Development: trunk

Question 1

what week of development: gastrulation

Answer 1

third week

Question 2

gastrulation: features

Answer 2

• embryo axial orientation
• bilaminar-> trilaminar disc:
• ectoderm
• mesoderm
• endoderm

Question 3

primitive streak should disappear by what week?

Answer 3

• end of 4th week

- if not, benign tumour- sacrococcygeal teratoma

Question 4

notochord: function

Answer 4

• basis of development of axial skeleton
• indicator for future sites of vertebral bodies
• induce thickening of ectoderm and formation of neural plate

Question 5

development of neural tube:

Answer 5

• neural plate and neural crest - neural groove - neural tube with neural crest merged - crest becomes spiral ganglion

Question 6

somites: formed by

Answer 6

• mesoderm and neural tube form columns of paraxial mesoderm

- segment into cube structures

Question 7

somites differentiates into:

Answer 7

• myotome
• dermatome
• sclerotome

Question 8

myotomes: contribute to

Answer 8

• development of skeletal muscles of neck, trunk and limbs

Question 9

dermatomes: contribute to

Answer 9

connective tissue

- dermis of the skin

Question 10

sclerotomes: contribute to

Answer 10

• vertebrae and ribs

Question 11

development of vertebral column: 4th week

Answer 11

• each mesenchymal (sclerotome) segment (somite) differentiates into cephalic (less condensed) and caudal part (more condensed cells)
• notochord in middle (nucleus pulposus)
• sclerotome forms annulus fibrosus

Question 12

synovial joint development: what week?

Answer 12

• 6th week

- by 8th week resemble adult joints

Question 13

synovial joint development: how

Answer 13

• interzonal mesenchyme differentiate to form capsule and ligaments (peripheral)
• form joint capsule (centrally)

Question 14

how does spinous and transverse processes develop?

Answer 14

• extensions of chondrification centres in vertebral arches

Question 15

ossification of vertebra: begins

Answer 15

• during embryonic period, primary ossification centres

Question 16

ossification of vertebra: at birth

Answer 16

• 3 bony parts connected by cartilage

- for growth of spinal cord

Question 17

ossification of vertebra: secondary ossification centre

Answer 17

• after puberty

- unite at around 25yrs

Question 18

muscle differentiation: pathway

Answer 18

• myoblasts migrate to muscle location
• fuse to form myotubules - begin to express contractile proteins - formation of sarcomeres leads to maturation in myofibrils

Question 19

development of muscles: myotome somite divides into

Answer 19

• dorsal (epiaxial) division

- ventral (hypaxial) division

Question 20

development of muscles: genes

Answer 20

• MyoD
• Myf5
• initiate and regulate muscle development

Question 21

development of vertebral column: genes

Answer 21

• Pax-1

- regulates development

Question 22

what muscles arise: epaxial division

Answer 22

• extensors of neck/ vertebral column

intrinsic

• superficial (splenius)
• intermediate (erector spinae)
• deep (transversospinalis)

sacral/ coccygeal region:
- myotomes form sacrococcygeal lig

Question 23

what muscles arise: hypaxial division- cervical region

Answer 23

• scalenes
• longus capitis
• longus colli

Question 24

what muscles arise: hypaxial division- thoracic region

Answer 24

• intercostals
• transversus thoracis
• subcostals
• diaphragm

Question 25

what muscles arise: hypaxial division- abdomino-pelvic region

Answer 25

- internal/ ext obliques - transversus abdominus - psoas - quadratus lumborum - obturator ext/ int

Question 26

what nerves supply: epaxial division

Answer 26

- posterior rami of spinal nerves

Question 27

what nerves arise: hypaxial division

Answer 27

- anterior rami of spinal nerves

Question 28

vertebra T10 corresponds to which spinal cord segments:

Answer 28

L1, L2

Question 29

vertebra T11 corresponds to which spinal cord segments:

Answer 29

L3, L4

Question 30

vertebra L1 corresponds to which spinal cord segments:

Answer 30

sacral and coccygeal cord segments

Question 31

list 3 main developmental abnormalities:

Answer 31

- variation in no. of vertebrae - variation in normal architecture of vertebra - tumours of embryological remnants

Question 32

eg. brevicollis

Answer 32

- short neck - low hairline - restricted head movements - from undeveloped vertebral body/ defect in vertebral segmentation

Question 33

eg. accessory rib

Answer 33

- in lumbar/ cervical region - if cervical, could present some neurovascular symptoms (numbness of upper limb) - extra rib

Question 34

anomalies of ribs: eg.

Answer 34

- pliable ribs - pectus excavatum (sunk in ribcage) - pectus carinatum (pigeon chest)

Question 35

eg. sacralisation of L5:

Answer 35

- L5 incorporated into sacrum | - back pain

Question 36

eg. lumbarisation of S1

Answer 36

- S1 separated, | - not many symptoms

Question 37

eg. hemivertebra

Answer 37

- failure of one chondrification centre - failure of half vertebra undeveloped - hemivertebra (wedge) - butterfly (2 hemivertebra) - changes posture, scoliosis

Question 38

eg. block vertebra:

Answer 38

- failure of segmentation of two or more vertebrae

Question 39

distortion: scoliosis eg.

Answer 39

- spinous process deviated to one side - rib pushed posteriorly, thoracic cage narrowed - other rib laterally and anteriorly

Question 40

eg. kyphosis

Answer 40

- anteriorly - failure of formation of v. body, - failure of segmentation - spinal osteoporosis (elderly)

Question 41

eg. schmorl's node

Answer 41

- protrusion of cartilage of IV disc | - through vertebral body endplate into adjacent vertebra

Question 42

eg. spina bifida oculta

Answer 42

- vertebral arches must fuse completely - lamina of L5/ S1 fail to develop and fuse normally - everything normal - extra hair - asympotomatic

Question 43

eg. spina bifida cystica

Answer 43

- 1+ vertebral arches fail to develop - protrude out of lumbar region meningocele: - herniation of meninges (only space, but everything ok) meningomyelocele: - herniation of meninges and spinal cord

Question 44

eg. spina bifida cystica symptoms

Answer 44

- severe meningomyelocele - paralysis of limbs - loss of bladder control - loss of bowel control - recurrent CNS infections

Question 45

can you prevent spina bifida?

Answer 45

prenatal screening: - ultrasound - aminocentesis - blood test prevent: - folic acid supplements

Question 46

eg. teratoma

Answer 46

- benign tumour - from primitive streak - develops from independent cells from any of 3 embryonic germ layers - any type of tissue (bone, hair, skin, muscle)

Question 47

eg. chordoma

Answer 47

- from persistent notochord - slow growing malignant tumour - common at base skull - difficult to remove-> infiltrates bone - once detected, too late - can develop in lumbosacral region