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EMBRYONIC DEVELOPMENT & STEM CELL COMPENDIUM

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I. V ertebral column

 A. SPINA BIFIDA OCCULTA results from failure of fusion of t he halves of 

the vertebral arch, most often in the lumber and sacral regions

1. It is a common defect but usually of no significance

2. The skin over the b ifid spine is usually intact, and there may be

no visible signs of the defec t exce pt for a "dimple" or tuft of 

hair

3. Severe types do exist and are described under Nervous system

development

B. KLIPPEL-FElL SYNDROME (brevicollis): very rare; extreme shortening of 

the neck due to a reduced number of cervical vertebrae. The rest of 

the cervical vertebrae are usually abnormal in shape and may be fused.

 Associated with othe r abnormalities

C. ASY MMETRICALLY FUSED VERTEBRAE or parts of vertebrae missing;

an increase or decrease in vertebral number is not uncommon due to

the complicated process of formation and rearrangement of the

segmental sclerotomes in development

II. Ribs: defe cts are mostly secondary to malf ormations of the vertebral column

 A. IF PART OR ALL OF A VERTEBRA is missing, t he corresponding ribs aregenerally gone

B. IN SEVERE CONGENITAL SCOLIOSIS, the ribs on the concave side of 

the chest are often fused or branched

C. ACCESSORY RIBS: usually the cervical rib (lumbar ribs are less

common)

1. Att ached to t he seventh cervical vertebra; may be unilateral or

bilateral

2. Pressure effec ts on the brachial plexus or subclavian vessels

may produce symptoms

3. From retention and development of costal processes of cervical

or lumbar vertebrae

D. FUSED RIBS: this may occur poste riorly when 2 or more ribs arise from

a single vertebra

1. Often associated w ith a hemivertebra which may produce

scoliosis

III. Sternum

 A. CLEFT STERNUM

1. Minor clefts or notches are common and are seen as isolated

anomalies

2. Major clefts are usually associated w ith severe malformations of 

the chest

3. Large clefts are rare ( heart); associated w ith herniation of 

thoracic viscera

IV. The clavicles

 A. CLEIDODYSOST OSIS: absence o f all or part of t he c lavicle

1. Usually bilateral and the shoulde rs are drawn forward to meet

under the chin

68. Congenital Malformations of The Skeletal System

Review of MEDICAL EMBRYOLOGY Book by BEN PANSKY, Ph.D, M.D.

PREV NEXTTABLE OF CONTENT67. Appendicular Skeleton And Skull Development 69. Development Of The Limbs

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2. Often associated w ith skull defe cts (cleidocranial dysostosis)

 V. Skull malformations range from major defects incompatible w ith life to those

that are minor and relatively unimportant. The abnormalities are manifold, and

either all or part of the skull may be involved. They are frequently associated

with brain defect s

 A. CRANIOSCHISIS OR ACRANIA: the cranial vault is almost absent and a

large spinal defect is often present. Also associated with anencephaly

1. Due to a failure of the cranial end of the neural tube t o close

during we ek 4, thus the cranial vault does not form

B. CRANIOSYNOSTOSIS OR CRANIOSTENOSIS: due to premature

closure of skull sutures

1. More common in male than female; associated with ot her

skeletal abnormalities

2. Type of de formed skull depends on which sutures close

prematurely

a. If sagittal suture: a long, narrow, wedge-shaped skull

(scaphocephaly)

b. If the coronal suture: a high, towerlike skull (oxyce phaly

or acrocephaly)

c. If coronal or lambdoid suture closes on one side:

twisted and asymmetric skull (plagiocephaly)

C. MICROCEPHALY : cranium is normal size or slight ly small, but the re is no

abnormal closure of the sutures. It is primarily an abnormality of the

CNS in which the brain and skull both fail to grow

Related Pages

Related Organs

Bone

Cartilage

Related Anatomical Compartments

Cartilage > Annulus Fibrosus

Bone > Central Neural Arch

Bone > Distal Rib

Bone > Dorsal Neural Arch

Somite > Dorsomedial Sclerotome

Cartilage > Intervertebral Disc

Bone > Lateral Neural Arch

Cartilage > Nucleus Pulposus

Bone > Proximal Rib

Bone > Rib

Bone > Spinous Process Of Verteb rae

Somite > Ventrolateral Sclerotome

Somite > Ventromedial Sclerotome

Bone > Vertebrae

Bone > Vertebral Body

Related Cells

Bone > Spinous Process Of Vertebrae > Prechondrocytic Mesenchymal

Cells

Bone > Dorsal Neural Arch > Prechondrocytic Mesenchymal Cells

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Bone > Central Neural Arch > Prechondrocytic Mesenchymal Cells

Bone > Proximal Rib > Prechondrocytic Mesenchymal Cells

Bone > Distal Rib > Prechondrocytic Mesenchymal Cells

Cartilage > Annulus Fibrosus > Prechondrocytic Mesenchymal Cells

Bone > Ve rtebral Body > Prechondrocytic Mesenchymal Cells

Bone > Lateral Neural Arch > Prechondrocytic Mesenchymal Cells

Somite > Cervical Mesenchymal Sclerotome > Sclerotome Cells

Somite > Lumbar Mesenchymal Sclerotome > Sclerotome Cells

Somite > Thoracic Mesenchymal Sclerotome > Sclerotome Cells

Somite > Sacral Mesenchymal Sclerotome > Sclerotome Cells

PREV NEXTTABLE OF CONTENT67. Appendicular Skeleton And Skull Development 69. Development Of The Limbs

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