9. The Cranium Flashcards
Function of skull
Provides support and protection for brain and spinal cord
What does it mean to say the skull is isotropic?
When a force is applied to the cranium, it radiates around the structure rather than focusing on one point
Layers of bones in skull and their composition
Inner table - compact bone
Diploe - similar to cancellous bone
Outer table - compact bone
What are wormian bones?
Extra irregular bones that occur within a suture in the cranium
What do extocranial and endocranial mean?
Extocranial - external skull
Endocranial - inner surface of skull
Cranial bones
Frontal Parietal (2) Occipital Temporal (2) Ethmoid Sphenoid
Facial bones
Maxillae (2) Palatines (2) Nasals (2) Lacrimals (2) Zygomatics (2) Vomer Inferior nasal conchae Mandible
Ear ossicles
Malleus
Incus
Stapes
Types of adult teeth
8 incisors
4 canines
8 premolars
12 molars
Where is the metopic suture?
Between frontal bones
Usually completely disappears
Retained metopic suture = non metric trait
Lambda
Meeting point of sagittal and lambdoid sutures
Bregma
Meeting point of coronal and sagittal sutures
Pterion
The region where frontal, parietal, temporal, sphenoid bones join together
Anterior cranial fossa
Consists of frontal, ethmoid and sphenoid bones
Middle cranial fossa
Consists of sphenoid and temporal bones
Contains pituitary and 4 foramen
Posterior cranial fossa
Consists of occipital and temporal bones
Articulations of frontal bone
Parietal Zygomatic Lacrimal Nasal Maxillae Sphenoid Ethmoid
Frontal bosses
Primary ossification centres
More prominent in females
Glabella
Brow ridge
Supraorbital margin
Superior half of orbital rim
Supraorbital formen/notch
Small groove at the superior/medial margin of orbit
Supraorbital nerve passes through
Frontal crest
Anchors falx cerebri
Falx cerebri
Large cresecent shaped fold of dura mater
Descends vertically in fissure between cerebral hemispheres of brain
Sagital sulcus
Groove left by sagital venous drainage structure in frontal bone
Arachnoid granulations
Projections from the arachnoid which create small holes in the inner surface of frontal bone
Articulations of parietal bone
Other parietal Sphenoid Occipital Temporal Frontal
Sagittal sinus
Runs alongside endocranial sagittal suture
Where are arachnoid granulations in the parietal bone?
Near the sagittal suture
Parietal striae
Distinct thin furrows along the squamosal border
Meningeal grooves
Created by meninges
In the parietal bone
Begin at front of bone and branch backwards getting thinner
How do you side the parietal bone?
90 degree angle at bregma
Middle meningeal vessel anteriorly is close to coronal suture
Articulations of temporal bone
Parietal Sphenoid Occipital Zygomatic Mandible
Petrous/mastoid portion of temporal bone
Houses internal auditory meatus
What does the internal auditory meatus allow?
The passage of CNVII and CNVIII
What does the mastoid process have?
Mastoid foramina
Mastoid notch
What passes through the mastoid foramina?
Occipital veins and arteries
What muscle attaches to the mastoid notch?
Digastric
What attaches to the supramastoid/supramental crests?
Posterior temporalis muscle
What is the glenoid fossa?
Found anterior to the external auditory meatus
Involved in temporomandibular joint
Styloid process of the temporal bone
Attachment site for muscles and ligaments including stylohyoid
Has styloid foramen
What passes through the styloid foramen?
CNVII
Stylomastoid artery
What passes through the jugular foramen/fossa?
What two bones is the jugular foramen between?
CNIX
CNX
CNXI
Temporal and occipital
Articulations of occipital bone?
Parietals
Temporals
Sphenoid
Par lateralis of the occipital
Unfused lateral parts of occipital bone in young children
Forms occipital condyles that articulate with C1
Basilar process of the occipital
Undergoes synchondrosis to form a joint with sphenoid
What passes through the foramen magnum?
Spinal chord
What attaches to the superior nuchal line of the occipital?
Trapezius
What attaches to the middle nuchal line of the occipital?
Semispinalis capitis
What attaches to the inferior nuchal line of the occipital?
Rectus capitis posterior
Cruciform eminence
Cross shaped ridges that split the occipital bone into 4 sections
Found endocranially
Composed of four fossae
What does the superior fossae of the cruciform eminence house?
Cerebrum
What is the transverse sulcus of the occipital?
Groove for the transverse sinus which is continued from the parietal
Jugular notch of the occipital
Forms posterior border of jugular foramen
anterior portion formed by petrous portion of temporal bone
What passes through the hypoglossal canal?
CNXII
Articulations of sphenoid bone
Frontal Parietal Ethmoid Zygomatics Temporals Occipital Palatine Vomer
Greater wing of sphenoid
Articulates with frontal, parietal and temporal bones
Lesser wing of sphenoid
Sits internally
Medial and lateral ptyregoid plates of sphenoid
Sit inferio-posteriorly in the ptyregoid fossa
Open posteriorly
Articulate with palatine and maxilla
Function of ptyregoid muscles
Opening and closing of mouth
Where does the pituitary gland sit?
Sella turcica
Clinoid fossa of the sphenoid
Surrounds sella turcica on four corners
Sometimes forms a foramen
What passes through superior orbital fissure?
CNIII
CNIV
CNVI
Where is the superior orbital fissure?
Inferior to the lesser wing
Posterior surface of the orbit
What passes through the foramen spinosum?
Middle meningeal artery
What passes through the foramen rotundum?
CNV2
What passes through foramen ovale
CNV3
What passes through formen lacerum?
Carotid artery
Articulations of zygomatic bone
Frontal
Temporal
Maxilla
Sphenoid
What passes through the zygomaticotermporal foramen?
CNVII
Articulations of maxilla
Zygomatic Nasal Frontal Lacrimal Palatine Sphenoid Ethmoid
What is the frontal process of the maxilla part of?
Nasal aperture
What is in the alveolar process of the maxilla?
Tooth sockets
What does the palatine process form?
Anterior 2/3rds of palate and nasal cavity
What does the anterior nasal spine form?
Most inferior and anterior part of nasal aperture
What is the canine eminence formed by?
Large single root of the canine
What passes through the incisive foramen?
Blood vessels which supply the palate
What passes through the infraorbital foramen?
Infraorbital artery
Infraorbital vein
What separates the maxilla and the palatine bones?
Transverse palatine suture
What passes through the greater and lesser palatine foramen?
Arteries and nerves
What do the nasal bones articulate with?
Frontal
Maxilla
Articulations of the lacrimal bones?
Maxilla
Ethmoid
Frontal
(contribute to orbit)
What is inferior to the lacrimal bones?
Tear duct
How many bones does the ethmoid articulate with?
13: 2 x nasal 2 x maxillae 2 x lacrimal 2 x palatine 2 x inferior conchae frontal vomer sphenoid
What is large surface area of ethmoid used for?
Smell
What is in the cribiform plate?
Olfactory foramina
What passes through the olfactory foramina?
CNI
What does the inferior nasal conchae articulate with?
Ethmoid
Maxilla
Lacrimal
Palatine
Location of vomer?
Deep in nasal aperture
Function of vomer?
Covered in sensitive tissue that aids smell
Articulations of vomer?
Ethmoid
Sphenoid
Maxilla
Palatine
Where are the ear ossicles found?
Middle ear
Function of ear ossicles?
Conduct sound to middle ear
Articulations of mandible
Temporal
Indirectly - hyoid
What attaches to the coronoid process of the mandible?
Temporalis
What attaches to the gonial angle of the mandible?
Masseter
usually has a bump = gonial flaring
What attaches to the mental spines of the mandible?
Genioglossus
What passes through the mylohyoid groove of the mandible?
Mylohyoid vessels
CNV
What is the mylohyoid line of the mandible?
Continuation of mylohyoid groove
Attachement site of mylohyoid
Where and what are the sublingual and submandibular fossae?
Above (sublingual) and below (submandibular) mylohyoid line
Space for the salivary glands
What exits the mental foramen of the mandible?
CNV3