Cranial Foramen😍

A- Foramen Ovale

B - Foramen Spinosum

C -IAM

D - Jugular foramen

 

FROST

• F → SOF → V1

• R → F. Rotuntum → V2

• O → FO → V3

 

Cranial Foramen

• Superior Orbital Fissure (1 bone)
• Located between greater and lesser wing of the sphenoid.

• Foramen Lacerum (3 bones)
• Made up of 3 bone
• Space between:
• Sphenoid bone
• Apex of the petrous part of the temporal bone
• Basilar part of the occipital bone.
• Margins are lacerated.

• Jugular Foramen (2 bones)
• Space between temporal and occipital bone.

• Mneumonic: 1 SOFA, 2 jug, 3 lace

Superior Orbital Fissure

”Mneumonic:

• CN 3 and 6 → always medially/middle

• CN 4 and 5 → together outside
  (except Nasociliary branch of V is inside)

 

Ring of Zinn

• Gives origin to extraocular muscles (4 recti muscles).

Divides superior orbital fissure into 3 parts:

1. Superolateral (Mnemonic: LFT)
• Lacrimal nerve
• Frontal nerve (branch of cranial nerve V₁)
• Trochlear nerve
• Superior ophthalmic vein

2. Intermediate
• Nasociliary nerve (branch of cranial nerve V₁)
• Superior and inferior division of oculomotor nerve
• Abducent nerve

3. Inferomedial
• Inferior ophthalmic vein

Structures Passing Through Foramen

Foramen Rotundum

• Cranial nerve V₂ - Maxillary N

• RoTwo → V2

Foramen Ovale

• Mandibular nerve (V3)

• Accessory meningeal artery

• Lesser petrosal nerve

• Emissary vein

• (Mnemonic: MALE)

• ”Mneumonic: Man (Mandibular nerve) nu oval (Foramen Ovale) shape anenkil Less (Lesser petrosal nerve) Access (Accessory meningeal artery) to Missionary (emissary)

Foramen Spinosum

• Nervous spinosus

• Middle meningeal artery
• NS + MMA → supply dura
• Rupture of MMA leads to epidural hemorrhage (Biconvex shaped)
• Lucid interval is observed

Internal Acoustic Meatus

• CN 7 & 8 → Facial & Vestibulocochlear N

• Labyrinthine vessels

Jugular Foramen

Foramen Lacerum

Location

• Space between:
• Sphenoid bone.
• Apex of petrous temporal bone.
• Basilar part of occipital bone.

Contents

• Traversing structures:
• Meningeal branches of ascending pharyngeal artery.
• Emissary veins: Connects cavernous sinus to pterygoid venous plexus.

• Partial content: (Fills up)
• ICA (Internal Carotid Artery).
• Sympathetic plexus.
• Deep petrosal nerve.
• Greater petrosal nerve.
• Vidian nerve.

• Internal carotid artery (ICA) enters through the carotid canal.

• Passes through the upper part of the foramen.

• Surrounding the ICA is the sympathetic plexus.
• Deep petrosal nerve begins from the sympathetic plexus.
• Deep petrosal nerve combines with greater petrosal nerve (branch of the facial nerve).
• Together, they form nerve to the pterygoid canal (Vidian nerve).
• Vidian nerve ends in sphenopalatine ganglion → Lacrimal nerve.
• Mnemonic: Vidu Kanneer

Foramen Magnum

• Medulla oblongata

• Vertebral arteries
• 2 trunks of vertebral arteries combine to form anterior spinal artery.

• Spinal accessory nerve

• Apical ligament of dens

• Cruciform ligament

• Tectorial Membrane

Mandibular Foramen

Foramen with Cranial Nerves

 

• Cranial nerve I (Olfactory nerve)
• Intracranial spread of COVID is through the cribriform plate

• Cranial nerve II
• Passes through the optic canal.

• Cranial nerve III
• Has ventral origin from the midbrain.

• Cranial nerve IV
• Has dorsal origin from the midbrain.

• Cranial nerve V
• Trigeminal nerve is the largest cranial nerve.

• Cranial nerve 6
• Exits from pontomedullary junction
• (CN VI, VII, VIII exits from pontomedullary junction).
• Ascends up through the slope (clivus).
• Exits through superior orbital fissure.
• Supplies the lateral rectus muscle.

• Cranial nerves 7 and 8
• Pass through the internal acoustic meatus.

• Cranial nerves IX, X, and XI
• Pass through the jugular foramen.

• Cranial nerve XII (Hypoglossal nerve)
• Passes through the hypoglossal canal.

Triads

• Gradenigo's Syndrome:
• Petrous apicitis
1. Persistence of ear discharge (after cortical mastoidectomy)
2. Deep seated retro-orbital pain → D/t CN 5
3. Diplegia - Lateral rectus palsy due to CSOM → D/t CN 6
• Mnemonic: Pettennu (Petrositis) Granede (Gradenigo) 5,6 thavana itt → Kannilum cheviyilum kond → Eye pain + ↓ movement - case eduth(CSOM)

• Sampter's triad
• (Mnemonic: AAP): SAM → MAS → AS, AS, NAS
• AS - Asthma
• AS - Aspirin intolerance (& other NSAIDS that block COX1)
• NAS - Nasal polyp (Ethmoidal)

• Trotter's Triad
• Diagnostic of Nasopharyngeal Carcinoma
• NPC
• Temporoparietal neuralgia.
• Palatal paralysis.
• CN 10
• Tensor and Levator Veli Palatini involvement
• Unilateral conductive hearing loss.

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• CSOM → Lateral sinus thrombophlebitis signs



• Hectic picket fence type
• Intermittent septic emboli enter bloodstream
• Fever + rigors
• Fever does not touch baseline
• Tobey-Ayre's test:
• Compression of IJV on healthy side raises CSF pressure.
• Mnemonic: Tobey has lot of pressure in his head
• Crowe-Beck test:
• Pressure on IJV on healthy side causes engorgement of retinal veins.
• Mnemonic: Crow with red eyes
• Griesinger sign
• Mastoid emissary veins cannot drain
• Edema and bluish discoloration of the mastoid
• Similar to battle sign
• Mnemonic: Blue color grease

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• Grisel syndrome:
• Seen in Downs
• Non-traumatic inflammatory atlanto-axial subluxation
• Neck stiffness
• Torticollis
• Severe neck pain
• Due to paraspinal spasm from inflammation