Anatomy 15

Question 1

What happens during the 3rd week of development of the neural tube?

Answer 1

An ectodermal thickening appears in the middle of the trilaminar germ disc known as the neural plate.

Question 2

What happens to the neural plate during the development of the neural tube?

Answer 2

It invaginates to form a neural groove

Question 3

What happens to the neural groove during the development of the neural tube?

Answer 3

The lips of the neural groove approach each other and fuse together transforming the groove into a neural tube with anterior & posterior neuropores.

Question 4

What happens to neuropores during the development of the neural tube?

Answer 4

They are obliterated, transforming the neural tube into a closed tube.

Question 5

On what day is the anterior neuropore obliterated?

Answer 5

Day 25

Question 6

On what day is the posterior neuropore obliterated?

Answer 6

Day 27

Question 7

What is the matrix?

Answer 7

A one cell layer epithelium lining of the neural tube

Question 8

What is the ventricular zone?

Answer 8

The matrix

Question 9

Where does the matrix extend to?

Answer 9

From the cavity of the tube to the exterior

Question 10

What does the repeated division of the matrix cells result in?

Answer 10

An increase in length and diameter of the neural tube

Question 11

Where do the matrix cells migrate to?

Answer 11

Peripherally to form the intermediate zone (grey matter)

Question 12

What is the marginal zone (myelinated white matter)?

Answer 12

A layer external to the intermediate zone

Question 13

What forms the marginal zone (myelinated white matter)?

Answer 13

Neuroblasts that give rise to nerve fibers that grow peripherally

Question 14

Neuroblasts also give rise to:

Answer 14

1) Astrocytes

2) Oligodendrocytes

Question 15

Microglia is derived from:

Answer 15

Surrounding mesenchyme

Question 16

The cells in the lateral wall of the neural tube proliferate and are differentiated into 3 layers:

Answer 16

1) Inner ependymal Layer
2) Middle Mantle Layer
3) Outer Marginal Layer

Question 17

What does the inner ependymal layer do?

Answer 17

Forms the ependymal lining of the central canal and ventricles

Question 18

What does the Middle Mantle Layer do?

Answer 18

It’s a cellular layer which forms the grey matter of the spinal cord

Question 19

What does the Outer Marginal Layer do?

Answer 19

Forms the white matter of the spinal cord.

Question 20

What are the thick lateral walls connected together by?

Answer 20

Thin roof plate (dorsal) and floor plate (ventral)

Question 21

A groove (sulcus limitans) appears in the lateral wall dividing it into:

Answer 21

1) Dorsal part (Alar Plate)

2) Ventral part (basal plate)

Question 22

What does the Alar plate (Dorsal) do?

Answer 22

Expands to form the dorsal (sensory) horn.

Question 23

What does the Basal plate (Ventral) do?

Answer 23

Expands to form the ventral (motor) horn.

Question 24

What happens to the cavity of the neural tube?

Answer 24

It remains narrow and forms the central canal of the spinal cord.

Question 25

The pia, arachnoid and dura maters are formed from the:

Answer 25

Mesenchyme (sclerotome) that surrounds the neural tube.

Question 26

How does the subarachnoid space develop?

Answer 26

As a cavity in the mesenchyme, which becomes filled with cerebrospinal fluid

Question 27

During the first 2 months of intrauterine life, __.

Answer 27

The spinal cord is the same length as the vertebral column.

Question 28

Where does the coccygeal end of the cord lie at birth?

Answer 28

At the level of the third lumbar vertebra

Question 29

Where does the coccygeal end of the cord lie in adults?

Answer 29

At the level of the lower border of the body of the first lumbar vertebra.

Question 30

Which nerves form cauda equina?

Answer 30

The oblique spinal nerves below L1

Question 31

What is Spina bifida occulta?

Answer 31

Absent vertebral arch with normal spinal cord. Usually covered with hairy skin.

Question 32

Which area does Spina bifida occulta affect?

Answer 32

The lumbosacral area

Question 33

What is Spina bifida cystica (Meningocele)?

Answer 33

The meninges herniate through the spina bifida to form subcutaneous sacs filled with CSF.

Question 34

What is Spina bifida cystica (Meningomyelocele)?

Answer 34

The spinal cord herniates through the meningocele

Question 35

What is Spina bifida cystica (Myelocele (Rachischisis))?

Answer 35

Failure of obliteration of the neural tube

Question 36

The cranial part of the neural tube forms 3 brain vesicles:

Answer 36

1) Forebrain vesicle(Prosencephalon) 2) Midbrain vesicle (Mesencephalon) 3) Hindbrain vesicle (Rhombencephalon)

Question 37

What does the Forebrain vesicle (Prosencephalon) form?

Answer 37

1) 2 lateral evaginations which develop to form the 2 cerebral hemispheres (their cavities form the lateral ventricles) 2) The median part develops to form the diencephalon (its cavity forms the 3rd ventricle)

Question 38

What does the Midbrain vesicle (Mesencephalon) form?

Answer 38

``` The midbrain (its cavity forms the cerebral aqueduct) ```

Question 39

What does the Hindbrain vesicle (Rhombencephalon) form?

Answer 39

1) Pons 2) Medulla 3) Cerebellum (Its cavity forms the 4th ventricle.)

Question 40

The medulla will have an alar plate & a basal plate separated by a ___ and connected by:

Answer 40

Sulcus limitans ;a thin roof plate and a floor plate.

Question 41

What happens to the lateral walls during the development of the medulla oblongata?

Answer 41

They move away from each other stretching the roof plate and enlarging its cavity which forms the 4th ventricle.

Question 42

What does the alar plate form?

Answer 42

The sensory nuclei of the medulla

Question 43

What does the basal plate form?

Answer 43

The motor nuclei of the medulla

Question 44

What happens between the 4th and 5th months during the development of the medulla oblongata?

Answer 44

Local resorptions of the roof plate occur, forming lateral foramina of Luschka, and a median foramen of Magendie

Question 45

What differs from the development of the medulla and the development of the pons & cerebellum?

Answer 45

The alar plates bend medially to form 2 rhombic lips.

Question 46

What do the rhombic lips do during the development of the pons & cerebellum?

Answer 46

The rhombic lips approach each other & fuse together forming a cerebellar plate.

Question 47

What does the cerebellar plate differentiate into?

Answer 47

1) A median part which forms the vermis | 2) 2 lateral masses which form the cerebellar hemispheres.

Question 48

The cavity of the pons & cerebellum forms:

Answer 48

Part of the 4th ventricle

Question 49

What differs from the development of the medulla and the development of the midbrain?

Answer 49

1) The alar plates develop to form the tectum which is divided by vertical & transverse grooves into 4 colliculi. 2) The basal plate forms the motor nuclei in the tegmentum of midbrain

Question 50

What happens to the marginal layer of the basal plate during the development of the midbrain?

Answer 50

It enlarges greatly to form the crus cerebri.

Question 51

What happens to the cavity of the midbrain?

Answer 51

It remains narrow and forms the cerebral aqueduct.

Question 52

What does the development of the diencephalon consist of?

Answer 52

2 lateral walls connected by a roof plate and a floor plate

Question 53

Which cavity is in the diencephalon?

Answer 53

The 3rd ventricle

Question 54

What does the anterior part of the roof plate in the diencephalon develop into?

Answer 54

The choroid plexus of the 3rd ventricle

Question 55

What does the posterior part of the roof plate in the diencephalon develop into?

Answer 55

The pineal body

Question 56

What appears in the lateral wall during the development of the diencephalon?

Answer 56

A hypothalamic sulcus, which separates the thalamus above from the hypothalamus below

Question 57

What does the floor plate of the diencephalon form?

Answer 57

The posterior lobe of the pituitary gland.

Question 58

The 2 cerebral hemispheres arise as:

Answer 58

2 evaginations from the lateral wall of the | forebrain.

Question 59

Each cavity of the cerebral hemisphere expands to form the:

Answer 59

Lateral ventricle

Question 60

The wall of the hemisphere consists of 3 layers:

Answer 60

1) Ependymal 2) Mantle 3) Marginal

Question 61

What does the mantle layer at the base of the cerebral hemisphere form?

Answer 61

The basal ganglia

Question 62

The hemispheres enlarge and overlap:

Answer 62

1) The brain stem | 2) The cerebellum

Question 63

What are the 2 types of hydrocephalus?

Answer 63

1) Internal hydrocephalus | 2) External hydrocephalus

Question 64

What is internal hydrocephalus?

Answer 64

Excessive accumulation of CSF within the ventricles of the brain.

Question 65

What is external hydrocephalus?

Answer 65

Excessive accumulation of the CSF between the brain and arachnoid mater.

Question 66

What is Exencephaly due to?

Answer 66

Failure of closure of anterior neuropore

Question 67

What is Exencephaly?

Answer 67

The vault of the skull is absent and the brain is exposed.

Question 68

What is Anencephaly?

Answer 68

When the brain is degenerated

Question 69

What is Menigocele?

Answer 69

The meninges herniated through a deficient part of the skull.

Question 70

What is Meningoencephalocele?

Answer 70

Part of the brain herniated through the meningocele

Question 71

What is Meningo-hydro-enecephalocele?

Answer 71

Part of the ventricle is found within the brain tissue which herniated through the meningocele.

Question 72

What is Holoprosencephaly?

Answer 72

Results from degeneration of midline structures leading to fusion of lateral ventricles, orbital & nasal cavities.