Anatomy II: Lecture 15 Osteology of the Skull Flashcards
What underlies the brainstem?
Bones of the base of the skull
What type of bones are the bones of the base of the skull?
Endochondral
Which means they are preceded by carilage
What type of bones are the bones forming the sides and roof of the skull?
Dermal bones
(Which means they are not preceded by cartilage)
(They are the bone that makes up the face)
What forms the branchial arches?
Cartilage-replacement elements
Neoteny of the skull
Failure to replace cartilage with bone in the adult
(Animals that do this: sharks, skates, and rays)
(something that resembles fetal characteristics: Here, it is the loss in the ability to replace cartilage with bone)
The skull is a combination of
cartilage, dermal bone, and/or endochondral bone
Openings in the skull are called _____
They allow passage to ____
Foramina
Nerves and blood vessels
Cartilaginous capsules develop to enclose ____
Special sensory organs such as olfactory apparatus, eyes, and semicircular canals
The skull is made of two components. What are they?
Chondrocranium and Dermatocranium
Chondocranium is made of
Neurocranium: Cartliage and/or endochondral bone
Splanchnocranium (viscerocranium): Cartilage and/or endochondral bone
Dermatocranium is made of
Dermal bone
What is made up of the mass of cartilage that condenses beneath the embryonic brain and the bones that replace the cartilage?
The braincase, or neurocranium
What contains the three pairs of cartilaginous capsules?
Braincase
What are the two pairs of cartilaginous plates of the neurocranium?
Parachordals (Flanks the cranial end of the notochord)
Prechordals (Hypophyseals) (Cranial to notochord and parachordals)
What is the posterior wall of the neurocranium?
Foramen Magnum
T/F the roof of the neurocranium is usually closed?
False: They are usually open
What represents the primitive vertebrate braincase?
Bones of basicranium (within the Neurocranium)
Where do all nerves and vessels passing to and from the brain pass through?
Through the foramina of the bones of the basicranium
What are the five bones of the basicranium?
Ethmoid
Sphenoid
Left and Right Temporals
Occipital bone
What is the only basicranial bone that is entirely preformed in cartilage?
Ethmoid Bone***
Others are mostly preformed, but they have dermal bone components too
What are the components of the ethmoid?
Cribriform plate Crista Galli Perpendicular plate Labyrinth Ethmoid air cells
What is the attachment for falx cerebri?
Crista galli
What contains superior and middle nasal conchae?
Labrinth of the ethmoid bone
What are the components fo the sphenoid?
- Pterygoid plates
- Body
- Greater and lesser wings
What are the components of the pterygoid plates of the sphenoid?
Medial and lateral plates hang down
Dermal components attached to endochondral portion of sphenoid base
Lateral
Medial
What are the components of the body of the sphenoid?
Hypophyseal fossa
Four clinoid processes
T/F the Greater wings are the lower flaps
False: They contain lower and upper flaps
The greater wings’ lower flaps of the sphenoid bone contribute to the cranial fossa that contains the
temporal lobes of the brain
What is the passageway for V2?
Foramen rotundum of the greater wings’ lower flaps of the sphenoid bone
(V2 = Second part to cranial nerve five)
What is the passageway for V2
Foramen ovale of the greater wings’ lower flaps of the sphenoid bone
(V3 = the third part to cranial nerve five)
What is the passageway for the middle meningeal vessels?
Foramen Spinosum of the greater wings’ lower flaps of the sphenoid bone
What are the two foraminae of the upper flaps of the greater wings in the sphenoid bone?
Optic canal
Anterior clinoid process
What are the three foraminae of the lower flaps of teh greater wings in the sphenoid bone?
Foramen rotundum
Foramen ovale
Foramen spinosum
What surrounds the ear apparatus?
Petrous part of the temporal bones
Where is the first pharyngeal pouch growing and what does it form?
Petrous part of the temporal bones
Expands to form the middle ear chamber
Where are the cavities that connect the pharynx to the eustachian tube?
Petrous part of the temporal bones
What forms the carotid canal for the internal carotid canal?
Petrous part of the temporal bones
What is a mass of air-filled outpocketings (air cells) from petrous part?
mastoid process of the temporal bones
The styloid process of the temporal bones:
- Are derived from second-gill arches
- Fuses with petrous portion in front of mastoid
- Attachment site for muscles and ligaments
The squamous part of the temporal bones are
Thin sheets of dermal bone, forming lateral wall of braincase ABOVE auditory meatus
What is part of the temporal bone that forms a ring of dermal bone around the eardrum?
Tympanic part
It expands after birth to become the external auditory meatus leading to ear drum from the outside
What is a large dermal bone that forms the lower back of the head?
Squamous part of the occipital bone
What forms from four separate bones that fuse around the spinal cord to form the foramen magnum?
Basilar part of the occipital bone
T/F the frontal bone is paired in fetus and fused in adults
True
Where can the supraorbital foramina be found?
In the frontal bone of the membrane bones of the skull
What do the maxillary bones of the membrane bones of the skull contain?
The alveolar process and the infraorbital foramina
What creates the superior and inferior temporal lines?
The parietal bones of the membrane bones of the ksull
What the membrane bones of the skull?
Frontal bone maxillary bones Zygomatic bones Nasal Bones Parietal Bones
What are the bones of the anterior skull?
Sphenoid: Greater wing Sphenoid: Lesser wing Ethmoid Lacrimal Vomer
What are the occipitals of the base of the skull?
Occipital condyles Foramen magnum Supreme, superior, inferior nuchal lines External occipital protuberance Pharyngeal protuberance
What does the body of the mandible contain?
mental protuberance and mental foramen
The posterior cranial fosse contains the
cerebellum, pons, and medulla
