ppt

1. Functional localization:The
peripheral nerves(roots,plexus
and individual nerves)
Presenter- Eleni A.(R3)
Moderators – Dr Nebiyu B(Neurologist)
- Dr Samson Y.(Neurologist)

2. Introduction
• Throughout the nervous system, motor systems tend to be more
ventral, or anterior, and sensory systems more dorsal, or posterior.
• The same holds true for the spinal cord. Thus, dorsal nerve roots
convey mainly afferent sensory information into the dorsal spinal
cord, while ventral nerve roots carry mainly efferent motor signals
from the ventral spinal cord to the periphery.
• The segments and nerve roots of the spinal cord are named according
to the level at which they exit the bony vertebral canal.
• Thus, there are cervical, thoracic, lumbar, and sacral nerve roots

3. Peripheral nervous system
Cranial nerves
There are 31 spinal nerves:
 8 cervical (C1–C8),
12 thoracic (T1–T12)
5 lumbar (L1–L5)
5 sacral (S1–S5), and
1 coccygeal (Co1) spinal segments

4. Introduction
• Peripheral nerves are composed of sensory, motor, and autonomic
elements.
• Diseases can affect the cell body of a neuron or its peripheral processes,
namely the axons or the encasing myelin sheaths
• Most peripheral nerves are mixed and contain sensory and motor as well as
autonomic fibers.
• Nerves can be subdivided into three major classes: large myelinated, small
myelinated, and small unmyelinated

5. Introduction
• Motor axons are usually large myelinated fibers that conduct rapidly
(approximately 50 m/s).
• Sensory fibers may be any of the three types.
• Large-diameter sensory fibers conduct proprioception and vibratory sensation
• Smaller-diameter myelinated and unmyelinated fibers transmit pain and
temperature sensation
• Autonomic nerves are also small in diameter

7. SPINAL NERVE ROOTS

8. Nerve Roots in Relation to Vertebral Bones,
Discs, and Ligaments
• The vertebral bones function both as the
central mechanical support for the body
and as protection for the spinal cord.
• Separated by intervertebral discs,
consisting of a central nucleus pulposus
surrounded by a capsule called the annulus
fibrosus

9. Nerve Roots in Relation to Vertebral Bones,
Discs, and Ligaments
• Posteriorly, the neural elements are surrounded by an arch of bone
formed by the pedicles, transverse processes, laminae, and spinous
processes
• Spinal cord -runs through the spinal canal (vertebral foramen) and is
surrounded by pia, arachnoid, and dura mater
• layer of epidural fat between the dura and the periosteum
• there is a valveless meshwork of epidural veins called Batson’s plexus

10. Nerve Roots in Relation to Vertebral Bones,
Discs, and Ligaments
• Sensory fibers(afferent)- dorsal
root and motor neurons(efferent)
from Ventral root merge together
with autonomic nerves and form
spinal nerve
• The nerve roots exit the spinal
canal via the neural
(intervertebral) foramina
• Devide to primry anterior and
posterior rami

11. Principles of Spinal Nerve and Root
Localization
• Differentiation from peripheral nerve or plexus lesions -
Segmental character of the sensory and motor signs and symptoms.
Dermatomes and Myotomes
• The sensory region of skin innervated by a nerve root is called a
dermatome
• The muscles innervated by a single nerve root constitute a myotome

13. Clues to consider nerve root
lesion(Radiculopathy)
• Sensory symptoms
• Radicularor root pain- sharp lanscinating, electric or burning quality
• Well localized referred to specific dermatome or myotome
• Accentuated by maneuvers that increase interspinal pressure(coughing,
straining, valsalva or spine movements)
• Later may develop paresthesia or dysesthesia
• Note that there is considerable overlap between adjacent dermatomes,
cutaneous nerves- sensory loss
• Motor(ventral)- weakness and atrophy of myotomal distribution of
affected root
• Reflex – hypo/areflexia on the muscle supplied

15. Disk herination
• Cervical nerve roots – exit above the corresponding bone
• Cervical nerve roots have a fairly horizontal course
• Cervical discs are usually constrained by the posterior longitudinal
ligament to herniate laterally toward the nerve root
• Cervical disc herniation usually compresses the nerve root exiting at
that level - number of the lower vertebral bone at that interspace

16. Nerve Roots in Relation to Vertebral Bones,
Discs, and Ligaments
• Thoracic, lumbar, and sacral nerve roots exit below the
correspondingly numbered vertebral bone
• nerve roots exit some distance above the intervertebral discs
• posterolateral disc herniations in the lumbosacral spine usually
impinge on nerve roots on their way to exit beneath the next lower
vertebral bone
• Lumbosacral disc herniation - usually spares the nerve root exiting at
that level and compresses the nerve root exiting at the next level
down.
• corresponds to the number of the lower vertebral bone at the level of
the herniation

17. C: Far lateral lumbosacral disc herniation affects the nerve root exiting at that level,
and central lumbosacral disc herniation can cause cauda equina syndrome

21. Lumbosacral radiculopathy

22. MAJOR PLEXUSES AND
PLEXOPATHIES

23. Cervical Plexus
• plexus formed by branches
of CN XII and C1 through
C5 called the cervical
plexus, which supplies
mainly the neck muscles.
• The phrenic nerve, which
supplies the diaphragm,
arises from C3, C4, and C5.

24. Lesions of cervical plexus
• Penetrating wounds
• Surgical procedures
• Mass lesions
Sign & symptoms:
Involvementt of the cutaneous branches results in altered sensation
When muscular branches are injured there is weakness of infrahyoid & scalene
muscles(anterior and lateral head flexion)
Injuries to phrenic nerve (C3-C5)

25. Phrenic nerve lesions
• A mediastinal process
• Loss of diaphragmatic movement
• Unilateral lesions:
Little disability at rest
Dyspnea may occur with exertion
• Bilateral lesions:
Exertional dyspnea
Severe alveolar hypoventilation
with hypercapnia
Symptoms worse in recumbency

26. Brachial Plexus
• The brachial plexus is formed by nerve roots arising from the cervical
enlargement at C5, C6, C7, C8, and T1
• These nerve roots provide the major sensory and motor innervation
for the upper extremities.
• The nerves of the brachial plexus are clinically important

29. Lesions of brachial plexus
• Common causes:
Trauma (motor bike accident, shoulder dystosia)
Neurovascular injury
Medial brachial fascial compartment Sxx
Radiation, infectious, serum/vaccine
Mass (tumors)
Hereditary
Poor positioning
Metastasis

30. Neuralgic Amyotrophy
• Acute, severe shoulder pain
radiating to arm, neck & back
• Parsonage-Turner Sxx
• Ideopathic brachial plexitis or
multiple mononeuritis
• Flexion adduction sign
• Upper trunck

31. Upper plexus paralysis (Erb-Duchenne Type)
• C5–C6 (upper trunk)
• Motor:
• shoulder abduction(deltoid), external
rotation(Infraspinatous), elbow
flexion(biceps, brachradialis), and
supination(biceps) affected
• hand movement preserved
• limb hangs straight down, hand pronated.
• Breathing arm
• Sensory: deficit on lateral aspect of the arm
and forearm(mild)
• Reflex: biceps and brachioradialis

32. Lower plexus paralysis (Klumpke–Dejerine
palsy)
• Lower trunk(C8-T1)
• Motor: weakness of the hand
muscles
• atrophy of the intrinsic muscles
produces a claw hand deformity.
• sensation: deficit in ulnar aspect of
the forearm and in the hand.
• Horner syndrome.
• Finger flexor reflex absent

33. Lumbosacral Plexus
• The lumbosacral plexus arises from L1, L2, L3, L4, L5, S1, S2, S3, and
S4 at the lumbosacral enlargement - innervation to the lower
extremities and pelvis
• The muscles innervated by each of the lumbosacral nerve branches
should be reviewed
• The most clinically important nerve branches arising from the
lumbosacral plexus are the femoral, obturator, sciatic, tibial, and
peroneal nerves

36. Lumbosacral plexopathies causes
• Retroperitoneal hematoma(anticoagulant)
• Psoas abscess
• Neoplasm
• Radiation
• Diabetic radiculoplexus neuropathy
• Lithotomy positioning
• Hip arthroplasty , pelvic fractures
• Obstetric injury

37. Lumbar plexopathy
• Motor: weakness of hip flexion and knee extension, thigh
adduction and external rotation.
• Sensory: deficit in inguinal area ,genitalia, lateral medial anterior
thigh, medial lower leg
• Reflex: patellar(femoral),cremasteric reflex(genitofemoral)affected

38. Sacral plexopathy
• Motor:
• weakness of the gluteal muscles,hamstrings, and
plantar and dorsiflexors of the foot and toes.
• sensory:
• deficit on the dorsal aspect of the thigh, calf, and foot
• Reflex:
• ankle reflex
• Sphincter:
• bladder & bowel control

39. PERIPHERAL NERVES

40. The Median Nerve
• Elbow- Innervating twigs are given off from
the lateral head to the pronator teres and
flexor carpi radialis muscles.
• The main trunk passes through the two
heads of the pronator teres muscle and
beneath an aponeurosis connecting the two
heads of the flexor digitorum superficialis
(the sublimis bridge).

41. The Median Nerve
• Just distal to the pronator teres -the
nerve gives off the anterior interosseous
nerve (AIN)- innervates - the median
head (lateral portion) of the flexor
digitorum profundus (FDP), the flexor
pollicis longus, and the pronator
quadratus.
• Distal forearm- giving off muscular
branches to the palmaris longus and
flexor digitorum superficialis.

42. The Median Nerve
• The median nerve crosses from the distal forearm
to the hand through the carpal tunnel.
• The walls and floor of the tunnel are formed by the
carpal bones and the roof by the transverse carpal
ligament (TCL).
• canal - 8 deep and superficial finger flexor
tendons and the tendon of the flexor pollicis
longus surrounded by a complex synovial sheath.

43. The Median Nerve
• The palmar cutaneous branch - leaves the main trunk 5 to 8 cm
proximal to the wrist crease- innervate thenar eminence
• After exiting the carpal tunnel - recurrent thenar motor branch - to
innervate the median thenar muscles (abductor pollicis brevis,
opponens pollicis, and lateral head of the flexor pollicis brevis).

45. The Median Nerve
• Sensory- The palmar surfaces of the thumb,
index and middle fingers,
• Palmar aspect of the radial half of the ring
finger, and
• The dorsal aspect of the middle and distal
phalanges of the index and middle fingers and
radial half of the ring finger.

46. Nerve lesions
Lesions in the Axilla and upper arm
• triad neuropathy - median, ulnar, and radial nerves, usually from a
lesion in the axilla , for example, crutch palsy, or of the BP distal
branches.
• It may be involved in dislocations of the shoulder,fractures of the
humerus, penetrating wounds, or compression injuries,AV fistulas
• Paresis of all muscles supplied by median nerve with associated
sensory loss

47. Clinical feature
• atrophy of the thenar eminence- the abductor pollicis
brevis and the opponens pollicis.
• Because of this atrophy – recession of the metacarpal
bones of the thumb to the plane of the other
metacarpal bones, the hand takes on an abnormal
appearance called simian hand or apehand.
• This appearance results from the unopposed action of
the extensor pollicis longus(radialnerve) and the
adductor pollicis(ulnarnerve).

48. • Because the second finger cannot be flexed and the third finger can
be flexed only partially, when the person attempts to make a
fist,these fingers remain extended.
• The hand then takes on the appearance of that of a clergy man
offering benediction(benediction hand)

49. • The sensory changes involve the
radial side of the palm, including
the thenar region (palmar
cutaneous distribution), the index
and middle fingers, and the radial
half of the ring finger.
• There are no significant reflex
changes.
• Vasomotor and trophic changes

50. Entrapment of median nerve
• Pronator Teres syndrome - Hypertrophy of the pronator teres has been
implicated.
• There is often pain in the proximal forearm, and there may be tenderness and/or a
Tinel’s sign over the pronator muscle.
• Depending on the individual anatomy and the origin of the branch to the pronator
teres, the pronator teres may or may not be involved in a pronator syndrome.
• Complete AIN paralysis causes inability to flex the distal phalanx of either
the thumb or index finger.
• The patient cannot make a circle by touching the tip of the thumb to the tip of the
index finger, making a triangle instead by touching the finger pads (pinch sign, or OK
sign [the patient is unable to make the OK sign with the involved hand])

51. Cont…
• Carpal Tunnel Syndrome- Entrapment of the
median nerve beneath the TCL(transvers
carpal ligament)
• Causes -mass lesions narrowing the
passageway, ganglion, osteophyte, lipoma,
aneurysm, anomalous muscle).
• systemic conditions,
• rheumatoid arthritis, diabetes mellitus, chronic
renal insufficiency and hemodialysis,
hypothyroidism, amyloidosis, myeloma,
acromegaly, and pregnancy.

52. Clinical characterstics
• hand pain, numbness, and paresthesias, all
usually more severe at night.
• relief by shaking or flicking the hand(flick out)
• Proximal upper-extremity pain, usually in the
forearm.
• Many patients complain of “whole hand”
numbness, and rarely, for unclear reasons, a
patient with CTS may present with ulnar or even
radial distribution paresthesias.
• sensory

53. Carpal Tunnel Syndrome
• Mild CTS - trivial sensory loss over the fingertips
• Paresis of abductor polisis and opponenes polisis
• Tinel’s sign - paresthesias produced by percussion over a peripheral
nerve that may indicate focal nerve pathology.
• Phalen’s (wrist flexion) test is numbness or paresthesias in the median
distribution - flexion of the wrist for 1 minute.
• The reverse Phalen’s (prayer) test is the same but with the wrist
hyperextended.
• Carpal compression test, elevated arm stress test (Roos’ test)
• Cuff compression test of Gilliatt and Wilson (tourniquet test)

55. ULNAR NERVE(C7-T1)

57. Ulnar neuropathy at the elbow
• Includes both neuropathy
following remote elbow
fracture(Tardy ulnar palsy
• Cubital tunnel syndrome-
entrapment under humeroulnar
arcade
• Causes- trauma, prolonged
elbow flexion, arthritis…
• Clinically- sensory symptoms –
dorsal ulnar and plamar
cutaneous territory
• Worse in elbow flexion(talking
on the phone)
• Motor- mild weakness to severe
claw deformity
• hypothenar eminence and
interossei are atrophied and
flattened

58. Ulnar neuropathy at the elbow
• “claw-hand”deformity(main engriffe),
• The fifth, fourth, and, to a lesser extent, the third fingers are hyperextended
at the metacarpophalangeal joints and flexed at the interphalangeal joints.
• Hyper extension at the metacarpophalangeal joints is due to paralysis
of the interossei and ulnar lumbricals –results in unopposed action of
the long finger extensors(extensor digitorum)
• The flexion at the interphalangeal joints is due to the pull exerted by
the long flexor tendons

59. • Paresis or paralysis of the ulnar flexion
• Froment prehensile thumb sign(signedujournal) - Adductor pollicis
affection
• Tinel test- firm percussion over the ulnar groove, cubital tunnel,
guyon’s canal
• Sustained elbow flexion

61. • Sensory findings
• Because all three sensory branches of the
ulnar nerve are affected(palmar, dorsal,
and superficial terminal
cutaneousbranches),
• Paresthesias and sensory loss occur on the
dorsal and palmar surfaces of the fifth and
ulnar half of the fourth finger and the
ulnar portion of the hand to the wrist

62. ULNAR NEUROPATHY AT THE WRIST
• Typically- hand weakness, atrophy, loss of dexterity and variable
sensory involvement
• Injury to the nerve in the guyon’s canal
• Ulnar paradox- distal lesion more severe deformity than proximal
lesion

63. Radial nerve(C5-T1)

64. Sensory

68. Lower extremity nerves

69. The Sciatic Nerve
• The sciatic, superior gluteal, and
inferior gluteal nerves all exit the
pelvis through the greater sciatic
foramen.
• The sciatic – exits beneath the
piriformis muscle
• Travels beneath glutus maximus
• In its course through the thigh, it
innervates the hamstring muscles
and also sends a twig to the
adductor magnus.

70. The Sciatic Nerve
• two divisions:
• The fibular (peroneal, lateral) and – posterior devision
• The tibial (medial) – anterior devision

72. The Sciatic Nerve injury
• result in weakness of both the common peroneal and tibial
innervated muscles - most often the peroneal(biceps femoris)
• Hamstring muscle weakness clearly indicates that the lesion involves
the main trunk of the sciatic nerve.
• sensory loss involves all but the anteromedial aspect of the leg
(saphenous distribution)

73. The Sciatic Nerve
• Knee flexion is greatly impaired.
• Flexion and extension of the ankle and toe joints and inversion and
eversion of the foot are lost.
• The patient cannot stand on either heel or toes.
• Trophic disturbances and neuropathic pain are frequent

74. Cont…
• Causes- pelvic fractures, hip fracture or dislocation, total hip
arthroplasty and other orthopedic procedures on the hip, intragluteal
injections, gluteal hemorrhage or compartment syndrome, and
penetrating wounds.
• The nerve may be compressed by prolonged sitting in the lotus
position (lotus neuropathy) or prolonged pressure from a toilet seat,
both termed “another Saturday night palsy”
• In the hanging leg syndrome, sciatic neuropathy, with accompanying
femoral neuropathy, develops from having the legs hanging off the
bed with hips hyperextended while intoxicated or in coma.

75. The Sciatic Nerve
• The piriformis syndrome is sciatic compression by the piriformis
muscle as it exits the pelvis.
• The existence of this syndrome is controversial.
• External compression of the nerve in the hip may occur with pressure
due to a fat wallet or coins or a pistol in the hip pocket (pistol packer’s
palsy).
• Such instances do not qualify as piriformis syndrome.

76. • Common Peroneal Neuropathy at the
Fibular Head
• Common peroneal mononeuropathy at the
fibular head - weakness of dorsiflexion of the
foot and toes and weakness of ankle eversion.
• Severe peroneal neuropathy causes a foot
drop.
• Sensation is lost over the dorsum of the foot.
• Habitual leg crossing

77. The Tibial Nerve injury
• If the tibial nerve is injured - there is weakness distal to the lesion,
• sensory loss over the plantar and lateral aspects of the foot, the heel,
and the posterolateral aspects of the leg and ankle.
• The patient may be unable to plantar flex or invert the foot or to flex,
adduct, or abduct the toes.
• Trophic changes and pain are common.
• The Achilles reflex is lost.

78. The Tibial Nerve
• Tarsal tunnel syndrome [TTS]- Compression by the flexor retinaculum
behind the medial malleolus (lancinate ligament)
• burning pain and sensory loss in the toes and sole of the foot and
• paresis or paralysis of the small muscles of the foot
• Patients may have sensory symptoms provoked by weight bearing and
relieved by rest

79. • sensory loss over the sole- especially in the medial plantar
distribution, usually sparing the heel (calcaneal branch);
• tenderness behind medial malleolus; and
• Tinel’s sign over the tarsal tunnel
• Phalen’s, passively holding the ankle maximally everted and
dorsiflexed with the toes pulled up to elicit paresthesias

80. The Tibial Nerve
• A test similar to Phalen’s, passively holding the ankle maximally
everted and dorsiflexed with the toes pulled up to elicit paresthesias,
is said to be useful.

82. Thank you