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NEET MDS Synopsis - Lecture Notes
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📖 Anatomy

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The Palate
Anatomy

The Palate

  • The palate forms the arched roof of the mouth and the floor of the nasal cavities.
  • The palate consists of two regions: the anterior 2/3 or bony part, called the hard palate, and the mobile posterior 1/3 or fibromuscular part, known as the soft palate.
Muscles acting on the Temporomandibular Joint
Anatomy

Muscles acting on the Temporomandibular Joint

  • Movements of the temporomandibular joint are chiefly from the action of the muscles of mastication.
  • The temporalis, masseter, and medial pterygoid muscles produce biting movements.
  • The lateral pterygoid muscles protrude the mandible with the help from the medial pterygoid muscles and retruded largely by the posterior fibres of the temporalis muscle.
  • Gravity is sufficient to depress the mandible, but if there is resistance, the lateral pterygoid, suprahyoid and infrahyoid, mylohyoid and anterior digastric muscles are activated.

 

Actions Muscles
Depression (Open mouth)
Lateral pterygoid
Suprahyoid
Infrahyoid
Elevation (Close mouth)
Temporalis
Masseter
Medial pterygoid
Protrusion (Protrude chin)
Masseter (superficial fibres)
Lateral pterygoid
Medial pterygoid
Retrusion (Retrude chin)
Temporalis
Masseter (deep fibres)
Side-to-side movements (grinding and chewing)
Temporalis on same side
Pterygoid muscles of opposite side
Masseter
Genioglossus Muscle
Anatomy

Genioglossus Muscle

  • Origin: Mental spine of the mandible.
  • Insertion: Dorsum of the tongue and hyoid bone.
  • Nerve Supply: Hypoglossal nerve (CN XII).
  • Arterial Supply: Sublingual and submental arteries.
  • Action: Depresses and protrudes the tongue.
The Orbital Vessels
Anatomy

The Orbital Vessels

  • The orbital contents are supplied chiefly by the ophthalmic artery.
  • The infraorbital artery, the continuation of the maxillary, also contributes blood to this region.
  • Venous drainage is through the superior orbital fissure to enter the cavernous sinus.

The Ophthalmic Artery

  • This artery arises from the internal carotid artery as it emerges from the cavernous sinus.
  • It passes through the optic foramen within the dural sheath of the optic nerve and runs anteriorly, close to the superomedial wall of the orbit.

 

The Central Artery of the Retina

  • This is the one of the smallest but most important branches of the ophthalmic artery.
  • It arises inferior to the optic nerve until it approaches the eyeball.
  • It then pierces the optic nerve and runs within it to emerge through the optic disc.
  • The central artery of the retina spreads over the internal surface of the retina and supplies it.

 

The Ophthalmic Veins

The Superior Ophthalmic Vein

  • The superior ophthalmic vein anastomoses with the facial vein.
  • It has no valves and blood can flow in either direction.
  • It crosses superior to the optic nerve, passes through the superior orbital fissure and ends in the cavernous sinus.

The Inferior Ophthalmic Vein

  • This begins as a plexus on the floor of the orbit.
  • It communicates with the inferior orbital fissure with the pterygoid plexus, crosses inferior to the optic nerve, and ends in either the superior ophthalmic vein or the cavernous sinus.