Detailed Skull, Lect 3 Module 4 Anat

Front 1

What are 4 structures we can find in the anterior cranial fossa?

Back 1

The orbital plates of the frontal bone are convex elevations to either side of the cribriform plates. The orbital plates form the roof of the bony orbit below.
• The crista galli (crest of the rooster) of the ethmoid bone projects upward in the midline. It also provides attachment for the falx cerebri .

• The cribriform plates of the ethmoid bone are perforated areas on either side of the crista galli. The small perforations communicate with the roof of the nasal cavity below and transmit the olfactory nerve (cranial nerve I)
• The lesser wing of the sphenoid can be found at the posterior aspect of the anterior cranial fossa

Front 2

1) Anterior clinoid process

Back 2

1) extends posteriorly from lesser wing of sphenoid and provide attachments for dura

You can also see greater wing of sphenoid, spuamous (flat part of lateral view) and petrous portion (bulky part) of temporal bone

Front 3

1) sella turcica
2) hypophyseal (pituitary fossa)
3) dorsum sellae
4) posterior clinioid porcesses

Back 3

1) "Turkish saddle"; part of sphenoid bone in middle cranial fossa
2) seat of the sella turcica; has pituitary gland
3) back of the saddle
4) extends posteriorly from either end of dorsum sellae and provides dural attachments

Front 4

1) optic canals
2) superior orbital fissure

Back 4

still in middle cranial fossa
• optic canals which pass forward to the orbits and transmit the optic nerves and the ophthalmic arteries
•
• superior orbital fissure, is an inverted, comma-shaped gap between the greater and lesser wings of the sphenoid bone found under the cover of the lesser wing that communicates with the orbit anteriorly and through which pass the ophthalmic veins and cranial nerves III, IV, VI , and V-1

Front 5

1) foramen rotundum
2) foramen ovale
3) foramen spinosum

Back 5

• foramen rotundum, a round opening posterior to the inferior orbital fissure that transmits the maxillary nerve (CN V-2)
• foramen ovale, an oval-shaped opening posterior to the foramen rotundum, that leads to the infratemporal region below the skull and transmits the mandibular nerve (CN V-3)
• foramen spinosum, which lies immediately behind and lateral to the foramen ovale; is a small round opening leading from the infratemporal region below that transmits the middle meningeal artery

we're still in the middle cranial fossa

Front 6

1) foramen lacerum
2) carotid canal

Back 6

still in middle cranial fossa

foramen lacerum, which provides an opening on either side of the hypophyseal fossa for the entrance of the internal carotid artery (nothing actualy goes through it, its just an opening)
• carotid canal: found at the junction of the greater wing of the sphenoid and the petrous portion of the temporal bone (ICA actually goes through the carotid canal; roof of which is cartilage which disintegrated)

Front 7

Hiatus for greater petrosal nerve
Hiatus and groove for lesser petrosal nerve

Back 7

still in middle cranial fossa
hiatus for the greater petrosal nerve, which exits from the anterior slope of the petrous temporal ridge (the groove can be followed to the foramen lacerum). The hiatus and groove transmit the greater petrosal nerve
• hiatus and groove for the lesser petrosal nerve, which run parallel and inferior to the greater hiatus and groove, which leads toward the foramen ovale and transmits the lesser petrosal nerve

Front 8

What landmark begins the posterior cranial fossa?

Back 8

petrous ridge of the temporal bone

Front 9

1) clivus
2) foramen magnum
3) hypoglossal canal

Back 9

clivus: consists of the body of the sphenoid bone behind the dorsum sellae which becomes fused with the aportion of the occipital bone anterior to the foarmen magnumThe clivus slopes posteriorly and inferiorly to end as the anterior margin of the foramen magnum.
• foramen magnum: large, oval- shaped opening through which the spinal cord is continuous with the brainstem above.
• hypoglossal canal: found on the lateral margin of the foramen magnum anterior to the occipital condyle. It runs obliquely anteriorly and laterally and transmits the hypoglossal nerve (CN XII).

Front 10

Jugular foramen

Back 10

Not a feature of any one bone.
a large opening lateral to the foramen magnum that leads to the base of the skull below. It transmits the internal jugular vein and cranial nerves IX, X , and XI .

Front 11

Internal auditory meatus and internal occipital protuberance

Back 11

internal auditory meatus (IAM): lies on the posterior slope of the petrous temporal ridge just above the jugular foramen. Passing through this opening to the middle ear region within the temporal bone are CN VII and VIII

internal occipital protuberance: an internal projection of bone at the posterior pole of the internal aspect of the skull. (IOP)

Front 12

Base of the skull (inferior view)
Where is the anterior and posterior transverse lines?

Where do they pass through?

Back 12

The anterior transverse line joints the right and left articular eminences.
• The articular eminence is a rounded ridge of bone that runs transversely across the anterior limit of the mandibular fossa.
– The posterior transverse line joins the anterior aspects of the right and left mastoid processes

The anterior and posterior lines pass through several key structures and also divide the base of the skull into anterior, intermediate, and posterior regions .

Front 13

The hard palate consists of 2 bones...

Back 13

Palatal process of maxilla (anterior 2/3s)
palatal process of palatine bones (posterior 1/3) ending as a double crescent-shaped, posterior free border.
• The posterior nasal spine is a midline posterior projection from the posterior border of the bony palate.

Front 14

What's the mouth of the incisive canal?

Back 14

1) incisive foramen. behind the central incisor. The foramen is the common opening for the right and left incisive canals. It transmits the nasopalatine nerve and vessels.

Front 15

What does the greater palatine canals open as?

Back 15

greater palatine foramen onto the palatal process of the palatine bone in line with the last maxillary molar. It transmits the greater palatine nerve and vessels.
– lesser palatine foramen posterior to the greater palatine foramen. It transmits the lesser palatine nerve and vessels .

Front 16

What are posterior choanae?

Back 16

aka posterior nasal apertures - represent posterior limits of nasal cavity.
-The free edge of the bony nasal septum formed by the vomer divides the nasal cavity into right and left chambers.

Front 17

What does the pterygoid process of the sphenoid bone consist of?

Back 17

right at the midline.
has 2 parts:
The lateral plate provides attachment for both lateral and medial pterygoid muscles .
– The medial pterygoid plate forms the posterior limit of the lateral wall of the nasal cavity.

**lateral plate of pterygoid process is the attachment for both LATERAL AND MEDIAL pterygoid muscles

Front 18

What does the medial plate end as inferiorly?

What is the scaphoid fossa?

Back 18

The medial plate ends inferiorly as the hamulus, a small, slender hook.

The scaphoid fossa is a canoe-shaped shallow depression at the base of the medial pterygoid plate.
– The tensor palatini muscle originates from this area.

Front 19

Where does the palatovaginal canal run?
How about the pterygoid canal?

Back 19

runs near the base of the vomer
passes through the base of the pterygoid process. The mouth of the canal is immediately medial to the scaphoid fossa, passing into the anterior margin of the foramen lacerum

Front 20

Intermediate area structures
1) mandibular fossa
2) tympanic plate
3) external auditory meatus
4) squamotympanic fissure

Back 20

• mandibular fossa, which accommodates the condyle of the mandible
• tympanic plate, which forms the anterior wall of the external auditory meatus and the posterior, nonfunctioning wall of the mandibular fossa
• external auditory meatus, which lies behind the mandibular fossa (EAM)
• squamotympanic fissure/ petrotympanic fissure: transmits the chorda tympani nerve, a branch of cranial nerve VII *

Front 21

More medially, we see the following
1) spine of sphenoid
2) foramen spinosum
3) foramen lacerum
4) foramen ovale

Back 21

• spine of the sphenoid, a pointed projection medial to the mandibular fossa; a ligament joins the spine to the lingula of the mandible (sphenomandibular ligament)
• foramen spinosum, a small opening just anterior to the spine of the sphenoid, which transmits the middle meningeal artery from the base of the skull to the interior of the skull
• Also note the foramen lacerum, usually occupied by cartilage in life
• And, finally, the foramen ovale, which has been shown from an interior view and is now visible in the inferior view

Front 22

Posterior Line of norma basalis
1) mastoid process of ..
2) stylomastoid foramen
3) styloid process

Back 22

The mastoid process of the temporal bone (M)
• The stylomastoid foramen, which lies between the styloid and mastoid processes, allowing passage of the facial nerve (CN VII) from within the temporal bone
• The styloid process, (S) a long, slender, needle-like process, that points downward, forward, and medially and that is joined to the lesser horn of the hyoid bone by the stylohyoid ligament; also provides attachment for several muscles

Front 23

Posterior line of norma basalis
1) jugular foramen
2) entrance to the carotid canal
3) tympanic canaliculus

Back 23

• The jugular foramen, a large opening through which the internal jugular vein and cranial nerves IX, X, and XI pass
• The entrance to the carotid canal, which is immediately anterior to the jugular foramen and separated from the jugular foramen only by a small wedge of bone
• The tympanic canaliculus is a small opening located inferiorly on the wedge of bone separating the carotid canal and the jugular foramen. The tympanic canal transmits the tympanic branch of the glossopharyngeal nerve (CN IX).

Front 24

What are 3 other structures we see in the posterior line

Back 24

The occipital
condyles
• Hypoglossal canal
• Foramen magnum (FM)