Skeletal Flashcards
Cribriform plate
Location:
• Ethmoid bone
Description:
• Bony plate with foramina (holes) that transmit olfactory nerves (CN I)
Comment:
• Contributes to anterior midline portion of anterior cranial fossa
Crista galli
Description:
• Triangular process that projects superiorly from cribriform plate of ethmoid bone
Comment:
• Contributes to anterior midline portion of anterior cranial fossa
• Anterior point of attachment for falx cerebri
Ethmoid bone
Location:
• Nasal cavity
Description:
• Irregular-shaped bone
• Characteristic features include cribriform plate, crista galli, and perpendicular plate
Comment:
• Contributes to anterior cranial fossa, nasal cavity, and orbit
• Contains numerous sinuses (air cells)
Ethmoidal cells
Location:
• Ethmoid bone
Description:
• Paired, thin-walled, mucous membrane-lined cavities
• Clustered into anterior, middle, and posterior cells
• One of paranasal air sinuses
Also known as:
• Ethmoidal air cells
Comment:
• Posterior ethmoidal cells open into superior nasal meatus
• Anterior and middle ethmoidal cells open into middle nasal meatus
Middle nasal concha
Description:
• Shelf-like projection of bone
• Covered by thick mucosa
• Part of ethmoid bone
Function:
• Increases surface area of nasal cavity
• Warms, filters, humidifies inhaled air
Orbital plate of ethmoid bone
Description:
• Thin-walled, smooth lateral surface of ethmoid
• Forms large part of medial wall of orbit
• Covers middle and posterior ethmoidal air cells
Comment:
• Medial wall of orbit formed by ethmoid (orbit plate), frontal (orbital surface), and lacrimal bones, and lesser wing of sphenoid
Perpendicular plate of ethmoid
Location:
• Ethmoid bone
Description:
• Thin, vertical projection of ethmoid in nasal cavity
Comment:
• Forms superior part of nasal septum
• Articulates with vomer and nasal septal cartilage
Superior orbital fissure
Description:
• Oblique fissure
• Bordered by body, greater wing, and lesser wing of sphenoid, and frontal bone (orbital surface)
Function:
• Connects orbit with middle cranial fossa
• Transmits oculomotor (CN III), trochlear (CN IV), and abducens (CN VI) nerves, branches of
Sella turcica
Location:
• Sphenoid bone
Description:
• Prominent depression on sphenoid body in middle cranial fossa
• Formed by tuberculum sellae (anteriorly), hypophysial fossa (central), and dorsum sellae and posterior clinoid processes (posteriorly)
• Contains pituitary gland in hypophysial fossa
Comment:
• Latin: sella = saddle, turcica = Turkish
Optic canal
Location:
• Orbit (posterior)
• Middle cranial fossa
Description:
• Short canal
Function:
• Connects orbit with middle cranial fossa
• Transmits optic nerve (CN II) and ophthalmic artery
Foramen rotundum
Location:
• Middle cranial fossa
• Sphenoid bone (greater wing)
• Just inferior to medial end of superior orbital fissure
Description:
• Horizontal canal
• Connects middle cranial fossa with pterygopalatine fossa
Comment:
• Transmits maxillary (CN V2) nerve
Foramen spinosum
• Sphenoid bone (greater wing)
Description:
• Round hole
• Superior opening in middle cranial fossa
• Inferior opening in infratemporal fossa
Comment:
• Middle meningeal artery passes through this opening
Foramen ovale
Location:
• Sphenoid bone (greater wing)
Description:
• Oval-shaped hole
• Superior opening in middle cranial fossa
• Inferior opening in infratemporal fossa
Comment:
• Mandibular division of trigeminal nerve (CN V3) passes through this opening
Foramen magnum
Location:
• Occipital bone
Description:
• Large opening in inferior part of posterior cranial fossa
Comment:
• Traversed by spinal root of accessory nerve (CN XI), and vertebral and spinal arteries
• Brainstem and spinal cord continuous through this opening
Maxillary sinus
Location:
• Maxilla (upper jaw)
• Lateral to nasal cavity and inferior to orbit
Description:
• Paired, mucous membrane-lined cavity
• Largest paranasal air sinus
Comment: • Drains into middle nasal meatus • Common site of sinus infection • Contributes to voice resonance • Paranasal sinuses include: frontal, maxillary, and sphenoidal sinuses, and ethmoidal cells (sinus)
