norma lateralis (temporalis)

what is the norma lateralis?

it is the lateral side of the skull

what is the norma lateralis formed of?

• it is formed of the:

  • nasal, frontal and parietal bones superiorly

  • and the maxilla, zygomatic bone, the greater wing of the sphenoid, squamous part of the temporal bone and mastoid part of the occipital bone inferiorly

what is the zygomatic bone?

it is also known as the cheekbones. it is a membranous bone that has a smooth, lateral surface that forms the inferior orbital margin

the zygomatic process of the temporal part is located in what direction?

it is posterior to the zygomatic bone

the temporal process of the zygomatic bone is located in what direction?

it is anterior to the zygomatic bone

the lower border and inner surface of the zygomatic arch gives origin to what muscle?

the masseter muscle

where is the external auditory meatus located? what does it give attachment to?

• it is located below the root of the zygomatic arch

• it gives attachment to the cartilaginous part of the meatus

what is the supra meatal triangle bounded by?

• it is bounded anteriorly by the posterior-superior margin of the external auditory meatus

• it is bounded posteriorly by a tangent line to the posterior margin of the external auditory meatus

• it is bounded superiorly by the suprameatal crest superiorly

what are the temporal lines? what do they divide into?

they start anteriorly at the zygomatic process of the frontal bone, splitting into the superior temporal line and the inferior temporal line

where does the superior temporal line pass from?

it passes backwards, attaching to the temporal fascia and the epicranial aponeurosis

where does the inferior temporal line pass from?

it curves backwards and forwards, merging with the supramastoid crest, giving origin to the temporalis muscle

the outer surface of the mastoid crest gives insertion to what muscles?

• sternomastoid muscle

• splenius capitis

• longus capitis

the inner surface of the mastoid crest gives origin to what muscles?

the posterior belly of the digastric muscles

where is the supramastoid crest located? what does it contain?

• it is at the lower end of the temporal line and becomes posterior at the end of the zygomatic process of the temporal superiorly.

• it has a mastoid foramen nearby to help transmit emissary veins

where is the styloid process located? what does it give attachment to?

• it is located in front of the mastoid process

• it gives attachment to the following muscles

  • stylohyoid

  • styloglossus

  • stylopharyngeal

• it also gives attachment to the following ligaments

  • stylohyoid

  • stylomandibular

what does the styloid process separate?

the internal and external carotid artery

what is the pterion?

the H-shaped junction meeting area of the frontal, parietal, squamous temporal and greater wing of sphenoid bone.

what is the pterion the landmark area of?

the anterior branch of the middle meningeal artery, which is 4cm above the middle zygomatic arch

what is the asterion?

the meeting point of the parietal, occipital and mastoid temporal bones, internally related to the highest point of the transverse sinus.

what is the temporal fossa bounded by?

• superiorly and posteriorly, it is bounded by the superior temporal line

• inferiorly, it is bounded by the zygomatic arch

• anteriorly, it is bounded by the frontal process of the zygomatic bone

what muscles arise from the temporal fossa?

• the temporalis muscle arises from the floor of the temporal fossa

• the masseter muscle, however, arises from the lower border and inner surface of the zygomatic arch

what is the infratemporal fossa bounded by?

• anteriorly, it is bounded by the posterior surface of the maxilla

• medially, it is bounded by the lateral surface of the lateral pterygoid plate

• superiorly, it is bounded by the Infratemporal surface of the greater wing of the sphenoid

• inferiorly, it is bounded by the zygomatic arch and the coronoid process of the mandible

what does the infratemporal fossa contain?

• medial and later pterygoid muscles

• mandibular nerve

• maxillary artery

• pterygoid plexus of veins

what does the infratemporal fossa communicate with?

• temporal fossa through space deep to the zygomatic arch

• pterygoidpalatine fossa through the pterygo-maxillary fissure

• orbit through the inferior orbital fissure

• middle cranial fossa through the foramen ovale and foramen spinosum

what is the pterygopalatine fossa?

a triangular space below and behind the apex of the orbit

what is the pterygopalatine fossa bounded by?

• it is bounded anteriorly by the posterior surface of the maxilla

• it is bounded posteriorly by the pterygoid process

• it is bounded superiorly by the body of the sphenoid bone

• it is bounded medially by the perpendicular plate of palatine

• it is bounded laterally by infra-temporal

what are the contents of the pterygopalatine fossa?

• maxillary nerve

• maxillary artery

• sphenopalatine ganglion