Cranial Nerves II Flashcards
Innervation Chart
CN VII Modalities
- Facial nerve
- Visceromotor (GVE)
- Branchiomotor (SVE)
- Somatosensory (GSA)
- Viscerosensory (GVA)
- Special sensory (SVA)
Facial Canal
Between the IAM and stylomastoid foramen
CN VII exits the cranial cavity through…
the internal acoustic meatus
- Facial canal
- Geniculate ganglion
- contains cell bodies for sensory neurons (1o GSA/GVA/SVA) in CN VII
- Vestibular nerve (CN VIII)
- Cochlear nerve (CN XIII)
- Geniculate ganglion
- Chorda tympani
- Cochlea
- Semicircular canals (vestibular apparatus)
- Malleus
- Tympanic membrane
- Auditory canal
CN VII: Visceromotor (GVE)
- Lacrimal gland
- Nasal mucosa
- Sublingual gland
- Submandibular gland
- Functions
- parasympathetic: stimulates productions of tears, mucous, and saliva
CN VII: Branchiomotor (SVE)
- Muscles of facial expression
- Stapedius muscle
- Posterior belly of digastric muscle
- Stylohyoid muscle
CN VII: Somatosensory (GSA)
External ear (pinna)
CN VII: Viscerosensory (GVA)
- Sensation from the mucosal lining of the nasopharynx and soft palate
- Follows the same path as SVA fibers
CN VII: Special sensory (SVA)
- taste of anterior 2/3 of tongue
- synapse in geniculate ganglion
- Chorda tympani n.
CN VIII
- Vestibulocochlear nerve
- Modalities: SSA
- Sensations of hearing (from cochlea) and balance (from vestibular apparatus)
Middle ear function
transmit sounds between tympanic membrane (ear drum) and the cochlea (inner ear); convert mechanical vibrations to pressure waves in cochlear fluid
3 ossicles of middle ear
- Malleus (“hammer”): sits on the tympanic membrane
- Incus (“anvil”)
- Stapes (“stirrup”): sits on the oval window of the cochlea
Middle ear muscles
- Stapedius m.
- CN VII (SVE)
- Stabilize stapes
- Tensor tympani m.
- CN V3 (SVE)
- Dampens sounds (e.g. chewing sounds)
The middle ear connects
- pharynx via the auditory tube
- mastoid air cells via the aditus ad antrum
Inner ear
- Cochlea
- spiral shaped organ responsible for hearing
- Vestibular apparatus
- balance and orientation in space
- semicircular canals: measure head rotations
- otoliths: measure linear acceleration, contained within utricle and saccule
CN IX modalities
- Glossopharyngeal nerve
- Viscermotor (GVE)
- Branchiomotor (SVE)
- Somatosensory (GSA)
- Viscerosensory (GVA)
- Special sensory (SVA)
CN IX: Visceromotor (GVE)
- Parotid gland
- Parasympathetic, stimulates saliva production
CN IX: Branchiomotor
Stylopharyngeus m.
CN IX: Somatosensory (GSA)
Posterior 1/3 of tongue
CN IX: Special Sensory (SVA)
Taste from posterior 1/3 of tongue
CN IX: Viscerosensory (GVA)
- Carotid sinus (baroreceptors)
- Carotid body (chemoreceptors)
- Upper pharynx
- Oro- and naso- pharynx
- Middle ear
CN X Modalities
- Vagus nerve
- Visceromotor (GVE)
- Branchiomotor (SVE)
- Somatosensory (GSA)
- Viscerosensory (GVA)
- Special sensory (SVA)
CN X: Visceromotor (GVE)
- Mucous membranes
- pharynx
- larynx
- trachea
- thoracic organs
- heart and lungs
- abdominal organs
- foregut and midgut
CN X: Branchiomotor (SVE)
- Soft palate mm.
- Levator veli palatini m.
- Palatopharyngeus m.
- Palatoglossis m.
- Salpingopharyngeus m.
- Pharyngeal constrictors
- Intrinsic laryngeal muscles (via recurrent laryngeal nerve)
- Cricothyroid m. (via external branch od superior laryngeal nerve)
CN X: Somatosensory (GSA)
- External ear and canal
- Tympanic membrane (external)
CN X: Viscerosensory (GVA)
- Inferior pharynx
- Laryngopharynx
- Larynx
- Thoracic organs
- heart and lungs
- aortic body
- Abdominal organs
- foregut and midgut
CN X: Special sensory (SVA)
- Sense of taste
- Root of tongue
- Epiglottis
CN IX
- Spinal accessory nerve
- Two parts:
- Cranial part (CN XIC)
- Spinal part (CN XIS)
- Modalities
- SVE (CN XIC)
- GSE (CN XIS)
- Two parts:
Cranial part of CN XI: Branchiomotor (SVE)
- Accompanies CN X
- Motor part of pharyngeal plexus
- Musculus uvulae m.
- Levator veli palatini m.
CN XIC is functionally (clinically) and often anatomically indistinguishable from CN X
Spinal part of CN XI: Somatomotor (GSE)
- Trapezius m.
- Sternocleidomastoid m.
CN XII Modalities
- Hypoglossal Nerve
- Somatomotor (GSE)
CN XII: Somatomotor (GSE)
- Extrinsic tongue mm.
- Genioglossus m.
- Hyoglossus m.
- Styloglossus m.
- Intrinsic tongue mm.
Clinical tests for lower cranial nerves
- Shrug test
- elevate shoulders against resistance
- Motor: Accessory nerve (CN XI)
- structure: trapezius
- Head turn
- turn head against resistance
- motor: accessory nerve (CN XI)
- structure: SCM muscle
- Tongue protrusion
- Motor:
- Tongue deviates towards side of lesion
- Unopposed genioglossus m. (protracts tongue)
- Left hypoglossal nerve lesion
- Soft palate- uvula position
- left CN X/XIC lesion (nucleus ambiguus)
- uvula deviates away from side of lesion
- unopposed levator veli palatini m. (elevates uvula)
