0414 - Cranial Nerves 2 - CS Flashcards
a. Describe the types of nerve fibres in CN V
1-Mainly sensory - tactile innervation to most superficial and deep facial structures2-Some (important) motor3-Something special - jaw proprioceptors4-Autonomics: Sympathetics - picks up postganglionic axons of superior cervical ganglion, from the carotid nerve
aa. What are the three branches of V and what type of nerve fibres do they contain?
V1: opthalmicV2: maxillaryV3: mandibular
b. Describe the type of fibres in CN VII
facial (V) nerve: mixture of 4 types1-Some (important) sensory - skin on external ear2-Mainly motor - muscles of facial expression3-Something special - taste anterior ⅔ o tongue4-Autonomic: Major parasympathetic component - provides (almost) all parasymp to face and deep face
c. Describe the type of fibres in CN IX
1-Sensory - tactile from post ⅓ of tongue, visceral sensory from carotid arterySensory - from middle ear and auditory tube2-Some motor - to striated muscles in pharynx3-Special - taste from posterior ⅓ of tongue4-Parasympathetic - innervate the parotid gland
d. Describe the type of fibres in CN X
1-Sensory - some tactile fibres2-Motor - contains fibres from XI that innervate striated muscle in the larynx and pharynx2-Parasympathetic - innervate the heart, bronchi and GIT
e. Describe the type of fibres in CN XI
1-Motor - Made up of fibres from two different sources - spinal and cranial that innervate striated muscle in the larynx and pharynx
1a. Describe the attachment to the brainstem, intracranial course and cranial exit of CN V
Trigeminal nerve (V) emerges from the brainstem at the anteriolateral surface of the pons as a large sensory root and small motor root. It continues towards the middle cranial fossa where its sensory root expands into the trigeminal ganglion. It then branches into three:V1: goes under the anterior clinoid process to enter the orbit via the superior orbital fissure (cranial exit) then branches into three (frontal, lacrimal and naso-ciliary)V2: passes through the foramen rotundum (cranial exit) to reach the pterygopalatine fossa then gives off several branches (including the zygomatic branch which communicates with CN VII by receiving postganglionic parasympathetic fibres)V3: passes through foramen ovale (cranial exit) to enter the infratemporal fossa then branches into four sensory branches (auriculotemporal, inferior alveolar, lingual, nervus spinosum) and communicates with CN VII (lingual branch is joined by chorda typani branch of CN VII) and some motor branches (to muscles of mastication)
1b. Describe the type of fibres, attachment to the brainstem, intracranial course and cranial exit of CN VII
Facial nerve emerges from the lateral surface of the brainstem, between the pons and medulla oblongata as a large motor root and smaller sensory and parasympathetic root (nervus intermedius). These roots enter the skull through the internal acoustic meatus then reform within the facial canal, distal to the ganglion, then split into three branches:1. ‘Motor’ nerve - exits skull through stylomastoid foramen and innervate the muscles of facial expression2. Chorda tympani - crosses the ear drum and exits the skull near the foramen ovale and carries parasymp fibres and taste fibres and communicates w CN V (joins branch of V3)3. Greater petrosal nerve - carries only pregang parasymp fibres and branches off at the geniculate ganglion. Has its own ganglion at the pterygopalatine ganglion (behind the orbit)
How many ganglions does CN VII have?
1x sensory ganglion - geniculate2x parasympathetic ganglia - pterygopalatine and submandibular
What nerve is affected by Bell’s Palsy and why is this condition particularly dangerous?
Facial nerve (VII).Affects muscles of facial expressionDangerous because can’t blink, cornea dries out
1c. What is the cranial exit for CNs IX, X and XI?
all through the jugular foramen
1d. Describe the attachment to the brainstem, intracranial course and cranial exit of CN IX and X
Glossopharangeal (IX) nerve arises from the brainstem as several rootlets on the anterolateral surface of the upper medulla oblongata.Vagus (X) nerve arises from the brainstem as a group of rootlets on the anteriolateral surface of the medulla oblongata (just inferior to IX)Rootlets of IX and X both cross the cranial fossaIX and X rootlets all enter the skull at the jugular foramenWithin the jugular foramen, the IX rootlets merge to form the IX nerve and the X rootlets merge to form X.All exit the skull via the jugular foramen. Immediately outside the jugular foramen are the superior and inferior ganglia
1d. Describe the attachment to the brainstem, intracranial course and cranial exit of CN XI
Accessory nerve (XI) roots arise from motor neurons in the upper five segments of the cervical spinal cord.Rootlets of XI join together as they ascend.XI enters the cranial cavity through the foramen magnum.Passes through the cranial fossa and exits via the jugular foramen, along with IX and X
- Explain communications between V and VII, and its significance in innervation of the face and deep face
There are 3 crucial areas in which there are exchanges of fibres between V and VII#1 TEARS: Zygomatic branch of V2 (innervates skin lateral to orbit) receives postganglionic parasympathetic fibres (secretomotor fibres that make tears) from ? branch of VII and carries them to the lacrimal gland#2 SPIT: Lingual branch of V3 (tactile fibres to tongue) is joined by the chorda tympani branch of VII (taste from anterior tongue and preganglionic parasympathetic sublingual and submandibular glands that make salivar)#3 SNOT: Parasympathetic fibres from VII join branches of V2 that (supply mucosa of nasal and paranasal synuses)
3. Explain the relationships between CNn IX, X and XI
All three exit the skull through the jugular foramenCNs X and XI each have a superior and inferior ganglion (four ganglions in total)The cranial component of XI joins X at X’s inferior ganglion (see diagram)Fibres from X branch off at X’s superior ganglion and join IX at IX’s inferior ganglionIX has many small parts (including sensory, motor, special sensory, parasymp)Together they:1. Provide parasympathetic innervation to the parotid gland (IX), the bronchial tree (X), the heart (X), and to the GIT (X) as far as the left colic flexure.2. Sensory innervation from the soft palate (IX), larynx, pharynx (IX) and middle ear (IX).3. Special sensory (taste) info from the posterior ⅓ of the tongue and soft palate (IX).4. Info about blood pressure, blood chemistry from the division of the carotid (IX) and from the aortic synus (X)5. Motor innervation of the pharyngeal (IX, XI), laryngeal (XI) muscles and to the large superficial neck/back muscles
