cranial
system
Cranial nerves and
cranial nerves are twelve pairs of nerves that start from the base of the brain
or brain stem level and emerge through the holes in the skull base, distributed
by the head, neck, chest and abdomen. The International Anatomical Nomenclature
includes the terminal nerve as cranial nerve, despite being atrophic in humans
and closely related to the olfactory nerve.
The cranial nerves
are apparent origin that is where it leaves or enters the brain. The real
origin is different according to the function they perform. The fibers of the
cranial nerves with motor function (efferent) originate from cell clusters that
are deep in the brain stem (motor nuclei) and are homologous to the anterior
horn cells of the spinal cord. The fibers of the cranial sensory function or
sensory (afferent) have their cells of origin (first order nuclei) outside the
brain stem, usually in glands that are homologs of the dorsal root of spinal
nerves. The second-order sensitive cores are in the brainstem.
The nuclei of cranial
nerves where they leave are located in a region widely known as the tegmentum
that runs through the brain stem.
At the level of the
midbrain, the upper structure of the brain stem, split the pair III
and IV
At the level of the
pons, the average structure of the brain stem, split pairs V, VI, VII and VIII
At the level of the medulla oblongata, the lower structure of the brain stem, split cranial nerves IX, X, XI and XII
functional
classification
According to its
functional aspect, they are grouped as follows:
The pairs I, II and
VIII are devoted to special sensory input.
The couple III, IV
and VI control eye movements, reflexes fotomotores and accommodation.
The couple XI and XII
are pure motor nerves (XI for the sternocleidomastoid and trapezius muscles and
XII for the tongue).
The pair V, VII, IX
and X are mixed.
The couple III, VII, IX and X are
parasympathetic fibers
Disorders
The causes of alteration of the morphology of the
skull are called craniosynostosis primarily, caused by premature closure of one
or multiple sutures, preventing normal growth of the skull and
craneosinostósicas cranial deformities that are not
positional cranial remodeling produced in the intrauterine or more commonly
postnatal
The craniosynostosis can be simple, when you commit a
single suture and multiple, the first may be classified as:
a) Scaphocephaly: caused by closure of the sagittal
suture, is the most common form corresponding to 60% of the synostosis.
b) Plagiocephaly anterior / posterior: generated by
unilateral closure of the coronal suture (anterior, or frontal parietal
bregmatic) or lambdoid suture (posterior parietal or occipital).
c) trigonocephaly: commitment caused by suture
metopic (between the two frontal bones). The
craniosynostosis are classified as:
a) Brachycephaly: originated by bilateral locking of
the coronal suture. The subsequent mild braquicefalias may be
positional, but if
are severe are due to a true synostosis.
b) Oxicefalia: commitment generated by coronal
and sagittal sutures simultaneously
Skull
The skull (from the
Greek and Latin κρανίον kranion cranium) is a bony case that protects and
contains the brain primarily. The human skull consists of 8 huesos1 joint,
forming an open cavity of variable thickness and ovoid, with an approximate
capacity of 1,450 ml (adults).
The skeleton of the
head, or solid neo-facial skeleton is the set of skull bones (ossa cranii PNA)
and facial bones (ossa faciei PNA), known colloquially as skull, but
anatomically is the head bone, the skull being a part of the head. It is common
to the whole skull designates the bone head, which is improper in the anatomy
study. However, in other areas (embryology, biology, etc..) Is considered
synonymous with the skull of the head skeleton.
The distinction
between skull and face is very clear: the skull houses the brain
essentially-the-neurocranium, while the face provides attachment for the
muscles of facial expression and mastication and houses some of the sense
organs. The skull plays an important role as it is concerned to contain the
entire central nervous system, except for the core.
bones of the skull
The bones of the
skull are eight, four are odd and half situation, and the other four are two
pairs and symmetrical lateral position.
Front (1)
Parietal (2)
Temporary (2)
Occipital (1)
Sphenoid (1)
Ethmoid (1)
sutural bones
The skull, as a
cavity, can be seen from inside the cavity as endocranium, or from the outside
as exocráneo. In turn, overall, can be divided by a horizontal section passing
through the middle frontal eminence and the external occipital protuberance, in
two parts:
a top, the cranial
vault or skull (calvaria PNA);
a bottom, the base of
the skull (basis cranii PNA).
This division is not
arbitrary. Part of different embryological origin of the bony structures:
endochondral ossification for the bones of the skull base, and intramembranous
ossification for the bones of the skull.
The vault is formed
by the parental (vertical part), the parietal, temporal scales of the occiput
(top). It is covered by the scalp, bones are joined by a few joints called
sutures: coronal suture or frontoparietal, between the frontal and parietal,
interparietal or sagittal suture between the two parietal or parietooccipital
and lambdoid suture between the occipital and parietal.
joints
The joints of the
skull bones are sinartrosis, immobile joints that hold the bone pieces together
by cartilage (synchondrosis) or fibrous connective tissue (sinfibrosis).
Those bones which
form part of the skull base, developed by endochondral ossification are joined
together through synchondrosis. And the bones from the cranial vault (and also
facial bones), developed from sketches of connective tissue, are joined
together by sutures sinfibrosis or (suturae PNA).
Depending on the
configuration of the articular surfaces involved in bone union, there are four
types of sutures (sinfibrosis) in the skull:
serrated sutures
arising from the union "for gear" of the articular surfaces. It is
the joint that connects the frontal, occipital, parietal, sphenoid and ethmoid
(fronto-parietal joints; parieto-parietal, parieto-occipital, fronto-ethmoidal,
fronto-sphenoidal) and joints with craniofacial (fronto-malar; fronto-nasal,
etc.)..
the sutures arising
from the union of rough surfaces and "bevel cut". Temporomandibular
joint is parietal.
acrania
Acrania is a cephalic
disorder of a human fetus characterised by a partial or complete absence of the
cranium. The condition is frequently, though not always, associated with
anencephaly. The anomaly Acrania is a partial or complete absence of the
calvarium with abnormal brain tissue development. This anomaly is lethal in all
cases and has important implications for obstetrical management and counseling.
Acrania can be diagnosed early in pregnancy through an ultrasound. The fetus is
said to suffer from acrania if it meets the following criteria: the fetus
should have a perfectly normal facial bone, a normal cervical column but
without the fetal skull and a volume of brain tissue equivalent to at least one
third of the normal brain size. When no brain or little traces of it are
detected, the anomaly is referred to as Anencephaly
Diagnosis
Ultrasound
can be Involved in diagnosis.This anomaly Appears During The Beginning or end
of the fourth week of the fetus' development, when to the previous neuropore
closes. The desmocranium Normally Becomes the epidermis of the scalp, But
Remains in acrania desmocranium to the membranous coverage. THEREFORE, the
migration of tissue under the calvarium mesenchmal ectoderm does not happen,
leading to an Absence of the calvarial bones of the skull dermal, related
musculature, and dura mater. The brain may still Develop Normally, But without the
walls of the cranium shaping it, it will not differentiate Between the two
Hemispheres and will morph into a single mass That will not be Able to sustain
life. In all cases Acrania is lethal, no human being can live without the skull
and there is
Craniosynostosis
It is a congenital (present at birth) that causes
abnormal premature closure of one or more sutures on a baby's head. Sutures are
connections that separate each individual skull bones. The early closing of a
suture leads to an abnormally shaped head.
Causes, incidence, and risk factors
The cause of craniosynostosis. The abnormal head shape
is determined depending on the sutures involved.
Your genes may play a role in craniosynostosis. The
hereditary form often occurs with other defects that can cause seizures,
diminished intellectual capacity and blindness. Genetic disorders commonly
associated with craniosynostosis include Crouzon, Apert, Carpenter, Chotzen,
and Pfeiffer.
However, most cases of craniosynostosis occur in a
family with no history of illness and children with the disease, except for
this, are healthy and have normal intelligence.
There are different types of craniosynostosis sagittal
synostosis (scaphocephaly) is the most common type that affects the main
(sagittal) either at the top of the head. The early closing forces the head to
grow long and narrow, instead of growing in width. Babies with this type of
craniosynostosis tend to have a broad forehead and a condition is more common
in boys than in girls.
Frontal plagiocephaly is the next most common is the
closure of one side of the suture that runs from ear to ear at the top of the
head, and is more common in girls.
Metopic synostosis is a rare form of craniosynostosis
that affects the suture close to the front. The shape of the child's head can
be described as trigonocephaly, and the deformity may range from mild to
severe.
symptoms
Absence of the normal
feeling of a "soft spot" (fontanelle) on the baby's skull
Disappearance of the
fontanelle early
Raised hard ridge
along the affected sutures
Irregular head shape
Little or no increase
in head size over time as the baby grows
Signs and tests
The doctor will feel
the baby's head and perform a physical exam. A neurological exam would also
help diagnose the condition. You can perform the following tests:
A measurement of the
circumference of the baby's head
Radiographs of the
skull
Head CT
treatment
The main treatment
for craniosynostosis is surgery that is performed while the child is still a
baby, and whose objectives are:
Relieve any pressure
on the brain
Ensure there is
enough space in the skull to allow for proper brain growth
Improve the
appearance of the child's head
spina bifida
Spina bifida is a congenital neural tube, which is
characterized by one or more vertebral arches have not fused properly later in
pregnancy and spinal cord is no bone protection.
The main cause of spina bifida is the deficiency of
folic acid in the mother during the months prior to pregnancy and three months,
although a 5% of cases of unknown cause. Already today it has been found that
spina bifida is not a hereditary component, which would inherit the mother's
difficulty to process folic acid, which occurs very rarely. It was also found
that a person with spina bifida children will not necessarily with the same
disability. There are basically two types of spina bifida, spina bifida occulta
and open spina bifida or cystic.
Spina bifida occulta
Displayed a small defect or gap in one or more
vertebrae. Some have a lipoma, dimple, hairy, dark spot or bump on the affected
area. The spinal cord and nerves are not altered.
Many people with spina bifida occulta not know they
have it, or your symptoms do not appear until later. These symptoms can be of
three types:
Neurological: Weakness in the lower extremities,
atrophy of the leg or foot, low sensitivity or impaired reflexes.
Genito-Urinary incontinence of urine or feces or urine
retention.
Orthopedic foot deformity or differences in size.
Open spina bifida or cystic
This is the most serious, the injury is clearly seen
as a lump as a cyst in the back area affected. Are several types:
Meningocele and lipomeningocele
Forms are less frequent. One or more vertebrae present
a looming opening a cyst filled with cerebrospinal fluid that contains part of
the meninges but not the spinal nerves. Its consequences are less severe, both
locomotives and urinary functions. The most effective treatment for any type of
spina bifida is the movement.
myelomeningocele
Is the more severe and more frequent. The cyst
contains both membranes and nerve roots of the spinal cord and often the cord
itself. Occasionally the spinal cord and nerves are exposed. It is necessary to
surgically close the opening once the baby is born to avoid infection.
Causes and risk factors
Spina bifida usually comes from the union of a genetic
predisposition and environmental factors. Among the environmental causes we can
say:
98% of cases are caused by a deficiency of folate in
the mother in the moments before or immediately after pregnancy occur.
Maternal treatment with drugs: valproic acid
(anticonvulsant), etetrinato (treatment for psoriasis and acne), carbamazepine
(psychiatric treatment) and hormonal medications.
Other risk factors:
foot deformity
The deformity has
always anatomic integrity (present all the bones, muscles and the different
structures of the deformed body). The failure occurred during the fetal period
and affects the evolution and growth of structures already formed and complete
equinus
Foot deformity
characterized in that the entire it is held in
position with plantar flexion
relation to the leg.
Contracture of the triceps muscle (Achilles shortened)
causes the foot
adopt this position.
The individual will perform up with support from the
forefoot (up on tiptoe) .
There is often an
isolated disease entity. usually
be associated with
other deformities of the foot:
- Pie equinovarus
(clubfoot).
- Tip foot valgus
(posterior tibial muscle paralysis).
- Pie equine
neuromuscular disorders. Especially cerebral palsy (ICP). is the
most common deformity
in these patients.
His assessment and
treatment should be performed in pediatric orthopedic service.
valgus
This type of
deformation is defined as the foot whose heel is everted and the distal part is
in eversion and abduction. The arc of dorsiflexion and ankle plantar flexion
is normal.
There is one way in
which the foot is in complete eversion (valgus) with maximum dorsiflexion,
which constitutes the talipes valgus. The soft tissues of dorsal and lateral
foot contraction show (peroneal muscle contracture) and limits the plantar
flexion and inversion. Radiographically, they are feet normal bone structure.
No dislocation or subluxation of the tarsal bones.
foot varus
It is the foot
deformity in which the heel (rearfoot) is reversed and the distal part of the
foot is adducted and investment, with the limits of normal dorsiflexion. The
isolated varus deformity of the hindfoot does not exist. Usually accompanies or
associates of the forefoot adduction deformity with cavus, or horses,
constituting cavo-varus foot or equine-varus (clubfoot), which are often
associated with neuromuscular processes of the type of myelomeningocele,
Charcot-Marie-Tooth or spastic paralysis. Must be treated by specialists in
pediatric orthopedics, requiring in most cases surgical treatment
cavus foot
Is the foot that has
an abnormal increase in the height of the arch in the midfoot flexion
accentuated the metatarsals. It is a complex entity given the etiological
diversity, their different developments and
its many forms of
treatment. The age of onset is between 8 12 years, although sometimes present
at birth with the first finger claw 9
.
Rarely idiopathic,
most of the time (80%) associated with a neurological cause (especially, look
for a lesion of the conus medullaris that is accompanied sometimes a nocturnal
enuresis, or a birthmark in the lumbar region) ; to illness heredodegenerative
type Charcot-Marie-Tooth, or lumbosacral malformation (spina bifida occulta,
spondylolisthesis).
Behaves classically
arched feet:
- An increase in the
convexity of the arch of the foot back to the age progresses slowly from 5 to
11 years.
- A calcaneal varus (valgus rarely).
- Claw fingers
flattening of the talus.
Heels
The heel or heel is the back foot at the bottom of the
leg below the calf.The heel most famous in literature is that of Achilles, for
whom it was his only weakness, dying to be hurt in that place by an arrow shot
by Paris.
