Skull Bones (Viva)

Q.1 What is the total number of bones in the skull?


Q.2 How the skull is held in a normal anatomical position?

By considering any one of the following two planes:

  • Reid’s baseline:
    Horizontal line between the infraorbital margin and center of the external acoustic meatus.

  • Frankfurt horizontal plane:
    Joint infraorbital margin and upper margin of the external acoustic meatus.

Q.3 What are sutures?

The joints between the various skull bones. These are immovable and fibrous in type.

 Q.4 What are the different sutures seen in the superior view (Norma verticalis) of the skull.

  • Coronal: Between frontal and two parietal bones.
  • Sagittal: Between two parietal bones.
  • Lambdoid: Between occipital and two parietal bones.
  • Metopic: In 3-8% between two halves of frontal bones.

Q.5 What is vertex?

It is the highest point on the sagittal suture.

Q.6 What is Bregma?

Meeting point between coronal and sagittal sutures. In foetal skull, represents anterior fontanelle, which closes at the age of 1½ years.

Q.7 What is Lambda?

Meeting point between sagittal and lambdoid sutures. In foetal skull, represent the posterior fontanelle, which closes by the age of 2-3 months.

Q.8 Name the structures attached to external occipital protuberances?

Trapezius, in the upper part.

Ligamentum nuchae, in the lower part.

Q.9 What is ‘Occipital point’?

Median point just above inion (most prominent part of external occipital protuberance) which is farthest from the glabella.

Q.10 What is ‘glabella’?

The meeting point of two superciliary arch in midline.

Q.11 What is ‘Nasion’?

Median point at the root of the nose, where the internasal suture meets with the frontonasal suture.


Q.12 Name the bones forming medial orbital margin.

Frontal process of maxilla, mainly.
Nasal part of the frontal bone, in the upper part.

Q.13 Name the sutures present in Norma frontalis?

  • Internasal
  • Frontonasal
  • Nasomaxillary
  • Lacrimo-maxillary
  • Fronto-maxillary
  • Inter-maxillary
  • Zygomatico-maxillary
  • Zygomatico-frontal

Q.14 What is ‘Jugal point’?

Anterior end of the upper border of the zygomatic arch.

Q.15 What are the boundaries of the supramental triangle?

Above: Supramastoid crest

Front: Posterosuperior margin of the external auditory meatus.

Behind: Vertical tangent to posterior margin of meatus.

Q.16 What is the significance of tegmen tympani?

It is a thin plate of bone formed by petrous temporal bone. It separates the middle cranial fossa from the cavities of the middle ear, auditory tube, and mastoid antrum.

Q.17 Name the structures attached to the mastoid process.

From before backward:

  • Sternomastoid,
  • Splenius capitis,
  • Longissimus capitis and
  • Posterior belly of digastric attached to mastoid notch.

Q.18 What are the relations of the styloid process?

Laterally: Parotid gland.

Medially: Internal jugular vein.

Base: Ensheathed by tympanic plate. Related to facial nerve.

Apex: Posterior border of ramus of mandible, laterally

Q.19 Name the structures attached to the styloid process.


  • Styloglossus,
  • Stylohyoid and
  • Stylopharyngeus.


  • Stylohyoid and
  • Stylomandibular

Q.20 What is ‘Pterion’?

H-shaped suture seen in norma lateralis formed by the frontal, parietal, sphenoid, and temporal bone.

Q.21 What is ‘asterion’?

The point at which parietomastoid suture (formed by mastoid part of the temporal bone with parietal bone) and occipitomastoid suture (formed by mastoid part of the temporal bone with occipital bone) meet.

Q.22 Name the structures related to pterion.

  • Middle meningeal vein,
  • Anterior division of middle meningeal artery and
  • Stem of lateral sulcus of the brain.

Q.23 What are the boundaries of temporal fossa?

Superior: Temporal line

Inferior: Zygomatic arch

Floor: By parts of the frontal, parietal, squamous temporal, and greater wing of sphenoid bone.

Anterior wall: Mainly by the temporal surface of zygomatic bone. Also by greater wing of sphenoid and frontal bone.

Q.24 What is the origin, insertion, and nerve supply of temporalis muscle?

Origin: Floor of temporal fossa

Insertion: Coronoid process of mandible

Nerve supply: Deep temporal nerve, branch of the anterior division of the mandibular nerve.

Q.25 What are the boundaries of infratemporal fossa?

Roof: Mainly by greater wing of sphenoid. Also squamous temporal bone.

Medial: Pterygoid process of sphenoid

Anterior: Posterior surface of maxilla.

Q.26 What are the communications of infratemporal fossa?

  • Temporal fossa: Superiorly through the gap between the zygomatic arch and the rest of the skull.
  • Pterygopalatine fossa: Through pterygopalatine fissure.
  • Orbit: Anteriorly through inferior orbital fissure.

Q.27 What are the contents of ‘infratemporal fossa’?

  • Muscles: Lower part of temporalis, Lateral pterygoid, Posterior part of buccinator, and medial pterygoid.
  • Ligaments: Sphenomandibular.
  • Arteries: First and second part of the maxillary artery and their branches.
  • Veins: Pterygoid plexus of veins and Maxillary vein.
  • Nerves: Mandibular, Chorda tympani and Maxillary.

Q.28 Name the bones forming hard palate.

Anterior 2/3: Palatine processes of maxilla.

Posterior 1/3: Horizontal plates of palatine bones.

Q.29 Name the structures attached to the lateral pterygoid plate.

Lateral surface: Lower head of lateral pterygoid.

Medial surface: Deep head of medial pterygoid.

Posterior border: Pterygospinous ligament.

Q.30 Why the upper surface of the body of sphenoid is called ‘Sella turcica’?

Because it is hollowed out in the form of a ‘Turkish saddle’.

Q.31 What lodges the hypophysis (Pituitary gland)?

Hypophyseal fossa of sphenoid bone.

Q.32 What are the boundaries of ‘superior orbital fissure’?

Above and medially: Lesser wing of sphenoid.

Below and laterally: Greater wing of sphenoid.

Q.33 What are the boundaries of inferior orbital fissure?

Above and laterally: Greater wing of sphenoid.

Below and medially: Orbital surface of the maxilla.

Q.34 What are the relations of the ‘spine of sphenoid’?

Lateral: Auriculotemporal nerve.

Medial: Chorda tympani nerve. Auditory tube.

Tip: Attachment to sphenomandibular ligament.

Anterior: Origin of fibers of tensor palati.

Q.35 Name the structures passing through internal acoustic meatus.

  • 7th and 8th cranial nerves.
  • Labyrinthine vessels.

Q.36 What are the boundaries of the optic canal?

Lateral: Lesser wing of sphenoid

Medial: Body of sphenoid.

Q.37 What structures are transmitted through the optic canal?

  • Optic nerve,
  • Meningeal sheath of optic nerve and
  • Ophthalmic artery.

Q.38 Name the structures passing through superior orbital fissure?

It is divided into three parts by a common tendinous ring of Zinn.

It transmits:

  • Lateral part:

– Lacrimal nerve, Branch of ophthalmic division

– Frontal nerve, of the trigeminal nerve

– Trochlear nerve

– Recurrent branch of the ophthalmic artery and

– Superior ophthalmic vein.

  • Middle part:

 – Upper and lower division of oculomotor nerve,

– Nasociliary nerve, branch of the ophthalmic division of V nerve and

– Abducent nerve.

  • Medial part: 

– Inferior ophthalmic vein.

Q.39 What structure passes through Foramen rotundum?

Maxillary nerve.

Q.39.1 What structures pass through the Foramen ovale?

  • Mandibular division of V nerve,
  • Lesser petrosal nerve,
  • Accessory meningeal artery and
  • Emissary vein connecting cavernous sinus to pterygoid venous plexus.

Q.40 Name the structures passing through Foramen spinosum.

  • Middle meningeal artery,
  • Meningeal branch of mandibular nerve and
  • Emissary vein.

Q.41.0 What are the boundaries of Foramen magnum?

Anterior: Basiocciput

Posterior: Squamous occipital

On each side: Condylar part of occipital bone

Q.41 Name the structures passing through Foramen magnum.

  • Through wider posterior part:

– Lower part of medulla.
– Tonsils of cerebellum.
– Meninges.

  • Through narrow anterior part:

– Apical ligament of dens.
– Membrana tectoria.
– Superior band of cruciform ligament.

  • Through subarachnoid space:

– Spinal accessory nerve.
– Vertebral arteries
– Sympathetic plexus.
– Posterior spinal arteries.
– Anterior spinal arteries.

Q.42 Name the structure transmitted by mastoid foramen.

Emissary vein connecting sigmoid sinus to occipital vein.

Q.43 Name the structure transmitted by sphenopalatine foramen.

Nasopalatine nerve and vessels.

Q.44 What are the contents of the Hypoglossal canal?

  • Hypoglossal nerve.
  • Meningeal branch of ascending pharyngeal artery.
  • Emissary vein

Q.45 Name the structures passing through Jugular foramen?

  • Through the anterior part:

– Inferior petrosal sinus

  • Through the middle part:

– IX, X, and XI cranial nerves.
– Meningeal branch of ascending pharyngeal artery.

  • Through the posterior part:

– Lower end of sigmoid sinus
– Meningeal branch of the occipital artery.
– Emissary vein connecting sigmoid sinus to occipital vein.

Q.46 Name the structures transmitted by the carotid canal.

  • Internal carotid artery (ICA)
  • Venous and sympathetic plexuses around ICA.

Q.47 Name the structures transmitted by inferior orbital fissure.

  • Maxillary nerve
  • Zygomatic nerve
  • Orbital branches of the pterygopalatine ganglion
  • Infraorbital vessels
  • Emissary vein connecting inferior ophthalmic vein to pterygoid plexus.

Q.48 Deep petrosal and greater petrosal nerve passes through which foramen of the skull?

Foramen lacerum

Q.49 Name the structures passing through stylomastoid foramen?

  • Facial nerve,
  • Stylomastoid branch of posterior auricular artery.

Q.50 What are Wormian bones?

These are small irregular bones found in the region of fontanelles and are formed by the additional ossification centers.

Q.51 Which skull bone is formed by intramembranous ossification?

Frontal, parietal, zygomatic, palatine, nasal, lacrimal, maxilla and vomer.

Q.52 Which skull bone is formed partly in cartilage and partly in membrane?

Occipital, sphenoid, temporal, and mandible.

Q.53 Which skull bone is formed entirely in cartilage?

Ethmoid and inferior nasal concha.

Q.54 What is the Cephalic index?

It is the ratio of the breadth (widest diameter) and length (longest diameter) of the skull.

Q.55 What is the clinical importance of the Cephalic index?

  • In the subdivision of the human population into different races.
  • In medicological practice:
    To know the race to which the person belonged when the skull and other bones are found.

Q.56 What is ‘Scaphocephaly’?

Boat-shaped skull resulting from early union of the sagittal suture.

Q.57 What is ‘Acrocephaly’?

 Pointed skull as a result of the early union of the coronal suture.