Skull Flashcards
diploë
The skull bones are made up of external and internal tables of compact bone separated by a layer of spongy bone called the diploë
cranial bones
Frontal bone: 1 ■■ Parietal bones: 2 ■■ Occipital bone: 1 ■■ Temporal bones: 2 ■■ Sphenoid bone: 1 ■■ Ethmoid bone: 1
facial bones
Zygomatic bones: 2 ■■ Maxillae: 2 ■■ Nasal bones: 2 ■■ Lacrimal bones: 2 ■■ Vomer:1 ■■ Palatine bones: 2 ■■ Inferior conchae: 2 ■■ Mandible: 1
orbital margins
bounded by the frontal bone superiorly
the zygomatic bone laterally
the maxilla inferiorly
processes of the maxilla and frontal bone medially.
nasal septum is formed by
vomer & ethmoid
parts of the temporal bone
squamous, tympanic, mastoid process, styloid pro- cess, and zygomatic process
pterion
the thinnest part of the lateral wall of the skull where the anteroinferior corner of the parietal bone articulates with the greater wing of the sphenoid
it overlies the anterior division of the middle meningeal artery and vein.
pterygopalatine fossa
is a small space behind and below the orbital cavity. It communicates laterally with the infratemporal fossa through the pterygomaxillary fissure, medially with the nasal cavity through the sphenopalatine foramen, superiorly with the skull through the foramen rotundum, and anteriorly with the orbit through the inferior orbital fissure
ligamentum nuchae attaches to?
external occipital protuberance
pterygoid hamulus
The inferior end of the medial pterygoid plate is prolonged as a curved spike of bone
anterior clinoid process
the lesser wing of the sphenoid forms the anterior clinoid process on each side, which gives attachment to the tentorium cerebelli.
crista galli
is a sharp upward projection of the ethmoid bone in the midline for the attachment of the falx cerebri
posterior boundary of anterior cranial fossa
lesser wing of sphenoid
floor of anterior cranial fossa
laterally orbital plates of frontal bome
medially by cribriform plate of ethmoid
nerve of the pterygoid canal
The greater petrosal nerve enters the foramen lacerum deep to the trigeminal ganglion and joins the deep petrosal nerve to form the nerve of the pterygoid canal
arcuate eminence
The arcuate eminence is a rounded eminence found on the anterior surface of the petrous bone and is caused by the underlying superior semicircular canal
tegmen tympani
a thin plate of bone, is a forward extension of the petrous part of the temporal bone and adjoins the squamous part of the bone From behind forward, it forms the roof of the mastoid antrum, the tympanic cavity, and the auditory tube. This thin plate of bone is the only major barrier that separates infection in the tympanic cavity from the temporal lobe of the cerebral hemisphere
parts of sella turcica
dorsum sellae
tuberculum sellae
hypophysial fossa
parts of occipital bone
lateral parts
squamous part
basillar part
Perforations in cribriform plate of
Ethmoid bone transmits
Olfactory nerves
Optic canal (Lesser wing of sphenoid) transmits?
Optic nerve, ophthalmic artery
Superior orbital fissure (Between lesser and greater wings of sphenoid) transmits
Lacrimal, frontal, trochlear, oculomotor, nasociliary, and abducent nerves; superior ophthalmic vein
foramen rotundum (gw) transmits
Maxillary division of the trigeminal nerve
foramen ovale (gw) transmits
Mandibular division of the trigeminal nerve, lesser petrosal nerve
foramen spinosum (gw) transmits
middle meningeal artery
foramen lacerum (Between petrous part of temporal and sphenoid) transmits:
internal carotid artery
foramen magnum transmits:
Medulla oblongata, spinal part of accessory nerve, and right and left vertebral arteries
Hypoglossal canal transmits:
hypoglossal nerve
jugular foramen (Between petrous part of temporal and condylar part of occipital) transmits:
Glossopharyngeal, vagus, and accessory nerves; sigmoid sinus becomes internal jugular vein
internal acoustic meatus (petrous part of temporal bone)
Vestibulocochlear and facial nerves
which structures reinforce the base of the skull?
The petrous parts of the temporal bones and the occipital crests strongly reinforce the base of the skull and tend to deflect linear fractures.
In fractures of the anterior cranial fossa, which structure is most likely damaged?
cribriform plate of ethmoid bone
which leads to bleeding from the nose (epistaxis), leakage of cerebrospinal fluid into the nose (cerebrospinal rhinorrhea).
In fractures of the posterior cranial fossa
blood may escape into the nape of the neck deep to the postvertebral muscles. Some days later, it tracks between the muscles and appears in the pos- terior triangle, close to the mastoid process. The mucous mem- brane of the roof of the nasopharynx may be torn, and blood may escape there.
most common facial fractures
Fractures of the nasal bones, because of the prominence of the nose
bones of vault form via
membranous ossification
bones of the cranial base form via
endochondral ossification
neonatal skull
no diploe
mobile bones
bones are separated by unossified membranous intervals called fontanelles
mastoid process is not present at birth and develops later in response to the pull of the sternocleid- omastoid muscle when the child moves his or her head
angle of the mandible at birth is obtuse
structure susceptible to damage by forceps in a difficult delivery
facial nerve
