Development & Organization of the Skull Flashcards
What is the calvarium?
The components of the neurocranium that provide a protective cover around the brain and special sense organs, formed via intramembranous ossification
How are the bones of the calvarium formed?
Intramembranous ossification
What are the bones of the calvarium?
Parietal, frontal, squamous portion of occipital, squamous portion of temporal
What is the basicranium?
Bones of the neurocranium that form the supportive floor/cranial base. Acts as an interface between upper neurocranium and facial skeleton. Bones formed endochondrally from cartilaginous precursors.
How are the bones of the basicranium formed?
Endochondrally from cartilaginous precursors
What are the bones of the basicranium?
Ethmoid, sphenoid (primary components), temporal (petrous and mastoid parts), occipital (condyles and basilar portion)
What is the viscerocranium?
Facial skeleton derived from the branchial arches flanking the foregut
What are the bones of the viscerocranium?
Maxilla, zygomatic, nasal, lacrimal, palatine, vomer, mandible
What is the cranial cavity?
A bony cavity that contains brain and associated soft tissues
What is an orbital cavity?
A bony cavity that contains eyeballs and associated soft tissues
What is a temporal bone cavity/canals?
A bony cavity that contains soft tissues associated with hearing and balance
What is a nasal cavity?
A bony cavity that contains structures associated with olfaction, respiration, and thermoregulation
What is an oral cavity?
A bony cavity that contains soft tissue associated with taste, suckling, chewing, swallowing, speech, and respiration
What are fibrous joints?
Connective tissue sutures that connect bones of the skull, which allows for growth to occur and the brain to expand
What are gomphosis joints?
Fibrous peridontal ligaments that anchor tooth roots into the alveolar process of the bony maxilla or mandible
What are synchondroses?
Cartilaginous growth plates (ex. basioccipital synchondrosis) that fuse at some point (some fuse before birth, others in early adulthood)
What is a symphysis?
An area of connective tissue that connects two halves of the mandible that fully ossifies and fuses at around 2 yrs of age
Where does endochondral ossification typically occur?
Occurs in hyaline cartilage prototype models of future bones (ex. postcranial bones, skull base)
Where does intramembranous ossification usually occur?
Occurs in dense sheets of membranous connective tissue that transforms into bone (ex. large portions of skull, most of clavicle)
Which bones of the calvarium form intramembranously?
Frontal, parietals, squamous occipital, squamous temporal
How are viscerocranium bones predominantly formed?
Intramembranous ossification
What is the ossification pathway:
Frontal bone
Intramembranous ossification
What is the ossification pathway:
Parietal bone
Intramembranous ossification
What is the ossification pathway:
Temporal bone
Endochondral with intramembranous parts
What is the ossification pathway:
Occipital bone
Endochondral with intramembranous parts
What is the ossification pathway:
Sphenoid bone
Endochondral with intramembranous parts
What is the ossification pathway:
Ethmoid bone
Endochondral ossification
Which facial bones form endochondrally?
Inferior concha, hyoid
Which bones of the skull are derived from the head ectomesenchyme?
Frontal bones, anterior portion of chondrocranium (ethmoid, anterior part of sphenoid), and viscerocranial bones
How is the head ectomesenchyme derived?
From cells of the neural crest
What is craniosynostosis?
Premature closure/fusion of cranial structures that lead to skull bone deformities
What are fontanelles?
Gaps between skull bones that have yet to ossify
What are the three primary patterns of bone growth in the skull?
1) cellular proliferation at cartilaginous growth plates
2) sutural growth (osteoblastic activity within sutures)
3) remomdeling through resorption/deposition
