Skull: Internal view
1. Frontal Sinus
2. Foramen Cecum
the point of attachment of the thyroglossal duct.
3. Crista Galli (Latin: "crest of the cock")
The point where the falx cerebri attaches anteriorly to the skull.
4. Cribriform Plate
The part of the ethmoid bone; it is perforated by foramina for the passage of the olfactory nerves (CN I)
5. Anterior Cranial Fossa
The floor of the fossa: is formed by the orbital plates of the frontal bone, the cribriform plate of the ethmoid bone, and the small wings and front part of the body of the sphenoid; it is limited behind: by the posterior borders of the small wings of the sphenoid and by the anterior margin of the chiasmatic groove
6. Lesser Wing of Sphenoid
7. Chiasmatic Groove
8. Sella turcica – “Turkish saddle” (hypophyseal fossa)
saddle-shaped depression in the sphenoid bone
9. Dorsum Sella
Forms the posterior part of the Sella turcica. The dorsum sella is terminated laterally by the posterior clinoid processes.
10. Optic Canal
transmits the optic nerve and ophthalmic artery (with accompanying sympathetic nervefibers) into the orbital cavity. The left and right optic canals are 25mm apart posteriorly and 30mm apart anteriorly. They are funnel-shaped (narrowest anteriorly). The optic foramen is the opening to the optic canal.
11. Anterior Clinoid Process
12. Foramen Rotundum
a circular hole in the sphenoid bone that connects the middle cranial fossa and thepterygopalatine fossa.
The maxillary nerve V2 passes through it.
13. Foramen Ovale
14. Foramen Spinosum
an opening in the greater wing of the sphenoid bone, in front of the spine. Transmits the middle meningeal artery,
15. Squamous Part of Temporal
Its outer surface is smooth and convex; it affords attachment to the temporalis muscle, and forms part of the temporal fossa; on its hinder part is a vertical groove for the middletemporal artery. The internal surface of is concave; it presents depressions corresponding to the convolutions of the temporal lobe of the brain, and grooves for the branches of the middle meningeal vessels.
16. Petrous Part of Temporal bone
is pyramidal and is wedged in at the base of the skull between the sphenoid and occipital. Directed medially, forward, and a little upward, it presents for examination a base, an apex, three surfaces, and three angles, and contains, in its interior, the essential parts of the organ of hearing.
17. Groove for Transverse Sinus
18. Posterior Cranial Fossa
The posterior cranial fossa is part of the intracranial cavity, located between theforamen magnum and tentorium cerebelli. This is the most inferior of the fossae. It houses the cerebellum, medulla and pons. Anteriorly it extends to the apex of the petrous temporal. Posteriorly it is enclosed by the occipital bone. Laterally portions of the squamous temporal and mastoid part of the temporal bone form its walls.
19. Foramen Magnum
A large opening in the occipital bone in the base of the skull. The medulla oblongata (an extension of the spinal cord) enters and exits the skull vault through it. Also transmits the Spinal Accessory nerve (CN XI), vertebral arteries, the anterior and posterior spinal arteries, the membrana tectoria and alar ligaments.
20. Hypoglossal Canal
A bony canal in the occipital bone. Transmits hypoglossal cranial nerve (CN XII)
21. Jugular Foramen
is formed in front by the petrous portion of the temporal bone, and behind by the occipitalbone. It may be subdivided into three compartments, each with their own contents.
22. Internal Acoustic Meatus
a canal in the temporal bone. The opening to the internal acoustic meatus is located inside the cranial cavity, near the center of the posterior surface of the temporal bone. It is short (about 1 cm) and runs laterally into the bone. At its end are the openings for three different canals, one of which is the facial canal. It does not transmit sound waves. It instead transmits the facial (CN VII) and vestibulocochlear nerves (CN VIII) and thelabyrinthine artery (an internal auditory branch of the basilar artery). The facial nerve travels through the facial canal, eventually exiting the skull at the stylomastoid foramen.
23. Posterior Clinoid Process
24. Foramen Lacerum
a triangular hole in the base of the skull located at the base of the medial pterygoid plate. The foramen is mostly filled with cartilage. Some nerves, arteries, and veins do pass through the cartilage plug of the foramen lacerum: the artery of pterygoid canal, the nerve of pterygoid canal, and some venous drainage.
25. Superior Orbital Fissure
a foramen in the skull, although strictly it is more of a cleft, lying between the lesser andgreater wings of the sphenoid bone. Transmits:
· superior and inferior divisions of oculomotor nerve (III)
· trochlear nerve (IV)
· abducens nerve (VI)
· superior and inferior divisions of ophthalmic vein