonvital centers
What does the myelencephalon medulla nuclei make up?
Vestibular nuclear complex Sensory nuclei Portions of reticular formation
What do myelencephalon medulla pyramids consist of?
Lateral corticospinal tracts
What is the Myelencephalon medulla olives the site of?
Site of nuclei related to cerebellum
Metencephalon Pons Nuclei makes up what?
1. cranial nerve nuclei V-VII 2. Pontine nuclei: Relay between cerebrum and cerebellum
What do the Mesencephalon Centers make up?
Sleep center respiratory centers
The Mesencephalon Tectum (Roof) consists of what?
Superior colliciuli (visual refelxes) Inferior colliculi (auditory and olfactory reflexes)
What does the cerebellum have?
Has a cortex
What are the functions of cerebellum?
coordinate skeletal muscle movement maintain equilibrium and posture synergic control of muscle activity (other muscles are quieted to help other muscles do their job)
What is the diencephalon thalamus?
major relay center for afferenet and efferent informaiton to and from cerebrum and other areas of the brain... olfactory does not pass through
What is the diencephalon epithalamus?
habenular nuclei involved in emotional and visceral responses to odors and pineal body
What is the Diencephalon hypothalamus?
Mamillary bodies involved in olfactory relfexes and emotional responses to odors. Supraoptic and paraventricular nuclei
What is the function of the Diencephalon?
controls and integrates ANS associated w many kinds of visceral activity intermediary btw nervous and endocrine systems controls normal body temp maintains extracellualr fluid volume biorhythm oscillator
What are the parts of the telencephalon?
olfactory bulbs basal nuclei (ganglia) And cerebral cortex
What is the function of the telencephalon basal nuclei (ganglia)?
subconscious motor control and muscle tone
What is Anencephaly?
Failure of cranial end of neural tube to close
What is Arnold- Chiari deformity?
Inferior cerebellum and medulla are elongated and protrude into vertebral canal Medulla and pons are small and deformed Hydrocephalus- blockage of fluid flow Malformation of lower cranial nerves -deafness -tongue, facial muscle, lateral eye movement weakness
What is spina bifida occulta?
Normally hidden results from a failure of the inferior neuropore to close vertebral arches fails to develop in caudal area spinal cord function is usually normal
What is spina bifida cystica?
Characterized by a sac-like cyst at the caudal end of spine Spinal cords and/or meninges may be found in the cyst Spinal cord funciton may be impaired May be lower extremeity dysfunction Bladder and bowl function may be impaired
What is meningocele?
Form of spina bifida cystica Only meninges found in sac Spinal cord function may be impaired Signs and symptoms vary depending on location and severity of malformation
What is meningomyelocele?
Form of spinal bifida cystica Both meninges and spinal cord are found in sac Always results in abnomral growth of spnial cord Lower extremity paralysis Bowel and bladder dysfunction Lillioss of sensation to lower limbs
What is myeloschisis
Failure of caudal neural folds to close Most severe of the defects
What is holoprosencephaly?
Failure of prosencephalon to divide into two cerebral hemispheres Often associated with facial deformities --single orbit with two eyes or one eye or no eye --proboscis type nose located above eye --cleft lip and palate
When does superior (anterior or cranial) neuropore closes?
by day 27
When does inferior (posterior or caudal) neuropore closes?
by day 30
caudal end froms the....
subdivion of cranial end of neural tube
tripartite brain and then pentapart brain
myelencephalon medulla, various nonvital centers
hick up, vomitting, diahrea
cranial nerve nuclei III-IV
red nucleus substantia nigra (parkinsons) various tracts
telencephalon cerebral cortex
divided into paired lobes surface w gyri and sulci
When does the superior (anterior or cranial) neuropore close?
By day 27
When does the inferior (posterior or caudal) neuropore close?
By day 30
What does the myelencephalon medulla vital reflex centers make up?
Cardiac center Vasomotor center Centers related to respiration
What are the parts of the metencephalon?
Pons and cerebellum
What are the parts of mesencephalon?
Nuclei, Tectum (roof), and Tegmentum
What does the mesencephalon nuclei make up?
The cranial nerve nuclei III-IV
What does the mesencephalon tegmentum make up?
Red nucleus, substantia nigra, various tracts
The cerebellum is connected to other parts of the brain via what?
Large pairs of fibers tracts called peduncles
What is each part of the cerebellum connected to?
Inferior connected to medulla and spinal cord Middle connected to pons Superior connected to midbrain
What are the parts of diencephalon?
Thalamus, epithalamus, and hypothalamus
What are the characteristics of the telencephalon cerebral cortex?
Divided into paired lobes Surface with gyri and sulci