ANATOMY

• Cranial nerves


  • Olfactory nerve
  • Optic nerve
  • Oculomotor nerve
  • Trochlear nerve
  • Trigeminal nerve
  • Abducent nerve
  • Facial nerve
  • Vestibulocochlear nerve
  • Glossopharyngeal nerve
  • Vagus nerve
  • Accessory nerve
  • Hypoglossal nerve

  
• Olfactory nerve


  • Abbreviation: CN I
  • Type: Special sensory
  • Foramen: Cribriform plate (ethmoid bone)
  • Brain location: Uncus (cerebrum)
  • Function: Smell
• Optic nerve


  • Abbreviation: CN II
  • Type: Special sensory
  • Foramen: Optic canal
  • Brain location: Occipital lobe (cerebrum)
  • Function: Sight / vision
• Oculomotor nerve


  • Abbreviation: CN III
  • Type: Motor
  • Foramen: Superior orbital fissure
  • Brain location: Midbrain
  • Functions: Eye movement, Open eyelids, Light reflexes

  
• Trochlear nerve

  • Abbreviation: CN IV
  • Type: Motor
  • Foramen: Superior orbital fissure
  • Brain location: Midbrain (posterior)
  • Function: Eye movements
• Trigeminal nerve


  • Abbreviation: CN V
  • Type: Mixed (motor and sensory)
  • Foramina: 1st part: superior orbital fissure, 2nd part: foramen rotundum, 3rd part: foramen ovale
  • Brain location: Pons
  • Motor function: Muscles of mastication
  • Sensory function: Skin over face

  
• Abducent nerve


  • Abbreviation: CN VI
  • Type: Motor
  • Foramen: Superior orbital fissure
  • Brain location: between pons and medulla oblongata
  • Function: Eye movements

  
• Facial nerve


  • Abbreviation: CN VII
  • Type: Mixed (motor and sensory)
  • Foramina: Internal acoustic meatus, Stylomastoid foramen
  • Brain location: Between pons and medulla oblongata
  • Motor functions: Facial expression muscles, Secretion of tears and saliva
  • Sensory functions: Taste of anterior 2/3 of tongue
• Vestibulocochlear nerve


  • Abbreviation: CN VIII
  • Type: Special sensory
  • Foramen: Internal acoustic meatus
  • Brain location: Between pons and medulla oblongata
  • Functions: Hearing, Balance / equilibrium

  
• Glossopharyngeal nerve

  • Abbreviation: CN IX
  • Type: Mixed (motor and sensory)
  • Foramen: Jugular foramen
  • Brain location: Medulla oblongata
  • Motor functions: Salivation of parotid gland, Swallowing and gagging
  • Sensory functions: Taste of posterior 1/3 of tongue, Sensations from tongue, outer ear, Regulation of blood pressure and respiration
• Vagus nerve


  • Abbreviation: CN X
  • Type: Mixed (motor and sensory)
  • Foramen: Jugular foramen
  • Brain location: Medulla oblongata
  • Motor functions: Speech, Gastro-intestinal secretion and motility, Bronchoconstriction, Decrease heart rate
  • Sensory functions: Taste of epiglottic area, Hunger sensations / fullness, Gastro-intestinal discomfort
• Accessory nerve


  • Abbreviation: CN XI
  • Type: Motor
  • Foramina: Foramen magnum, Jugular foramen
  • Brain location: Medulla oblongata
  • Motor functions: Sternocleidomastoid, Trapezius

  
• Hypoglossal nerve


  • Abbreviation: CN XII
  • Type: Motor
  • Foramen: Hypoglossal canal
  • Brain location: Medulla oblongata
  • Functions: Muscles of the tongue (EXCEPT palatoglossus)

  
• Trigeminal nerve (CN V) branches

  • Supraorbital n
  • Supratrochlear n
  • Infratrochlear n
  • Lacrimal n
  • External nasal n
  • Zygomaticotemporal n
  • Zygomaticofacial n
  • Infraorbital n
  • Auriculotemporal n
  • Buccal n
  • Mental n

  
• Mandibular nerve (V3)


  • 3 motor branches
  • 1 sensory branch
  • Trunk
  • Anterior division
  • Posterior division

  
• Mandibular nerve (V3) branches

  • Nerve to medial pterygoid
  • Nerve to tensor veli palatini
  • Nerve to tensor tympani
  • Nervus spinosum
  • Nerve to masseter
  • Nerve to temporal (deep temporal)
  • Nerve to lateral pterygoid
  • Buccal nerve
  • Auriculotemporal nerve
  • Lingual nerve
  • Inferior alveolar nerve
  • Mylohyoid (br. of inf. alveolar n.)

  
• Lingual nerve


  • Descends between tensor veli palatini and lateral pterygoid muscle
  • Crosses lateral surface of the medial pterygoid muscle
  • Joined by chorda tympani branch of the facial nerve (VII) in infratemporal fossa
  • Enters oral cavity at attachment of superior constrictor to pterygomandibular raphe and posterior attachment of mylohoid to mylohyoid line
  • Runs in shallow groove on medial aspect of mandible
  • Runs to tongue lateral to hyoglossus
  • GVA innervation: Anterior two-thirds of the tongue, Oral mucosa on the floor of the oral cavity, Lingual gingivae

  
• Inferior alveolar nerve


  • Originates deep to lateral pterygoid muscle
  • Descends on lateral surface of the medial pterygoid muscle
  • Between the sphenomandibular ligament and the ramus of mandible
  • Enters mandibular canal through the mandibular foramen
• Mandibular nerve (V3) summary

  • Small meningeal branch (spinosum) (sensory)
  • Nerve to medial pterygoid (motor)
  • Nerve to tensor veli palatini (motor)
  • Nerve to tensor tympani (motor)
  • Buccal nerve (sensory)
  • Masseteric nerve (motor)
  • Deep temporal nerve (motor)
  • Nerve to lateral pterygoid (motor)
  • Auriculotemporal nerve (sensory)
  • Lingual nerve (sensory)
  • Inferior alveolar nerve (sensory)
  • Nerve to mylohyoid (motor)

  
• Facial nerve (CN VII)


  • Origin: Lat. to CN VI @ pontomedullary junction
  • Motor root (large): Muscles of facial expression, Glands
  • Sensory root (smaller): Taste & skin behind ear
  • Enters internal acoustic meatus
  • Runs within facial canal in temporal bone, Gives off greater petrosal n. , nerve to stapedius & chorda tympani
  • Exits skull via stylomastoid foramen
  • Nuclei in brain stem, Exits the brainstem between pons and medulla oblongata
• Facial nerve (CN VII) branches

  • Posterior auricular nerve
  • Branches to post. belly of digastric & stylohyoid mm.
  • Branches to supply muscles of facial expression (divides within parotid gland): Temporal branch, Zygomatic branch, Buccal branch, Marginal mandibular branch, Cervical branch

  
• Chorda Tympani branch of VII

  • Branches from VII within temproral bone
  • Exits through petrotympanic fissure
  • Joins lingual nerve (V3) in infratemporal fossa
  • SVA innervation: Anterior two-thirds of the tongue (taste)
  • GVE innervation: Parasympathetic innervation to submandibular and sublingual salivary glands via submandibular ganglion
• Glossopharyngeal nerve (CN IX)


  • Origin: Ant Lat. upper medulla oblongata
  • Between CN VIII & X
  • Exits through jugular foramen
  • Enter pharynx between sup. & middle pharyngeal constrictor muscles
  • Tympanic branch (middle ear) – Lesser petrosal nerve

  
• Glossopharyngeal nerve (CN IX) functions

  • Sensory input post. ⅓ tongue, palatine tonsils, oropharynx, mucosa middle ear, pharyngotympanic tube
  • Taste post. ⅓ tongue
  • Secretion parotid glands
  • Pharyngeal mm.
  • Stylopharyngeus m.
• Each hemisphere has four lobes - frontal lobe, parietal lobe, temporal lobe, occipital lobe
• The cerebrum is divided into two hemispheres by a deep groove called the longitudinal fissure.
• Vagus nerve (CN X)


  • Origin: AntLat. Medulla oblongata (inf. to CN IX)
  • Exits through jugular foramen
  • Branches: Auricular branch (Floor external acoustic meatus), Pharyngeal branch, Superior laryngeal n. (internal & external), Recurrent laryngeal n. (right & left)

  
• Vagus nerve (CN X) functions

  • Sensory input larynx, laryngopharynx, deep auricle, external acoustic meatus, Esophagus, bronchi, lungs, heart, abdominal viscera
  • Taste @ epiglottis & pharynx
  • Smooth mm. & glands of pharynx, larynx, viscera
  • Palatoglossus, soft palate mm., pharynx mm.

  
• Hypoglossal nerve (CN XII)


  • Origin: Ant. medulla oblongata
  • Exit via hypoglossal canal
  • Motor: Tongue (Hyoglossus, styloglossus, genioglossus & intrinsic mm.)

  
• The brain is the largest organ in the body, weighing about 1300-1400 grams.
• The brain is protected by three layers of membranes known as meninges.
• The middle layer of the meninges is the arachnoid mater, which is made up of delicate collagenous tissue with many small blood vessels.
• The outermost layer of the meninges is the dura mater, which consists of dense connective tissue that forms a tough fibrous sheath around the brain and spinal cord.
• The outermost layer of the meninges is the dura mater, which consists of dense connective tissue.
• The middle layer of the meninges is the arachnoid mater, which contains small blood vessels that supply nutrients to the brain.
• The innermost layer of the meninges is the pia mater, which closely adheres to the surface of the brain and spinal cord.
• The innermost layer of the meninges is the pia mater, which closely adheres to the surface of the brain and spinal cord.
• The brain is protected by three layers of meningeal membranes: dura mater, arachnoid mater, pia mater.
• The cerebrospinal fluid (CSF) circulates within the subarachnoid space between the pia mater and arachnoid mater, providing nutrients and protecting the central nervous system from injury.
• The ventricles are cavities filled with CSF located inside the brain.