Anatomy of the child - features of the newborn Flashcards
What happens with the neonatal skull?
- The skull is massive in comparison to rest of body.
- Edentulous jaws.
- Shallow maxillae.
- Short face vertically.
- Bulging cheeks forward - to accommodate their tissues.
When do children lose their big “baby cheeks”?
At 6-7 years old. When their permanent teeth arrive and there is rapid increase in the size of the maxillary sinuses.
Describe the neck of a newborn baby?
No visible neck:
- Lower jaw and chin touch its shoulder and thorax.
What happens to the neck in a baby?
Gradually elongates and the chin loses contact with the chest.
What happens to the head in a baby as it gets older?
It becomes more mobile in flexion, extension and rotation as the neck gets longer and stronger.
What happens to the abdomen of a baby over time?
At birth it is not prominent but becomes more prominent as the child gets older.
Why do babies/toddlers/children have pot-belly’s?
Large liver and the small pelvis, the pelvic organs lie in the abdominal cavity.
What happens to pelvic organs in later childhood?
They sink into the developing pelvic cavity and the rate of growth of the abdominal walls outspaces that of the liver. The belly then flattens.
How are the limbs developed at birth?
The upper limbs are fully developed but the movements aren’t controlled well and normally ataxic.
How are fingers of babies?
- Flexed.
- Hyperextended.
- Powerful grasping reflex.
How does development of the hand work in terms of time?
Takes many months to become the chief tactile organs, until then the lips are used for feeling.
Describe the proportion of the cranial vault and the facial skeleton?
The cranial vault is a very large proportion to the face.
How is the skull of a newborn compared to that of an adult?
The fetal skull is very round, this is due to the underdevelopment of the face.
What is the difference between the cranial vault of an adult and fetal skull?
They are the same proportions.
What is the difference between the facial skeletons of an adult and fetal skull?
Fetal skull:
- Vertical diameter of the orbit = vertical height of maxilla and mandible combined.
Adult skull:
- Vertical diameter of orbit = 1/3 of vertical height of maxilla and mandible combined.
How are the bones of vault and facial skeletons developed?
Ossification in membrane.
How are the bones of the base of the skull developed?
Ossification in cartilage.
When are the vault and facial bones ossified by?
Most are ossified by time of birth, however, they are mobile on each other and can be readily disarticulated.
What bones are most mobile over each other in the fetal skill?
Cranial vault. They can overlap quite easily and can mould which is helpful during birth.
How are the bones of the vault connected?
Fetal skull:
- Separated by linear attachments of fibrous tissue and by fontanelles in larger areas.
Adult skull:
- Interdigitate in sutures.
Where do the anterior and posterior fontanelle lie?
Midline of the vault.
What bones does the anterior fontanelle lie between?
- Two parietal bones - bound it behind.
- Two halves of frontal bone lie in front.
What happens to the two halves of the frontal bone as the child grows?
Unite by age 2.
When does the anterior fontanelle close?
2 years old.
When is the anterior fontanelle not palpable?
18 months.
Where does the posterior fontanelle lie?
Between the apex of the squamous part of the occipital bone and psoterior edges of the two parietal bones.
When does the posterior fontanelle close?
End of first year.
How does growth of the vault work?
Deposition of bone around the esges of the separate bones, these separate bones come to interdigitate with each other along the various sutures.
What other type of growht is there in the bones of the vault?
Interstitial growth in thickness, which is accompanied regularly throughout by a moulding of each bone ie. absorption of inner surfaces of bone by osteoclasts accompanies the laying down of new external surfaces by osteoblasts.
In the vault skull which type of bone is present at birth?
Compact bone - over time it becomes cancellous bone and red bone marrow fills the interstices.
What pieces does the temporal bone develop into?
- Two pieces in the membrane.
- two pieces in the cartilage.
What do the squamous and tympanic bone develop into?
Membrane.
What do the petromastoid and styloid process develop into?
Cartilage.
What happens to the squamous (part of the temporal bone) bone?
Increases in size by appositional growth combined with a continuous process of moulding.
What is the tympanic bone like at birth?
Originally present at birth as the tympanic ring (c-shape). It is underneath the petrous and squamous parts and encloses the tympanic membrane.
Describe the baby external acoustic meatus (newborn)?
Wholly cartilaginous.
Describe the tympanic membrane?
Nearly as big as the adult tympanic membrane, but faces more downwards and less outwards than the adult ear drum. Thus appears smaller and more oblique when viewed through the otoscope.
What happens to the tympanic ring in development?
Elongates by growth from the lateral rim of its whole circumference and the tympanic plate is formed, so it forms its bony part of the external acoustic meatus. It pushes the cartilaginous part of the meatus laterally and further from the ear drum.
What happens to the tympanic ring as the tympanic plate grows laterally?
It tilts to face more laterally and less downwards.
Describe the growth rate of the tympanic ring?
Growth is originally rapid anteriorly and posteriroly but less rapid inferiorly.
What does the petromastoid enclose?
Internal ear and tympanic antrum.
Describe the mastoid process in a newborn?
Not developed and the stylomastoid foramen is near the lateral surface of the skull.
What covers the stylomastoid formaen?
Thin fibres of sternocleidomastoid muscle.
What happens to the mastoid process as the child develops/grows?
By the second year the mastoid process is “aerated” - air cells grow into it from the tympanic antrum. This is done by the age of 2.
What are full size by the time of birth?
- Cochlea.
- Vestibule.
- Semicircular canals.
What is the roof of the middle era?
Tegmen tympani - plate of bone.
Where does the tegmen tympani come from?
Projects laterally from the petrous bone.
What is the tegment tympani like at birth?
it is not fully grown and does not cover the geniculate ganglion of the facial nerve.
What is the geniculate ganglion of the facial nerve in contact with?
Dura mater of the middle cranial fossa.