Past Questions - Anatomy of the Skull

Question 1

Describe posterior cranial fossa

Answer 1

The posterior cranial fossa is the deepest and largest of the three cranial fossae, located at the back of the skull. It houses the cerebellum, pons, and medulla oblongata. The foramen magnum, through which the spinal cord passes, is a key feature. Other important structures include the jugular foramen, internal acoustic meatus, and hypoglossal (CN XII) canal.

Question 2

Describe the anterior cranial fossa.

Answer 2

The anterior cranial fossa is the most superficia and superior fossa, forming the floor of the frontal part of the skull. It houses the frontal lobes of the brain. Key features include the cribriform plate of the ethmoid bone (allowing passage of the olfactory nerves), the frontal bone, and the lesser wings of the sphenoid bone.

Question 3

Describe the temporal fossa

Answer 3

Depression on lateral side of skull. Limited by superior temporal line, zygomatic arch, frontal process of zygomatic, infratemporal crest, greater wing of phenoid and squamous part temporal bone.

1) Temporalis muscle: Originate from temporal fossa and insert coronoid process of mandible. Covered by temporal fascia.
2) Superficial Temporal Artery: Ext. Carotid branch to supply scalp + temporalis
3) Deep Temporal Arteries: Maxillary branch to supply temporalis.
4) Deep Temporal Nerves: Mandibular V3 branches to innervate temporalis (Motor)
5) Auriculotemporal Nerve: Mandibular V3 branches for temporal sensation

Question 4

Pterygopalatine fossa (contents, limits, communications)

Answer 4

Contents
• Maxillary nerve (V₂) and branches
• Pterygopalatine ganglion (parasympathetic)
• Third part of maxillary artery and veins

Limits
• Anterior: Maxilla
• Posterior: Pterygoid process (sphenoid)
• Medial: Palatine bone
• Lateral: Infratemporal fossa
• Superior: Sphenoid bone
• Inferior: Greater palatine canal

Communications
• Foramen rotundum & Pterygoid canal → Middle cranial fossa
• Pterygomaxillary fissure → Infratemporal fossa
• Inferior orbital fissure → Orbit
• Sphenopalatine foramen → Nasal cavity
• Palatine canals → Oral cavity

Question 5

Describe maxillary bone

Answer 5

The maxilla is a paired facial bone that forms the upper jaw, part of the orbit, nasal cavity, and hard palate. It articulates with the frontal, ethmoid, zygomatic, nasal, lacrimal, palatine, vomer, and sphenoid bones.

• Around the nose, above the teeth.
• Contains maxillary sinus
• Infraorbital Foramina, CN 2 - 5
• Anterior two thirds of the Palate. (Hard palate)
• Incisive Foramen, for the Incisive nerve and artery.

Question 6

Describe zygomatic bone

Answer 6

The zygomatic bone is a paired facial bone that forms the cheekbone and part of the lateral orbit. It articulates with the frontal, maxillary, sphenoid, and temporal bones. It consists of structures such as:

•	Temporal process: Connects to the temporal bone, forming the zygomatic arch.
•	Frontal process: Articulates with the frontal bone.
•	Maxillary process: Connects to the maxilla.
•	Orbital surface: Contributes to the lateral wall of the orbit.

The zygomatic bone plays an important role in facial aesthetics, protecting the eye, and supporting the muscles of facial expression.

Question 7

Describe the temporal bone

Answer 7

The temporal bone is a paired bone located on the sides and base of the skull, forming part of the cranium. It plays a key role in housing structures related to hearing, balance, and the protection of the brain.

• Origin of the ear.
• External Occipital Protuberance.
• External Acoustic Meatus for the ear.
• Petrous part of the temporal bone, Lateral floor of Middle Cranial Fossa.
• Mandibular Fossa, for the Mandibular condyle.
• Styloid process.
• Stylomastoid Foramen, for the Facial nerve/CN-7.
• Mastoid process, SCM insertion. Contains air cells inside for middle ear communication.

Question 8

Describe the structures and communications of middle cranial fossa (communications, arteries, veins and nerves)

Answer 8

The middle cranial fossa is a depression in the floor of the cranial cavity, situated between the anterior and posterior cranial fossae. It houses parts of the brain and is involved in several neurovascular communications.

Structures:
• Sella turcica: Houses the pituitary gland.
• Temporal lobes of the brain.
• Foramen rotundum: Transmits maxillary nerve (V2).
• Foramen ovale: Transmits mandibular nerve (V3) and accessory meningeal artery.
• Foramen spinosum: Transmits middle meningeal artery and meningeal branch of V3.
• Optic canal: Transmits optic nerve (II) and ophthalmic artery.
• Carotid canal: Transmits internal carotid artery and sympathetic nerve plexus.

Communications:
• Foramen rotundum → Pterygopalatine fossa (maxillary nerve).
• Foramen ovale → Infratemporal fossa (mandibular nerve).
• Foramen spinosum → Middle meningeal vessels.
• Optic canal → Orbit (optic nerve and ophthalmic artery).
• Carotid canal → Neck (internal carotid artery).

The middle cranial fossa is vital for the transmission of several major nerves and arteries to the face, brain, and neck.