Nervous System and Integument > Cranial Nerves > Flashcards

Cranial Nerves Flashcards

(19 cards)

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1
Q

CN I

A
  • Olfactory Nerve
  • Transmits the sense of smell
  • rostral
  • -Olfactory nerve attaches to olfactory bulb
  • F. Exit: Cribiform plate
  • Sensory fibres
  • SVS
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2
Q

CN II

A
  • Optic N.
  • Transmits visual information to the brain
  • Optic nerve attaches to diencephalon (optic chiasma)
  • F. Exit: Optic canal
  • Sensory
  • SSS
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3
Q

CN III

A
  • Oculomotor N.
  • innervates the eye muscles
  • Att: Midbrain
  • Exit: Orbital fissure
  • Motor
  • GSM, GVM
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4
Q

CN IV

A
  • Trochlear N.
  • Innervates the superior oblique muscle of the eye
  • ATT: Midbrain (dorsal)
  • Exit: Orbital fissure
  • Motor
  • GSM
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5
Q

CN V

A
  • Trigeminal N.
  • Recieves sensation from the face
  • Innervates the muscle of mastication
  • recieves pain sensation from eyeball, causes retraction
  • ATT: Pons
  • Exit: Orbital fissure, F. rotundum, F. ovale
  • Sensory and Mixed
  • GSS, SVM
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6
Q

CN VI

A
  • Abducens N.
  • Innervates the lateral rectus m.
  • ATT: Medulla Oblongata
  • Exit: Orbital Fissure
  • Motor
  • GSM
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7
Q

CN VII

A
  • Facial N.
  • Provides motor innervation to muscles of facial expression
  • ATT: Medulla Oblongata
  • exit: sylomastoid foramen
  • Mixed: Motor and Sensory
  • SVM, GVM, SVS
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8
Q

CN VIII

A
  • Vestibulocochlear N. (has loads of other names)
  • Senses sound, rotation & gravity
  • ATT: Medulla Oblongata
  • Exit: Int. accoustic meatous
  • Sensory
  • SSS
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9
Q

CN IX

(“69”)

A
  • Glossopharyngeal N.
  • Motor: Pharynegeal musculature
  • Sensory: posterior part of the tongue, tonsil, pharynx
  • ATT: Medulla Oblongata
  • EX: Jugular foramen
  • Mixed
  • GVM, SVM,GVS,SVS
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10
Q

CN X

A
  • Vagus N.
  • Motor: heart, lungs, bronchi & GIT
  • Sensory: heart, lungs, bronchi, trachea, GIT & external ear
  • ATT: Medulla Oblongata
  • Exit: Jugular foramen
  • Mixed
  • GVM,SVM,GSS, GVS
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11
Q

CN XI

A
  • Cranial Accessory (Accessory) N.
  • Controls sternocleidomastoid and trapezius muscles
  • ATT: Medulla Oblongata
  • Motor
  • GSM??
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12
Q

CN XII

A
  • Hypoglossal N.
  • Provides motor innervation to the muscles of the tongue
  • ATT: Medulla Oblongata
  • Exit: Hypoglossal canal
  • Motor
  • GSM
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13
Q

Cranial Nerves

A
  • Definition: A nerve attaching to the brain (as oppose to spinal nerves which attach to the spinal cord) Supply: Most structures in head (and some beyond) so MAJOR TOPIC
  • Structures in the head supplied by cranial nerves
  • Only 2 structures not supplied by cranial nerves, but vast majority are-Some cranial nerves supply beyond the head
  • Numbering/ nomenclature: All mammals have 12 cranial nerves
  • Attachment to brain:
  • Olfactory nerve attaches to olfactory bulb- I attaches to olfactory bulb (which is still part of the brain)- does so over its surface using very fine filaments. Nerve fibers are all separate unlike most cranial nerves. Separate filaments are very imp. Characterisitc to cranial nerve I
  • Optic nerve attaches to diencephalon
  • All other cranial nerves (3-12) attach to the brainstem (rostral to caudal)- NOT JUST THE MEDULLA OBLONGATA
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14
Q

Functional Composition of Cranial Nerves

A

All spinal nerves are mixed in composition, but cranial nerves can be:

  • Mixed (V, VII, IX, X) - Trigeminal, Facial, Glossopharyngeal, Vagus
  • Purely Sensory (I, II, VIII)- Olfactory, Optic, Vestibulocochlear
  • Purely Motor (III, IV, VI, XI, XII)- Oculomotor, Trochlear, Abducens, Accessory, Hypoglossal
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15
Q

Nerves Types

(Spinal Nerves)

A
  • Spinal Nerves: Have 2 types of motor fibres & 2 types of sensory fibres

​

  • GSM- General Somatic Motor- supply skeletal muscles (aka somatic muscle- derived from somites). supply striated skeletal muscles. All innervated by GSM type
  • GVM- General Visceral Motor (autonomic)- supply the viscera (organs). general visceral motor fibres. Supply other structures than skeletal striated. Cardiac, glandular, smooth, etc. other excitable tissues
  • GSS- General Somatic Sensation- convey info from skin, proprioceptors. general somatic sensory fibres. Convey info from skin (touch, pain) and also sensors from proprioceptors (muscles, tendons, joints, etc.). Sense inflammation back into the CNS
  • GVS- General Visceral Sensation (viscera)- convey info about visceral sensations. general visceral sensory info. From organs (i.e. GIT). Not always clear of what is happening in the gut but will let the CNS know if there is distention for sure. Horses–> colic. Horses feel pain from distention. Also pain sensed by lack of blood supply to an organ (heart attack, ischemia). A lot of these organs have their own nerve regulation, but will relay certain signals back to CNS
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16
Q

Nerve Types

(Cranial Nerves)

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A
  • Cranial nerves: Have the same fibre types as spinal nerves & 3 additional ones (1 motor, 2 sensory):
  • SVM- Special Visceral Motor- aka Branchial Motor fibres- supply muscles but develop from pharyngeal/ branchial arches in the embryo (not from the somites).
  • motor fibres which supply striated muscles of body (same type of tissue) which are branchial arches/pharyngeal arches origin (i.e. muscles that move jaws in mastication, mandible muscles). Other types as well. Innervated by this nerve fibre type) rather than somatic origin. Different embryonic origin!
  • SSS- Special Somatic Sensory- convey info from outside of body (including sight, sound & vestibular). Pick up sensory information from outside the body. Outside surfaces of the body. (i.e. cornea of the eye). Visual information from outside that enriches the eye. Also hearing: sound waves reach the body from outside and reach sensory tissues through ear canal
  • SVS- Special Visceral Sensory- info comes from inside the body/ organs. information picked up within the body. Taste: picked up from taste buds, etc from within the body. Olfaction: sense of smell is picked up within the nasal cavity
17
Q

Location of Nerve Cell Bodies and Connections

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A
  • After development of the pontine flexure, the alar lamina moves to lie lateral to the basal lamina
  • Sensory nuclei within the CNS are composed of clumps of nerve cell bodies of association neurones (interneurons) which develop from the alar lamina of the NT
  • Receive sensory input from sensory fibres which develop from the neural crest ∴ have their cell bodies in ganglia outside of the CNS. -Sensory (Afferent) neurons develop from neural crest rather than neural tube. Adult neural crest cells are found outside of CNS on either side it in PNS in clumps called GANGLIA.
  • Motor fibres develop from basal lamina of NT ∴ their cell bodies come to lie within the CNS. The BL is divided into 3 different territories from which the 3 different fibre types of motor neurones develop: GSM=medial, SVM=central & GVM= lateral
  • A single cranial nerve can contain different motor fibre types e.g. CNIII contains GSM & GVM
18
Q

Ganglia

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A
  • Collection of nerve cell bodies in the peripheral NS
  • Not within the CNS
  • Think of sensory (afferent neurons developing from neural crest)
  • Various cranial nerves have ganglion associated with them, but some don’t - because some are purely motor and all their ganglion will be located within the CNS! (all hterefore being a basal lamina origin)
19
Q

Cranial Nerve Nuclei

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A
  • Neural tube: forms early stages of the spinal cord and brain
  • Alar Lamina lies dorsal to the Basal Lamina on the tube
  • As the hindbrain develops further, get this splitting of the pontine flexure –> thin roof plate will become much wider to a wider horizontal cavity
  • After this split the Alar lamina lies lateral to the basal lamina! (which lies closer to the midline)
  • Basal Lamina: is the source of the many efferent (motor) neurons of entire NS. Including some CN where most originate from the brain stem (pons/medulla oblongata) .cell bodies therefore close to midline (GSM, SVM, GVM)

​-these different types of fibres develop from different parts of the basal lamina which accounts for final locations of cell bodies in the brain stem. GSM- most medial- general somatic motor column, GVM-most lateral, SVM (CN only)- intermediate origin

  • ex: general somatic motor column of basal lamina will have cell bodies along it supplying those cranial nerves only with that fibre type (III, IV, XI, and XII)
  • Alar lamina: Sensory Fibres! GVS- more medial, SSS/SVS- intermediate, GSS lateral
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