Spinal Nerves

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Spinal Nerves Spinal Nerves Thirty-one pairs of mixed nerves Thirty-one pairs of mixed nerves arise from the spinal cord and arise from the spinal cord and supply all parts of the body supply all parts of the body except the head except the head They are named according to their They are named according to their point of issue point of issue 8 cervical (C 8 cervical (C 1 -C -C 8 ) ) 12 thoracic (T 12 thoracic (T 1 -T -T 12 12 ) ) 5 Lumbar (L 5 Lumbar (L 1 -L -L 5 ) ) 5 Sacral (S 5 Sacral (S 1 -S -S 5 ) ) 1 Coccygeal (C 1 Coccygeal (C 0 ) )

description

Spinal Nerves. Thirty-one pairs of mixed nerves arise from the spinal cord and supply all parts of the body except the head They are named according to their point of issue 8 cervical (C 1 -C 8 ) 12 thoracic (T 1 -T 12 ) 5 Lumbar (L 1 -L 5 ) 5 Sacral (S 1 -S 5 ) 1 Coccygeal (C 0 ). - PowerPoint PPT Presentation

Transcript of Spinal Nerves

Page 1: Spinal Nerves

Spinal NervesSpinal Nerves Thirty-one pairs of mixed nerves arise from the Thirty-one pairs of mixed nerves arise from the

spinal cord and supply all parts of the body spinal cord and supply all parts of the body except the headexcept the head

They are named according to their point of They are named according to their point of issueissue 8 cervical (C8 cervical (C11-C-C88)) 12 thoracic (T12 thoracic (T11-T-T1212)) 5 Lumbar (L5 Lumbar (L11-L-L55)) 5 Sacral (S5 Sacral (S11-S-S55)) 1 Coccygeal (C1 Coccygeal (C00))

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Spinal NervesSpinal Nerves

Figure 13.6

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Spinal Nerves: RootsSpinal Nerves: Roots Each spinal nerve connects to the spinal cord Each spinal nerve connects to the spinal cord

via two medial rootsvia two medial roots Each root forms a series of rootlets that attach Each root forms a series of rootlets that attach

to the spinal cord to the spinal cord Ventral roots arise from the anterior horn and Ventral roots arise from the anterior horn and

contain motor (efferent) fiberscontain motor (efferent) fibers Dorsal roots arise from sensory neurons in the Dorsal roots arise from sensory neurons in the

dorsal root ganglion and contain sensory dorsal root ganglion and contain sensory (afferent) fibers(afferent) fibers

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Spinal Nerves: RootsSpinal Nerves: Roots

Figure 13.7a

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Spinal Nerves: RamiSpinal Nerves: Rami The short spinal nerves branch into three or The short spinal nerves branch into three or

four mixed, distal ramifour mixed, distal rami Small dorsal ramusSmall dorsal ramus Larger ventral ramusLarger ventral ramus Tiny meningeal branchTiny meningeal branch Rami communicantes at the base of the ventral Rami communicantes at the base of the ventral

rami in the thoracic regionrami in the thoracic region

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Nerve PlexusesNerve Plexuses All ventral rami except TAll ventral rami except T22-T-T1212 form interlacing form interlacing

nerve networks called plexusesnerve networks called plexuses Plexuses are found in the cervical, brachial, Plexuses are found in the cervical, brachial,

lumbar, and sacral regionslumbar, and sacral regions Each resulting branch of a plexus contains Each resulting branch of a plexus contains

fibers from several spinal nervesfibers from several spinal nerves

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Nerve PlexusesNerve Plexuses Fibers travel to the periphery via several Fibers travel to the periphery via several

different routesdifferent routes Each muscle receives a nerve supply from Each muscle receives a nerve supply from

more than one spinal nervemore than one spinal nerve Damage to one spinal segment cannot Damage to one spinal segment cannot

completely paralyze a musclecompletely paralyze a muscle

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The back is innervated by dorsal rami via The back is innervated by dorsal rami via several branchesseveral branches

The thorax is innervated by ventral rami TThe thorax is innervated by ventral rami T11--TT1212 as intercostal nerves as intercostal nerves

Intercostal nerves supply muscles of the ribs, Intercostal nerves supply muscles of the ribs, anterolateral thorax, and abdominal wallanterolateral thorax, and abdominal wall

Spinal Nerve Innervation: Back, Spinal Nerve Innervation: Back, Anterolateral Thorax, and Anterolateral Thorax, and

Abdominal WallAbdominal Wall

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Spinal Nerve Innervation: Back, Spinal Nerve Innervation: Back, Anterolateral Thorax, and Anterolateral Thorax, and

Abdominal WallAbdominal Wall

Figure 13.7b

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Cervical PlexusCervical Plexus The cervical plexus is formed by ventral rami of The cervical plexus is formed by ventral rami of

CC11-C-C44

Most branches are cutaneous nerves of the neck, Most branches are cutaneous nerves of the neck, ear, back of head, and shouldersear, back of head, and shoulders

The most important nerve of this plexus is the The most important nerve of this plexus is the phrenic nervephrenic nerve

The phrenic nerve is the major motor and The phrenic nerve is the major motor and sensory nerve of the diaphragmsensory nerve of the diaphragm

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Cervical PlexusCervical Plexus

Figure 13.8

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Brachial PlexusBrachial Plexus Formed by CFormed by C55-C-C8 8 and Tand T11 (C (C44 and T and T22 may also may also

contribute to this plexus)contribute to this plexus) It gives rise to the nerves that innervate the It gives rise to the nerves that innervate the

upper limbupper limb

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Brachial PlexusBrachial Plexus There are four major branches of this plexus There are four major branches of this plexus

Roots – five ventral rami (CRoots – five ventral rami (C55-T-T11)) Trunks – upper, middle, and lower, which form Trunks – upper, middle, and lower, which form

divisionsdivisions Divisions – anterior and posterior serve the front Divisions – anterior and posterior serve the front

and back of the limband back of the limb Cords – lateral, medial, and posterior fiber bundlesCords – lateral, medial, and posterior fiber bundles

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Brachial PlexusBrachial Plexus

Figure 13.9a

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Brachial Plexus: NervesBrachial Plexus: Nerves Axillary – innervates the deltoid and teres minorAxillary – innervates the deltoid and teres minor Musculocutaneous – sends fibers to the biceps Musculocutaneous – sends fibers to the biceps

brachii and brachialisbrachii and brachialis Median – branches to most of the flexor muscles of Median – branches to most of the flexor muscles of

armarm Ulnar – supplies the flexor carpi ulnaris and part of Ulnar – supplies the flexor carpi ulnaris and part of

the flexor digitorum profundusthe flexor digitorum profundus Radial – innervates essentially all extensor musclesRadial – innervates essentially all extensor muscles

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Brachial Plexus: Distribution of Brachial Plexus: Distribution of NervesNerves

Figure 13.9c

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Brachial Plexus: NervesBrachial Plexus: Nerves

Figure 13.9b

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Lumbar PlexusLumbar Plexus Arises from LArises from L11-L-L44 and innervates the thigh, and innervates the thigh,

abdominal wall, and psoas muscleabdominal wall, and psoas muscle The major nerves are the femoral and the The major nerves are the femoral and the

obturatorobturator

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Lumbar PlexusLumbar Plexus

Figure 13.10

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Sacral PlexusSacral Plexus Arises from LArises from L44-S-S44 and serves the buttock, and serves the buttock,

lower limb, pelvic structures, and the perineumlower limb, pelvic structures, and the perineum The major nerve is the sciatic, the longest and The major nerve is the sciatic, the longest and

thickest nerve of the bodythickest nerve of the body The sciatic is actually composed of two The sciatic is actually composed of two

nerves: the tibial and the common fibular nerves: the tibial and the common fibular (peroneal) nerves(peroneal) nerves

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Sacral PlexusSacral Plexus

Figure 13.11

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DermatomesDermatomes A dermatome is the area of skin innervated by A dermatome is the area of skin innervated by

the cutaneous branches of a single spinal nervethe cutaneous branches of a single spinal nerve All spinal nerves except CAll spinal nerves except C11 participate in participate in

dermatomesdermatomes

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DermatomesDermatomes

Figure 13.12