Anatomy 3

• Olfactory Nerve (I)


  • Location: Originates in the olfactory epithelium in the nasal cavity and enters the brain through the cribriform plate of the ethmoid bone
  • Function: Responsible for the sense of smell
  • Test Method: Testing involves sniffing aromatic substances
• Optic Nerve (II)


  • Location: Begins at the retina in the eye and enters the brain through the optic canal
  • Function: Carries visual information from the retina to the brain
  • Test Method: Visual acuity tests and examination of the eye fundus
• Oculomotor Nerve (III)


  • Location: Emerges from the midbrain and enters the orbit via the superior orbital fissure
  • Function: Controls most of the eye's movements, the constriction of the pupil, and the ability to keep the eyelid open
  • Test Method: Pupil response to light and eye movement tests
• Trochlear Nerve (IV)


  • Location: Also originates from the midbrain but passes through the superior orbital fissure to reach the eye
  • Function: Controls the superior oblique muscle of the eye, which helps in rotary movement and looking downward
  • Test Method: Ask to follow an object moving in different directions
• Trigeminal Nerve (V)


  • Location: Emerges from the pons and divides into three branches (ophthalmic, maxillary, and mandibular) that pass through different parts of the skull
  • Function: Facial sensation, as well as biting and chewing
  • Test Method: Facial sensation tests and clenching the teeth
• Abducens Nerve (VI)


  • Location: Originates from the pons and enters the orbit through the superior orbital fissure to innervate the lateral rectus muscle
  • Function: Controls the lateral rectus muscle, which turns the eye outward
  • Test Method: Eye movement examination, particularly lateral movement
• Facial Nerve (VII)


  • Location: Exits the brainstem at the pontomedullary junction, travels through the internal acoustic meatus, and enters the facial canal in the temporal bone
  • Function: Controls facial expressions, secretion of saliva and tears, and taste sensations from the front two-thirds of the tongue
  • Test Method: Facial movements such as smiling, frowning, and taste tests
• Vestibulocochlear Nerve (VIII)


  • Location: Runs adjacent to the facial nerve through the internal acoustic meatus to the inner ear
  • Function: Responsible for hearing and balance
  • Test Method: Hearing tests and balance assessments
• Glossopharyngeal Nerve (IX)


  • Location: Emerges from the medulla and exits the skull through the jugular foramen
  • Function: Taste and sensations from the back one-third of the tongue, control of some muscles used in swallowing
  • Test Method: Gag reflex and taste tests on the posterior aspect of the tongue
• Vagus Nerve (X)


  • Location: Also exits the medulla and leaves the skull through the jugular foramen, extending down to the neck, chest, and abdomen
  • Function: Controls the heart, lungs, and digestive tract. Also involved in swallowing and speaking
  • Test Method: Monitoring heart rate variability, speech, and swallowing tests
• Accessory Nerve (XI)


  • Location: Originates from the upper spinal cord (C1-C5), enters the skull through the foramen magnum, and exits through the jugular foramen
  • Function: Controls muscles used in head movement and shoulder elevation
  • Test Method: Shoulder shrug and head turn against resistance
• Hypoglossal Nerve (XII)


  • Location: Leaves the medulla and exits the skull through the hypoglossal canal
  • Function: Controls tongue movements
  • Test Method: Stick out the tongue and move it side to side
• Neuron Components


  • Axon
  • Dendrites
  • Soma (Cell Body)
  • Schwann Cells
  • Axonal Terminal
  • Node of Ranvier
• Axon


  Carries electrical impulses away from the neuron's cell body
• Dendrites


  Receive electrical messages
• Soma (Cell Body)


  Contains the nucleus and cytoplasm
• Schwann Cells


  Support nerve regeneration
• Axonal Terminal


  Releases neurotransmitters
• Node of Ranvier


  Gaps in the myelin sheath that facilitate rapid signal transmission
• Components of the CNS

  • Brain
  • Spinal Cord
• Brain


  Composed of the cerebrum, cerebellum, and brainstem, the brain processes sensory information, regulates body functions, and facilitates intellect and emotion
• Olfactory Nerve (I)


  Responsible for the sense of smell. Has sensory receptors in the nasal cavity that detect odor molecules.
• Optic Nerve (II)


  Transmits visual information from the eye to the brain. Carries signals from the rods and cones in the retina to the visual cortex.
• Oculomotor Nerve (III)


  Controls the movement of the eye and the size of the pupil. Innervates the muscles that move the eye in different directions and constrict the pupil.
• Spinal Cord


  Delivers messages to and from the brain and the body, and executes reflex actions
• Trochlear Nerve (IV)


  Controls the movement of the eye, specifically the superior oblique muscle. Allows for downward and outward rotation of the eye.
• CNS Supporting Cells


  • Microglia
  • Astrocytes
  • Oligodendrocytes
  • Ependymal Cells
  • Schwann Cells (PNS)
• Trigeminal Nerve (V)


  Has both sensory and motor functions. Carries sensory information from the face, scalp, and mucous membranes of the mouth and nose. Controls the muscles of mastication (chewing).
• Abducens Nerve (VI)


  Controls the movement of the eye, specifically the lateral rectus muscle. Allows for outward movement of the eye.
• Facial Nerve (VII)


  Has both sensory and motor functions. Carries taste sensations from the anterior two-thirds of the tongue and controls the muscles of facial expression.
• Vestibulocochlear Nerve (VIII)


  Responsible for hearing and balance. Has two branches: the vestibular nerve, which controls balance, and the cochlear nerve, which controls hearing.
• Glossopharyngeal Nerve (IX)


  Has both sensory and motor functions. Carries taste sensations from the posterior one-third of the tongue and controls the muscles of swallowing.
• Vagus Nerve (X)


  Has both sensory and motor functions. Carries sensory information from the internal organs and controls the muscles of the larynx and esophagus.
• Microglia


  Act as the main form of immune defense in the CNS, active in immune surveillance and removing debris through phagocytosis
• Accessory Nerve (XI)


  Controls the muscles of the neck and shoulder, specifically the trapezius and sternocleidomastoid muscles.
• Hypoglossal Nerve (XII)


  Controls the muscles of the tongue. Allows for movement of the tongue for speech and swallowing.
• Astrocytes


  Maintain the blood-brain barrier, provide structural support, regulate ion and nutrient concentrations, and absorb and recycle neurotransmitters
• Oligodendrocytes


  Produce myelin in the CNS, which insulates neuronal axons to increase the speed at which electrical impulses propagate
• Ependymal Cells


  Line the ventricles of the brain and the spinal canal, involved in the production and circulation of CSF
• Schwann Cells (PNS)


  Part of the Peripheral Nervous System (PNS), they function similarly to oligodendrocytes by myelinating axons in the PNS, facilitating faster electrical impulses and aiding in the repair of damaged nerves