Mẹo về Are cranial nerves part of the CNS Mới Nhất
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Cranial Nerves
Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), in contrast to spinal nerves (which emerge from segments of the spinal cord). Ten of the cranial nerves originate in the brainstem. Cranial nerves relay information between the brain and parts of the body toàn thân, primarily to and from regions of the head and neck. Spinal nerves emerge sequentially from the spinal cord with the spinal nerve closest to the head (C1) emerging in the space above the first cervical vertebra. The cranial nerves, however, emerge from the central nervous system above this level. Each cranial nerve is paired and is present on both sides. In humans there are twelve cranial nerves pairs, which are assigned Roman numerals I–XII. The numbering of the cranial nerves is based on the order in which they emerge from the brain, front to back (brainstem).
Nội dung chính- Cranial NervesAttributionsWhat nerves are in the CNS?What system are the cranial nerves part of?
Above: Lateral view of the brain stem showing the locations of the cranial nerves III - XII.
The, olfactory nerves (I) and optic nerves (II) emerge from the cerebrum or forebrain, and the remaining ten pairs arise from the brainstem, which is the lower part of the brain.
Above: Inferior view of the brain with the pairs of cranial nerves labeled.
The cranial nerves are considered components of the peripheral nervous system (PNS), although on a structural level the olfactory (I), optic (II), and trigeminal (V) nerves are more accurately considered part of the central nervous system (CNS).
Humans are considered to have twelve pairs of cranial nerves (I–XII). They are: the olfactory nerve (I), the optic nerve (II), oculomotor nerve (III), trochlear nerve (IV), trigeminal nerve (V), abducens nerve (VI), facial nerve (VII), vestibulocochlear nerve (VIII), glossopharyngeal nerve (IX), vagus nerve (X), accessory nerve (XI), and hypoglossal nerve (XII).
C.N. #
C.N. Name
Associated Opening(s)
Nerve Type
Innervation
C.N. I
olfactory nerve
olfactory foramina (cribriform plate of the ethmoid bone)
special sensory
olfaction (smell) - olfactory epithelium
C.N. II
optic nerve
optic canals
special sensory
retina of the eye (sight)
C.N. III
oculomotor nerve
superior orbital fissure
motor
inferior oblique, medial rectus, superior rectus, and inferior recuts muscles of the eye
C.N. IV
trochlear nerve
superior orbital fissure
motor
superior oblique muscle of the eye
C.N. V
trigeminal nerve
C.N. V, branch 1: ophthalmic nerve
superior orbital fissure, supraorbital foramen
sensory
skin on the upper third of the face
C.N. V, branch 2: maxillary nerve
foramen rotundum, infraorbital foramen
sensory
skin on the middle third of the face
C.N. V, branch 3: mandibular nerve
foramen ovale, mandibular foramen, mental foramen
sensory
skin on the lower third of the face, pain from the tongue
C.N. VI
abducens nerve
superior orbital fissure
motor
lateral recuts muscle of the eye
C.N. VII
facial nerve
internal acoustic meatus, stylomastoid foramen
motor, special sensory
motor: muscles of facial expression special sensory: taste buds on the anterior two-thirds of the tongue
C.N. VIII
vestibulocochlear nerve
internal acoustic meatus
special sensory
auditory (hearing), balance, and equilibrium - inner ear (cochlear and vestibular apparatus)
C.N. IX
glossopharyngeal nerve
jugular foramen
motor, special sensory
motor: pharynx muscles
special sensory: taste buds on the posterior third of the tongue
C.N. X
vagus nerve
jugular foramen
motor, sensory, special sensory
motor: heart, smooth muscle of pharynx and organs of the gut
sensory: skin across the throat and the external acoustic meatus
special sensory: taste, gag reflex
C.N. XI
accessory nerve
jugular foramen, foramen magnum
motor
trapezius, sternocleidomastoid, muscles of the pharynx
C.N. XII
hypoglossal nerve
hypoglossal canal
motor
muscles of the tongue
Mnemonic phrases can be helpful to remember the order of the cranial nerves. Here are two popular mnemonics for the order of the cranial nerves (I-XII):
- Oh Once One Takes The Anatomy Final, Very Good Vacations Are HeavenlyOh, Oh, Oh,
To Touch And Feel Very Good Velvet, A-H
The cranial nerves carry motor, sensory, and/or special sensory signals. Motor signals innervate muscles/tissues, sensory signals send information to the CNS from sensory receptors, and special sensory signals send information to the CNS from the special senses (vision, hearing and balance, and taste). Some cranial nerves carry more than one type of signal; one cranial nerve even carries all three types of signals.
To enter/exit the skull, cranial nerves pass through openings in the base of the skull.
Above: Diagram showing how the cranial nerves enter/exit the cranial cavity through the skull.
Above: Image of cadaver with the left cranial nerves labeled.
Attributions
- "Anatomy 204L: Laboratory Manual (Second Edition)" by Ethan Snow, University of North Dakota is licensed under
CC BY-NC 4.0"Anatomy and Physiology I Lab" by Victoria Vidal is licensed under
CC BY 4.0"Brain human normal inferior view.svg" by Patrick J. Lynch, medical illustrator is licensed under
CC BY 2.5
What nerves are in the CNS?
The retina, optic nerve, olfactory nerves, and olfactory epithelium are sometimes considered to be part of the CNS alongside the brain and spinal cord. This is because they connect directly with brain tissue without intermediate nerve fibers.What system are the cranial nerves part of?
The cranial nerves begin toward the back of your brain. They are a key part of your nervous system. Tải thêm tài liệu liên quan đến nội dung bài viết Are cranial nerves part of the CNS