crane foetale

• Module 5 covers Anatomy Specialties in Medicine, Obstetrics, Odontology, and Kinesitherapy.
• The focus is on the fetal skull and its adaptation to the adult skull.

Comparative Anatomy: Skull of a Fish

• The viscerocranium derives from cartilaginous arches and allows for nutrition.
• It forms the mandible in humans.
• The chondrocranium is cartilaginous, surrounds the brain, and becomes the base of the skull in humans.
• The desmocranium consists of cartilaginous plates and delimits the rest of the head.
• It forms the vault and facial bones in humans.

Skull, Face, and Mandible

• The cranium is a box containing the encephalon (brain) and provides protection.
• The base is the inferior part of the cranium formed by cartilaginous ossification.
• Foramina present within the skull allow entry and exit for vasculo-nervous elements.
• The vault is the superior and peripheral part of the cranium, formed by direct ossification.
• Facial bones are appendages to the cranium and made via direct ossification.
• The mandible participates in the masticatory system, originating from the first branchial arch.
• It gives rise to the malleus and incus bones.

Fetal Skull

• Relative to the adult skull, the fetal skull is more elongated.
• It conforms to a rectangular shape.
• The exoccipital and occipital squama fuse in adulthood.
• The tympanic bone borders the external meatus
• The temporal squama emits the zygomatic process.
• It features an anterior and lateral elongation but is less wide that the adults.
• Not present in the fetal skull, the mastoid process forms during development.
• The parietal bone is the most voluminous section of the fetal skull.
• The frontal bone is anterior to the parietal bone.
• The sphenoid bone has a temporal plan on its greater wing.

Structures of the Fetus Face

• The zygomatic bone includes a temporal process.
• Newborns present practically horizontal orbits.
• The mandible is underdeveloped and undergoes remodeling during development.

Fetal Skull Sutures

• Fibrous membranes connect the periosteum of adjacent bones and widen to form fontanelles.
• They are located on the four corners of the parietal bones.
• The coronal suture is located between the frontal and parietal bones.
• The parietosquamous suture lies between the parietal bone and the temporal squamae.
• The lambdoid suture is positioned between the occipital bone and the parietal bone.
• The metopic suture lies between the two frontal bones and disappears during adulthood.
• The sagittal suture is located between the two parietal bones and continues the metopic suture.

Clinical Applications of the Fetal Skull

• Microcephaly involves a defect in cerebral development resulting in a smaller head.
• Intracranial hypertension causes the fontanelles to bulge outward.
• Palpitation indicates they are very hard and tense.
• It may indicate hydrocephalus resulting from dilation of the cerebral ventricles or macrocephaly.
• A macrocranium may provoke intracranial hypertension.
• Transfontanellar Echography (ETF) allows visualization of brain anatomy in newborns through fontanelles.
• Disjunction of a suture is an abnormal separation between two cranial bones at a suture site.

Fetal Skull Fontanelles

• Fontanelles allow the cranial bones to overlap during childbirth.
• The allow for cerebral growth.
• Monitoring cranial perimeter aids in tracking cerebral growth.
• Fontanelles signal intracranial pressure, best assessed in a calm, seated infant.
• They facilitate draining subdural hematomas or ventricles, utilizing a catheter.
• Lambdoid fontanelles are triangular, situated between parietal and occipital bones, at the posterior end of the sagittal suture.
• Pterional fontanelles are sphenoidal, located between the parietal, frontal, sphenoid, and temporal bones at the inferior end of the coronal suture.
• Asterisk fontanelles are situated between the occipital, parietal, and temporal bones, at the end of the lambdoid suture.
• The bregma fontanelle is the largest, located between the frontal and parietal bones on the cranial vault along the midline.
• It takes a diamond shape at the intersection of the metopic, sagittal, and coronal sutures.

Timing of Fontanelle Closure

• The lambdoid fontanelle closes first, around two months.
• The Pterional fontanelle closes second, between 3 and 6 months.
• The asterisk fontanelle closes third, before 12 months.
• The bregma frontalle closes last, between 6 and 18 months.
• It remains open longer if a hydrocephaly exists.

Craniostenosis

• Premature suture closure causes other sutures to overgrow, resulting in skull deformation.
• Possible intellectual impairment can result as a consequence.
• Treatment involves cutting the closed suture followed by creating a new suture.
• Acrobrachycephaly is premature closure of the coronal sutures, compensated by the sagittal and metopic sutures.
• The cranium is round and short, with a raised vertex.
• Scaphocephaly is a premature fusion of the sagittal and/or metopic suture.
• It creates a non-homogeneous development of the cranial sutures
• The skull is elongated and narrow.

Adult Skull - Bones Forming the Vault and Base

• The occipital bone forms the posterior part of the vault and presents an external occipital process.
• The temporal squama has a zygomatic process articulating with the zygomatic bone's temporal process.
• Together, the zygomatic and temporal bones form the zygomatic arch, which provides passage for the temporal muscle.
• It is connected to strong muscles and these connections cause the bones to develop.
• The frontal bone's vertical squama contributes to the cranial vault, while the horizontal section contributes to the cranial base.
• The frontal bone forms the anterior part of the cranium.
• the zygomatic and maxillary process articulate to the frontal bone.

Adult Skull - Bones Forming the Vault Only

• The parietal bone articulates with the temporal, occipital, and frontal bones, as well as the contralateral parietal bone.

Adult Skull - Foramen Passages

• Three pairs of foramina for passage of the trigeminal nerve branches include the supraorbital (V1), infraorbital (V2), and mental (V3).

Adult Skull Face Structures

• The zygomatic bone, or cheek bone, forms a tripod shape.
• The is made of frontal, temporal, and maxillary processes.
• The maxilla bears upper teeth and articulates with the frontal bone superiorly via its frontal process, and the nasal bone medially.
• It articulates with the zygomatic bone laterally, utilizing a large zygomatic process.
• They present bony plates covered of mucosa.
• The orbital cavities houses the eyeballs
• The mandible bears lower teeth.
• It contains angular branches, and features and condyle.

Adult Skull - Internal & External Views

• External aspects include an external occipital protuberance.
• On the internal side of the vault is a sinus of the dura mater.
• The sinus drains venous blood.

Meningeal Artery - Middle

• The middle meningeal artery is a branch of the maxillary artery and a branch of the external carotid.
• It runs within a small groove along the skull, located in the extra-dural space between the dura mater and the cranium, and is covered by the dura mater.
• These arteries supply the internal face of the skull
• Rupture of this vessel presents with a Hextra-dural hematoma that may compress the brain causing a critical situation.

Skull Base

• The base is similar to a staircase with 3 steps.
• They include anterior, middle and posterior steps.
• The middle step is recessed bellow the anterior step.
• Each level has foramen for the passage of nervous or vascular structures.
• Cranial nerves connect to the brain.

Skull Base - Anterior Stage

• The most high stage is the most anterior part of the base
• Accommodates the frontal lobe.
• The anterior area is the orbital roof, formed by the sphenoid and ethmoid bones.
• The posterior areas contains small wings and crinoid processes.
• Located medially, canal optic provides a way of nervous II and ophthalmic artery
• Pathological alterations could affect vision.

Skull Base - Middle Stage

• This are is occupied by the temporal lobe.
• The posterior side is borded by the os peteosus "rock".
• The medial side presents the corps sphenoid process and a gutter for the hypophysis.
• The middle contains the os petreus parts and the horizontal or temporal scales.
• 3 foramen structures are visibles in the vista superior part, and two in the coronal part

Middle Crate Stage

• Through the Foramen lacerum is passed the internal carotide and is is an accute structure.
• Through the spunous foramen makes it possible the artery that connects the middles lining
• It is created in the great ale where structures are found on the middles and great ales of this stage.
• It makes the mandibular nervous connects to the trigeminal 3 structure.
• The nervous is in the sensitivity of part of the mandible.
• All of this connects to the skull.

Fissure orbitaire

• The fissure provides a way of the oclumotor or nervous 3.
• Tochea and Abduncens that provide structures to vision.
• The fissure and the nervous also provides sensitive information to the front.
• The structure is delimited by some of the wing processes.
• It is on the side and allows connectively.

Skull Bone Composition

• The ethmoidal, sphenoid structure provides many nervouse structures.
• The top is horizontal to facilitate the process.

Skull Base - Posterior Stage

• The posterior stage is lower than all of the parts that forms the skull.
• It conteins the cerebelem, spinal bone marrow
• The vertical is formed by the pertrous structure.
• The region limits the occipital and other structures
• The skull contains a channel that contains a synus
• The magnum and the processes connects the spine.
• There are other nervous channels and the Jugulars structures.
• Seperarted by a layer that contaisns a sinus.