Cranial Nerves Flashcards
What are cranial nerves?
They are nerve bundles that issue from the brain
They supply ( or innervate):
- Tissues of the head and neck region
- Some also supply viscera outside of the head and
neck region
They have specialisations that make them distinct from other nerves the body
Describe the cranial nerves. (not each individually)
There are twelve pairs of cranial nerves
They supply largely the head and neck region
- Muscles (efferent)
- Viscera (afferent & efferent)
- General sensation (afferent)
- Special sense organs (afferent)
Some supply viscera outside of the head and neck region
They are largely bilaterally symmetrical
They exit the brain from its inferior surface apart from one
2 are atypical in which they are brain tracts and not nerves
List the twelve cranial nerves
CNI Olfactory CNII Optic CNIII Oculomotor CNIV Trochlear CNV Trigeminal CNVI Abducent CNVII Facial CNVIII Vestibulochoclear CNIX Glossopharyngeal CNX Vagus CNXI Accessory CNXII Hypoglossal
Tell me about Cranial Nerve I.
Olfactory nerve
Sub-serves the sense of smell
An entirely “sensory nerve”
(Olfactory nerve process leave the nasal cavity to ascend intra-cranially via the cribriform plate of the ethmoid bone where they form the olfactory bulb)
Tell me about Cranial Nerve II.
Optic nerve Sensory nerve Sub-serves vision Test by checking: - Visual acuity - Colour vision - Visual fields - Pupillary reflexes - Fundoscopy
Tell me about Cranial Nerve III.
Oculomotor nerve
A mixed nerve
Somatic motor:
- All extraocular muscles
- Except:
- Lateral rectus (LR6)
- Superior oblique (SO4)
- Levator palpebrae superioris muscle of upper eyelid
Autonomic (parasympathetic):
- Constrictor pupillae of eyeTell me about Cranial Nerve IV.
Trochlear nerve
Supplies superior oblique only
When damaged, diplopia occurs on looking downwards and inwards
Tell me about Cranial Nerve V.
Trigeminal nerve
Three divisions:
- Ophthalmic (CNVi)
- Maxillary (CNVii)
- Mandibular (CNViii)
It is a mixed nerve:
- Sensory
- Ophthalmic
- Scalp, forehead, upper eyelid. dorsum of nose.
cornea and conjunctiva
- Maxillary
- Skin of lower eyelid, cheek, upper lip, mucosa of
nasal cavity, paranasal sinuses, palate, roots of
upper teeth
- Mandibular
- Skin of temples, cheeks, chin, mucosa of inner
check, anterior 2/3 tongue, roots of lower teeth
- Motor
- Mandibular division only
- Muscles of mastication
- Temporalis
- Masseter
- Medial pterygoidsTell me about Cranial Nerve VI.
Abducent nerve
Supplies lateral rectus muscle
When damaged patient is unable to look outwards
Tell me about Cranial Nerve VII.
Facial nerve Mixed nerve Motor: - Muscles of facial expression - Stapedius (hyperacusis) Sensory: - General sensation of the concha of the auricle and behind the ear - Taste in anterior 2/3 via chorda tympani Autonomic: - Glands: - Lacrimal - Submandibular - Sublingual - Mucous membranes of: - Nasopharynx - Paranasal sinuses - Hard palate - Soft palate
Tell me about Cranial Nerve VIII.
Vestibulocochlear nerve
Sub-serves 2 special sense modalities:
- Balance (vestibular nerve)
- Hearing (cochlear nerve)
Tell me about Cranial Nerve IX.
Glossopharyngeal nerve Mixed sensory and motor nerve Motor: - Branchiomotor - stylopharyngeus - Visceromotor (parasymp) - parotid gland Sensory: - Viscerosensory - carotid body & carotid sinus - Pharynx & middle ear - Special sensory - posterior 1/3 tongue Gag reflex - sensory limb
Tell me about Cranial Nerve X.
Vagus nerve
Mixed sensory & motor nerve
Motor:
- Intrinsic muscles of pharynx
- Muscles of the palate
- Smooth muscle - Bronchi, digestive tract
- Secretomotor - thoracic & abdominal viscera
Sensory:
- External ear, auditory canal & eardrum
- Pharynx & larynx
- Visceral sensation - thorax & abdomen
Tell me about Cranial Nerve XI.
Accessory nerve Has 2 anatomical divisions: - Cranial division - Spinal division Motor nerve: - Sternocleidomastoid - Trapezius
Tell me about Cranial Nerve XII.
Hypoglossal nerve
Motor
Muscles of the tongue
