Module 4: Development of the Nervous System, Musculoskeletal System, and Limbs Flashcards
1
Q
When does development of brain vesicles begin
A
-week 5
1
Q
Where do brain vesicles begin to form
A
-cranial end of neural tube
2
Q
3 brain vesicles
A
-prosencephalon
-mesencephalon
-rhombencephalon
3
Q
Prosencephalon derivatives
A
-cerebrum
4
Q
Mesencephalon derivatives
A
-midbrain
5
Q
Rhombencephalon derivatives
A
-pons, medulla, cerebellum
6
Q
When does brain flexure begin
A
-week 5
-same time as development of vesicles
7
Q
Where does brain flexure begin
A
-cranial end of neural tube
8
Q
3 brain flexures
A
-midbrain flexure
-cervical flexure
-pontine flexure
9
Q
Midbrain flexure
A
-first flexure to appear
-in region of mesencephalon
10
Q
Cervical flexure
A
-second to appear
-at junction between future spinal cord and rhombencephalon
11
Q
Pontine flexure
A
-third to appear
-when neural tube bends anteriorly at cervical and midbrain flexures, but the pontine flexure is directed posteriorly
12
Q
What is the pituitary gland derived from
A
-ectoderm that develops from rathkes pouch and infundibulum
13
Q
Rathkes pouch
A
-ectodermal out-pocketing of developing mouth
14
Q
Infundibulum
A
-downward extension of the hypothalamus
15
Q
Rathkes pouch derivative
A
-forms anterior lobe of pituitary gland
16
Q
Infundibulum derivative
A
-posterior lobe of pituitary gland
17
Q
Development of the pituitary gland stages
A
-outpocketing
-migration
-regression
-detachment
-differentiation
18
Q
Pituitary gland outpocketing
A
-infundibulum and rathkes pouch outpocket from hypothalamus and stomodeum
19
Q
Pituitary gland migration
A
-infundibulum and rathkes pouch migrate towards eachother
20
Q
Pituitary gland regression
A
-connecting stalk between stomodeum and rathkes pouch regresses
21
Q
Pituitary gland detachment
A
-rathkes pouch detaches from the stomodeum and becomes associated with the developing posterior pituitary
22
Q
Pituitary gland differentiation
A
-rathkes pouch differentiates to form anterior pituitary
-meanwhile distal portion of infundibulum differentiates to form posterior pituitary
23
Q
Cellular layers of the neural tube
A
-ventricular layer
-mantle layer
-marginal layer
24
Ventricular layer
-innermost layer
-lies adjacent to the lumen of neural tube
25
What kind of cells does ventricular layer contain
-neuroepthelial cells
-which are precursors to cells that comprise CNS
26
What is the first generation of cells produced by neuroepithelial cells
-neuroblasts
27
Neuroblasts
-eventually become neurons in the CNS
28
Mantle layer
-once ventricular layer is formed, neuroblasts migrate away to form this layer
29
What does mantle layer become
-grey matter in CNS
30
Marginal layer
-formed from neuronal processes that germinate from neuroblasts
31
What does marginal layer become
-white matter of the CNS
32
Spinal cord development
-proliferation of neuroblasts within ventricular layer causes differential thickening of mantle layer creating alar and basal thickenings
33
Where is alar thickening
-dorsal region
34
Where is basal thickening
-ventral region
35
Alar plate
-grey matter of dorsal half
-separated from eachother by roof plate
36
What kind of neurons does alar plate contain
-sensory
37
Basal plate
-white matter of ventral half
-separated by floor plate
38
What kind of neurons does basal plate contain
-motor neurons
39
Sulcus limitans
-appears in lateral wall of neural tube
-separating it into dorsal and ventral halves throughout future spinal cord and brainstem
40
Holoprosencephaly
-occurs when prosencephalon fails to develop
-can include neurological deficits, seizures, vision and motor difficulties
-craniofacial malformations, reduction of frontonasal prominence
41
Which horn do motor nerves emerge from
-ventral horn
42
Which horn do sensory nerves emerge from
-dorsal horn
-dorsal root ganglion
43
Which horn do autonomic nerves emerge from
-lateral horns
44
Formation of motor nerves
-begins with outgrowth of axons from motor neuroblasts located in basal plate
45
Formation of sensory nerves
-derived from neural crest cells
46
Formation of sensory nerve dendrites
-grow toward nerve cell body
47
Formation of sensory nerve axons
-terminate in the alar plate
48
Formation of autonomic nerves
-similar to sensory nerves, autonomic nerves are also derived from neural crest cells
49
Ventral pathway development
-some of the cells travelling ventrally stop migrating as soon as they enter the somite
-these cells give rise to dorsal root ganglia
-cells that tale ventral pathway also form autonomic ganglia
50
Discrete peripheral nerves
-built by channelling neural crest cells through a restricted region of the somite
51
Hirschsprung's disease
-results from the absence of nerve cells in some parts of the large intestine
-incomplete innervation of the smooth muscle layers of gastrointestinal tract
52
Newborn symptoms of hirschsprungs disease
-constipation
-bowel obstruction
53
Somites derivative
-muscle and bone
54
Coelom derivative
-body cavities
55
How many pairs of somites will be formed from the paraxial mesoderm in week 5
-42-44
56
Somite development stages
-segmentation
-epithelialization
57
Somite segmentation
-process of somite formation from paraxial mesoderm
58
Somite epithelialization
-once the paraxial mesoderm becomes segmented to form epithelial somites with somitocele cells inside them
59
2 somite cell groups
-sclerotome
-dermomyotome
60
Sclerotomes
-formed from ventral portion of somite
61
Sclerotomes fate
-will contribute to cartilage and bone of vertebral column and ribs
62
Dermomyotomes
-formed from dorsal part of somite
63
Dermomyotomes fate
-gives rise to overlying dermis of back and to the skeletal muscles of the limb
64
Divisions of dermomyotomes
-myotomes
-dermatomes
65
Myotomes fate
-will develop into striated muscle
66
Myotomes divisions
-dorsal myotome
-ventral myotome
67
Dorsal myotome fate
-back musculature
68
Ventral myotome fate
-muscle cells of rest of the trunk and limbs
69
Dermatomes fate
-form the dermis
70
Development of skeletal muscle stages
-dividing myoblasts
-cell alignment
-myotube formation
-muscle fibre formation
71
Dividing myoblasts
-they proliferate in early development if there is enough fibroblast growth factor (FGF) present
72
Cell alignment
-when FGF runs out, myoblasts cease division, and these cells begin to align for myotube formation
73
Myotube formation
-alignment of myoblasts results in structures called myotubes
74
Muscle fibre formation
-myotubes fuse to form a multinucleated muscle fibre
75
Types of ossification
-endochondral ossification
-intramembranous ossification
76
Endochondral ossification
-process of forming a bone through a cartilage intermediate
77
What bones form from endochondral ossification
-skull base
-vertebral column
-long bones
-pelvis
78
Intramembranous ossification
-directly forms bone from mesenchyme
79
What bones form from intramembranous ossification
-cranial vault
-maxilla/mandible
-clavicle
80
Endochondral ossification stages
-mesenchymal cells
-chondroblasts
-osteoblasts
-continued growth
81
Endochondral ossification mesenchymal cells
-differentiate into chondroblasts that form cartilagenous skeletal precursor of bones
82
Endochondral ossification chondroblasts
-produce hyaline cartilage which resembles future shape of bone
83
Endochondral ossification osteoblasts
-formed from invasion of blood vessels
-restricts chondrocytes to ends of bones
-chondrocytes in shaft of bone mineralize surrounding matrix
-osteoblasts bind to this matrix and deposit bone matrices to form bone tissue
84
Endochondral ossification continued growth
-this process repeats while growth plates continue to elongate into adulthood
85
Intramembranous ossification stages
-osteoblasts
-osteocytes
-spongy bone
-compact bone
86
Intramembranous ossification osteoblasts
-mesenchymal cells differentiate into osteoblasts and are grouped into ossification centres
87
Intramembranous ossification osteocytes
-secrete osteiod and binding of calcium to this osteoid results in hardening of matrix and entrapment of osteoblasts
88
What is osteoid
-unminealized portion of bone matrix that eventually calcifies
89
Intramembranous ossification spongy bone
-osteoid continues to be secreted by osteoblasts around blood vessels forming trabeculae (spongy bone)
90
Intramembranous ossification compact bone
-periosteum is formed when calcified spicules become surrounded by compact mesenchymal cells
-this layer forms superficially to spongy bone
91
Development of spinal cord stages
-migration
-neuronal extension
-division
-resegmentation
92
Vertebral column migration
-cells of sclerotome begin to migrate toward and around notochord and neural tube creating template of vertebrae
93
Von ebners fissues
-splits the sclerotome in half
94
Vertebral column neuronal extension
-neural tube neurons extend to innervate nearby myotomes and dermatomes
95
Vertebral column division
-nerves pass through von ebners fissures within each sclerotome to pass through mytotome and dermatome
96
Vertebral column resegmentation
-the bodies of vertebrae form where the sclerotome cells of the caudal part of one somite pair intermingle with the cells of the cranial part of the following pair
97
Development of intervertebral discs
-notochord persists in the region between the adjacent vertebrae as nucleus pulposus
-together with a circular anulus fibrousus the discs are formed
98
Ascent of the spinal cord
-vertebral column outgrows the spinal cord and the cord appears to acsend within column
-this is why spinal cord segments for not line up, and how cauda equina is formed
99
Parts of the skull
-viscerocranium
-membranous neurocranium
-chondrocranium
100
Viscerocranium
-bones of face
101
How is viscerocranium formed
-first 2 pharyngeal arches
102
Membranous neurocranium
-surrounds brain
103
How is membranous neurocranium formed
-from neural crest cells and paraxial mesoderm
-formed from intramembranous ossification
104
Chondrocranium divisions
-prechordal chondrocranium
-chordal chondrocranium
105
How is chondrocranium formed
-separate cartilages that fuse via endochondral ossification
106
Limb development stages
-limb buds
-apical ectodermal ridge
-handplates and footplates
107
Limb buds
-outpocketings from body wall, consist of a mesenchyme core covered by ectoderm
108
Apical ectodermal ridge
-distal end ectoderm thickens to form this
-cells from this further differentiate into cartilage and muscle
109
Handplates and footplates
-limb buds become flattened to form the handplates and footplates terminally
110
When do fingers and toes develop on hand and footplates
-when apoptosis in apical ectodermal ridge separates the plates into 5 parts
111
Syndactyly
-when apical ectodermal ridge does not regress, causes 2 or more fingers to be fused (webbed)
-most often only skin connected but can sometimes be bones as well
-treated surgically
112
Limb rotation parts
-upper limb
-lower limb
113
Upper limb rotation
-rotates laterally so that palm of hand faces anteriorly and thumb is on lateral side
114
Lower limb rotation
-rotates medially so that big toe is on medial side of foot
115
Epidermal ridges
-ridges of epidermis on palms of hands and soles of feet
-what makes up the fingerprint
116
Volar pads
-temporary swellings of tissues on ventral surfaces of fingers and toes
117
When do volar pads regress
-weeks 10-12
118
Epidermal ridge patterns
-loop
-whorl
-arch
119
Loop epidermal ridge pattern
-volar pad is intermediate
-results in loop configuration
120
Whorl epidermal ridge pattern
-volar pad is high and round
-epidermal ridges form a whorl
121
Arch epidermal ridge pattern
-volar pad is low
-epidermal ridges form an arch
