FORAMENS OF SKULL

Mandibular nerve

Maxillary nerve

Foramen rotundum: It is situated behind the medial end of superior orbital fissure. It perforates the greater wing of sphenoid and transmits the maxillary nerve from the trigeminal ganglion to the pterygopalatine fossa.

Foramen ovale: It lies posterolateral to the foramen rotundum. It perforates the greater wing of sphenoid and transmits the large sensory root and small motor root of the mandibular nerve to the infratemporal fossa.

Ref: Tsai L.M., Kamenetzky S.A. (2010). Chapter 37. The Eye & Ocular Adnexa. In G.M. Doherty (Ed), CURRENT Diagnosis & Treatment: Surgery, 13e.

• Foramen ovale
• Foramen lacerum
• Foramen spinosum
• Foramen rotundum
• Superior orbital fissure

• Foramen lacerum transmits the internal carotid artery.
• Foramen magnum transmits the medulla and its membranes, the spinal accessory nerves, the vertebral arteries, and the anterior and posterior spinal arteries.

D. i.e. Bile duct anteriorly 

D. i.e. Incisive foramen

The incisive foramen is dividing landmark between the primary & secondary palateQ; and anterior & posterior cleft deformities

A i.e. Foramen ovale 

Vidian nerve and artery pass through pterygoid canal.

Foramen spinosum passes MEN i.e. Middle meningeal artery, Emissary vein & Nervous spinosus (meningeal br. of mandibular nerve).

Foramen ovale passes MALE i.e. Mandibular nerve, Accessory meningeal artery, Lesser petrosal nerve and Emissary vein.

D i.e. 12^th nerve 

A i.e. Cranial nerve VI

A. i.e. Oculomotor nerve; B i.e. Trochlear nerve; C i.e. Lacrimal nerve

B i.e. Vertebral artery 

B. i.e. Spinal cord 

Lower part of medulla oblongata (not the spinal cord) passes through posterior part of foramen magnum, and vertebral arteries are transmitted through the subarachnoid space in foramen magnum.

B i.e. It is an opening through diaphragm C i.e. Superior epigastric vessels passes through it. 

C i.e. Passes through foramen ovale

Answer is ‘a’ i.e. Congenital hernia 

Trochlear and Abducent nerves exit the cranium through the superior orbital fissure.

The optic nerve runs backward and medially and passes through the optic canal to enter the middle cranial fossa

Inferior orbital fissure transmits maxillary nerve, the zygomatic nerve, etc.

Infraorbital foramen transmits the infraorbital nerve and vessels

The Structure Marked is Foramen Magnum 

Lower part of medulla oblongata (not the spinal cord) passes through posterior part of foramen magnum, and vertebralarteries are transmitted through the subarachnoid space in foramen magnum

Apart from the transmission of the medulla oblongata and its membranes, the foramen magnum transmits the vertebral arteries, the anterior and posterior spinal arteries, the tectorial membranes and alar ligaments. It also transmits the accessory nerve into the skull.

Mental Foramen is marked in the Diagram.

• The mental foramen is one of two foramina (openings) located on the anterior surface of the mandible. 
• It transmits the terminal branches of the inferior alveolar nerve and vessels (the mental artery). 
• The mental foramen descends slightly in toothless individuals.

Ans. is ‘a’ i.e., Lesser wing of sphenoid

The optic nerve leaves the orbit is the optic canal to enter the cranial vault.

The optic canal is the most posterior landmark of the orbit. It measures 10 mm in length.

The thin piece of bone separating the optic canal from the superior orbital fissure is the optic strut.

The optic strut and optic canal are a part of the lesser wing of sphenoid bone.

Foramen ovale

Epiploic foramen (foramen of Winslow or aditus to lesser sac) is a slit-like opening through which lesser sac communicates with greater sac. It is situated at the level of the T₁₂ vertebra. Its boundaries are:-

• Anterior:- Right free margin of lesser omentum (contains portal vein, hepatic artery proper and bile duct).
• Posterior:- IVC, right suprarenal gland and T₁₂ vertebra.
• Superior:- Caudate lobe of the liver.
• Inferior:- 1^st part of the duodenum and horizontal part of the hepatic artery.

OPHTHALMIC ARTERY

Origin

The ophthalmic artery is a branch of the cerebral part of the internal carotid artery, given off medial to the anterior clinoid process close to the optic canal.

Course and relations

1. The artery enters the orbit through the optic canal, lying inferolateral to the optic nerve. Both the artery and nerve lie in a common dural sheath.
2. In the orbit, the artery pierces the dura mater, ascends over the lateral side of the optic nerve, and crosses above the nerve from lateral to medial side along with the nasociliary nerve. It then runs forwards along the medial wall of the orbit between the superior oblique and the medial rectus muscles, and parallel to the nasociliary nerve.
3. It terminates near the medial angle of the eye by dividing into the supratrochlear and dorsal nasal branches. Branches

Ophthalmic artery gives following branches :

1. Central artery of retina.

2. Lacrimal artery:-

It gives following branches :

i)  Lateral palpebral branch.

ii) Zygomaticotemporal

iii) Zygomaticofacial

iv) Recurrent meningeal

3. Meningeal

4. Ciliary

5. Anterior ethmoidal

6. Posterior ethmoidal

7. Medial palpebral

8. Supratrochlear

9. Supraorbital

10. Dorsal nasal

Ophthalmic artery is the first and most important branch. It is an end artery.

Ans. is ‘b’ i.e., Enters skull through foramen magnum

Vertebral artery

• It is the largest branch of subclavian artery.
• Vertebral artery traverses through vertebral triangle, foramina transversaria of upper six cervical vertebrae, suboccipital triangle, posterior atlanto-occipital membrane, vertebral canal, pierce duramater and arachnoid (Subarachnoid) and passes through foramen magnum to enter posterior cranial fossa. It gives following branches:-

1. Cervical branches :- Spinal branches, muscular branches (to suboccipital muscle).
2. Cranial branches :- Posterior inferior cerebellar artery, medullary artery, meningeal branches, anterior spinal artery, posterior spinal artery and both vertebral arteries unite to form basilar artery.

Ans. is ‘c’ i.e., 2^nd part of duodenum

Ans. is ‘d’ i.e., Jugular foramen – External jugular vein

Jugular foramen transmits internal jugular vein (not external jugular vein).

Ans. is ‘c’ i.e., C.N. 3, 4, 5, 6

The superior orbital fissure is a cleft between the lesser and greater wing of sphenoid.The structures passed through superior orbital fissure are 3rd, 4th, 6th nerve, ophthalmic division of 5th nerve, superior & inferior division of ophthalmic vein and sympathetic fibres.

The Structure Marked is Foramen Magnum 

Lower part of medulla oblongata (not the spinal cord) passes through posterior part of foramen magnum, and vertebralarteries are transmitted through the subarachnoid space in foramen magnum

The lateral segments of the middle fossa are deeper than its middle portion; they support the temporal lobes of the brain and show depressions that mark the convolutions of the brain. These segments are traversed by furrows for the anterior and posterior branches of the middle meningeal vessels, which pass through the foramen spinosum.

Ans. is ”A i.e., Lesser wing of sphenoid

The optic nerve leaves the orbit is the optic canal to enter the cranial vault.

The optic canal is the most posterior landmark of the orbit. It measures 10 mm in length.

The thin piece of bone separating the optic canal from the superior orbital fissure is the optic strut.

The optic strut and optic canal are a part of the lesser wing of sphenoid bone

The glossopharyngeal nerve, the vagus nerve and the accessory nerve, so cranial nerves IX, X and XI pass through the jugular foramen. That’s four structures to remember. You’ve got cranial nerves IX, X and XI and you’ve got the internal jugularvein.

Ans. is ‘a’ i.e., Pudendal nerve

Three structures pass through both greater and lesser sciatic foramen :-

• Pudendal nerve
• Internal pudendal vessels
• Nerve to obturator internus

Structure passing throught greater sciatic foramen

1.  Piriformis fills the foramen almost completely
2. Structures passing above the piriformis

• Superior gluteal nerve
• Superior gluteal vessels
• Structures passing below the piriformis
• Inferior gluteal nerve
• Inferior gluteal vessel.
• Sciatic nerve
• Posterior cutaneous nerve of thigh
• Nerve to quadratus femoris
• Pudendal nerve
• Internal pudendal vessels
• Nerve to obturator internus

Note : Last three structures also enter the lesser sciatic foramen.

• Structures passing through lesser sciatic foramen
• Pudendal nerve
• Internal pudendal vessels
• Nerve to obturator internus

Ans. is ‘c’ i.e., Mandibular nerve

Ans. is ‘d’ i.e., Middle meningeal artery 

Foramen ovate transmits (mnemonic – MALE) :-

1. Mandibular nerve
2. Accessory meningeal artery
3. Lesser petrosal nerve
4. Emissory vein