แกะเทป developmental of musculoskeletal system

7/29/2019 Developmental of Musculoskeletal System

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Dr.Ronnarong Palasoon:Anatomy Unit, Faculty of Science, Rangsit University

Developmental Anatomy for DT(ANA 222; 1/2013)

Musculoskeletal andIntegumentary Systems

Objectives: To describe

1. the developments of the axial and appendicular skeletons and joints

2. the developments of the skeletal, cardiac and smooth muscles

3. the developments of the skin and its appendages

4. Some clinical correlations
http://www2.rsu.ac.th/files/2010LogoF4_JPG.ziphttp://www2.rsu.ac.th/files/2010LogoF4_JPG.zip


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The Skeletal System


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The Regulation of Somite Differentiation

Sonic hedgehog and noggin causethe ventral part of the somite to formsclerotome and to express PAX1.

PAX1 controls chondrogenesis andvertebrae formation.

PAX3 demarcates the dermomyotome.

WNT proteins activate PAX3 anddirect the dorsomedial portion of thesomite to differentiate into muscleprecursor cells.

Neurotrophin 3 directs the middorsalportion of the somite.

The activating WNT proteins andinhibitory BMP4 protein influence thedorsolateral portion of the somite tothe other muscle precursor cells.


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The Development of Skeletal System

1. Paraxial mesoderm

- vertebrae and ribs

- some bones of skull base

2. Lateral plate (parietal layer)

mesoderm

- pelvic and shoulder girdles,

limbs and sternum3. Neural crest in the head

- skull : cranial vault, face


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Phases of Chondrogenesis and Its Regulation Pathways


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Skull


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Development of the Cranium

At 6 weeks At 7 weeks

At 12 weeks At 20 weeks


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Skull

NEUROCRANIUM

Chondrocranium

OccipitalSphenoidEthmoidPetrous and mastoid part oftemporal

Membranous Neurocranium

Interparietal part of occipitalParietalFrontalSquamous part of temporal


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VISCEROCRANIUM

Cartilaginous ViscerocraniumPharyngeal Arch I

Meckel's cartilageMalleusIncus

Pharyngeal Arch II

Reichert's cartilageStapesStyloidprocess

Membranous ViscerocraniumMaxillary process (superficial)

Squamous part of temporalZygomaticMaxillaryPremaxillaryNasal?Lacrimal?

Maxillary process (deep)

PalatineVomerPterygoidlaminae

Mandibular process

Mandible

Tympanic ring

Skull


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Skull of Newborn

sultures fontanelles molding


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scaphocephaly- the sagittal suture

brachycephaly- the coronal sulture

plagiocephaly-the coronal andlambdoid sutures on one

side of the skull

Craniosynostosis premature closure of one or more sultures


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Cranioschisis

the cranial vault fails to formfailure of the cranial neuropore to close

anencephaly

meningocele


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Vertebral column

Vertebra


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sclerotome:- notochord, neural tube, and

the body wall- paired condensation

- loosely arranged cells, cranially

- densely packed cells, caudally

resegmentation:- the caudal half of each

sclerotome grows into andfuses with the cephalic half ofeach subjacent sclerotome

HOX genes Formations:

- centrum- neural arch- nucleus pulposus- costal processes

Vertebral column


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Vertebral Development

5th week 6th week 7th week

At birth


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Developments of Ribs and Sternum

Ribs the costal processes of

thoracic vertebrae

Sternum

the parietal layer oflateral plate mesodermtwo sternal bands oneither side of the midlinecartilaginous models ofthe manubrium,sternebrae, and xiphoidprocess


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Vertebral and Rib Abnormalities


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Anatomy of the Muscular System

1. The axial muscles

Muscles of head- Muscles of facial expression

- Muscles of mastication

Muscles of the neck and throatBack musclesThorax musclesAbdominal wall musclesMuscles of pelvic floor

2. The appendicular muscles

Muscles of upper limbsMuscles of lower limbs


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The Development of Muscular System

The muscular system develops from the mesodermal germ layer.

Skeletal muscle is derived fromparaxial mesodermforming somites fromthe occipital to the sacral regions and somitomeres in the head.

Smooth muscle differentiates fromvisceral splanchnic mesodermsurrounding the gut and its derivatives and fromectoderm (pupillary,mammary gland, and sweat gland muscles).

Cardiac muscle is derived fromvisceral splanchnic mesodermsurroundingthe heart tube.

Myoblasts (embryonic muscle cells) are derived from mesenchyme .

MyoD, a member of the family of myogenic regulatory factors, activates transcriptionof muscle-specific genes and is considered an important regulatory gene for theinduction ofmyogenic differentiation.


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The development of skeletal muscle

Signaling molecules : regulate the beginning of myogenesis and the inductionof the myotome .

- Shh, from the ventral neural tube and notochord- Wnts, BMP-4,from the dorsal neural tube- Wnts, BMP-4, overlying ectoderm

Myogenesis (muscle formation)

the elongation of the nuclei and cell bodies of mesenchymal cells

Myoblasts

(MyoD, myogenin, Myf-5, and myogenic regulatory factor 4)

Myotubes: elongated, multinucleated, cylindrical structures


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The development of skeletal muscle

epaxial division (Myf-5)

hypaxial division (MyoD)

Myotome:

The development of cardiac muscle

Cardiacmyoblasts

Primordialmyocardium

Heart muscle(the fourth week)

Purkinje fiber (late embryonic period)


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The development of smooth muscle

Mesenchyme spindle-shaped myoblasts(with elongated nuclei)

Smoothmuscle

dorsal aorta andlarge arteries

lateral plate mesodermand neural crest cells

coronary arteriesproepicardial cells and neuralcrest cells (proximal segments)

wall of the gut andgut derivatives

splanchnic layer oflateral plate mesoderm

sphincter and dilatormuscles of the pupiland muscle tissue inthe mammary and

sweat glands

ectoderm


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Anomalies of Muscles

Poland syndrome:

Absence of the pectoralis major, often its sternal part,is usually associated with syndactyly (fusion of digits).

Prune belly syndrome:Partial or complete absence of abdominal m.


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Anomalies of Muscles

Congenital Torticoll is Arthrogryposis(congenital joint contractures)


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Development of the limb buds


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Development of the limb buds

Days:

Days:

27 32 41 46 50 52

28 36 46 49 52 56


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Cartilage and Bone of Limbs

The 6th week:

hyaline cartilage models

The 12th week:

primary ossification center

endochondral ossification

diaphysis

At birth:

completed ossification of

diaphysis

secondary ossification center

epihysis


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Regulation of Limb Patterning and Growth

Limb outgrowth:- lateral plate mesoderm cells- TBX5 and FGF10 (forelimb)- TBX4 and FGF10 (hindlimb)

BMPs (bone morphogenetic proteins) induce formation of the AER.

Radical fringe restricts the location of theAER to the distal tip of the limbs.

SER2 is expressing at the AER (apical ectodermal ridge).

Engrailed-1 represses expression of Radical fringe.

The ridge expresses FGF4 and FGF8, which maintain the progress zone.

Patterning of proximodistal axis


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Regulation of Limb Patterning and Growth

Patterning of anteroposteroir axis

Patterning of dorsoventral axis

The zone of polarizing activity (ZPA): a cluster ofcells at the posterior border of the limb.The cells in ZPA produce retinoic acid (vitamin A). RA initiates expression ofsonic hedgehog (SHH)regulating the anteroposterior axis.

BMPs in the ventral ectoderm induce expressionof EN1. EN1 represses WNT7a expression, restricting it tothe dorsal limb ectoderm. WNT7a induces expression ofLMX1 specifingcells to be dorsal. In addition, WNT7a maintains SHH expression inthe ZPA and therefore indirectly affects

anteroposterior patterning as well.


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Types of Joint


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Joint Formations

J oints are formed in thecartilaginous condensations.

Ajoint interzone is inducedwhen chondrogenesis is arrested.

Ajoint cavity is formed by cell

death.

Surrounding cells differentiate intoajoint capsule.

WNT14 appears to be theinductive signal regulating thepositioning of joints.

synovial, cartilaginous, andfibrous joints


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5 weeks

7 weeks

11 weeks

Epidermis

layer of surface ectodermal cells:primordium of epidermis

the periderma basal (germinative) layer

periderm continually undergo keratinizationand desquamation and are replaced by cellsarising from the basal layer.

vernix caseosa:

the white greasy substance

protects the developing skinfacilitates birth of the fetus.

At 10 weeks: epidermal ridges

Late embryonic period:

melanoblasts melanocytes

(neural crest cells)

D i


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Dermis

- three sources:

(a) lateral plate mesoderm: dermis in the limbs andbody wall

(b) paraxial mesoderm: dermis in the back(c) neural crest cells: dermis in the face and neck.

During the third and fourth months:

dermal papillae

Sweat Glands

two types : eccrine and apocrine

Eccrine sweat glands- skin throughout most of the body

- function shortly after birthApocrine sweat glands

- axilla, pubic, and perineal regions andareolae of the nipples

- develop during puberty- arise from the same epidermal buds that

produce hair follicles


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M Gl d


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Mammary Glands


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Mammary Glands

a modified and highly specialized type of sweat glands.

Mammary buds: solid downgrowths of the epidermis into the underlying

mesenchymethe , at sixth week , responding to an inductive influence from

the mesenchyme.

mammary crests: thickened strips of ectoderm extending from the axillary

to the inguinal regions, appeared during the fourth week

Canalization of these buds: induced by placental sex hormones and

continued until late gestation, and by term

lactiferous ducts and their branches

The fibrous connective tissue and fat: the surrounding mesenchyme

mammary pit : the late fetal period


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Clinical correlations

Hypertrichosis

Hyperpigmentation

Ichthyosis

Angiomas

AlbinismSupernumerary Breasts

- extra breast (polymastia)

- nipple (polythelia)


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Development of Nails

Toenails and fingernails begin to develop at the tips of the digits at about 10 weeks.

nail fields: the primordia of nails, thickened areas of epidermis at the tip of each digit

nail folds: surrounded nail fields laterally and proximally

nail plate: cells from the proximal nail fold growing over the nail field and keratinizing

eponychium (cuticle): a narrow band of epidermis

Hyponychium: the skin under the free margin of the nail

The fingernails reach the fingertips by approximately 32 weeks

the toenails reach the toetips by approximately 36 weeks.


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Two sets of teeth : deciduous and permanent teeth.

Teeth develop from oral ectoderm, mesenchyme, and neural crest cells.

Development of Teeth

8 weeks 10 weeks

3 months 6 months

Bud stage Cap stage

Bell stage



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dental lamina: the basal layer of the epithelial lining of the oral cavity

forms a C-shaped structure, at the sixth week

dental buds

cap stage: invagination of the buds into the deep surface

- a cap an outer layer, the outer dental epithelium

- an inner layer, the inner dental epithelium

- a central core of loosely woven tissue, the stellate reticulum.

dental papilla: the mesenchyme originating in the neural crest

bell stage: the dental cap grows and the indentation deepens

- odontoblasts: producing dentin

- the pulp of the tooth

- ameloblasts: epithelial cells of the inner dental epithelium

enamel knot regulating early tooth development

D l t f T th


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epithelial root sheath: the dental epithelial layers penetrating into the

underlying mesenchyme, formation of the root of the tooth

cementoblasts: mesenchymal cells on the outside of the tooth and in

contact with dentin of the root, producing the cementum

periodontal ligament: mesenchyme outside the cement layer

The eruption of deciduous or milk teeth occurs 6 to 24 months after birth.

The tooth just

before birth

The tooth just

after eruption

Anomalies of teeth


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Anomalies of teeth

enamel hypoplasia: defective enamel formation causes pits and/or fissures in theenamel of teeth

variations of tooth shape: abnormally shaped teeth enamel pearls: spherical masses of enamel on the root of a tooth numerical abnormalities: supernumerary teeth, anodontia, gemination Amelogenesis imperfecta: a complex group of at least 14 different clinical entitiesthat involve developmental aberrations in enamel formation in the absence of anysystemic disorder

แกะเทป developmental of musculoskeletal system

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