The Skull Flashcards
What is a suture
fibrous connective tissue and collagen (forms a narrow band)
Describe articulations between bones
o Generally non moveable sutures (exception of moveable joints between ossicles and temperomandibular joints)
o Fibrous joins that can ossify with age
Name the bones of the cranium, face and ossciles of ear
Cranium: Frontal (1) Temporal (paired) Parietal (paired) Occipital (1) Ethmoid (1) Sphenoid (1)
Face: Maxilary (paired) Zygomatic (paired) Lacrimal (paired) Nasal (paired) Inferior nasal concha (paired) Palatine (paired) Mandible (1) Vomer (1)
Ossicles:
Malleus (paired)
Incus (paired)
Stapes (paired)
Explain the variation in infants in terms of bones of the skull
Frontal bone is in half- separated by the metopic (interfrontal) suture
What is a process/plate/spine and its function
Extension from the body of a bone
- Articulation with other bones
- Attachment of muscles/ligaments
What is an eminence?
Bony bump or elevation overlying some deep soft structure
What is an impression?
Grooves on the surface of the bone indicating the presence of some overlying soft tissue structure
T/F?
- Nerves and blood vessels develop first and the bone forms later around them
true
What is a meatus?
Relatively large tube like passage way
What are the three openings on the anterior skull that generally form a straight line?
Supraorbital foramen
Infraorbital foramen
Mental foramen
List the components of the temporal bone
Squamous part Petrous part Mastoid process Mastoid notch Styloid process Tympanic part
What attaches at the tympanic part of the temporal bone?
(forms the bony wall of the external acoustic meatus)
Attachment of cartilaginous external acoustic meatus, part of the parotid capsule, tympanic membrane/eardrum
Zygomatic process of the temporal bone
What is the purpose of the superior and inferior temporal lines?
Attachment of temporalis fascia and muscle
What forms the prominence of the cheek and part of the side wall of the orbit?
Zygomatic bone
Where is the zygomaticofacial foramen located?
At the base of the lateral orbital margin
Where is the zygomaticotemporal foramen located?
Medial side of base of the frontal process of zygomer
T/F
The Pterygopalatine fossa is NOT part of the temporal bone
true
What provides the thin part of the temporal bone with some protection?
temporalis muscle and fascia
What is the temporal fossa?
Indentation where the temporal muscle attaches
Describe the pterygopalatine fossa
→ extends medially and passes under the orbit, caries a variety of blood vessels, carries the pterygopalatine ganglion (parasympathetic of facial nerve)
What does the saggital suture separate?
The two parietal bones
What does the lambdoid suture separate?
Parietal and occipital bones
What does the coronal suture separate?
frontal and parietal bones
Are the fossae single or paired structures?
Single
Which fossa is the sphenoid bone a part of?
lesser wing= anterior
Greater wing= middle
Describe the ethmoid bone
in anterior cranial fossa
Central= crista galli (attachment of falx cerebri)
on either side are the cribriform plates
Which part of the ethmoid bone do the orbital parts of the frontal bone articulate with?
articulate medially with the two cribiform plates
What bone makes up the floor of the middle cranial fossa?
medially= body of sphenoid laterally= greater wing of sphenoid
Where is the trigeminal impression located?
medial part of the petrous temporal
What is the dorsum sellae?
bony ridge between posterior clinoid processes
What does the petrous temporal encase?
organs of hearing and balance
What is the arcuate eminence?
bony bump on petrous temporal bone which overlies the superior/anterior semicircular canal of the inner ear
What is tegmen tympani?
indented region of bone anterolateral to arcuate eminence (overlies middle ear)
List and describe the openings in the middle cranial fossa
Optic canal= optic nerve CN II, brings optic nerve from the retina back towards the brain
Superior orbital fissure= passes into the orbit, contains cranial nerves III, IV and branches of CN V/1, CN VI
Foramina rotundum= maxillary nerve CN V/2
Foramen ovale= mandibular nerve CN V/3, opens onto underside of the skull
Foramen spinosum= middle meningeal artery
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)
- Large and irregular
- Connects with the canal carrying the internal carotid
What bones make up the posterior cranial fossa?
Floor= occipital bone, surrounds the foramen magnum Clivus= between the hypophyseal fossa and foramen magnum
List and describe the openings in the posterior cranial fossa?
Internal acoustic meatus (temporal)- transmits facial (CN VII) and vestibulocochlear nerve (CN VIII)
Jugular foramen (lateral to foramen magnum)- transmits CN IX (glossopharyngeal), CN X (vagus), cranial nerve XI (accessory) and internal jugular
Foramen magnum
Hypoglossal canal (wall of foramen magnum)- transmits hypoglossal nerve (CN XII)
What are the 3 sutures of the hard palate?
Intermaxillary
Interpalatine
Palatomaxillary
List the openings in the hard palate
Incisive fossa/canal
Greater/less palatine foramina
What forms the pterygoid plates?
Sphenoid bone
What is the hamulus and scaphoid fossa?
Hamulus= bony hook on anteroinferior medial plate
Scaphoid fossa= posterior end of the medial pterygoid plate
What muscles attach to the medial and lateral pterygoid plates?
Medial= muscles to move soft palate Lateral= muscles to move jaw
What makes up the nasal septum?
vomer (posteroinferiorly) and ethomoid (anterosuperiorly)
What bone makes up the chonchae?
Superior and middle= ethmoid bone
Inferior is a separate bone
What are the occipital condyles?
Lateral to foramen magnum
Articulate with atlas
Where are the nuchal lines found?
Occipital bone
Inferior and superior
Squamous occipital bone
Attachment of neck muscles
What is the purpose of the pharyngeal tubercle?
Attachment of the pharyngeal constrictor muscle
List and describe the openings on the inferior surface of the skull
Petrotympanic fissure
- Posterior to articular fossa
- Exit of chorda tympani= branch of facial nerve (taste)
Stylomastoid foramen
- Between mastoid and styloid process
- Exit of facial nerve
Palatopharyngeal canal (palatovaginal)
- Posterolateral to nasal septum
- Takes nerves to upper pharynx
Pterygoid canal
- Between schapoid fossa and foramen lacerum
- Posterior to medial pterygoid plate
Carotid canal
- Entry of internal carotid
Opening of bony auditory tube
- Medial to spine of sphenoid
- Groove running into this indicates position of cartilaginous part of auditory tube
Foramina ovale, spinosum, lacerum, jugular foramen
(NOT foramina rotundum= opens into pterygopalatine fossa)
List and describe the notches/processes on the inferior surface
Masotid
- Temporal bone
Mastoid notch/diagastric notch/ diagastric groove
- Temporal bone
- Medial to mastoid
- Attachment of posterior belly of diagastric
Styloid process
- Temporal bone
- Anteromedial to mastoid
- Often damaged
Spine of sphenoid
- Sphenomandibular ligament, part of stabilizing structures of TMJ attaches here
- Irregular bony bump between formane spinosum and carotid canal
What is the articular fossa?
articulation with mandible (temporomandibular joint)
Describe the orbit
Posterior wall= superior orbital fissure, inferior orbital fissure, optic canal
Floor=Infraorbital canal and foramen= transmits infraorbital nerve (terminal branch of maxillary nerve)
Medial wall= Anterior and posterior ethmoid canals (branches of ophthalmic division of trigeminal)
Lacrimal canal (drainage of tears)
Lateral wall=Zygomaticoorbital foramen= for zygomaticoorbital branch of maxillary nerve
What are emissary foramina?
Small openings in the bone of the skull
veins connecting the dural venous sinuses with venous structures outside the skull
blood can flow in either direction but usually towards the outside of the skull
What are the paranasal sinuses?
Maxillary
Frontal
Sphenoid
Ethmoid
Drain into nasal cavities
Mastoid air cells do NOT drain into nasal cavities and are therefore NOT paranasal sinuses
Which artery passes across the body of the mandible?
Facial artery
What is the angle of the mandible?
junction between body and ramus
What is the mandibular notch?
Separates coronoid process and condyle (head and neck) of ramus
What attaches to the digastric fossa
anterior belly of digastric muscle
Where is the mental foramen
External surface of mandible below 2nd pre-molars
What travels through the mandibular foramen?
Inferior alveolar branch of mandibular nerve (supplies teeth)
What travels through the mylohyoid groove?
Path of the mylohyoid nerve (branch of the inferior alveolar nerve which does not enter bone)
Runs anteromedially from mandibular foramen
Describe the mylohyoid line
across body from below 3rd molar to mental symphysis
attachment of mylohyoid muscle (floor of mouth)
What are the two layers of the dura
Periosteal= no epidural space here (only in vertebral column)
Meningeal layer
- Fused mostly except where there are cavities for vessels of when they form extensions/folds
Describe dural sinuses
- Endothelial lined spaces between the layers of dura
- Drain blood from brain and cranial bone
- No valves
- Ultimately drain into the internal jugular
Describe the dural folds
- Falx cerebri= folds into longitudinal fissure between hemispheres
- Tentorium cereblli= between cerebellum and occipital lobes of cerebral hemispheres
- Falx cerebelli= folds into posterior cerebellar notch to partly separate cerebellar hemispheres. Attached to inferior surface of tentorium cerebelli
- Sella diaphragm= covers sella turica and contained pituitary. Has an opening to accommodate infundibulum which is attached to the hypothalamus. Sella diaphragm is continuous with dura of the floor of the middle cranial fossa.
Where does the arachnoid penetrate sulci?
Only in the longitudinal fissure
What does the arachnoid space contain?
CSF
