1. Cervical Plexus, Accessory Plexus Flashcards by J L

Each pair of spinal nerves is formed by the convergence of nerve roots arising from the dorsal and ventral aspects of an individual SEGMENT of the cord

Arising from each segment are the which supply, respectively:
GSA & GSE fibers which supply, respectively:

A specific area of body wall, the ____

and a specific muscle mass, the ____

dermatome

myotome

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Dorsal (Posterior) Root comprised of
somatic
\_\_\_\_
fibers carrying information
from the periphery TO the CNS

“Mixed” spinal nerve in an ____

Ventral (anterior)
root
comprised of somatic ____ fibers carrying Information FROM
the CNS to the periphery

afferent
iv foramen
efferent

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Ventral rami of spinal nerves…

Innervate the skin of the ____ and both extremities
Innervate ____ muscles derived from the hypomeres of the ____ of the somites
Often converage to form ____ where fibers are exchanged and give rise to named ____ (i.e. brachial and lumbosacral plexuses)• Today we’ll focus on the cervical plexus formed between C1-C4 ventral rami

anterolateral body wall
hypaxial
myotomes
plexuses
peripheral nerves

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Note first that while there are SEVEN cervical vertebrae, there are ____ cervical spinal nerves

The C1 spinal nerves pass between the ____ and
the ____ to leave the vertebral canal

The C2 spinal nerves exit the intervertebral foramina between the ____ and ____

The C8 spinal nerves exit the intervertebral foramina between ____ and ____

eight
skull
atlas
atlas
axis
C7
T1

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So…with the exception of the C8 spinal nerves, each cervical nerve is numbered
according to the number of the vertebra contributing to the ____ margin of the intervertebral foramen thru which is emerges.

In contrast… ____ and ____ spinal nerves are numbered according to the number of the overlying vertebra, as shown at left.

inferior
thoracic
lumbar

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The cervical plexus arises with contributions from the ____ ventral rami

We’ve already met a number of the MUSCULAR BRANCHES of the cervical plexus that innervate anterior and prevertebral cervical musculature

C1-C4

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Recall that most of the infrahyoid “strap” muscles are innervated by branches of the ____…
… with the exception of the ____, which is innervated
directly by ____ fibers

The ansa cervicalis is formed by the contributions from ____ “roots”

ansa cervicalis
thyroid
C1
two

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Ansa Cervicalis

The superior root or ____ arises from ____

The inferior root arises from ____ and ____

descendens
hypoglossi
C2
C3

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The PHRENIC nerves
Arise ____ with contributions from
The ____, ____ and ____ ventral rami…

____ - provides most of the fibers that are contained in the phrenic nerve

…and descend through the neck On the ____ muscles to reach the ____

bilaterally
C3
C4
C5
C4

anterior scalene
superior thoracic aperture

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GSE fibers innervate the ____

GSA fibers innervate the \_\_\_\_
lining the thorax,
and portions of
the \_\_\_\_ surrounding the heart:
	• \_\_\_\_ lining the pulmonary cavities
	• \_\_\_\_ surrounding the heart
	• \_\_\_\_ lining the underside of the peritoneum

diaphragm
parietal pleura
pericardium
parietal pleura
pericardium
parietal periotoneum

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Four sets of
____
arise from the cervical plexus

Note the cutaneous innervation of the posterior scalp and posterior neck by branching of ____

cutaneous nerves

cervical dorsal rami

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Lesser occipital: ____
Supraclavicular: ____
Great auricular: ____
Transverse cervical: ____

C2
C3, C4
C2, C3
C2, C3

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C4 afferents
Referred diaphragmatic pain
Is perceived in the ____ region - in the ____

Diaphragm

“shoulder pad”

C4 dermatome

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Two branches of cervical plexus join with branches of CN ____, the ____, in providing the cutaneous innervation of the face

Lesser occipital
Great auricular

Particularly in females, the pain of ____ may be referred to the skin overlying the angle of the ____

V
trigeminal nerve
myocardial infarction
mandible

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These nerves may be anaesthetized by
an injection at
____
Aka the ____

Why might an ipsilateral shoulder drop result from on the injection at this location?

Because the ____ crosses the posterior triangle to reach the ____

Erb’s point
puncta nervosum
spinal accessory nerve
trapezius

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Though somewhat unique from an anatomical perspective, the
____ offers us the
opportunity to begin an in-depth consideration
of the 12 pairs of
CRANIAL NERVES
that will dominate this module

accessory nerve (CN XI)

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From a functional perspective, the
ACCESSORY NERVE (CN XI) is relatively simple, comprised exclusively
of \_\_\_\_ fibers which, you will recall, innervate two large, superficial \_\_\_\_

GSE

cervical muscles

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POSTERIOR CRANIAL FOSSA

FORAMEN MAGNUM
transmits the ____ root of CN XI ____ the posterior cranial fossa

JUGULAR FORAMEN
Transmits CN ____, plus ____ and ____ out of the posterior cranial fossa

spinal
INTO
XI
IX
X

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“SPINAL ROOT” carrying axons of Lower Motor Neurons in the ____
within the lateral ventral horns of the ____ cord segments

Nucleus ambiguus
“Cranial root”
Vagus
SCM
Trapezius

Note the ____ fibers projecting to upper cervical spinal nerves

accessory nucleus
C1-C5
GSA

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CN XI is vulnerable to lesion as it crosses the ____ … often ____
e.g. with radical neck dissection

posterior cervical triangle

iatrogenic

Peripheral Nerve Injuries (lesions) I

Irritative
- Caused by acute or chronic mechanical trauma or inflammation (i.e. ____, constriction, or ____)
- May initiate impulses in sensory or motor fibers
– If sensory fibers are stimulated… ____ or ____ results.
– If motor fibers are stimulated… ____ or ____ results.

compression
stretching
pain
parasthesia (altered sensation)
muscle spasm
twitching

So with the accessory nerve, an \_\_\_\_ lesion of the fibers of the spinal root in any
of the following locations
• \_\_\_\_
• posterior cranial fossa
• \_\_\_\_
• below the skull base
may cause \_\_\_\_

Characterized by uncontrollable ____ and ____ spasms of SCM and trapezius

irritative
vertebral canal
jugular foramen
neurogenic spasmodic torticollis (cervical dystonia)

clonic (jerky)
intermittently tonic (sustained)

Peripheral Nerve Injures (lesions) II

Destructive
- May result from ____ or ____
- Motor symptoms (muscle [____] or ____)
- Sensory symptoms (____ or ____)

trauma
neuropathy
paralysis
paresis (weakness)
cutaneous anesthesia
hypesthesia (diminished sensation)

Destructive Lesions
of CN XI (right)

Ipsilateral “shoulder drop”
____ paresis

Weakness in contralateral rotation of head and C-spine against resistance
____ paresis

trapezius

SCM

Mindful of the fact that the first and second “cranial nerves” are in fact extensions of the CNS, the remaining nerves (with the exception of CN ____) may be seen exiting from the ____, ____, or ____

CN XI midbrain pons medulla

There are six major components of the CNS, five of which develop from the ____ of the neural tube (The spinal cord extends inferiorly from the medulla but is not derived from a ____)

secondary vesicles | secondary vesicle

``` Mesencephalon, Metencephalon, and Myelencephalon give rise to ____, ____, and ____ respectively, the three parts of the ____ ``` The brainstem also contains a core of diffusely organized nuclei known as the ____ playing a crucial role in maintaining behavioral arousal and ____ Also plays a role in ____

``` midbrain pons medulla brainstem reticular formation consciousness pain modulation ```

In the brainstem, ____ giving rise to the efferent fibers (GSE, SVE, GVE) in cranial nerves are located in the ____ group of cranial nerve nuclei

lower motor neurons motor

Primary sensory neurons giving rise to ____ fibers in cranial nerves are usually located in ganglia outside the ____ which in turn project to secondary neurons in the ____ of the brain stem

afferent CNS dorsal gray

Cranial Nerve Components - In addition to GSE, GSA, GVE or GVA fibers, cranial nerves may also contain: - ____ - ____ - ____

special somatic afferents special visceral afferents special visceral efferents

``` SVE - Innervate ____ derived from the pharygneal arches ____ VII ____ X ```

skeletal muscle V IX

SVA - Convery information realted to those ____ associated with the ____ of food - Smell: ____ - Taste: ____, ____, ____

``` special senses ingestion CN I CN VII, IX X ```

SSA - Convey information pertaining to those ____ which relate the body to the ____ - Vision: from ____ (and ____) - Sound: from ____ - Equilibrium: from labyrinth of the ____

``` special senses external environment retina CNII cochlea inner ear ```

Functional components of the Cranial Nerves Know these eventually!

YA!

``` CN V contains two functional components: ____ Afferents mediate general sensation from: Skin of the ____ and ____ Most dura Cornea and conjunctiva Nasopharyngeal mucosa Oral, nasal and paranasal ____ Lingual body mucosa ____, gingivae and periodontal tissues As well as ____ and ____ from ____ arch muscles and the ____ ``` The nerve emerges from the lateral aspect of the ____ within the posterior cranial fossa as a ____ and a ____

``` GSA face anterior scalp muscoa mucosa pain proprioception first TMJ ``` midpons large sensory root smaller motor root

CN V SVE Branchial motor Recall that SVE fibers are limited to the ____ division of CN V Branchial ____ innervate eight muscles derive from the ____ pharyngeal arch

mandibular | first

Borders between V1, V2, and V3 dermatomes are ____, unlike those of ____ dermatomes

sharpe | spinal nerve

CN V GSA fibers project to the ____ nucleus of CN V TRIGEMINAL GANGLION Afferent neurons similar to ____ cells ____ Proprioception ____ Touch sensation from the face Spinal trigeminal tract & nucleus ____ This nucleus also receives ____ inputs from CN ____, ____ and ____

``` sensory DRG mesencephalic nucleus pontine trigeminal (principal sensory) nuceus pain and temperature GSA VII IX X ```

The ____ has 3 components that begin at the point of entry of CN V in the ____ and extend caudally through the length of the ____ The ____ part of the spinal nucleus is an extension of the principal sensory nucleus and also receives ____ from the face, scalp, oral cavity, and nasal cavity. The ____ part is in the rostral medulla and responds to ____ sensations from the tooth pulp. The ____ part extends through the caudal medulla to upper cervical spinal cord and responds to ____ sensations from face, scalp, oral cavity, nasal cavity, and supratentorial dura

``` rostral pons brainstem oral tactile inputs interpolar pain and temperature caudal pain and temperature ```

Face Pain and temp The ____ is somatotopically organized with a concentric “onion skin” topographic representation.

caudal nucleus

SVE fibers (V3) Arise from lower motor neurons in the ____ or ____ nucleus of CN V in the ____ of the pons

motor masticator tegmentum

The cell bodies of ____ sensory neurons concerned with proprioception are found in the ____ (derived from ____) Fibers arising in the MOTOR NUCLEUS are found only in ____ The pontine and spinal trigeminal nuclei contain ____ neurons receiving input from primary neurons in the ____ Tapping the mandible at a downward angle just below the lips at the chin when the mouth is slightly open may induce a ____ as masseter contracts

primary mesencephalic nucleus neural crest V3 secondary neurons trigeminal ganglion jaw jerk reflex

The jaw-jerk reflex is a true ____ STRETCH REFLEX initiated by stimulation of muscle spindle proprioceptors The reflex is normally absent or weakly present, upon a response to a stimulus An exaggerated and brisk response suggests an ____ neuron lesion above the ____

monosynaptic upper motor mastication nucleus

TRIGEMINAL GANGLION sits in the ____ on the floor of the middle cranial fossa in the dural ____ V1 - ophthalmic division ____ V2 - maxillary division ____ V3 - mandibular division ____

trigeminal impression meckel's cave superior orbital fissure foramen rotundum foramen ovale

MIDDLE CRANIAL FOSSA SUPERIOR ORBITAL FISSURE transmits CN V1 Into the ____ FORAMEN ROTUNDUM transmits CN V2 Into the ____ FORAMEN OVALE transmits CN V3 Into the ____

orbit pterygopalatine fossa infratemporal fossa

Like CN III, CN IV and CN VI, CN V1 and V2 course through the ____ en route to leaving the middle cranial fossa

cavernous sinus

All three divisions contribute MENINGEAL BRANCHES... .. innervating dura of the ____ and ____ cranial fossae.. As well as the ____ and ____

anterior middle falx cerebri tentorium cerebelli

Testing the integrity of the three divisions of CN V ____ ____

light touch | pain

Recall that the four ____ of the head are all suspended from branches of CN V and all send postganglionic fibers via terminal branches of the nerve to reach their targets

parasympathetic ganglia