Cranial Nerves (Lecture) Flashcards
T or F: cranial nerves and their ganglia are part of the peripheral nervous system
True
Which cranial n. does not originate from the cranial cavity?
XI
Where do cranial nerves travel before exiting the named foramina and fissures?
On the Cranial Floor
What gives rise to the origin or a spinal nerve?
Fusion of dorsal (sensory) and Ventral (motor) rootlets
T or F: like spinal nerves cranial nerves also participate in forming similar nerve plexuses
False
T or F: crainial motor and sensory fibers of the cranial nerves are combined and attached at approximately the same point on the brain
True
What cranial nerves direct their fibers into sensory ganglia?
Most of the CNs that contain a sensory component:
- V, VII, VIII, IX, and X
e.g. Trigeminal Ganglion
T or F: the sensory ganglia of cranial nn. are often further removed from the origin of the nerve in the CNS than the sensory ganglia of spinal cords
True
What two cranial nerves are sensory yet do not associate with an organized sensory ganglia?
I and II
*Note: these nerves are purely sensory
What do GSA cranial nerves do?
Sensation from:
- Somatic Structures (skin, msucle, fascia, joints, tendons, peristeom etc.)
Sensation of Mucosal Lining:
- Oral Cavity
- Nasal Cavity
- Nasal Sinuses
- Pharynx
- Esophagus
- Larynx
- Trachea
- Middle Ear
What does the GVA component of cranial nerves do?
- Sensation from visceral structures of the head (carotid body and carotid sinus)
- Thoracic and Abdominal Viscera (Foregut and Midgut)
What does the SA component that’s unique to cranial nerves do?
- Sensation from specialized receptors in the head which are related to (Vision, Hearing, Equilibrium, Taste and Smell)
What cranial nerves contain a special sensory component?
- I, II, VII, VIII, IX, X
What does the GSE component of Cranial Nerves do?
- Motor innervation to skeletal muscle in the head derived from SOMITE MESODERM
What does the GVE component of Cranial nerves do?
- CNs involved
- Parasympathetic Motor Innervation to smooth muscle and glands of the head
- Only in CNs III, VII, IX, X
What does the BE (Branchiomeric Motor, SVE) component of Cranial Nerves do?
- Motor to Skeletal Muscle in head derived from branchial (pharygeal arch) mesoderm
Which skeletal muscles of the head:
- Paraxial vs. Pharyngeal Arch mesoderm
- Location
- Innervation
Paraxial Mesoder:
- More Posterior
- Orbit and Tongue (and a couple other structures)
- Traditional GSE innervation
Pharyngeal Arch Mesoderm:
- More Anterior
- Everything else
- Branchiomeric Motor Innervation (BE)
What arises from the 5th pharyngeal arch?
Nothing, it rudimentary
What is the innervation of each of the Pharyngeal Arches?
Arch 1 (mandibular arch): V3 Mandibular of Trigeminal (V)
Arch 2 (Hyoid arch): VII Facial
Arch 3: IX Gloassopharyngeal
Arch 4-6: X Vagus
Which Muscles innervated by cranial nerves develop from Somite mesoderm?
- All muscle of the tongue (CN XII), EXCEPT palatoglossus
- Skeletal muscles of Orbit (III, IV and VI)
- Sternocleidomastoid (XI)
- Trapezius (XI)
**THESE ARE NOT branchiomeric muscles
What muscles are derived from the first pharyngeal arch?
- Innervation
MAST-MATT
Muscles of MASTication:
- Medial pterygoid
- Lateral Pterygoid
- Temporalis
- Masseter
Mylohyoid muscle
Anterior belly of digastric muscle
Tensor Veli Palatini Muscle
Tensor Tympani Muscle
**Innervation = CN V3 mandibular
What muscles are derived from the second pharyngeal arch?
- Innervation
Muscles of Fascial Expression
Posterior Belly of Digastric Muscle
Stylohyoid muscle
Stapedius Muscle
**Innervation = CN VII facial
What muscle are derived from the third pharyngeal arch?
- Innervation
Stylopharyngeus Muscle
**CN IX; glossopharyngeal
What muscles are derived from the 4th and 6th pharyngeal arches?
- Innervation
- All Muscles of larynx
- All muscles of palate, EXCEPT tensor veli palatini (V3)
- All muscles of pharynx, EXCEPT stylopharyngeus (IX)
What is the cell type of GSE fibers in the spinal cord?
- Cell body location
- Multipolar
- Spinal Cord Gray Matter (Ventral horn)
What is the cell type of GSA fibers in the spinal cord?
- Cell body location
- Pseudounipoalr
- Dorsal Root Ganglia
Where are GSA cell bodies located for cranial nerves.
- Cell type
- Peripheral Ganglia
- GSA sensory neurons
What cranial nerves have sensory function?
- associated ganglia
CN
I - NONE
II - NONE
V - Trigeminal Ganglion
VII - Geniculate Ganglion
VIII - Spiral Ganglion, Vestibular Ganglion
IX - Superior Ganglion, Inferior Ganglion
X - Superior Gnanglion, Inferior Ganglion
Why don’t cranial nerves I or II associate with a sensory ganglion?
CN I - Diffusely Dispersed in Olfactory Epithelium
CN II - Diffusely Dispersed in Retina
GSE/BE Motor neurons
- Cell type
- ganglia
- Multipolar
- brain Motor Nuclei
GVE sympathetic - Spinal Nerves
- vertebral level
- pre and post ganglionic
- T1-L2
Preganglionic bodies - Lateral Horn
Postganglionic bodies - Chain or Collateral Motor ganglia
GVE parasypathetic - Spinal Nerves
- vertebral Level
- pre and post ganglionic
- S2-S4
Preganglionic bodies- spinal cord gray matter of those segments
Postganglionic bodies- terminal motor ganglia near targe (hindgut and pelvis only)
Sympathetic Fibers for the Brain
- Where do the arise?
- Synapse?
- Path?
T1 and T2 lateral horn (T1 = more important contribution)
- Ascend Sympathetic Truck to Superior Cervical Chain Ganglia
- Synapse with post ganglionic
- Post ganglionics exit the chain to form Carotid Peri-arterial Plexus
- Travel on vessles to target
What are the sympathetic Targets in the Heat and neck?
- Sweat Glands
- Dilator Pupillae Muscle
- Vascular Smooth muscle
- Superior tarsal Muscle
Parasympathetic Distribution in the Head
- Cranial nn.?
- Pre-ganglionic Bodies
- Post-ganglionic bodies
- Cranial Nerves III, VII, IX, and X
- Pre-ganglionic bodies- brainstem motor nuclei o=
- Post-ganglionic bodies - terminal motor ganglia of the head
What terminal Motor ganglia are associated with CN III, VII, IX, X?
CN III - Ciliary Ganglion
CN VII - Submandibular Ganglion, Pterygopalatine ganglion
CN IX - Otic Ganglion
CN X - Intrinsic Ganglia of the Viscera of the Thorax, Foregut, and Midgut
How do Postganglionic parasympathetic fibers reach their distination in the head?
Hitchhike on named branches of the 3 divisions of the trigeminal nerve (CN V)
Where does cranial n. X exit the cranial cavity and what branches does it give off?
- Fiber type
- Exits via the jugular Foramen as GSA, GVA, SA, BE, and GVE.
- Auricular N. - GSA
- Menigeal N. - GSA
- Sinus Nerve - GVA
- Pharyngeal Branch - BE
- Internal Branch of Superior Laryngeal nerve - GSA
- External Branch of Superior Laryngeal nerve - BE
- Recurrent (inferior) laryngeal n - BE
- Cardiac Branches - GVE
***NOTE: NO GSA
What is supplied by the Auricular N.
GSA to External Ear
What is supplied by the Meningeal N.
GSA to the Dura in the Posterior Cranial Fossa
What is supplied by the Sinus N.
GVA to Carotid Body
What is supplied by the Pharyngeal branch
BE to:
- palatoglassus
- All muscle of Pharynx (except stylopharyngeus)
- All muscles of soft palate (except Veli Palatini)
What is supplied by the Internal Branch of Superior Laryngeal N.
GSA:
- mucosal lining of laryngopharynx down to vocal folds
- root of the tongue and epiglottis
GVE (parasympathetic):
- Glands of the pharynx
SA:
- Taste at root of tongue and epiglottis
What is supplied by the External Branch of Superior Laryngeal N.
BE:
- Cricothyroid Muscle
What is supplied by the Recurrent (inferior) Laryngeal N.
BE:
- all other muscles of vocal folds (except cricothyroid
GSA:
- to mucosal lining of the larynx below vocal folds
What is supplied by the Cardiac Braches
GVE (parasympathetic)
- to heart
Are sensory and motor components of cranial nerves all mixed like they are for the spinal nerves?
NO
Where do Cranial Nerves originate?
Brain and Brainstem
Which cranial nerves have mixed function?
V, VII, IX, X
What cranial nerve structure is equivalent to the DRG in spinal nerves?
Sensory Ganglia
