HEAD/NECK : Cranial Nerves
• Special Sense Nerves
–I,II,VIII
• Somatic Motor Nerves
–Eye—III,IV,VI
–Tongue--XII
• “Rest of body” nerves
–IX,X,XI
• Face and jaws
–VII, V
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Nerve “targets” in head
• SENSORY
• MOTOR
Special
Smell
Vision
Hearing
Muscles
Glands
eyes
salivary
extrinsic sweat
intrinsic lacrimal
jaws
mucous
facial expression
larynx
tongue
throat
ear
General
skin
teeth
eye
tongue
oral cavity
nasal cavity
middle ear
throat
meninges
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Base of the skull—cranial nerves out
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
• Ethmoid (olfactory)
I. Olfactory
• Sphenoid (optic)
II. Optic
III. Oculomotor
IV. Trochlear
VI. Abducens
• Temporal (otic)
VII. Acoustic/Auditory/
Vestibulocochlear
• Face/Jaws
V. Trigeminal
VII. Facial
• Throat (rest of body)
IX Glossopharyngeal
X. Vagus
XI. Spinal Accessory
XII. Hypoglosal
Special Sense Nerves
NERVE
TARGET
EXIT FROM
CRANIAL CAVITY
I. Olfactory
Olfactory
epithelium
Cribiform plate
(ethmoid)
II. Optic
Retina
Optic canal
(sphenoid)
VIII. Auditory Inner ear
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Internal auditory
meatus (temporal)
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Somatic Motor Nerves
(eye muscles and tongue)
NERVE
TARGET
IV. Trochlear
Superior oblique m.
(with trochlea)
VI. Abducens
Lateral rectus
III. Oculomotor
•Sup.,med.,inf.rectus
(Also parasympathetic
• Inferior Oblique
to ciliary mm, constrictor
•Levator palpebrae
pupillae)
superioris
XII. Hypoglossal
Intrinsic, extrinsic
mm. of tongue
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
EXIT CR. CAVITY
Sup. Orbital fissure
(sphenoid)
“
“
Hypoglossal canal
(occipital)
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
“Rest of body” nerves
(all exit from jugular foramen)
NERVE
TARGET
 Somatic motor to larynx/pharynx
 Parasympathetic to most of gut
 Taste to back posterior pharynx
XI: (Spinal)  Motor to traps,
Accesory
sternocleidomastoid
IX: Glosso-  Sensory to carotid body/sinus
pharyngeal  Taste to posterior tongue
 Sensory to ear opening/middle
ear
 Parotid salivary gland
X: Vagus
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Cranial Nerves
• Twelve pairs:
– 2 attach to forebrain (Telen- &
Diencephalon)
– 10 attach to
brainstem
(Mes-, Met- and Myelencephalon)
• Names relate to
appearance or function
• Classification ?
Olfactory Nerve (= CN or N I)
1º function?
Origin?
Destination? _____________(By way of
cribiform plate of ethmoid)
Only CN directly attached to Cerebrum
Visual System
• Eye
• Accessory structures
– Eyebrows, eyelids, eyelashes, tear glands
– Protect eyes from sunlight and damaging particles
• Optic nerve (II)
– Tracts
– Pathways
• Eyes respond to light and initiate afferent
action potentials
Optic Nerve (N II)
1º fu?
ori?
dest? - by way of
optic foramen
of sphenoid to
Diencephalon
(optic chiasma)
and to occipital
lobe
Oculomotor (N III)
C: Motor
O: Mesencephalon
D: Somatic motor to superior, inferior, medial recti
and inferior oblique; visceral motor to intrinsic
eye muscles
by way of superior orbital fissure
Trochlear (N IV)
C: Motor
O: Mesencephalon
D: superior oblique
by way of superior orbital fissure
Trigeminal (N V)
C: Mixed
three major branches
1. ophthalmic (sensory)
2. Maxillary (sensory)
3. Mandibular (mixed)
O: face / nuclei of pons
D: sensory nuclei in pons / muscles of mastication
V: Trigeminal (3 nerves in 1!)
• V1. Ophthalmic
– Exits with eye muscle group (superior orbital fissure, through orbit to
superior orbital notch/foramina)
– Sensory to forehead, nasal cavity
• V2. Maxillary
– Exits foramen rotundum through wall of maxillary sinus to inferior
orbital foramina)
– Sensory to cheek, upper lip, teeth, nasal cavity
• V3. Mandibular
–
–
–
–
Exits foramen ovale to mandibular foramen to mental foramen
Motor to jaw muscles--Masseter, temporalis, pterygoids, digastric
Sensory to chin
Sensory to tongue
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Abducens
(CN VI)
C: Motor
O: Pons
D: Runs lateral rectus eye muscle
VII: Facial Nerve
(exits cranial cavity with VIII--internal auditory meatus)
• Facial muscles (five branches fan out over face from
stylomastoid foramen)
–
–
–
–
–
Temporal
Zygomatic
Buccal
Mandibular
Cervical
• “chorda tympani” (crosses interior ear drum to join V3 )
– Taste to anterior 2/3 of tongue
– Submandibular, sublingual salivary glands
• Lacrimal glands
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Facial (N VII)
C: Mixed
O: sensory from taste receptors of anterior
2/3 of tongue / motor from pons
D: Sensory to sensory nuclei of pons / motor
muscles of facial expression, visceral
motor to tear gland.
Human Anatomy, Frolich, Head/Neck IV: Cranial Nerves
Vestibulocochlear (N VIII)
C
O ?
D
Glossopharyngeal (CN IX)
C: mixed
O: sensory from
posterior 1/3 of
tongue / motor from
medulla oblongata
D: medulla /
muscles for
swallowing, parotid
gland
Vagus (N X)
C: Mixed
O: Sensation from pharyngeal area and
outer ear / motor from medulla
D: Sensory to medulla / visceral motor
to thoracic and abdominal
cavities and their organs. Major
motor pathway for ANS
Accessory (N XI) and
C: Motor
O: Motor nuclei of medulla and spinal cord
D: Swallowing, trapezius & scm muscles
Hypoglossal (N XII)
C: Motor
O: Motor nuclei of medulla
D: Tongue musculature
Mnemonic
Out On Our Table Top Are Fruits,
Very Green Vegetables And
Hamburgers
Extrinsic Eye Muscles
Anatomy of the Eye
• Three coats or tunics
– Fibrous: Consists of sclera and cornea
– Vascular: Consists of choroid, ciliary body, iris
– Nervous: Consists of retina
Anatomy of the Eye
• Fibrous tunic: Outer
– Sclera: White outer layer,
maintains shape, protects
internal structures, provides
muscle attachment point,
continuous with cornea
– Cornea: Avascular,
transparent, allows light to
enter eye and bends and
refracts light
• Vascular tunic: Middle
– Iris: Controls light entering
pupil; smooth muscle
– Ciliary muscles: Control lens
shape; smooth muscle
• Retina: Inner
– Contains neurons sensitive to
light
– Macula lutea or fovea
centralis: Area of greatest
visual acuity
– Optic disc: Blind spot
• Compartments
– Anterior: Aqueous humor
– Posterior: Vitreous humor
– helps maintain ocular
pressure
– keeps eye inflated
– largely responsible for shape
of eye
• Lens
– Held by suspensory ligaments
attached to ciliary muscles
Functions of the Complete
Eye
• Eye functions like a camera
• Iris allows light into eye
• Lens, cornea, humors focus light onto
retina
• Light striking retina is converted into action
potentials relayed to brain
The Retina
• Provides black
backdrop for increasing
visual acuity
• Sensory retina and
pigmented retina
• Photoreceptors
– Rods: Noncolor vision
• Rhodopsin reduction:
Light adaptation
• Rhodopsin production:
Dark adaptation
– Cones: Color vision
Sensory Receptor Cells
Rods and Cones
• Photoreceptors are depolarized in the dark,
continuously releasing neurotransmitter.
• When hyperpolarized by light-->decrease
amount of neurotransmitter.
• Rods- activated below starlight. Scotopic
vision, no color, poor acuity.
• Cones- activated with brighter light. Photopic
vision. Color vision.
Rods and Cones
• Most of what we think of as seeing is mediated
by cones.
• Individual loses cone vision, legally blind.
• Individual loses rod vision, experience difficulties
at low levels of illumination (night blindness).
• Cones are only receptors in fovea.
Other visual pathways
• Ganglion cells--> pretectum. Between thalamus
and midbrain. Coordinates the pupillary reflex.
• Suprachiasmatic nucleus of the hypothalamus.
Involved in day/night cycle and biological
rhythms.
• Superior colliculus in midbrain. Coordinates
head and eye movements.