the skull - sphenoid and ethmoid

Question 1

how many bones in the neurocranium

Answer 1

8 bones + 6 ear ossicles

Question 2

how many ear ossicles are there

Answer 2

6

Question 3

name bones of the neurocranium

Answer 3

frontal parietal occipital temporal ear ossicles sphenoid ethmoid

Question 4

sphenoid bone

Answer 4

unpaired, complicated anatomy (butterfly shape)
occupies the middle of the skull
joins neurocranial and facial components of bones
peeks out in almost every aspect of the cranium
has a clear right and left side

Question 5

how many ossification centers does the sphenoid bone have

Answer 5

14, but is a single bone at birth

Question 6

what kind of ossification does the sphenoid bone undergo

Answer 6

endochondral (body, lesser wings) and intramembranous (pteryoid process), both in greater wings

Question 7

three main parts of the sphenoid

Answer 7

body, greater and lesser wings, pterygoid plates

Question 8

sphenoid body

Answer 8

air filled sinus inside and houses pituitary gland
located on midline
articulates with occipital @ basilar suture
forms nasal cavity wall anteriorly and articulates with ethmoid and vomer

Question 9

sphenoid greater and lesser wings

Answer 9

lateral projections from body

Question 10

pterygoid plates

Answer 10

inferior projections for attachment of muscles of mastication

Question 11

sphenoidal sinuses

Answer 11

in sphenoid body
hollow cavities
communicate anteriorly with the nasal canal

Question 12

greater wings

Answer 12

lateral projections
form most of middle cranial fossa
between maxilla and zygomatic

Question 13

lesser wings

Answer 13

smaller and medial to greater wings

Question 14

optic canals

Answer 14

carries optic nerve (visual signal from retina to brain) and ophthalmic artery (blood supply to eyes and nose)

Question 15

sella turcica/turkish saddle

Answer 15

saddle shaped depression, located posterior and inferior to optic canals
sits on top of sphenoid body on midline

Question 16

hypophyseal (pituitary) fossa

Answer 16

deepest depression of sella turcica
houses pituitary gland, important for growth

Question 17

anterior clinoid processes

Answer 17

posterior projections of the lesser wings
attachment site of tentorium cerebelli, segment of dura mater (meninges)

Question 18

superior orbital fissure

Answer 18

crescent shaped gap between greater and lesser wings
transmits cranial nerves
forms crescent of foramina

Question 19

crescent foramina

Answer 19

superior orbital fissure, foramen rotundum, foramen ovale, foramen spinosa (anterior to posterior)

Question 20

foramen rotundum

Answer 20

perfect circle foramen under superior orbital fissure
inferior to superior orbital fissure at junction of greater wings and body
maxillary nerve

Question 21

foramen ovale

Answer 21

posterior to foramen rotundum
oval shaped
mandibular nerve
seen best from basilar view (base of skull)

Question 22

foramen spinosum

Answer 22

located posterolateral to foramen ovale on greater wings
middle meningeal vessels and branches from mandibular nerve

Question 23

orbital surfaces

Answer 23

anterior portion of greater wings
contribute to lateral walls of eye orbits

Question 24

pterygoid processes

Answer 24

inferior projections from body of sphenoid
divided into two thin plates (medial and lateral)

Question 25

medial pterygoid plate

Answer 25

articulates with palatine bone has pterygoid hamulus

Question 26

pterygoid hamulus

Answer 26

hook like process at inferior tip articulates with tensor veli palatini

Question 27

lateral pterygoid plate

Answer 27

parallel and lateral to medial pterygoid plate thin vertical inferior projection

Question 28

medial surface of lateral pterygoid plate

Answer 28

attachment site for medial pterygoid muscle elevates mandible (closes mouth)

Question 29

lateral surface of lateral pterygoid plate

Answer 29

attachment site for lateral pterygoid muscle depresses mandible (opens mouth)

Question 30

ethmoid bone

Answer 30

unpaired bone of the upper nose, between the orbits along midline light and spongy (delicate) approximately the size of an ice cube undergoes endochondral ossification

Question 31

where is the ethmoid bone visible

Answer 31

medial side of eye orbits through ethmoid notch of the frontal bone (anterior cranial fossa)

Question 32

cribriform plate

Answer 32

located along the midline covers superior aspect of ethmoid (between eye orbits) perforated by many tiny foramina olfactory nerve

Question 33

crista galli/rooster crest

Answer 33

perpendicular projection of the cribriform plate between olfacturly bulbs in anterior cranial fossa continuation of frontal crest attachment

Question 34

ethmoidal labyrinth (sinus)

Answer 34

lies on either side of the midline contains numerous thin walled air cells lateral walls (lamina orbitalis) form part of medial orbital walls

Question 35

perpendicular plate

Answer 35

flat bony lamina (plate) located along midline inferior to crista galli and between the labyrinths forms part of nasal septum