Cranial Nerves Flashcards
1
Q
Cranial nerves have four types of functions…
They are = ?
Cranial Nerves
A
- 1) Somatosensory information from the skin and muscles of the face and from the temporomandibular joint (TMJ).
- 2) Special sensory information related to visual, auditory, vestibular, olfactory, and visceral sensations.
- 3) Motor innervation to the muscles of the face, eyes, tongue, jaw, and two neck muscles.
- 4) Parasympathetic regulation of pupil size, curvature of the lens of the eye, heart rate, blood pressure, breathing, and digestion.
2
Q
CN I = ?
Cranial Nerves
A
Cranial Nerve 1
- Olfactory nerve
- Sensory
- Sense of smell
3
Q
CN II = ?
Cranial Nerves
A
Cranial Nerve 2
- Optic nerve
- Sensory
- Vision
4
Q
CN III = ?
Cranial Nerves
A
Cranial Nerve 3
- Oculomotor nerve
- Motor
- Eye movements; papillary constriction and accommodation
5
Q
CN IV = ?
Cranial Nerves
A
Cranial Nerve 4
- Trochlear nerve
- Motor
- Eye movements (intorsion, downward gaze)
6
Q
CN V = ?
Cranial Nerves
A
Cranial Nerve 5
- Trigeminal nerve
- Sensory and motor
- Somatic sensation from face, mouth, cornea; muscles of mastication
7
Q
CN VI = ?
Cranial Nerves
A
Cranial Nerve 6
- Abducens nerve
- Motor
- Eye movements (abduction or lateral movements)
8
Q
CN VII = ?
Cranial Nerves
A
Cranial Nerve 7
- Facial nerve
- Sensory and motor
Controls:
- Muscles of facial expression
- Taste from anterior tongue
- Lacrimal & salivary glands
9
Q
CN VIII = ?
Cranial Nerves
A
Cranial Nerve 8
- Vestibulocochlear nerve (auditory nerve)
- Sensory
- Hearing; sense of balance
10
Q
CN IX = ?
Cranial Nerves
A
Cranial Nerve 9
- Glossopharyngeal nerve
- Sensory & motor
Sensation from:
- Posterior tongue & pharynx
- Taste from posterior tongue
- Carotid baroreceptors and chemoreceptors
11
Q
CN X = ?
Cranial Nerves
A
Cranial Nerve 10
- Vagus nerve
- Sensory & motor
Major Functions:
- Autonomic functions of gut
- Sensation from larynx and pharynx
- Muscles of vocal cords & swallowing
12
Q
CN XI = ?
Cranial Nerves
A
Cranial Nerve 11
- Spinal accessory nerve
- Motor
- Shoulder and neck muscles
13
Q
CN XII = ?
Cranial Nerves
A
Cranial Nerve 12
- Hypoglossal nerve
- Motor
- Movements of tongue
14
Q
What is the primary function of cranial nerve I, the olfactory nerve?
Cranial Nerves
A
The primary function of the olfactory nerve is sensory, transmitting information from nasal receptors to the olfactory bulb, and then to the olfactory cortex located in the insula.
15
Q
How often do the cells of the olfactory nerve undergo replacement, and how does this process change with age?
Cranial Nerves
A
- The cells of the olfactory nerve undergo replacement approximately every 30-90 days, but this process declines with age.
16
Q
What parts of the brain does the olfactory nerve transmit information to within the limbic system?
Cranial Nerves
A
- The olfactory nerve transmits information to the amygdala for emotional responses to odor and to the parahippocampal gyrus for perceiving the quality of aromas.
- Additionally, it sends information to the secondary olfactory area in the orbitofrontal cortex for making value judgments and decisions.
17
Q
What are the components of the limbic system?
Cranial Nerves
A
- The components of the limbic system include:
- Cingulate gyrus
- Fornix
- Amygdala
- Hippocampus
18
Q
What functions are associated with the limbic system?
Cranial Nerves
A
The limbic system is associated with learning, emotions, and processing special sensory information such as afferents for olfaction.
19
Q
What are the three concentric layers that make up the wall of the eye?
Cranial Nerves
A
(1) Outer layer:
- Sclera = outermost tough connective tissue
- Cornea = transparent, allow light to enter
- Conjunctiva
(2) Middle layer (vascular):
- Ciliary body = ciliary muscles connected to lens by zonular fibers
- Lens = focus light on retina, visual information is transduced
- Iris = 2 layer of pigmented smooth muscle, pigment determines the eye color, regulates the diameter of pupil
- Pupil = hole in the center of iris that allow light to enter
(3) Inner layer (neural):
- Retina = photoreceptors that detect light waves, conversion of light energy to electric energy
- Fovea = greatest visual acuity
- Optic disk = optic nerve and blood vessels supplying the eye pass through the retina- blind spot
20
Q
The eye
Outer layer = ?
(one part is not pictured )
Cranial Nerves
A
(1) Outer layer:
- Sclera = outermost tough connective tissue
- Cornea = transparent, allow light to enter
- Conjunctiva
21
Q
The eye
Middle layer = ?
Cranial Nerves
A
(2) Middle layer (vascular):
- Ciliary body = ciliary muscles connected to lens by zonular fibers
- Lens = focus light on retina, visual information is transduced
- Iris = 2 layer of pigmented smooth muscle, pigment determines the eye color, regulates the diameter of pupil
- Pupil = hole in the center of iris that allow light to enter
22
Q
The eye
Inner layer = ?
Cranial Nerves
A
(3) Inner layer (neural):
- Retina = photoreceptors that detect light waves, conversion of light energy to electric energy
- Fovea = greatest visual acuity
- Optic disk = optic nerve and blood vessels supplying the eye pass through the retina- blind spot
23
Q
CN II: Optic
Optic nerve transmits visual information from the retina to the = ?
Cranial Nerves
A
CN II: Optic (sensory):
- Optic nerve transmits visual information from the retina to the lateral geniculate body of the thalamus, then to the visual cortex:
- Visual Information Flow: From the retina, to the midbrain, to the lateral geniculate, and then to the visual cortex, where conscious vision is provided.
24
Q
CN II: Optic
Optic nerve transmits visual information from the retina to the lateral geniculate body of the thalamus, then to the visual cortex:
- Visual signals in this pathway are involved in = ?
Cranial Nerves
A
CN II: Optic (sensory):
- Optic nerve transmits visual information from the retina to the lateral geniculate body of the thalamus, then to the visual cortex:
- Visual signals in this pathway are involved in analysis and conscious awareness of visual information
25
# **CN II**: Optic
Visual signals sent to the midbrain are involved in reflexive responses of the pupil.
## Footnote
*Cranial Nerves*
**CN II**: Optic (sensory):
* To nuclei in the midbrain: Visual signals sent to the midbrain are involved in ***reflexive responses*** of the pupil.
26
**?**
## Footnote
*Cranial Nerves*
**Pupil**:
27
**?**
## Footnote
*Cranial Nerves*
CN II: **Optic Nerve**:
28
**?**
## Footnote
*Cranial Nerves*
**Optic Chiasm**:
29
**?**
## Footnote
*Cranial Nerves*
**Optic Tract**:
30
**?**
## Footnote
*Cranial Nerves*
**Lateral Geniculate body**:
31
**?**
## Footnote
*Cranial Nerves*
**Visual Cortex**:
32
CN's involved in speaking = **?**
## Footnote
*Cranial Nerves*
**-** Speaking requires cortical control and coordinated action of CN's 5, 7, 10, 12 for articulation and sound production.
* **CN V - Trigeminal**:
* **CN VII - Facial**:
* **CN X - Vagus**:
* **CN XII - Hypoglossal**:
33
CN Involved in Swallowing = **?**
## Footnote
*Cranial Nerves*
Swallowing Process:
**-** **Oral Stage**: Involves lips, jaw, tongue movements
* CN V - Trigeminal
* CN VII - Facial
* CN XII - Hypoglossal
**Pharyngeal Stage**: Soft palate, pharynx, larynx movements
* CN IX - Glossopharyngeal
* CN X - Vagus
**Esophageal Stage**: Peristalsis moves food into the stomach.
* CN X - Vagus
34
# Functions of Cranial Nerves
Sensory = **?**
* A ) Transmit sensory information from specific regions.
* B ) Control voluntary and involuntary muscle movements.
* C ) Regulate visceral functions such as digestion, heart rate, and pupil constriction.
* D ) Mediate various reflex actions like blinking, gagging, and swallowing
## Footnote
*Cranial Nerves*
**-** Functions of Cranial Nerves:
* **Sensory**: Transmit sensory information from specific regions.
## Footnote
* **Motor**: Control voluntary and involuntary muscle movements.
* **Autonomic**: Regulate visceral functions such as digestion, heart rate, and pupil constriction.
* **Reflexes**: Mediate various reflex actions like blinking, gagging, and swallowing
35
# Functions of Cranial Nerves
Motor = **?**
* A ) Transmit sensory information from specific regions.
* B ) Control voluntary and involuntary muscle movements.
* C ) Regulate visceral functions such as digestion, heart rate, and pupil constriction.
* D ) Mediate various reflex actions like blinking, gagging, and swallowing
## Footnote
*Cranial Nerves*
**-** Functions of Cranial Nerves :
* **Motor**: Control voluntary and involuntary muscle movements.
## Footnote
* **Sensory**: Transmit sensory information from specific regions.
* **Autonomic**: Regulate visceral functions such as digestion, heart rate, and pupil constriction.
* **Reflexes**: Mediate various reflex actions like blinking, gagging, and swallowing
36
Autonomic = **?**
* A ) Transmit sensory information from specific regions.
* B ) Control voluntary and involuntary muscle movements.
* C ) Regulate visceral functions such as digestion, heart rate, and pupil constriction.
* D ) Mediate various reflex actions like blinking, gagging, and swallowing
## Footnote
*Cranial Nerves*
**-** Functions of Cranial Nerves:
* **Autonomic**: Regulate visceral functions such as digestion, heart rate, and pupil constriction.
## Footnote
* **Sensory**: Transmit sensory information from specific regions.
* **Motor**: Control voluntary and involuntary muscle movements.
* **Reflexes**: Mediate various reflex actions like blinking, gagging, and swallowing
37
# Functions of Cranial Nerves
Reflexes = **?**
* A ) Transmit sensory information from specific regions.
* B ) Control voluntary and involuntary muscle movements.
* C ) Regulate visceral functions such as digestion, heart rate, and pupil constriction.
* D ) Mediate various reflex actions like blinking, gagging, and swallowing
## Footnote
*Cranial Nerves*
**-** Functions of Cranial Nerves:
* **Reflexes**: Mediate various reflex actions like blinking, gagging, and swallowing
## Footnote
* **Sensory**: Transmit sensory information from specific regions.
* **Motor**: Control voluntary and involuntary muscle movements.
* **Autonomic**: Regulate visceral functions such as digestion, heart rate, and pupil constriction.
38
Coordination between the two eyes is maintained by synergistic action of the eye muscles. For example, looking at a pen that moves toward you requires a coordination of right and left = **?**
| *What muscles*
## Footnote
*Cranial Nerves*
**Coordination - Eye movements and Head & Hye (H&E) movements**:
**-** Coordination between the two eyes is maintained by synergistic action of the eye muscles. For example, looking at a pen that moves toward you requires activation of
* Right & Left **medial rectus**
39
Are cranial nerves considered a part of the central nervous system?
## Footnote
*Cranial Nerves*
**No**, cranial nerves are considered a part of the peripheral nervous system.
40
# Coordination of H&E movements
H&E movement coordination is controlled by signals in **?** of brainstem **?**
## Footnote
*Cranial Nerves*
**Coordination - Eye movements and Head & Hye (H&E) movements**:
* H&E movement coordination is controlled by signals in ***medial longitudinal fasciculus*** of brainstem that provides bilateral connections among vestibular, oculomotor & spinal accessory nerve, trochlear, abducencs nuclei.
41
# Medial Longitudinal Fasciculus
Axons in the medial longitudinal fasciculus connect **which CN nuclei**; these coordinate head and eye movements **?**
| *5*
## Footnote
*Cranial Nerves*
**Medial Longitudinal Fasciculus** (MLF):
* Axons in the medial longitudinal fasciculus (color coded green) connect the **oculomotor**, **trochlear**, **abducens**, **vestibular**, and **accessory** nerve nuclei.
* Signals conveyed in this tract coordinate head and eye movements.
42
# Parasympathetic Functions of CN Nerve III (Oculomotor)
* Pupillary reflex = **?**
* Consensual reflex = **?**
## Footnote
*Cranial Nerves*
**Parasympathetic Functions of CN Nerve III** (Oculomotor):
**-** Besides control of voluntary movement, CN III has parasympathetic neurons
**-** Constriction of the pupil: pupillary and consensual reflex
* Pupillary and consensual reflexes are elicited by the same stimulus ( *e.g*., shining a bright light into one eye).
* **Pupillary reflex** is the constriction of the pupil in the eye directly stimulated by the bright light.
* **Consensual reflex** is the constriction of the pupil in the other eye.
Contraction of the muscles controlling the lens of the eye: accommodation reflex
Afferent: optic nerve
Efferent: oculomotor nerve
43
Accommodation reflex = **?**
| *BONUS* = What is **afferent**, what is **effect** ?
## Footnote
*Cranial Nerves*
**-** **Accommodation reflex**: Contraction of the muscles controlling the lens of the eye.
* **Afferent**: optic nerve (CN II)
* **Efferent**: oculomotor nerve (CN III)
44
# Pupillary and Consensual Reflexes
* The pupillary reflex is produced by = **?**
* The consensual reflex is elicited by = **?**
## Footnote
*Cranial Nerves*
**Pupillary and Consensual Reflexes**:
**-** Both pupillary and consensual reflexes are responses to bright light shined into one eye.
* Light shined into the left eye elicits reflexive constriction of both pupils.
* The optic nerve conveys information from the retina to the pretectal area.
* Interneurons from the pretectal area synapse in the parasympathetic nucleus of the oculomotor nerve.
* Efferents travel in the oculomotor nerve and then in the ciliary nerve to the pupillary sphincter muscle (circular muscle of iris).
**-** The pupillary reflex is produced by **ipsilateral neural connections**.
**-** The consensual reflex, constriction of the opposite pupil, is elicited by the **neuron connecting the left pretectal area with the right parasympathetic nucleus of the oculomotor nerve**.
45
# Pupillary Constriction
Parasympathetic stimulation of the = **?**
## Footnote
*Cranial Nerves*
**Pupillary Constriction**:
* Iris sphincter muscle / pupillary sphincter muscle / circular muscle of iris.
* Iris dilator muscle/ pupillary dilator muscle/ radial muscle of iris
46
# Pupillary Dialtion
Sympathetic stimulation of the = **?**
## Footnote
*Cranial Nerves*
**Pupillary Dialtion**:
* Iris sphincter muscle/ pupillary sphincter muscle/ circular muscle of iris.
* Iris dilator muscle/ pupillary dilator muscle/ radial muscle of iris.
47
# Accommodation reflex
When viewing objects closer than 20 cm, the ciliary muscle contracts, which (**increases** or **decreases**) the curvature of the lens **?**
| *BONUS* = what is the result ?
## Footnote
*Cranial Nerves*
**Parasympathetic Functions of CN Nerve III** (Occulomotor):
**-** Accommodation reflex: Visual response for focusing on near objects.
* When viewing objects closer than 20 cm, the ciliary muscle contracts, which **increases** the curvature of the lens
* Action is called accommodation; it increases refraction of light rays to ensure that the focal point will be maintained on the retina.
48
# CN, Category, and Function = **?**
Cranial Nerves
* III = **?**
* IV = **?**
* VI = **?**
## Footnote
*Cranial Nerves*
**-** CN III - **Occulomotor**:
Motor:
* Moves eyes up (superior rectus)
* "" Down (inferior rectus)
* "" Medial (medial rectus)
* Elevates eye lid (levator palpebrae superioris)
Parasympathetic:
* Efferent to pupillary, consensual and accommodation reflexes.
**-** CN IV - **Trochlear**:
Motor:
* Moves eye medially and down (superior oblique)
**-** CN VI - **Abducens**:
Motor:
* Abducts eye (lateral rectus)
49
# CN Reflexes - **Pupillary**
* Description = **?**
* Afferent Neurons = **?**
* Efferent Neurons = **?**
## Footnote
*Cranial Nerves*
CN Reflexes - **Pupillary**:
* **Description** = Pupil of eye constricts when light is shined into eye.
* **Afferent Neurons** = Optic
* **Efferent Neurons** = Oculomotor
50
# CN Reflexes - **Consensual**:
* Description = **?**
* Afferent Neurons = **?**
* Efferent Neurons = **?**
## Footnote
*Cranial Nerves*
CN Reflexes - **Consensual**:
* **Description** = Pupil of eye constricts when light is shined into other eye.
* **Afferent Neurons** = Optic
* **Efferent Neurons** = Oculomotor
51
# CN Reflexes - **Accomodation**:
* Description = **?**
* Afferent Neurons = **?**
* Efferent Neurons = **?**
## Footnote
*Cranial Nerves*
CN Reflexes - **Accomodation**:
* **Description** = Lens of eye adjusts to focus light on the retina, pupil constricts, and pupils move medially when viewing an object at close range.
* **Afferent Neurons** = Optic
* **Efferent Neurons** = Oculomotor
52
# CN Reflexes - **Masseter**:
* Description = **?**
* Afferent Neurons = **?**
* Efferent Neurons = **?**
## Footnote
*Cranial Nerves*
CN Reflexes - **Masseter**:
* **Description** = When masseter is tapped with a reflex hammer, the muscle contracts.
* **Afferent Neurons** = Trigeminal
* **Efferent Neurons** = Trigeminal
53
# CN Reflexes - **Corneal (blink)**:
* Description = **?**
* Afferent Neurons = **?**
* Efferent Neurons = **?**
## Footnote
*Cranial Nerves*
CN Reflexes - **Corneal (blink)**:
* **Description** = When the cornea is touched, the eyelids close.
* **Afferent Neurons** = Trigeminal
* **Efferent Neurons** = Facial
54
# CN Reflexes - **Gag**:
* Description = **?**
* Afferent Neurons = **?**
* Efferent Neurons = **?**
## Footnote
*Cranial Nerves*
CN Reflexes - **Gag**:
* **Description** = Touching the pharynx elicits contraction of pharyngeal muscles.
* **Afferent Neurons** = Glossopharyngeal
* **Efferent Neurons** = Vagus
55
# CN Reflexes - **Swallowing**:
* Description = **?**
* Afferent Neurons = **?**
* Efferent Neurons = **?**
## Footnote
*Cranial Nerves*
CN Reflexes - **Swallowing**:
* **Description** = Food touching entrance of pharnyx elicits movements of the soft palate and contraction of pharyngeal muscles.
* **Afferent Neurons** = Glossopharyngeal
* **Efferent Neurons** = Vagus
56
# What CN am I = **?**
* Sensory fibers transmit information from the face and TMJ
* Motor fibers innervate the muscles of mastication and middle ear.
## Footnote
*Cranial Nerves*
CN V - **Trigeminal**: Mixed nerve containing both sensory and motor fibers.
* Sensory fibers transmit information from the face and TMJ
* Motor fibers innervate the muscles of mastication, tensor tympani, a middle ear muscle that adjusts the tension of the eardrum and protect the inner ear.
**-** Trigeminal nerve named for its three branches:
* Ophthalmic
* Maxillary
* Mandibular
57
# Trigeminal nerve named for its three branches,
What are they = **?**
## Footnote
*Cranial Nerves*
**-** Trigeminal nerve named for its three branches:
* Ophthalmic
* Maxillary
* Mandibular
58
# CN, Category, and Function = **?**
CN V = **?**
## Footnote
*Cranial Nerves*
**-** CN V - **Trigeminal**:
***Somatosensory*** :
* Afferents for touch, proprioception, nociception and temperature information from the face, anterior 2/3rds of tongue, sinuses, and teeth.
***Motor*** :
* Efferent to mucles of mastication, and tensor tympani muscle.
***Reflex*** :
* Afferent limb corneal reflex, afferent and efferent for masseter reflex.
59
# What CN am I = **?**
* Mixed Nerve
* Motor innervatation = muscles of facial expression
* Sensory information from the anterior tongue
* Reflexes = carries efferent signals for the corneal (blink) reflex
## Footnote
*Cranial Nerves*
**CN VII - Facial**:
**-** Mixed nerve:
* **Motor**: Innervates muscles of facial expression and most glands.
* **Sensory** information from the anterior tongue (solitary nucleus).
**-** Reflexes:
* Carries efferent signals for the corneal (blink) reflex (afferent by trigeminal).
60
# Corticobrainstem tract...
* Provides _ **?** _ signals to innervate muscles in *upper* face, and _ **?** _ signals to innervate muscles in *lower* face.
## Footnote
*Cranial Nerves*
**Motor Nucleus of the Facial Nerve**:
* Corticobrainstem tract provide **bilateral** signals to the upper part of the facial nerve nucleus, neurons from upper facial nucleus innervate muscles in upper face.
* Corticobrainstem tracts provide **contralateral** signals to lower region of facial nucleus. Neurons from lower facial nucleus innervate muscles in the lower face.
61
# CN Disorders...
What is happening in **A** and **B** ?
## Footnote
*Cranial Nerves*
**Disorders - Cranial Nerves**:
**-** Motor neuron lesion versus motor tract lesion (corticobrainstem) affecting the facial nerve.
* In both A and B, the person has been asked to close the eyes and smile.
* Dotted lines indicate axons that, subsequent to the lesions, do not convey information.
(**A**), With a facial nerve lesion, motor neurons are interrupted, preventing control of the ipsilateral muscles of facial expression. Therefore the person cannot close the eye or contract the muscles that move the lips on the left.
(**B**), A corticobrainstem tract lesion prevents information from the left cortex from reaching the facial nerve nuclei. Because the contralateral cortex controls the muscles of the lower face, the person is unable to generate a smile on the right side.
* However, because the upper face is innervated bilaterally, the person with this corticobrainstem tract lesion can close both eyes.
62
# Facial paralysis
Bell's Palsy = **?**
## Footnote
*Cranial Nerves*
**-** **Bell's Palsy**:
* Characterized as a LMN.
* Results in paralysis of the ipsilateral (same side) face.
* The cause of Bell's Palsy is unknown.
**-** **Corticobrainstem Tract Lesion/Post-Stroke Paralysis**:
* This type of facial paralysis is due to a lesion in the pathway from the cerebral cortex to the brainstem, often seen in post-stroke patients.
**-** **Notes**:
* **Image A**: Shows Bell's palsy with a vertical space between the eyelids wider on the right side and drooping of the right side of the mouth.
* **Image B**: Depicts the patient attempting to close her eyes, with the right eyelid unable to close completely.
* **Image C**: Illustrates facial paralysis post-stroke, where voluntary control of the frontalis muscle is intact, but the right side of the mouth does not move when the patient smiles.
* **Image D**: Indicates that the patient cannot move the right side of the mouth, observed when the patient attempts to smile.
63
* Muscle = **?**
* CN = **?**
* Action = **?**
## Footnote
*Cranial Nerves*
* Muscle = **Medial rectus**
* CN = **CN III - Oculomotor**
* Action = **Pupil medial**
64
* Muscle = **?**
* CN = **?**
* Action = **?**
## Footnote
*Cranial Nerves*
* Muscle = **Lateral rectus**
* CN = **CN VI - Abducens**
* Action = **Pupil lateral**
65
* Muscle = **?**
* CN = **?**
* Action = **?**
## Footnote
*Cranial Nerves*
* Muscle = **Superior rectus**
* CN = **CN III - Oculomotor**
* Action = **Pupil up**
66
* Muscle = **?**
* CN = **?**
* Action = **?**
## Footnote
*Cranial Nerves*
* Muscle = **Inferior rectus**
* CN = **CN III - Oculomotor**
* Action = **Pupil down**
67
* Muscle = **?**
* CN = **?**
* Action = **?**
## Footnote
*Cranial Nerves*
* Muscle = **Superior oblique**
* CN = **CN IV - Trochlear**
* **Action** = If eye abducted, pupil down and in **/** If eye abducted, rotates eye.
68
* Muscle = **?**
* CN = **?**
* Action = **?**
## Footnote
*Cranial Nerves*
* Muscle = **Inferior oblique**
* CN = **CN III - Oculomotor**
* **Action** = If eye adducted, pupil up **/** If eye abducted, rotates eye.
69
CN III - Oculomotor, CN IV - Trochlear, and CN VI - Abducens nerves are motor neuron axons innervating the six extraocular muscles that move the eye, and control reflexive constriction of the pupil.
* They are = **?**
## Footnote
*Cranial Nerves*
CN **III - Oculomotor**, CN **IV - Trochlear**, and CN **VI - Abducens** nerves are motor.
**-** The contain motor neuron axons innervating the six extraocular muscles that move the eye, and control reflexive constriction of the pupil.
**-** Four straight muscles (lateral, medial, superior and inferior rectus)
**-** Two oblique muscles (superior and inferior)
70
# Control of Eye Movement
CN III - **Oculomotor**:
* Muscles = **?**
* Movements = **?**
## Footnote
*Cranial Nerves*
CN III - **Oculomotor**:
**-** Muscles & Movements:
* **Levator palpebrae superioris** = Lifts eyelids
* **Superior Rectus** = Pupil up
* **Medial Rectus** = Pupil medial
* **Inferior Rectus** = Pupil down
* **Inferior Oblique** = If eye adducted, pupil up **/** If eye abducted, rotates eye.
* **Pupillary sphincter** = Constricts pupil
* **Ciliary** = Increases curvature of the lens of eye
71
# Control of Eye Movement
CN IV - **Trochlear**:
* Muscles = **?**
* Movements = **?**
## Footnote
*Cranial Nerves*
CN IV - **Trochlear**:
**-** Muscles & Movements:
* **Superior Oblique** = If eye abducted, pupil down and in **/** If eye abducted, rotates eye.
## Footnote
**Simplified version**:
* "When the eye is moved outward, the pupil moves downward and inward. Additionally, when the eye is moved outward, it rotates downward."
72
# Control of Eye Movement
CN VI - **Abducens**:
* Muscles = **?**
* Movements = **?**
## Footnote
*Cranial Nerves*
CN VI - **Abducens**:
**-** Muscles & Movements:
* **Lateral Rectus** = Pupil lateral
73
CN VIII has two distinct branches, what are they = **?**
## Footnote
*Cranial Nerves*
CN VIII - **Vestibulocochlear**:
**-** Sensory nerve with two distinct branches.
**1**) **Vestibular branch** transmits information related to head position and head movement.
* Sensory information from the vestibular apparatus ( 3 paired semicircular canals, utricle and saccule).
**2**) **Cochlear branch** transmits information related to hearing.
* Sensory information from the cochlea.
74
# Vestibular apparatus
**?**
## Footnote
*Cranial Nerves*
**Cochlea**: A spiral-shaped, fluid-filled structure in the inner ear responsible for hearing. It's a key component of the auditory system, converting sound vibrations into electrical signals that the brain can interpret.
75
# Vestibular apparatus
**?**
Semicircular - **Anterior Canal**: Detects rotational movements of the head in the sagittal plane, such as nodding or tilting the head back and forth.
## Footnote
*Cranial Nerves*
76
# Vestibular apparatus
**?**
## Footnote
*Cranial Nerves*
Semicircular - **Lateral Canal**:
This means that the lateral semicircular canal detects movements of the head when shaking your head no or looking left to right.
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# Vestibular apparatus
**?**
## Footnote
*Cranial Nerves*
Semicircular - **Posterior Canal**
78
# Vestibular apparatus
**?**
## Footnote
*Cranial Nerves*
**Cupula**: Cone-shaped structure in the vestibular system located within the ampullae of the semicircular canals.
* It covers the crista ampullaris, the sensory organ that detects head rotations.
* When the head rotates, the fluid in the semicircular canals moves, and this motion displaces the cupula, bending the hair cells of the crista ampullaris and creating a signal that is sent to the brain to interpret head movement.
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# Vestibular apparatus
**?**
## Footnote
*Cranial Nerves*
**Ampullae**: Sensory organs that detect rotational movements of the head.
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# Vestibular apparatus
**?**
## Footnote
*Cranial Nerves*
**[Utricle](https://radiopaedia.org/articles/utricle-ear?lang=us)**
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# Vestibular apparatus
**?**
## Footnote
*Cranial Nerves*
**Saccule**: Plays a key role in balance and spatial orientation. It is one of the two otolithic organs (the other being the utricle) that sense gravity and linear acceleration.
82
Describe the steps in auditory conduction = **?**
## Footnote
*Cranial Nerves*
**Auditory Conduction** / **Auditory Pathways**:
* External ear directs the sound waves into the auditory canal - transmit sound waves into tympanic membrane which vibrates.
* Ossicles vibrate - stapes pushed into oval window.
* Movement displaces fluid in the cochlea.
* Sounds waves are transmitted and amplified from air filled external and middle ear to fluid filled inner ear (perilymph), which contains receptors.
* Vestibular and basilar membrane move relative to one another- bending of cilia on hair cells by a shearing force as the cilia push against the tectorial membrane.
* Bending of cilia- change in ion conductance of the hair cell membrane- change in membrane potential, receptor potential of the auditory hair cells.
* Depolarization opens voltage gated calcium channels in the presynaptic terminals of the hair cells,
* Release of glutamate, excitatory neurotransmitter- action potential in the afferent cochlear nerve- transmit information to the CNS.
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From the cochlear nuclei, auditory information is transmitted to three structures = **?**
## Footnote
*Cranial Nerves*
**Auditory Function in the CNS**:
**-** From the cochlear nuclei, auditory information is transmitted to three structures:
**1**) Provides conscious awareness and recognition of sounds.
* **Medial Geniculate Body**: Serves as a thalamic relay station for auditory information to the primary auditory cortex.
**2**) Orients the head and eyes toward sounds.
* **Inferior Colliculus**: integrate auditory information from both ears to ***detect the location of sounds*** .
* When location information is conveyed to superior colliculus, elicits movement of eyes and head toward sound
**3**) Increases the activity level throughout the CNS.
* **Reticular Formation**: Connections account for the activating effect of sounds on the CNS.
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# What reflex = **?**
Helps to stabilize visual images during head movements.
## Footnote
*Cranial Nerves*
**Vestibulooccular Reflex**: Helps to stabilize visual images during head movements
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# CN VIII
* Special Sensory function = **?**
* Reflex function = **?**
## Footnote
*Cranial Nerves*
CN VIII - **Vestibulocochlear**:
* **Special Sensory** = Afferents for sense of head movement and head position (vestibular nerve); hearing (cochlear nerve).
* **Reflex** = Afferent for vestibule-occular reflex
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Three cortical areas dedicated to processing auditory information = **?**
## Footnote
*Cranial Nerves*
**Cortical areas for processing auditory information**:
**-** Three cortical areas dedicated to processing information
**1**) **Primary Auditory cortex**: Conscious awareness of intensity of sound
**2**) **Secondary Auditory cortex**: Compares sound with memories of other sounds, categorizes sound as language, music or noise
**3**) **Wernicke’s Area**: Comprehension of spoken language.
87
# CN IX
* Sensory fibers from = **?**
* Motor component innervates = **?**
* Autonomic afferent from = **?**
* Autonomic efferent to = **?**
## Footnote
*Cranial Nerves*
CN IX - **Glossopharyngeal**:
**-** Mixed nerve containing sensory and motor and autonomic fibers.
* **Sensory fibers** from the soft palate, middle ear and pharynx
* **Motor** component innervates stylopharyngeal (elevates larynx, pharynx, swallowing) muscle
* **Autonomic afferent** from carotid sinus and carotid body convey blood pressure and chemical signals from the carotid artery, taste sensation from the posterior 1/3rd tongue.
* **Autonomic efferent**: to parotid gland
## Footnote
* CN IX sensory fibers contribute the **afferent limb** of the gag and swallowing reflexes and CN X provides efferent limb.
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# CN IX
* Sensory function = **?**
* Motor function = **?**
* Autonomic afferents function = **?**
* Autonomic efferent function = **?**
* Reflex function = **?**
## Footnote
*Cranial Nerves*
CN IX - **Glossopharyngeal**:
**Sensory** function = Afferent from pharynx, posterior 1/3rd of tongue, soft palate, middle ear and area near external ear canal.
**Motor** function = Efferent to Stylopharyngeal muscle.
* **Autonomic Afferents** function = Blood pressure and chemical information from the carotid artery, afferent for taste from posterior 1/3rd.
* **Autonomic Efferent** function = Efferent to parotid gland.
* **Reflex** function = Afferent limb of the gag and swallowing reflex.
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# CN X
* Sensory information = **?**
* Motor neurons innervate = **?**
* Motor function can be tested = **?**
* Autonomic axons are distributed to = **?**
## Footnote
*Cranial Nerves*
CN X - **Vagus**
Mixed nerve consist of sensory, motor and autonomic axons
**-** **Sensory** information from pharynx, larynx and part of external ear
**-** **Motor** neurons innervate muscles of pharynx and larynx
* Motor function can be tested by eliciting the gag and swallowing reflex.
**-** **Autonomic axons** (**afferent** and **efferent**) are distributed to larynx, pharynx, trachea, lungs, heart, GI tract (except lower large intestine), pancreas, gallbladder and liver.
* Decrease HR
* Constrict the bronchi
* Increase digestive activity
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# CN X
* Dorsal nucleus of Vagus, parasympathetic to = **?**
* Nucleus ambiguus, motor to = **?**
* Solitary nucleus = **?**
## Footnote
*Cranial Nerves*
CN X - **Vagus**:
* **Dorsal nucleus of Vagus**: Parasympathetic to abdominal and visceral organs like lungs, GI tract.
* **Nucleus Ambiguus**: Motor to pharyngeal and laryngeal muscles.
* **Solitary Nucleus**: Autonomic afferents
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# CN X
* Sensory function = **?**
* Motor function = **?**
* Visceral function = **?**
* Parasympathetic function = **?**
* Reflex function = **?**
## Footnote
*Cranial Nerves*
CN X - **Vagus **:
* **Sensory** function = Afferent from pharynx, larynx and skin in center of external ear.
* **Motor** function = Efferent to muscle of the pharynx, larynx.
* **Visceral** function = Afferent from pharynx, larynx, thorax and abdomen.
* **Parasympathetic** function = Efferent to smooth muscle and glands in the pharynx, larynx, thorax and abdomen.
* **Reflex** function = Efferent limb of gag and swallowing reflex.
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# Cranial Nerve Autonomic innervation
What are the functions of the cranial nerves III, VII, IX, and X, specifically in relation to the efferent and afferent fibers they contain.
## Footnote
*Cranial Nerves*
**-** Specific cranial nerves and their functions are:
**Oculomotor Nerve** (III):
* Efferent fibers to the ciliary muscle, which helps the lens of the eye in focusing.
* Efferent fibers to the pupillary sphincter, which controls the constriction of the pupil.
**Facial Nerve** (VII):
* Efferent fibers to the lacrimal glands (tear production), sublingual glands (beneath the tongue), and submandibular glands (below the jaw) for saliva secretion.
* Afferent fibers from taste receptors on the anterior portion of the tongue.
**Glossopharyngeal Nerve** (IX):
* Efferent to the parotid gland for saliva production.
* Afferent fibers from taste receptors on the posterior portion of the tongue and from the carotid sinus (which helps in regulating blood pressure).
**Vagus Nerve** (X):
* Afferent and efferent fibers to various organs such as the heart, lungs, trachea, bronchi, pharynx, and the gastrointestinal system. The vagus nerve plays a significant role in regulating the function of these organs.
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# CN XI
* Motor, provides innervation to = **?**
## Footnote
*Cranial Nerves*
Cranial Nerve XI - **Accessory**:
* **Motor**, provides innervation to the ***trapezius*** and ***sternocleidomastoid*** muscles.
94
# CN XI
* Motor function = **?**
## Footnote
*Cranial Nerves*
CN XI - **Accessory**:
* **Motor** = Efferent to sternocleidomastoid and trapezius
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# CN XII
* Motor nerve provides innervation to = **?**
* Cell bodies are located in the = **?**
## Footnote
*Cranial Nerves*
CN XII - **Hypoglossal**:
* Motor nerve, provides innervation to the **intrinsic** & **extrinsic muscles** of the **ipsilateral tongue**.
* Cell bodies are located in the **hypoglossal nucleus** of **medulla**.
96
# CN XII
Motor function = **?**
## Footnote
*Cranial Nerves*
CN XII - **Hypoglossal**:
* **Motor** = Efferent to intrinsic muscles and extrinsic muscles of tongue.
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## Footnote
*Cranial Nerves*
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## Footnote
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## Footnote
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## Footnote
*Cranial Nerves*
