Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MSK- Back!!! > MSK development - embryology 9/19 > Flashcards

MSK development - embryology 9/19 Flashcards

1
Q

Notochord secretes substances (noggin, chordin) which induce the overlying ectoderm to differentiate in a very specific manner. if this process is blocked, which structure will be most negatively affected

A
  • Ectoderm differentiates into spinal cord
  • vertebral column comes from mesoderm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Neural Tube

A
  • forms the entire CNS (brain and spinal cord)
  • begins with formation of the neural plate, lateral edges of neural plate elevate to form neural groove. Neural groove fuses to form the neural tube.
  • at the edges of the neural tube are the cranial and caudal neuropores which communicate with amniotic cavity and close on days 25-27
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

if there was a defect during formation of the neural tube epithelium, which of the following cell types would be unaffected?

A
  • which of these is not part of the CNS?

A. Astrocytes - glial cells of CNS

B. Dorsal Root Ganglion - sensory cell bodies part of PNS

C. Motor Neurons of Spinal Cord - part of CNS

D. Sensory neurons of spinal cord - part of CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Neural Crest Cells

A

- gives rise to all the PNS (just need to know part of PNS that it makes up)

  • arise from neuroectoderm as the neural tube is closing
  • migrate into underlying mesoderm
  1. Fate of cranial neural crest: bones, cartilate, fascia, ligaments, and tendons of face, neck, sensory ganglia, autonomic ganglia
  2. Fate of Spinal Neural Crest: dorsal root ganglia, autonomic ganglia, heart (fibrous skeleton)
  3. Shared fate of cranial and spinal neural crest: meninges, Schwann cell, Melanocytes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Spinal Cord

A
  • Made from the neural tube caudal to 4th pair of somites
  • three different regions will form in the neural tube as a reslut of neuron migration from the neuroepithelium: Ventricular, Mantle, Marginal Zones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Ventricular Zone

A
  • embryo: composed of the thick, pseudostratified epithelium called the neuroepithelium; will give rise to all neurons and most glia of spinal cord
  • in adult: composed of a simiple layer of ependymal cells (because all neuron growth has already ceased)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Mantle Zone

A
  • zone superficial to neuroepithelium
  • gray matter in adults
  • composed of neuroblasts (primitive neurons)
  • Alar and Basal plates:
  • Alar: forms sensory; dorsal horn
  • Basal: forms motor; ventral horn
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

marginal zone

A

outermost layer

  • forms white matter in adults
  • composed of nerve processes (axons, dendrites)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Spinal Nerves

A
  1. ventral nerve root + Dorsal nerve root
  2. Dorsal (muscles, skin, joints of back) and ventral rami (limbs, ventral body wall )
  3. dorsal root ganglia are derived from neural crest
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Neuroblasts

A
  • derived from neuroepithelium
  • form ventral motor horn neurons and dorsal sensory horn neurons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

glialblasts

A

derived from neuroepithelium

  • form astrocytes and oligodendrocytes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Positional changes of spinal cord

A
  1. 3rd month - spinal cord extends entire length of the vertebral column
  2. at birth, spinal cord ends at LV4/LV5
  3. in the adult, spinal cord ends at about LV1/LV2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Neuronal Pathfinding

A
  • active movement of axon toward an end organ or tartet. the nerve follows signals released from the somatic mesoderm “somites” (target organ)
  • “somites” guide the formation of the spinal nerve
  • Somites give rise to one dermatome, and will also split into a mytome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Epimere

A

Dorsal ramus of split somite

  • mostly forms back structures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

hypomere

A
  • ventral split of somite, forms ventral ramus
  • innervates trunk/limbs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

myotome

A

motor innervation is established as spinal nerve innervates the somite

  • mytome is the skeletal muscle innervated by one spinal nerve
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

dermatome

A
  • sensory innervation is established as spinal nerve innervates the somite
  • the dermatome is the area of skin innervated by one spinal nerve
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

newborn male is born with a large cyst overlying his lower lumbar vertebra. the boy is diagnosed with a meningocele. imaging of this patients cyst would show that it is filled with…

A

Meninges and CSF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Spina bifida Occulta

A

affects 15-20% of population

  • results when vertebral arches of spinal cord fail to fuse
  • typically does not involve meninges or nervous tissue
  • marked by a small patch of hair over the lumbosacral spinal cord region
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Spinal Bifida Cystics

A
  • involves the meninges and or neural tissue
  • spina bifida with meningocele (involves meninges and CSF)
  • spina bifida with meningomyelocele (involves meninges, spinal cord/nerves, CSF)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

spina bifida with myeloschisis

A
  • most severe spina bifida. results when neural plate fails to elevate and fold. the spinal cord remains open and is represented as a flattened mass of nervous tissue - very rudimentary
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

a patients has lateral curvature in vertebral column. has scans of a misformed vertebrae. what embryonic structue did not form correctly in this patient?

A

scholiosis of vertebral bodies - somites normally form the vertebrae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Somites form which three things

A
  1. Sclerotome: axial skeleton (vertebral column, ribs, portion of the skull)
  2. Dermotome: dermis
  3. Myotome: skeletal muscle
24
Q

congenital scoliosis

A
  • asymmetric fusion of vertebra
  • most often due to hemivertebrae (only half a vertebrae forming)
25
Q

Klippel-Feil Syndrome

A

formed by a fusion of cervical vertebrae - most often seen in C2/C3 and C4/C5

  • fusion happens when resegmentation doesn’t take place - if original sclerotome do not split
  • resutls in short neck, and restricted neck movements
  • genetic defect intrinsic to vertebral bodies
26
Q

Resegmentation of Vertebral Column

A
  • during wek 4, cells of the scloerotome shift to surround the spinal cord and notochord
  • Resegmentation:
  1. Caudal portion of each sclerotome proliferates and condenses; growth is so extensive that it reaches the crainial part of the adjacent sclerotome, forming the vertebral body
  2. Each vertebra is formed from caudal half of one somite and the cranial half of neighbor (ex. atlas - CV1, is formed from caudal half of first cervical sclerotome and cranial half of second cervical sclerotome)
  3. Intervertebral discs: annulus fibrosis from mesenchymal cells which remain between the cranial and caudal portions of the original sclerotome form the IV discs.
  4. Nucleus Pulposus: formed from notochord

the rearrangement of the sclerotome results in:

  • the myotomes spanning the IV discs
  • spinal nerves exit between contiguous vertebrae
  • intersegmental arteries pass midway over vertebral bodies
27
Q

Ribs

A
  • Origin: paraxial mesoderm, sclerotome
  • devlop from costal processes of the 12 thoracic vertebrae
28
Q

sternum

A
  • Origin: lateral plate mesoderm, somatic layer, — not from somite
  • ventral somatic mesoderm forms a pair of vertical bands called sternal bars
29
Q

Pectus excavatum and Pectus Carinatum

A
  • excavatum: anterior thoracic wall is sunken in
  • carinatum: anterior thoracic wall protrudes
  • both are congenital anomalies resulting from malformation of sternum and ribs - usually cosmetic, but can sometimes affect heart and lung function
  • ribs are too long!
30
Q

skeletal muscle developement

A
  • all skeletal muscle comes from mytome from paraxial mesoderm somites
  • the majority of smooth muslces arise from splanchic lateral plate mesoderm
  • cardiac muscles arise from a specialized region of splanchnic lateral plate mesoderm
31
Q

muscles arising from epimere

A
  • dorsal mytome split: gives rise to intrinsic muscles of back - erctor spinae, transversosplina. splenus, intersegmental group
  • inervated by dorsal primary rami because the come from the epimere
  • all the other muslces of the back/trunk/body come from the hypomere and are thus innervated by the ventral primary rami
32
Q

Dorsal part of myotome split…

A
  • forms the epimere!!!
  • innervated by dorsal rami
  • gives rise to intrinsic back muscles
33
Q

ventral part of myotome split

A
  • forms the hypomere!!!!
  • innervated by ventral rami
  • give rise to anterior and lateral neck musculature, trunk muscles and limbs
34
Q

tangenital splitting of myotomes

A
  • abdominal obliques and intercostal muscles
35
Q

longitudinal splitting of myotomes

A
  • results in trapezius and sternocleidomastoid muscles
36
Q

skeletal muscle myogenesis

A
  1. mesoderm cells differentiate into myoblasts (primordial muscle cells)
  2. myoblasts elongate and fuse together to form myotube -> this is what results in multinucleated skeletal muscle
  3. soon after the formation of myotubes, contractile filaments appear in the cytoplasm of hte myotube, called muscle fiber
37
Q

Poland Syndrome

A
  • absent or underdeveloped pectoralis muscles
  • usually unilateral, usually right side affected
  • most caes include syndactyly of the fingers
  • cause is unknown, but believed to involve loss of blood supply to the chest wall during developement
38
Q

embryological structure of limb developement

A
  • skeletal and CT components derived from lateral plate mesoderm:
  • muslce derived from mytome of somites
  • epidermis comes from surface ectoderm
39
Q

Limb Bud formation: AER

A
  • due to the cranial to caudal sequencing of developement, the upper limb forms around day 26-27 (two days before lower limb). upper limb forms opposite lower cervical and upper thoracic segments. lower limb forms opposite lumbar and upper sacral segments
  • AER (1st part of limb to form, signals for limb growth - without it, limbs will NOT form)
  • AER = apical ectodermal ridge, forms the apex of the limb bud
  • mesenchymal cells deep to the AER remain in an undifferentiated, rapidly dividing state (AER induces continued proliferation of distal limb bud mesenchyme)
  • More proximally situated mesenchymal cells differentiate into cartilage cells (chondroblasts), forming early bone models, blood vessels and other CT types
40
Q

Hand/Footplates

A
  • distal ends of limb buds flatten to paddle-like hand and footplates
  • separated from limb bud by circular constricution (future wrist or ankle joint)
41
Q

Digital Rays

A
  • 4 zones of apoptosis, will result in separation of the AER into 5 digital rays with AER on the end of each
  • this occurs in the 6th week for upper limb, and 7th week for lower limb
  • this is what will form future toes/fingers
42
Q

Limb Axes

A
  1. Proximal-distal axis extends from region that forms shoulder distally to fingertips.
    * signalled to form by AER
  2. Anterior-Posterior axis extends along hte axis that defines difference between thumb (anterior) and little finger (posterior)
  • thumb and great toe are anterior, little toe/little finger anterior
  • due to zone of polarizing activity - due to retinoic acid gradient
  1. Dorsal-ventral axis extends along the axis that extends from the back of the hand (dorsal) to the palm (ventral)
    * defines elbow and knee as dorsal, palm and bottom of foot as ventral
43
Q

Ossification

A
  • during week 5, cartilage formation begins (cartilage bone models) = endochondral ossification of lateral plate mesoderm for appendicular skeleton
  • cartilage model laid down first, then blood vessles migrate into shaft (primary sites), mesodermal cells differentiate into osteoblasts, and then the osteoblasts establish the bones
  • primary ossification centers form starting in the seventh week
  • present in all long bones by the 12th week
  • some bones begin ossification after birth (carpals, tarsals, patella)
  • secondary ossification - form mostly after birth; important for growth
  • The cartilage between the primary and secondary ossification centers is called the epiphyseal plate, and it continues to form new cartilage, which is replaced by bone, a process that results in an increase in length of the bone. Growth continues until the individual is about 20 years old or until the cartilage in the plate is replaced by bone. The point of union of the primary and secondary ossification centers is called the epiphyseal line.
44
Q

Joint formation

A
  • joints are formed in areas where mesnchyme is less dense (interzones)
  • these interzones form the joint cavity through the cell death; surrounding cells differentiate into joint capsule
45
Q

a newborn is born with her foot in a hyper-inverted and hyper-plantar flexed position. the muscle in the deformed structure is derived from the?

A

myotome

46
Q

limb musculature

A
  • hypomere portion contributes muscle to the limbs
  • in the 5th week myogenic cells from the myotome of the somite migrate into the limb bud
  • initially, myoblasts form one large muscle mass in each limb bud; later, splits into a ventral (flexor) and a dorsal (extensor) compartment
  • Myogenesis:
  1. mesoderm cells differentiate into myoblasts (primordial muscle cells)
  2. myoblasts elongate and fuse together to form myotubes
  3. contractile filaments appear in the cytoplasm of the myotube –> muscle fiber
47
Q

Limb Rotation

A
  • first form in the same position - thumb and great toe directed laterally. palm of head and plantar are anterior. elbow and knee are posterioally. the lower limb rotates 180 degrees medially so that great toe is medial, knee is anterior.
  • limb formation/rotation isn’t complete until toddler learns to walk
48
Q

limb innervation: sensory and motor

A
  • sensory nerve fibers are “pulled” into limb as it elongates from trunk
  1. spinal nerves migrate along with dermatomes as they are pulled into developing limb; sensory innervation is distrbuted radially on limb
  2. dermatomes “spiral” around limbs (especially lower) due to limb formation
  • motor nerve fibers grow into the limb along the myotomoal mesoderm- after limb has already been established - elongate longitudinally down the limb
  1. divide into anterior (flexor muscles) and posterior (extensor muscles) division
  2. upper spinal nerves supply more proximal muscle masses and lower spinal nerves supply more distal muscle masses; motor innervation si distributed longitudinally
  3. induce differentiation of myotome mesoderm into myoblasts (muscle precursors)
49
Q

Amelia

A

Absence of limb due to suppression of limb bud development during week 4 of developement

50
Q

Meromelia

A
  • absence of part of a limb
  • arrest of limb bud development during weks 5-7 of developement
  • phocomelia is a type of meromelia involving absence of lone bones
51
Q

Digit deformities

A
  1. Brachydactyly: shortness of digits
  2. Syndactyly: fusion of two or more digits (most common anomaly, due to insufficient apoptosis of mesenchyme between digital rays)
  3. Polydactyly: extra fingers or toes
  4. Ectrodactyly: absence of a digit
52
Q

Cleft hand/foot

A
  • “lobster claw deformity”
  • absence of third metacarpal (or metatarsal) and 3rd digit
  • fusion of thumb and second digit, and fusion of fourth and fifth digit
53
Q

Congenital clubfoot

A
  • abnormal position of foot; sole is inverted, foot is adducted and plantar flexed
  • common cause of oligohydramnios (too little amniotic fluid) - which leads to abnormal positioning/restricted movement of the foot in utero
54
Q

amniotic bands

A
  1. caused by fibrous bands of amnion membrane in amniotic fluid. these bands can encicle and entrap portions of the fetus, cuting off circulation as fetus develops like a turnicate
  2. may cause amputation of limbs or digits
55
Q

Congenital hip dislocation

A
  • underdevelopment of acetabulum and head of femur, laxity of joint capsule
  • dislocation occurs before birth
  • common with breech deliveries

MSK- Back!!! (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions