Week 2 Ch 3: Skeletal System

paranasal sinuses

paired; air-filled cavities in bones; lined with mucous membrane; sound resonators; lighten skull bones; communicates with nasal cavity through ostia in lateral nasal walls

frontal, sphenoidal, ethmoidal, maxillary sinuses

what are the paranasal sinuses?

primary sinusitis

can include allergies or an infection; mucous membranes can become inflamed and congested with mucus

performation

an abnormal hole in the wall of the sinus due to inflammatory process and an infection can occur

frontal sinuses

paired; located in frontal bone superior to nasal cavity; asymmetrical (2-3cm in diameter); divided by septum; communicates and drains into the nasal cavity by a constricted cana frontonasal duct to the middle nasal meatus

sphenoidal sinuses

paired; in the body of sphenoid bone; cannot be palpated; asymmetrical; communicate with and drain into the nasal cavity through an opening superior to each superior nasal conchae

ethmoidal sinuses

variable number of small cavities; located in lateral mass of each ethmoid bones; cannot be palpated; posterior sinuses open into superior meatus of nasal cavity; anterior and middle sinuses open into the middle meatus

maxillary sinuses

largest, paired, pyramid-shaped; located body of maxilla; posterior to max canines and premolars; discomfort with primary sinusitis can mimic discomfort of perio infection

temporal fossa

paired, flat, fan shaped depression; formed by 5 different bones - zygomatic, frontal, sphenoid, temporal, parietal; body of the temporalis muscle; divided by infratemporal crest

infratemporal fossa

paired depression; inferior to anterior of temporal fossa; viewed inferiorly; remove mandible; structures pass from this fossa to orbit via inferior orbital fissure and others pass from cranial cavity

pterygopalatine fossa

cone shaped, paired depression; deep into infratemporal fossa and posterior to maxilla; communicates via fissures and foramina’s; smaller but still important fossa is located btwn pterygoid process and max tuberosity, close to apex of orbit

orbit

protects eyeball; 4 walls, 1 apex

orbital apex

deepest part of orbit, made up of the lesser wing of the sphenoid bone and the palatine bone

optic canal

opening in orbital apex; between the lesser wings; C2 (optic nerve) and ophthalmic artery passes to reach the eye

superior orbital fissure

curved slit; between greater and lesser wings; connects the orbit with cranial cavity; C3, C4, C6 and ophthalmic nerve and vein all travel through this fissure

inferior orbital fissure

between greater wing and maxilla; connects orbit with intratemporal fossa and pterygopalatine fossa; infraorbital, zygomatic nerves and infraorbital artery enter orbit through this fissure

orbital rim

base of pyramid; rectangular; discontinuous at the lacrimal fossa

supraorbital rim

superior rim

infraorbital rim

inferior rim

frontal, zygomatic and maxilla bones

contribute to rim; protection; strong bones

zugomaticomaxillary suture

notch, midpoint of infraorbital rim; between zygomatic and maxilla

nasal cavity

superior part of respiratory tract; located between the orbits; lateral walls, floor, both anterior and posterior openings; made up of bone and cartilage

nasal bones

bridge of nose

nasion

junction of frontal and nasal bones

piriform aperture

anterior opening; large; triangular; anchors midline cartilage; lateral cartilaginous alae; nares

posterior nasal aperture

large deeper posterior opening

floor of nasal

palatine processes of maxillae anteriorly and horizontal plates of the palatine bones posteriorly

lateral walls

mainly made up of maxilla; each wall is made of 3 conchae and nasal meatus

medial side of conchae

increases surface area and helps direct inspired airflow

nasal meatus

helps protect conchae and has openings in the paranasal sinuses; nasolacrimal duct communicates with nasal cavity

nasal septum

anterior is formed by a perpendicular plate of ethmoid and inferiorly the nasal septal cartilage

posterior nasal apertures

posterior opening of nasal cavity; located between nasal cavity and nasopharynx for communication

pterygoid canal

superior border of each posterior nasal aperture to medial pterygoid plate of sphenoid to the posterior border of pterygopalatine flossa, thus carrying the pterygoid nerve and blood vessels

pterygoid process of sphenoid

lateral borders of posterior nasal aperture; consists of a thin medial pterygoid plate and flattened lateral pterygoid plate and in btwn is pterygoid fossa

external skull foramina

entrances and exits for arteries and veins that supply the brain and facial tissue; allows cranial nerves to pass to and from the brain

foramen ovale

larger anterior oval opening on sphenoid bone; for C5 trigeminal nerve

foramen spinosum

smaller more posterior opening; carries middle meningeal artery into cranial cavity

spine of sphenoid

posterior extremity of the sphenoid bone

foramen lacerum

large, irregularly shaped, filled with cartilage

carotid canal

posterolateral to foramen lacerum round opening; carries the internal carotid artery and carotid plexus of nerves

styloid process

pointed bony projection of temporal bone, lateral and posterior to carotid canal

stylomastoid foramen

posterior to styloid; C7 facial nerve exits

jugular foramen

passes the internal jugular vein, C9 glossopharyngeal, C10 vagus, C11 accessory nerves

foramen magnum

largest opening of occipital lobe, spinal cord, vertebral arteries and C11 accessory nerve pass