Transcript cranial nerves ppt

Cranial Nerves:
I & II
I. Olfactory -- sensory (smell)
°
°
°
nerves embedded in nasal mucosa
enter cranial cavity through olfactory foramina in
cribriform plate (ethmoid bone)
synapse with other neurons in olfactory bulb
impulse continues through olfactory tract
II. Optic -- sensory (sight)
°
°
°
°
nerves extend from retina
enter cranial cavity through optic foramina
(sphenoid bone)
medial fibers cross at optic chiasma (sits in
chiasmatic groove of sphenoid bone)
fibers continue as optic tracts
Illustration
Olfactory Nerve (I) – contain the sensory
nerves of smell
Optic Nerve (II) – sensory nerve of vision
Visual Fields
of the Eyes
Fig. 16.12, p. 584
Cranial Nerves:
III & IV
III. Oculomotor – motor
°
°
extrinsic muscles of eye except lateral rectus and
superior oblique (eye movement)
intrinsic smooth muscle of iris (constriction in
response to brightness) and lens (controls shape
for focusing)
IV. Trochlear – motor
°
superior oblique muscle of eye
Illustration
Oculomotor Nerve (III) – “eye mover”
innervates muscles that supply the eyeball
Trochlear Nerve (IV) – means “pulley” it
innervates an extrinsic eye muscle that loops
through a pulley-shaped ligament
Cranial Nerves:
V
V. Trigeminal – mixed; largest cranial nerve, major
sensory nerve serving face (skin, mucosae of
mouth, surface of eyes), also important motor nerve
(chewing)
mandibular division – motor to chewing muscles;
sensory from anterior tongue and lower teeth
- mandibular division exits/enters through foramen
ovale
° ophthalmic and maxillary divisions -- sensory
- ophthalmic division from area around eye and
forehead enters through superior orbital fissure
- maxillary division from area around nose, cheeks,
upper jaw enters through foramen rotundum
°
Illustration
Trigeminal Nerve (V) – supplies sensory
information to the face and chewing muscles
Cranial Nerves:
VI & VII
VI. Abducens – motor
°
°
lateral rectus muscle of eye
enters/exits cranial cavity through superior
orbital fissure
VII. Facial – mixed
°
°
°
°
sensory from taste buds on tongue
motor (ANS) to salivary and lacrimal glands
motor (somatic) to muscles of facial expression
enters/exits through stylomastoid foramen
Illustration
Abducens (VI) – controls the extrinsic eye
muscles that abduct (turn it laterally) the
eyeball
Facial Nerve (VII) – a large nerve that
innervates muscles of facial expression
Cranial Nerves:
VIII & IX
VIII.Vestibulocochlear – sensory
°
°
hearing and balance from inner ear
enters through internal acoustic meatus
IX. Glossopharyngeal -- mixed
°
°
°
motor to pharyngeal muscles and salivary
glands
sensory from taste buds
exits/enters through jugular foramen (border of
temporal and occipital bones)
Illustration
Vestibulococlear Nerve (VIII) – two branches
one for hearing, one for balance
Glossopharangeal (IX) – name means “tongue and
pharynx” innervates the tongue and pharynx
Cranial Nerves:
X
X.Vagus -- mixed
°
°
°
°
motor (somatic) to pharynx and larynx for
swallowing and speaking
motor (ANS: parasympathetic) innervation to
heart, lungs and abdominal viscera
sensory info from thoracic and abdominal
viscera
exits/enters through jugular foramen (border of
temporal and occipital bones)
Illustration
Vagus (X) –
name means
“wanderer”
only cranial
nerve to
extend
beyond the
head
Cranial Nerves:
XI & XII
XI. Accessory -- motor
°
°
muscles of neck
enters/exits through jugular foramen (border
of temporal and occipital bones)
XII. Hypoglossal – motor
°
°
muscles of tongue (chewing, swallowing and
speech)
enters/exits through hypoglossal canal
(superior to occipital condyles of occipital
bone)
Illustration
Accessory Nerve (XI) – joins to help the
vagus nerve, innervates neck musculature
Hypoglossal (XII) – innervates some tonguemoving muscles
Cranial Nerves: I - XII
Fig. 13.4, p. 484