TBL25 - Cranium (Skull) Flashcards
What does the neurocranium form? What forms the sides of the neurocranium?
1) The neurocranium forms a bony case that surrounds the brain
2) The flat frontal, parietal, sphenoid, temporal, and occipital bones form the sides of the case
What forms the calvaria (skull cap)? What separates the frontal and parietal bones and what separates the left and right parietal bones? What does the bregma mark?
1) Superior parts of the frontal, parietal, and occipital bones form the calvaria (skull cap)
2) The coronal suture separates the frontal and parietal bones and the sagittal suture separates the left and right parietal bones
3) The bregma marks the junction of the sagittal and coronal sutures
What is the superior most point of the calvaria? What do the lambdoid sutures separate and join? Observe the external occipital protuberance in the midline of the occipital bone.
1) The vertex, the midpoint of the sagittal suture, is the superior most point of the calvaria
2) The lambdoid sutures that separate the parietal and occipital bones join the sagittal suture at the lambda
At birth, what are the sutures made up of? What are fontanelles? Recognize the large anterior fontanelle.
1) At birth, the sutures are narrow seams of connective tissue
2) At points where more than two bones meet, the wider sutures are designated fontanelles
What are the functions of sutures and fontanelles and what is the value of postnatal palpation of the anterior fontanelle?
1) Sutures and fontanelles allow the bones of the skull to overlap (molding) during birth
2) In the first few years after birth, palpation of the anterior fontanelle may give valuable information as to whether ossification of the skull is proceeding normally and whether intracranial pressure is normal
How is brain development affected by cranial malformations resulting from premature closure of the sutures? (Is this right? What should I include instead?)
Premature closure of sutures usually does not affect brain development
Incising along the horizontal dotted line exposes the what? What is the floor formed by? What bones constitute the cranial base?
1) Incising along the horizontal dotted line exposes the floor of the neurocranium
2) The floor is formed by the cranial base
3) The frontal, sphenoid, temporal and occipital bones constitute the base
What derivatives form the bones of the neurocranium?
Osteoprogenitor cells derived from neural crest cells and mesenchymal cells of the paraxial mesoderm form the bones of the neurocranium (ignore the respective bony derivatives)
What forms the skeleton of the face? What occupies most of the facial skeleton? Locate the infraorbital foramen in the maxilla. What forms the skeleton of the lower jaw?
1) The viscerocranium forms the skeleton of the face
2) The bony orbits and maxilla occupy most of the facial skeleton
3) The mandible forms the skeleton of the lower jaw
Identify the nasal bone, recall the frontal bone, and locate the supraorbital margin and foramen. Find the zygomatic bone. To complete the viscerocranium notice the zygomatic arch, which is formed by the temporal and zygomatic bones.
Look at structures
What are the facial bones mainly derived from? What do neural crest-derived mesenchyme in the 1st pair of pharyngeal arches form?
1) The facial bones are mainly neural crest derivatives
2) Neural crest-derived mesenchyme in the 1st pair of pharyngeal arches forms the mandibular, maxillary, and frontonasal prominences
What are the nasal placodes and what prominences do they create? What are central invaginations of the nasal placodes?
1) The nasal placodes are bilateral ectodermal thickenings on the frontonasal prominence that create the lateral and medial nasal prominences
2) Nasal pits (future nostrils) are central invaginations of the nasal placodes
What does medial growth of the maxillary prominences result in? What does this midline fusion create?
1) Medial growth of the maxillary prominences results in midline fusion of the medial nasal prominences
2) This midline fusion creates the intermaxillary segment that forms the triangular primary palate and portions of the maxilla and upper lip
What does midline fusion of the mandibular prominences form?
Midline fusion of the mandibular prominences forms the mandible and lower lip
Why do infants have large calvaria and rudimentary development of the face? (why the rudimentary development?)
1) The large size of the calvaria in infants results from
precocious growth and development of the brain and eyes
2) The rudimentary development of the face makes the orbits appear relatively large. The smallness of the face results from the rudimentary development of the maxillae, mandible, and paranasal sinuses (air-filled bone cavities), the absence of erupted teeth, and the small size of the nasal cavities
