Skull and Meninges Flashcards
In the cranium which bones are paired? (2)
Temporal Parietal
In the cranium which bones are NOT paired? (4)
Frontal Occipital Ethmoid Sphenoid
In the face which bones are paired? (6)
Maxillary Zygomatic Lacrimal Nasal Inferior nasal concha Palatine
In the face which bones are NOT paired? (2)
Mandible Vomer
What are the ossicles of the ear? (3)
Malleus Incus Stapes
What are the bones of the skull? (4)
Cranium Face Ossicles of Ear Hyoid
What variations in the skull do infant skulls show?
The frontal bone in two halves separated by the metopic (interfrontal) suture. This suture is usually replaced with bone by 6-8 years but in minority of individuals may persist into adult life
What is a suture comprised of?
Fibrous connective tissue.
What are sutures replaced with in adult life? What is an example?
Bone. The lambdoid suture is obliterated in most individuals in the range 21-42 years.
What is the main part of the bone referred to as?
Body
What are processes/plates/spines? What purpose do they serve? Provide an example for each.
Bony extensions from the body. 1. For articulations with other cranial bones 2. For attachments of muscles or ligaments Temporal process of zygomatic bone which articulates with the zygomatic process of the temporal bone. Medial and lateral pterygoid plates - for attachment of muscles of pharynx, mastication, soft palate
What is an eminence? What is an example?
A bony bump of elevation overlying some deep structure. Arcuate eminence in the middle cranial fossa over inner ear (within bone)
What are impressions?
Grooves on the surface of bone indicating the presence of some overlying soft tissue structure.
When do soft tissue structures usually form? What is an example?
Before bone is laid down. Grooves for middle meningeal artery and its branches inside squamous part of temporal bone.
What is the function of openings/foramina/fossae/canals?
To allow cranial nerves and veins to leave the skull and arteries to enter the skull. They connect the inside of the skull with the outside.
Nerves and blood vessels develop first and the bone forms later around them. True or False?
True.
What do large foramina provide access for? What is an example?
Major structures. Internal carotid, facial nerve
What do small openings and canals allow the transmission of in the skull? What is an example?
Small branches of cranial nerves. For example, the chorda tympani - nerve involved in taste
What are small openings for small vessels called? Why are they important? What is an example?
Emissary foramina. These can be clinically significant. For example, the communication between the pterygoid venous plexus on the outside of the skull and the cavernous sinus on the inside of the skull.
Particular foramina can vary in number or can be absent. True or False?
True.
What is the meatus? What are 2 examples?
Relatively large tube-like passage way. External acoustic meatus. Groove for cartilaginous part of auditory tube.
The external acoustic meatus is posterior to the mastoid process. True or false.
False, it is anterior. The external acoustic meatus leads from the external surface of the head to the eardrum (tympanic membrane).
What doe the superior and inferior temporal lines cross?
Parietal and temporal bones.
What attaches to the superior and inferior temporal lines?
Temporalis and its overlying fascia.
What does the zygomatic bone form?
The prominence of the cheek and part of the side wall of the orbit.
What does the frontal process of the zygomer articulate with?
Frontal bone in the lateral orbital margin.
Where is the zygomaticofacial foramen usually present?
The lateral side of the base of the frontal process of the zygomer.
Where is the zygomaticotemporal foramen?
Medial side of base of frontal process of zygomer.
What does the temporal process of the zygomer articulate with? What does it form?
Zygomatic process of the temporal bone to form the zygomatic arch.
What does the temporal bone consist of?
- Temporal fossa
- Infratemporal fossa
What is the temporal fossa?
Indentation inferior to the temporal lines.
The infratemporal fossa is inferior to the temporal fossa and medial to the zygomatic arch. True or false?
True.
What does the infratemporal fossa open medially into?
Pterygopalatine fossa beneath the orbit.
What are the two parietal bones separated by?
Saggital suture.
At the posterior end of the parietal bones what strucutre is found? What does it separate?
Lambdoid suture. It separates the parietal bones from the occipital bone.
What is the floor in the anterior cranial fossa?
Orbital plate of the frontal bone (roof of the orbit) and lesser wing of the sphenoid.
What do the two orbital plates of the frontal bone articulate with medially? What does this structure transmit? Where does it transmit it to?
Cribriform plate of the ethmoid. Olfactory nerve filaments from the nose to the cranial cavity.
What does the cribriform plate form?
Part of the roof of the two nasal cavities.
What is the crista galli (ethmoid bone)? What attaches there?
Median bony crest that projects superiorly from the cribriform plate. Falx cerebri
What is the floor of the middle cranial fossa?
Body of sphenoid medially and greater wings of sphenoid laterally.
What is posterolateral in the middle cranial fossa?
Petrous and squamous temproal bones.
What impressions may be recognisable on the medial part of the petrous temporal bone?
Trigeminal
What crosses the thin squamous temporal bone.
Grooves for branches of the middle meningeal artery.
What does the hypophyseal fossa (sella turcica) contain?
Pituitary gland (hypophysis cerebri)
What are the bony projections overhanging the fossa?
Anteior and posteiror clinoid process.
What is the dorsum sellae?
Bony ridge between posterior clinoid processes.
What does the petrous temporal bone at the posterior end of the middle cranial fossa encase?
The organs of hearing and balance.
What is the arcuate eminence?
A bony bump of petrous temporal bone which overlies the superior/anterior semicircular canal of the inner ear.
What is the trigeminal impression?
An indentation on posteromedial part of petrous tempral marking the position of the trigeminal ganglion.
What is the tegmum tympani?
Indented region of bone anterolateral to the arcuate eminence (overlies the middle ear)
What are the openings in the middle cranial fossa and what do they transmit respectively?
- Optic canal (transmits optic nerve CNII) 2. Superior orbital fissure (transmits CNs III, IV, brahnces of CN V/1, VI) 3. Foramina rotundum (maxillary nerve CN V/2) 4. Foramen ovale (mandibular nerve CN V/3) 5. Foramen spinosum (middle meningeal artery) 6. Foramen lacerum (internal carotid enters skull via carotid canal, traverses posterior wall of foramen lacerum to enter middle cranial fossa; also transmits greater petrosal nerve - branch of facial nerve)