How can we help?

You can also find more resources in our Help Center.

89 terms

Skull Osteology

STUDY
PLAY
Two parts of the skull
Neurocranium and Viscerocranium
Neurocranium
forms a protective vault containing the brain
Viscerocranium
forms the skeleton of the face
Foramen
an aperture or perforation through a bone or a membranous structure
Hiatus
an aperture, gap, or fissure
Iter
A passage leading from one anatomical space to another
Paries
A wall, as of the chest, abdomen, or any hollow organ
Sinus
a general term for such spaces as the dilated channels for venous blood inside teh cranial cavity or teh air cavities in cranial bones which communicate with the nasal cavities
Somatic
relating to the soma or trunk or the wall of the body cavity; parietal
Squama
A thin plate of bone
Viscus
An organ of teh digestive, respiratory, urogenital, or endocrine systems as well as the spleen, the heart and the blood vessels; hollow and multilayered walled organs
Squama
flat surface forming the forehead
Frontal eminences
rounded elevations about 3 cm above each supraorbital margin
Supraorbital margins
superior borders of each orbit
Superciliary arches
prominent elevation above each supraorbital margin
Glabella
flat area of bone between superciliary arches
Zygomatic process
articulates with the zygomatic bone
Temporal lines
bilateral ridge arching superiorly and posteriorly from zygomatic process. Origin of m. temporalis. Demarcates the superior limit of the temporal fossa.
Nasion
midpoint of frontonasal suture
Sagittal sulcus
linear midline depression (internal); lodges parts of superior sagittal sinus (a large vein formed from periosteum and dural membranes)
Frontal crest
attachment for the falx cerebri
Orbital plates
forms roof of orbit
Lacrimal fossa
anterior and lateral depression of roof of orbit which accommodates the lacrimal gland
Ethmoidal notch
midline gap between orbital plates (only evident if ethmoid bone is removed)
Frontal air sinuses
cavities between bony plates of superciliary arches and cranial cavity
Foramen caecum
found at midpoint of frontoethmoidal articulation
Supraorbital foramen or notch
in medial 1/3 of supraorbital border and transmits supraorbital nerve, artery, and vein (NVB); occasionally multiple
Parietal eminence
smooth elevation near center of each bone
Temporal lines
continuous with temporal lines of frontal bone
Bregma
point of intersection of coronal (fronto-parietal) and sagittal sutures (site of anterior, or bregmatic, fontanelle in the newborn)
Lambda
point of intersection of lambdoidal (occipito-parietal) and sagittal sutures (site of posterior fontanelle in infants)
Parietal Foramina
Posteriorly, on either side of the sagittal suture; when present, it tranmits veins from the scalp to superior sagittal sinus (emissary veins)
External occipital protuberance
prominence midway between lambda and foramen magnum (=inion)
Superior nuchal line
ridges extending laterally from external occipital protuberance
Median nuchal line
crest descending from external occipital protuberance to foramen magnum;
Inferior nuchal line
ridges extending laterally from midpoint (at median nuchal line)
Internal occipital protruberance
(internal) midway between lambda and foramen magnum
Sagittal sulcus
groove extending superiorly from internal occipital protuberance
Internal occipital crest
ridge extending inferiorly from internal occipital protuberance
Grooves for transverse sinuses
extend laterally from internal occipital protuberance
Depression for confluence of sinuses (Torcular of Herophili)
at intersection of superior sagittal, transverse, occipital, and straight venous sinuses; may be on the right or left side of the midline
Condyles
articulate with atlas (the first cervical, or neck, vertebrae)
Condyloid fossae
posterior to each condyle; accomodate posterior margin of superior facet of atlas when head is bent backward
Pharyngeal tubercle
Anterior to foramen magnum, this is the attachment site for fibrous raphe of pharynx in the midline
Grooves for the inferior petrosal sinuses
(internal) along the anterior lateral margins
Condyloid Canal
Posterior to each condyle in condyloid fossa
Hypoglossal canal (anterior condyloid)
at anterior base of each condyle, this canal transmits hypoglossal nerve (XII) and meningeal branch of ascending pharyngeal artery
Jugular notch
on the anterior-lateral margin of the occipital bone - lateral to each condyle
Jugular notch becomes:
posterior margin of the jugular foramen
Jugular foramen
The jugular notch of the occipital bone, together with the jugular fossa of the temporal bone form a large foramen when these bones are articulated
Jugular foramen transmits:
CN XI (accessory), CN X (vagus) and the CN IX (glossopharyngeal).
Sinuses that drain into the jugular bulb:
INferior petrosal venous sinus passes over its lateral margin; the inferior petrosal venous sinus and the sigmoid sinus merge to form the internal jugular vein
Jugular bulb
a dilation at the top of the internal jugular vein; occupies the jugular fossa of the temporal bone
Foramen magnum
transmits spinal cord and meninges; vertebral arteries; vertebral venous plexus and CV XI
Zygomatic Process
articulates with zygomatic bone to form the zygomatic arch
Articular tubercle
eminence of anterior root of zygomatic process;
Temporal lines
continuous with those of frontal and parietal bones
Mandibular (glenoid) fossa
bounded anteriorly by the articular tubercle;
Petrotympanic fissure
splits the mandibular (glenoid) fossa
Suprameatal triangle
posterior-superior to external auditory meatus; an instrument may be pushed through the bone here into the tympanic antrum or middle ear chamber
External acoustic (auditory) meatus
bony part of external ear; extends about 2.5 cm anterior-lateral to tympanic membrane
Styloid process
bony projection extending antero-inferiorly from inferior surface of tympanic portion of temporal
Mastoid process
large downward projection containing air cells, posterior to tympanic part of temporal bone
Mastoid (digastric) notch / Digastric Groove
deep groove on medial aspect of mastoid prcoess
Occipital groove
just medial to mastoid notch; impression made by a occipital artery
Arcuate eminence
on antero-lateral surface; indicates position of superior semi-circular canal
Trigeminal impression
anterior surface near apex (above internal aperture of carotid canal). Lodges semilunar gasserian ganglion of CN V, trigeminal
Jugular fossa
the inferior surface of this fossa forms the anterior part of the jugular foramen; lodges bulb of the internal jugular vein in this deep fossa
Aquaeductus cochleae
fossa in the triangular depression posterior to external orifice of carotid canal; inferior to internal auditory meatus; contains a dural communication between perilymphatic and subarachnoid spaces (fluid-filled)
Aquaeductus vestibulae
posterior lateral to internal auditory meatus; transmits ductus endolympathicus (fluid filled) of the inner ear
Carotid canal
inferior petrous part, transmits internal carotid artery and carotid plexus
External auditory meatus
facial canal-bony canal transmitting portions of the facial N through the petrous pyramid to the stylomastoid foramen
Foramen lacerum
deficiency in floor of middle cranial fossa, anterior medial to internal orifice of teh carotid canal. In life, inferior part is filled with fibrocartilage over which courses the internal carotid artery and trhough which passes the nerve of the pterygoid canal (Vidian N) and a meningeal branch of the ascending pharyngeal artery
Hiatus of the facial nerve
anterior surface of petrous portion; transmits greater petrosal nerve (branch of CN VII)
internal acoustic meatus
located on the posterior surface of the petrous portion; transmits the facial nerve (CN VII) and the vestibulocochlear nerve (CN VIII) and the internal auditory branch of the basilar artery
Nasion
frontal and nasal bones meet here
Frontal crest
a projection of the dural membrane between the left and right cerebral hemispheres
Ethmoid notch
accommodates cribiform plate of ethmoid bone
Superior nuchal line
Origin of mm occiptalis, trapezius, sternocleidomastoid and splenius capitis
Median nuchal line
Origin of attachment of ligamentum nuchae
Inferior nuchal line
Insertion of mm. rectus capitis posterior major and minor
Condyloid canal
This canal transmits emissary vein
Internal jugular vein
forms from the merger of the inferior petrosal sinus and the sigmoid sinus
Articular tubercle
forms anterior boundary of mandibular fossa and attachment of temporomandibular ligament
Mandibular fossa
fossa is bound posteriorly by the tympanic part of the temporal bone
Mandibular fossa
anterior part receives the mandibular condyle; and the posterior is non-articular and lodges a small portion of the parotid gland
Styloid process
Origin for mm. Stylohyoid, styloglossus, and stylopharyngeus; and attachment for stlyohyold and sytlomandibular ligaments;
Mastoid process
attachment for m. stenocleidomastoid, splenius capitis, and longissimus capitis
Mastoid (diagastric) notch
attachment for m. digastric (posterior belly)