spinal nerves
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 PresentationTRANSCRIPT
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))
Spinal NervesSpinal Nerves
Figure 13.6
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
Spinal Nerves: RootsSpinal Nerves: Roots
Figure 13.7a
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
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
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
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
Spinal Nerve Innervation: Back, Spinal Nerve Innervation: Back, Anterolateral Thorax, and Anterolateral Thorax, and
Abdominal WallAbdominal Wall
Figure 13.7b
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
Cervical PlexusCervical Plexus
Figure 13.8
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
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
Brachial PlexusBrachial Plexus
Figure 13.9a
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
Brachial Plexus: Distribution of Brachial Plexus: Distribution of NervesNerves
Figure 13.9c
Brachial Plexus: NervesBrachial Plexus: Nerves
Figure 13.9b
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
Lumbar PlexusLumbar Plexus
Figure 13.10
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
Sacral PlexusSacral Plexus
Figure 13.11
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
DermatomesDermatomes
Figure 13.12