Head - book notes
Terms
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- what forms the forehead skeleton?
- squamous part of the frontal bone
- squamous
- flat
- squamous frontal bone articulates winferiorly with:
- nasal and zygomatic bones (inferiorly); also articulates w/ lacrimal, ethmoid/sphenoid.
- metopic suture
- remnant of frontal suture in adults
- where is the metopic suture
- in the glabella
- glabella
- smooth and sl. depressed area between superciliary arches
- superciliary arch
- ridge just superior to supraorbital margin, extending laterally from glabella
- what is the frontal suture?
- the dividing line between the frontal bones in fetal cranium
- intersection of frontal and nasal bones:
- nasion, aka bridge of the nose
- supraorbital margin:
- angular boundary between squamous and orbital parts of the frontal bone
- what passes through the supraorbital foramen?
- Supraorbital nerve and vessels
- What holes reside in the orbits?
-
-Superior/inferior orbital fissures
-Optic canals - These bones form the prominence of the cheeks:
- Zygomatic bones
- Small hole in the lateral zygomatic bone:
- Zygomaticofacial foramen
- Zygomatic bones articulate with:
-
-frontal
-sphenoid
-temporal
-maxillae - Anterior nasal opening in cranium:
- piriform aperture
- what divides the nasal cavity into right/left parts?
- nasal septum; connects the vomer and perpendicular plate of ethmoid.
- what form the upper jaw?
- maxillae
- what are alveoli in regard to maxillae?
- the tooth sockets
- what supports the alveoli?
- alveolar processes - on the maxillae; also suppor the teeth in the maxillae.
- what forms the infraorbital margins?
- maxillae
- what hole is found inferior to each orbit?
- infraorbital foramen
- what passes through the infraorbital foramen?
- infraorbital nerves/vessels
- what is the articulation btwn maxillae called?
- intermaxillary suture
- What makes up the lower jaw?
- mandible
-
In the mandible what denotes:
-the horizontal part
-the vertical part -
horizontal = body
vertical = ramus - what are the holes inferior to second premolars called?
- mental foramen
- what runs through the mental foramen?
- mental nerves/vessels
- what is the chin prominence called?
- mental protuberance
- what is the mandibular symphysis?
- the osseous union where the halves of the infantil mandible fuse.
- what are fractures of the maxillae called?
- Le Fort fractures
- What is a Le Fort I fracture?
- Horizontal fracture of maxillae, passing above the alveolar processes.
- What is a Le Fort II?
- a break passing from postero-lateral side of the maxillary sinuses, up to the bridge of the nose.
- What is the result of a LeFort II?
- the entire central part of the face seperates from the cranium.
- What is a Le Fort III fracture?
-
horizontal fracture thru superior orbital fissures, ethmoid, and nasal bones;
Laterally extends thru sphenoid greater wings and frontozygomatic sutures - what is the result of a lefort III?
- the MAxillae and Zygomatic bones separate from the cranium.
- How do mandible fractures usually present?
- As a double fracture - one on either side of the jaw.
- How does a hard blow to the jaw usually affect it?
- Fractures the mandibular neck, and the mandibular body in the opposite canine tooth region.
- What type of fracture is associated with the coronoid process?
- a single fracture - fairly uncommon.
- What causes alveolar bone resorption? What results?
- Extraction of teeth; causes alveolar process resorption, so mental foramen move superiorly.
- What can happen if the mental foramen move up on the mandible?
- Disappearance; the mental nerves can be exposed and injured.
- What is mandibular prognathism and what causes it?
- Overclosure of the jaw - due to the loss of all the teeth, which decreases the face vertically.
- What forms the boundaries of the temporal fossa?
-
Superior/posterior = superior adn inferior temporal lines
Anterior = frontal bone + zygomatic bone
Inferior = Zygomatic arch - What part of the brain does the superior border of the temporal fossa correspond to?
- The inferior limit of the cerebral hemisphere.
- What makes up the zygomatic arch?
-
Posterior: Temporal process of zygomatic bone
Anterior: Zygomatic process of temporal bone - Where is the pterion located?
- Anterior temporal fossa, 3-4 cm above zygomatic arch midpoint.
- What is the pterion?
- H-shaped union of the frontal, parietal, sphenoid (greater wing) and temporal bones.
- what is a meatus?
- A canal
- What is the entrance to the eardrum consist of?
-
-External acoustic opening
-External acoustic meatus
-Tympanic membrane - What type of fracture usually results from a hard blow to thinner areas of calvaria?
- Depressed - a bone fragment presses inward, may injure brain
- What is the most frequent type of depressed calvarial fracture?
- Linear - it occurs at the point of impact, but fracture lines radiate outward from it.
- What is a comminuted fracture?
- One in which bone is broken into several pieces.
- What is a contrecoup fractuer?
- One in which no fracture occurs at impact site, but on opposite side of the cranium.
- What fracture of the skull can be life-threatening especially?
- Fracture of the pterion.
- Why is a pterion fracture so threatening?
- Because it overlies the anterior branches of middle meningeal vessels.
- Where exactly are the middle meningeal arteries located?
- In grooves inside the lateral calvaria wall.
- What results from a hard blow to the pterion?
- Fracture of thin bones, rupture of mid. mening. aa anterior branch, and hematoma.
- What is the occipital aspect of the cranium composed of?
-
-Occiput (protuberance)
-Parts of parietal bones
-Mastoid parts of temporals. - What is the inion?
- a craniometric point defined by the tip of the external protuberance.
- What is the external occipital crest?
- Line descending from the inion to foramen magnum
- What is the line extending laterally from the inion called?
- Superior nuchal line
- What is the lambda?
- The junctio between the sagittal and lambdoid sutures.
- What are accessory bones called, and where are they usually found?
- Sutural bones - found near labmda or mastoid process.
- What are parietal eminences?
- Places on the parietal bones where they become broader and more oval.
- What suture separates the frontal and parietal bones?
- Coronal suture.
- What suture separates the parietal bones?
- Sagittal
- What suture seperates the parietal and temporal bones from occipital?
- Lambdoid
- What forms the bregma?
- Intersection of the sagittal and coronal sutures.
- What is the vertex?
- Most superior point of calvaria; near midpoint of sagittal suture.
- What are emisary foramina?
- Irregular, highly variable foramina that transmit emissary veins.
- What are emissary veins?
- Veins connecting scalp veins to venous sinuses of the dura mater.
- What emissary foramen may be found in the parietal bones?
- ironic, but its the parietal foramen.
- What makes up the external inferior surface of the cranium?
- alveolar arch of the maxilla - not the mandible.
- What forms the hard palate?
-
-Palatine processes of maxillae
-Horizontal plates of palatines - What is the free on the back of the hard palate called?
- Nasal spine - projects posteriorly to meet the vomer.
- What are choanae?
- The posterior nasal apertures that are just superior to the back of the hard palate.
- What seperates the 2 choanae?
- A quadrilateral bone, the VOMER.
- Vomer means
- plowshare
- What is the sphenoid wedged between?
- Frontal, temporal, and occipital bones.
- In general what does the sphenoid consist of?
-
-A body
-3 pairs of processes: Greater wings, lesser wings, pterygoid processes. - Where are the greater and lesser wings of the sphenoid?
- Spreadding laterally; the lesser wings are anterior to the greater.
- What makes up the pterygoid process?
-
Medial/Lateral Pterygoid wings
- hang down inferiorly from the body and the other wings. - What lies in a groove just posterior/medial to sphenoid spine?
- The cartilaginous part of the pharyngotympanic tube. It's under the articulation of the sphenoid greater wing and petrous part of temporal bone.
- What are mandibular fossae?
- Depressions in squamous temporal bones created by mandibular condyles when mouth is closed.
- What forms the posterior portion of the cranial base?
- Occipital bone + sphenoid
- What passes through foramen magnum?
-
1. Spinal cord
2. Meninges
3. Vertebral arteries
4. Ant/post spinal arteries
5. Accessory nerve CN XI - Where does the cranium and vertebral column articulate?
- At the occipital condyles.
- What structures pass through the jugular foramen in the cranium?
-
-Internal Jugular vein
-CN IX - CN XI - What passes through the stylomastoid foramen?
- the facial nerve and stylomastoid artery.
- Where is the stylomastoid foramen?
- Just posterior to the styloid process on the temporal bone.
- What are the fossae on the internal surface of the cranial base?
-
1. Anterior cranial fossa
2. Middle cranial fossa
3. Posterior cranial fossa - What bones form the anterior fossa?
-
1. Frontal bone
2. Ethmoid bone
4. Body/lesser wings of sphenoid. - What is the frontal crest?
- Median bony extension of the frontal bone
- What is at the base of the frontal crest?
- Foramen cecum
- What is foramen cecum's purpose?
- Gives passage to vessles in fetal development; insignificant postnatally.
- what structure is just posterior to foramen cecum?
- Crista galli
- what lies on either side of crista galli?
- the cribiform plate of the ethmoid bone.
- what passes through the cribiform plate?
- Olfactory nerves for CN I, on their way to the Olfactory Bulbs that lie on top of the plate.
- What makes up the central part of the middle cranial fossa?
- Sella turcica
- what separates the middle cranial fossa from the anterior?
-
Sphenoidal crests (laterally)
Sphenoidal limbus (centrally) - What makes the sphenoidal crests?
- Sharp posterior borders of the lesser wings.
- What structure do the sphenoidal crests end in posteromedially?
- Anterior Clinoid processes - the bedposts at the head of the bed.
- What is just posterior to the sphenoid limbus?
- Prechiasmatic sulcus
- What does the prechiasmatic sulcus extend between?
- the optic canals
- What bones make up the lateral borders of the middle fossa?
-
-Sphenoid greater wings
-Squamous temporal bones - What makes up the posterior border of the middle fossa?
-
-Petrous part of the temporals
-Dorsum sellae (back edge of sella tursica) - What is sella turcica?
- The saddle of the sphenoid
- What surrounds sella turcica at each corner?
- Clinoid processes - the bedposts.
- What makes up the seat of sella turcica?
- The hypophysicla fossa - the bed of the pituitary gland.
- What 3 things compose sella turcica?
-
1. Tuberculum sellae (the horn)
2. Hypophysial fossa (seat)
3. Dorsum sellae (back edge) - What 4 foramina perforate the sphenoid greater wings on either side of sella turcica?
-
1. Superior orbital fissure
2. Foramen rotundum
3. Foramen ovale
4. Foramen spinosum - Where exactly is superior orbital fissure located? What passes through it?
-
Between the greater/lesser wings
-Opthalmic veins
-Opthalmic nerves (3, 4, V1, 6)
-Sympathetic opthalmic nerves -
Where is foramen rotundum?
What passes through it? -
Just behind the medial part of superior orbital fissure.
-Transmits V2 -
Where is foramen ovale?
What passes through it? -
Just behind/lateral to foramen rotundum.
-Transmits V3, and a small acessory meningeal artery. -
Where is foramen spinosum found?
What passes through it? -
Just behind/lateral to foramen ovale.
-Transmits Middle Meningeal arteries and meningeal branch of mandibular nerve (?). - What is foramen lacerum?
- An artifact resulting from dead, dried up cranium; in life it's filled with cartilage.
- What passes above the cartilage that fills foramen lacerum?
-
Internal carotide artery
-Accompanying sympathetic/venous plexus - All on the way to the anterior boundary foraman. - What groove extends postero-laterally from foramen lacerum?
- The groove for the greater petrosal nerve.
- What brain structures lie within the posterior cranial fossa?
-
-Cerebellum
-Pons
-Medulla oblongata - What marks the incline of dorsum sellae medially?
- The clivus - leads to foramen magnum.
- What are the 2 large bilateral concave impressions of the posterior cranial cavity?
- Cerebellar fossae
- What landmark leads posteriorly from foramen magnum, dividing the cerebellar fossae?
- Internal occipital crest - ending in the internal occipital protuberance.
- What hole is found at the base of the petrous ridge?
- Jugular foramen
- What is transmitted through the jugular foramen?
-
-Sigmoid sinus - as the IJV
-Several cranial nerves - What hole is just in front of and above the jugular foramen?
- Internal acoustic meatus
- What does the internal acoustic meatus transmit?
-
-Facial nerve
-Vestibulocochlear nerve
-Labyrinthine artery - What goes through the hypoglossal canal?
- The hypoglossal nerve :)
- What is the structure of the calvaria bones like?
-
3 layered:
-Internal table of compact bone
-External table of compact bone
-Diploe in between - What is diploe?
- Cancellous bone that contains red bone marrow in life.
- By what type of ossification does the calvaria and part of cranial base form?
- Intramembranous
- By what type of ossification does the rest of cranial base form?
- Endochondral
- What sutures are present in infants that arent in adults?
-
-Frontal (mid frontal bone)
-Internasal
-Intermaxillary
-Mandibular symphysis - What processes in the cranial bones are lacking in infants at birth?
-
Mastoid processes
Styloid processes - What is the physiological result of lacking mastoid processes?
- The facial nerves emerge close to the surface of the skin when they go through stylomastoid foramina.
- What can be a pathological result of lacking the processes?
- Forceps can damage teh facial nerve, or ear surgery.
- What causes these processes to develop?
- Development of sternocleidomastoid muscles and their insertion on the mastoid processes of temporal bones.
- What 4 fontanelles are present in infants at birth?
-
-Anterior
-Sphenoidal
-Mastoid
-Posterior - What 3 things can be determined by palpating fontanelles?
-
1. Progress of growth of parietal/frontal bones
2. Degree of hydration
3. Level of intracranial pressure - What is the largest fontanelle and where is it located?
- Anterior - located at future bregma - junction of coronal and sagittal sutures.
- When does the anterior fontanelle no longer palpable?
- 18 months
- When do the frontal suture fuse completely?
- by the 8th year; except in 8% of people, who retain a metopic suture.
- Where is the posterior fontanelle located?
- At the future lambdoid
- What is the advantage of these loose connections and soft cranial bones in infants?
- Molding - changes in calvaria shape during birth