topic 3 cervical plexus - copy

7/31/2019 Topic 3 Cervical Plexus - Copy

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THINGS TO CLARRIFYTHINGS TO CLARRIFY


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CEREBRAL PEDUNCLECEREBRAL PEDUNCLEThe mesencephalon or midbrain is subdivided early in development into twoThe mesencephalon or midbrain is subdivided early in development into twoneuromeres, mesencephalon 1 and mesencephalon 2. It persists for a timeneuromeres, mesencephalon 1 and mesencephalon 2. It persists for a timeas a thin-walled tube enclosing a cavity of some size, separated from that of as a thin-walled tube enclosing a cavity of some size, separated from that of the prosencephalon by a slight constriction and from the rhombencephalonthe prosencephalon by a slight constriction and from the rhombencephalonby the isthmus rhombencephali (Figs 24.2 and 24.25). Later, its cavityby the isthmus rhombencephali (Figs 24.2 and 24.25). Later, its cavitybecomes relatively reduced in diameter, and in the adult brain it forms thebecomes relatively reduced in diameter, and in the adult brain it forms thecerebral aqueduct.aqueduct. The basal (ventrolateral) plate of the midbrainThe basal (v

entrolateral) plate of the midbrainincreases in thickness to form theincreases in thickness to form the cerebral peduncles , which are at

, which are at first of small size, but enlarge rapidly after the fourth monthfirst of small size, but enlarg

e rapidly after the fourth month ,

, when their when their numerous fibre tracts begin to appear in the marginal zone. The neuroblastsnumerous fibre tracts begin to appear in the marginal zone. The neuroblastsof the basal plate of mesencephalon 2 give rise to the nuclei of theof the basal plate of mesencephalon 2 give rise to the nuclei of theoculomotor nerve and some grey masses of the tegmentum, while theoculomotor nerve and some grey masses of the tegmentum, while thenucleus of the trochlear nerve remains in the region of the isthmusnucleus of the trochlear nerve remains in the region of the isthmusrhombencephali. The cells which give rise to the trigeminal mesencephalicrhombencephali. The cells which give rise to the trigeminal mesencephalicnucleus arise either side of the dorsal midline, from the isthmusnucleus arise either side of the dorsal midline, from the isthmusrhobencephali rostrally across the roof of the mesencephalon. Recentrhobencephali rostrally across the roof of the mesencephalon. Recentstudies have shown that the progenitors of these cells do not expressstudies have shown that the progenitors of these cells do not express

neural crest cell markers.neural crest cell markers.


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EPITHALAMUSEPITHALAMUS

The epithalamus is a (dorsal) posterior segment of the diencephalon (a segmentin the middle of the brain also containingthe hypothalamus and the thalamus )which includes the habenula and their interconnecting fibers the

habenular commissure , thestria medullaris and the pineal body . Itsfunction is the connection between the

limbic system to other parts of the brain.
http://en.wikipedia.org/wiki/Dorsum_(biology)http://en.wikipedia.org/wiki/Diencephalonhttp://en.wikipedia.org/wiki/Brainhttp://en.wikipedia.org/wiki/Hypothalamushttp://en.wikipedia.org/wiki/Thalamushttp://en.wikipedia.org/wiki/Habenulahttp://en.wikipedia.org/wiki/Habenular_commissurehttp://en.wikipedia.org/wiki/Stria_medullarishttp://en.wikipedia.org/wiki/Pineal_bodyhttp://en.wikipedia.org/wiki/Limbic_systemhttp://en.wikipedia.org/wiki/Limbic_systemhttp://en.wikipedia.org/wiki/Pineal_bodyhttp://en.wikipedia.org/wiki/Stria_medullarishttp://en.wikipedia.org/wiki/Habenular_commissurehttp://en.wikipedia.org/wiki/Habenulahttp://en.wikipedia.org/wiki/Thalamushttp://en.wikipedia.org/wiki/Hypothalamushttp://en.wikipedia.org/wiki/Brainhttp://en.wikipedia.org/wiki/Diencephalonhttp://en.wikipedia.org/wiki/Dorsum_(biology)


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The Cervical PlexusThe Cervical Plexus


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The cervical plexus is a network of nervesThe cervical plexus is a network of nervesformed by communications between theformed by communications between theanterior rami of the upper 4 cervicalanterior rami of the upper 4 cervicalnerves.nerves.It lies posterior to the internal jugular veinIt lies posterior to the internal jugular veinand the SCM muscles.and the SCM muscles.


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The Spinal NerveThe Spinal Nerve


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Branches of theBranches of the

Cervical PlexusCervical Plexus


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Branches of theBranches of theCervical PlexusCervical Plexus

A. Superficial or Cutaneous Branches A. Sup erficial or Cutaneous Branches

Deep branches or muscular and Deep branches or muscular and

communicating branchescommunicating branches


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A. Superficial or A. Supe rficial or Cutaneous BranchesCutaneous Branches


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1.1. Ascending branches Ascending branches a. Lesser occipital nervea. Lesser occipital nerveb. Great auricular nerveb. Great auricular nervec. Nervus cutaneous collic. Nervus cutaneous colli

2.2. Descending branchesDescending branchesa. Medial supraclavicular a. Medial supraclavicular b. Intermediate supraclavicular b. Intermediate supraclavicular c. Lateral supraclavicular c. Lateral supraclavicular


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1.1. Ascending branches Ascending branches

a. Lesser a. Lesser occipitaloccipitalnervenerve

b.b. GreatGreatauricular auricular nervenerve

c. Transversec. Transversecervical nervecervical nerve

**

*


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a. Lesser occipital nervea. Lesser occipital nerve

- Comes from the second- Comes from the secondcervical ventral ramus andcervical ventral ramus andsometimes also from the thirdsometimes also from the third

- curves around the accessory- curves around the accessorynerve and ascends along thenerve and ascends along theposterior border of theposterior border of thesternocleidomastoid.sternocleidomastoid.

- supplies the skin on the- supplies the skin on theupper third of the medialupper third of the medialauricular aspectauricular aspect

-connects with the posterior -connects with the posterior branch of the great auricular branch of the great auricular nerve.nerve.

*


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c. Transverse Cutaneous Nervec. Transverse Cutaneous Nerve

This arises from the secondThis arises from the secondand third cervical rami, curvesand third cervical rami, curvesround the posterior border of round the posterior border of the sternocleidomastoidthe sternocleidomastoid

It perforates the deep cervicalIt perforates the deep cervicalfascia, dividing under thefascia, dividing under theplatysma into ascending andplatysma into ascending anddescending branchesdescending branchesdistributed to the anterolateraldistributed to the anterolateralareas of the neck.areas of the neck.

distributed to the skin of thedistributed to the skin of theupper anterior areas of theupper anterior areas of theneck and anterolaterally to theneck and anterolaterally to theskin of the neck, as low as theskin of the neck, as low as thesternum.sternum.

*


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2. Descending branches2. Descending branches

a. Mediala. Medialsupraclavicular supraclavicular

b. Intermediateb. Intermediatesupraclavicular supraclavicular

c. Lateralc. Lateralsupraclavicular supraclavicular

*


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Supra Clavicular NervesSupra Clavicular NervesThese arise by a common trunk from the third and fourth cervicalThese arise by a common trunk from the third and fourth cervicalventral rami and emerge from the posterior border of theventral rami and emerge from the posterior border of thesternocleidomastoid, to descend under the platysma and the deepsternocleidomastoid, to descend under the platysma and the deepcervical fascia;cervical fascia;

3 branches:3 branches:1. The medial supraclavicular nerves supply the skin as far as the1. The medial supraclavicular nerves supply the skin as far as the

midline and as low as the second rib. They supply themidline and as low as the second rib. They supply thesternoclavicular joint.sternoclavicular joint.

2. The intermediate supraclavicular nerves cross the clavicle to supply2. The intermediate supraclavicular nerves cross the clavicle to supplythe skin over the pectoralis major and deltoid down to the level of the skin over the pectoralis major and deltoid down to the level of the second ribthe second rib

3. The lateral supraclavicular nerves supply the skin of the upper and3. The lateral supraclavicular nerves supply the skin of the upper andposterior parts of the shoulder.posterior parts of the shoulder.


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11 . Lateral branches:. Lateral branches:

a.a. Muscular branchesMuscular branchesgoing to thegoing to thefollowing:following:

i. SCMi. SCM

ii. Trapeziusii. Trapeziusiii. Levator scapulaiii. Levator scapulaiv. Scalenius mediusiv. Scalenius mediusv. Scalenius posterior v. Scalenius posterior

b. Communicatingb. Communicatingbranches to spinalbranches to spinal

accessory nervesaccessory nerves


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Deep BranchesLateral SeriesDeep BranchesLateral Series

Muscular branchesMuscular branches SternocleidomastoidSternocleidomastoid C2, 3, 4C2, 3, 4TrapeziusTrapezius C2, (3)C2, (3)

Levator scapulaeLevator scapulae C3, 4C3, 4Scalenus mediusScalenus medius C3, 4C3, 4

Communicating branchesCommunicating branches

Accessory Accessory NerveNerve C2, 3, 4C2, 3, 4


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2. Medial branches:2. Medial branches:

a. Muscular branches going to the following muscles:a. Muscular branches going to the following muscles:i. Prevertebral musclesi. Prevertebral muscles

ii. Infrahyoid muscles thru the ansa hypoglossiii. Infrahyoid muscles thru the ansa hypoglossiiii. Diaphragm thru the phrenic nerveiii. Diaphragm thru the phrenic nerve

b. Communicating branches to the vagus, hypoglossal andb. Communicating branches to the vagus, hypoglossal andsympathetic nervessympathetic nerves

c. Phrenic nerve is the most important branch because itc. Phrenic nerve is the most important branch because itsupplies the diaphragm which is the chief muscle for respiration.supplies the diaphragm which is the chief muscle for respiration.It is derived from cervical nerves 3, 4, and 5.It is derived from cervical nerves 3, 4, and 5.


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Communicating and Muscular Communicating and Muscular BranchesBranches

(Medial Series)(Medial Series)Communicating branches withCommunicating branches with

HypoglossalHypoglossal C1, 2C1, 2VagusVagus C14C14SympatheticSympathetic C1, 2C1, 2

Muscular branches toMuscular branches toRectus capitis lateralisRectus capitis lateralis C1C1Rectus capitis anterior Rectus capitis anterior C1, 2C1, 2

Longus capitisLongus capitis C13C13Longus colliLongus colli C24C24Inferior root of ansa cervicalisInferior root of ansa cervicalis C2, 3C2, 3

Phrenic nervePhrenic nerve C35C35


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The Phrenic nerveThe Phrenic nerve

This is the sole motor supply to theThis is the sole motor supply to thediaphragm, and also contains widespreaddiaphragm, and also contains widespreadsensory fibres.sensory fibres.


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topic 3 cervical plexus - copy

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