F25 IONM pt 1 > Peripheral Nerves > Flashcards

Peripheral Nerves Flashcards

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1
Q

What is a nerve plexus?

A

An interconnecting group of nerves that innervate the same area of the body

There are four main plexuses on each side, carrying afferent (sensory) and efferent (motor) information.

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2
Q

Name the four main nerve plexuses.

A
  • Cervical
  • Brachial
  • Lumbar
  • Sacral

Each plexus has specific spinal roots and regions it innervates.

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3
Q

What spinal roots correspond to the Cervical Plexus?

A

C1–C5

It innervates the neck, shoulders, and diaphragm.

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4
Q

What is the origin of the Phrenic Nerve?

A

C3–C5

It is crucial for breathing as it innervates the diaphragm.

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5
Q

What region does the Brachial Plexus innervate?

A

Upper Extremity (arm, forearm, hand)

It forms from the cervical enlargement.

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6
Q

What spinal roots correspond to the Lumbar Plexus?

A

T12–L4

It innervates the anterior and medial thigh.

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7
Q

What is the largest nerve in the body?

A

Sciatic nerve

It is part of the Sacral Plexus.

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8
Q

What mnemonic helps remember the Brachial Plexus structure?

A

Real Truckers Drink Cold Beer

This stands for Roots, Trunks, Divisions, Cords, Branches.

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9
Q

What are the major branches of the Brachial Plexus?

A
  • Musculocutaneous
  • Axillary
  • Radial
  • Median
  • Ulnar

These branches arise below the clavicle and target specific muscles.

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10
Q

What does the Femoral Nerve monitor?

A

Quadriceps muscles (knee extension)

It is part of the Lumbar Plexus (L2–L4).

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11
Q

What is the function of the Pudendal Nerve?

A

Innervates genitalia and sphincter muscles

It is part of the Sacral Plexus (S2–S4) and monitored using specific reflexes.

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12
Q

What neurotransmitter is released at the neuromuscular junction?

A

Acetylcholine (ACh)

It binds to nicotinic receptors on the sarcolemma.

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13
Q

Fill in the blank: Afferent fibers are responsible for _______ input.

A

Sensory

They receive input from mechanoreceptors in the skin.

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14
Q

What is the role of efferent fibers?

A

Receive messages from the brain to muscles

They signal travels to muscles for contraction.

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15
Q

What does the Tibial Nerve innervate?

A

Gastrocnemius (calf) for plantar flexion

It is part of the Sacral Plexus (L4–S3).

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16
Q

What are dermatomes?

A

An area of skin mainly supplied by branches of a single spinal sensory nerve root

Important for two-point discrimination and localizing sensory deficits.

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17
Q

What type of mechanoreceptor senses fine touch?

A

A-beta afferent fibers

They are responsible for fine touch, vibration, proprioception.

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18
Q

What is the function of Meissner’s corpuscles?

A

Sense temporary light touch

They are found in glabrous skin.

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19
Q

The Long thoracic nerve consists of what roots?

A

C5, C6, C7

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20
Q

The Long thoracic nerve innervates what muscles?

A

Serratus anterior

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21
Q

The Long thoracic nerve offers sensation for what areas?

A

None

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21
Q

The Long thoracic nerve controls what motion?

A

Winged Scapula

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22
Q

The superclavicular nerve consists of what roots?

A

C5, C6, C7

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23
Q

The superclavicular nerve innervates what muscles?

A

Supraspinatus

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24
The superclavicular nerve controls what motion?
Shoulder abduction
25
The superclavicular offers sensation for what areas?
None
26
The superclavicular nerve consists of what trunks?
None; they originate directly from the anterior rami of the cervical plexus
27
The Long thoracic nerve consists of what trunks?
None; they originate directly from the anterior rami of the brachial plexus
28
The axillary nerve consists of what roots?
C5, C6
29
The axillary nerve consists of what trunk?
Upper trunk (C5–C6)
30
The axillary nerve consists of what divisions?
Posterior division of the upper trunk
31
The axillary nerve consists of what cords?
Posterior cord
32
The axillary nerve innervates what muscles?
Deltoid and teres minor
33
The axillary nerve controls what motion?
Arm Abduction
34
The axillary nerve offers sensation for what areas?
Superior lateral cutaneous nerve of the arm (over the deltoid)
35
The superior trunk of the brachial plexus consists of what nerve roots?
C5, C6
36
The middle trunk of the brachial plexus consists of what nerve roots?
C7
37
The inferior trunk of the brachial plexus consists of what nerve roots?
C8, T1
38
The lateral cord of the brachial plexus consists of what divisions?
Anterior division of the Superior trunk AND Anterior division of the Middle trunk
39
The Posterior cord of the brachial plexus consists of what divisions?
Posterior division of the Superior trunk AND Posterior division of the Middle trunk AND Posterior division of the Inferior trunk
40
The Medial cord of the brachial plexus consists of what divisions?
Anterior division of the Inferior trunk
41
All 3 trunks of the brachial plexus seperate into...?
Divisions; 2 per trunk Anterior and Posterior
42
The musculocutaneous nerve consists of what roots?
C5, C6, C7
43
The musculocutaneous nerve consists of what trunks?
Upper AND Middle
44
The musculocutaneous nerve consists of what divisions?
Anterior division of the Superior trunk AND Anterior division of the Middle trunk
45
The musculocutaneous nerve consists of what cords?
Lateral Cord
46
The musculocutaneous nerve innervates what muscles?
Biceps brachii Brachialis Coracobrachialis
47
The musculocutaneous nerve controls what motion?
Elbow Flexion
48
The musculocutaneous nerve offers sensation for what areas?
Lateral Forearm
49
The redial nerve consists of what roots?
C5, C6, C7, C8, T1
50
The redial nerve consists of what trunks?
All three Upper trunk (C5–C6 fibers) Middle trunk (C7 fibers) Inferior trunk (C8–T1 fibers)
51
The redial nerve consists of what divisions?
All three Posterior division of Upper trunk (C5–C6 fibers) Posterior division of Middle trunk (C7 fibers) Posterior division of Lower trunk (C8–T1 fibers)
52
The redial nerve consists of what cords?
Posterior cord
53
The redial nerve innervates what muscles?
Extensor Carpi, Radialis longus Radialis brevis
54
The redial nerve controls what motion?
Extension of elbow and wrist
55
The redial nerve offers sensation for what areas?
posterior, lateral arm dorsum of the hand
56
The median nerve consists of what roots?
C5, C6, C7, C8, T1
57
The median nerve consists of what trunks?
All three Upper trunk (C5–C6 fibers) Middle trunk (C7 fibers) Lower trunk (C8–T1 fibers)
58
The median nerve consists of what divisions?
Anterior division of the Superior trunk AND Anterior division of the Middle trunk AND Anterior division of the Inferior trunk
59
The median nerve consists of what cords?
Lateral Cord AND Medial Cord
60
The median nerve innervates what muscles?
Pronator teres Pronator quadratus Flexor carpi radialis Flexors of fingers
61
The median nerve controls what motion?
Flexion of wrist and fingerws
62
The median nerve offers sensation for what areas?
Radial Palm Palmer surface Tips of lateral 3.5 fingers
63
The ulnar nerve consists of what roots?
C8, T1 (occasional C7)
64
The ulnar nerve consists of what trunks?
Inferior trunk (C8–T1 fibers)
65
The ulnar nerve consists of what divisions?
Anterior division of the Inferior trunk
66
The ulnar nerve consists of what cords?
medial cord
67
The ulnar nerve innervates what muscles?
Interossei and lumbricals Adductor pollicis
68
The ulnar nerve controls what motion?
Movement of medial 2 fingers
69
The ulnar nerve offers sensation for what areas?
Ulnar and dorsal palm Medial 1.5 fingers
70
The subcostal nerve consists of what roots?
T12
71
The subcostal nerve innervates what muscles?
External oblique Internal oblique Transversus abdominis Rectus abdominis (sometimes partially, via contribution to upper portions) Quadratus lumborum (minor contribution in some texts)
72
The subcostal nerve controls what motion?
Trunk flexion – bending forward (via rectus abdominis) Trunk lateral flexion – bending sideways (via obliques) Trunk rotation – twisting (via obliques) Abdominal wall tension / compression – important for forced expiration, coughing, defecation, urination, and stabilization of the trunk
73
The subcostal nerve offers sensation for what areas?
Lower anterior abdominal wall – just above the pubis Lateral hip / iliac crest region – along the upper lateral hip Sometimes small branches supply the upper gluteal region
74
The iliohypogastric nerve consists of what roots?
T12, L1
75
The iliohypogastric nerve consists of what divisions?
Anterior division of L1
76
The iliohypogastric nerve innervates what muscles?
Internal Oblique External Oblique Transversus abdominis
77
The iliohypogastric nerve controls what motion?
Anterior abdominal wall
78
The iliohypogastric nerve offers sensation for what areas?
- Inferior abdominal wall - Upper lateral quadrant of buttock
79
The ilioinguinal nerve consists of what divisions?
Anterior division of L1
80
The ilioinguinal nerve consists of what roots?
L1
81
The ilioinguinal nerve innervates what muscles?
Internal oblique
82
The ilioinguinal nerve controls what motion?
Anterior abdominal wall
83
The ilioinguinal nerve offers sensation for what areas?
- Inferior medical inguinal ligament - Genitalia
84
The genitofemoral nerves consist of what roots?
L1 - L2
85
The genitofemoral nerves consist of what divisions?
Anterior division of L1 and Anterior division of L2
86
The genitofemoral nerve innervates what muscles?
Cremaster (males) Sensory only (females)
87
The genitofemoral nerve offers sensation for what areas?
- Inferior medical inguinal ligament - Spermatic cord - Males: anterior scrotum - Females: mons pubis and labia majora
88
The lateral femoral cutaneous nerves consist of what roots?
L2 - L3
89
The lateral femoral cutaneous nerve innervates what muscles?
None
90
The lateral femoral cutaneous nerve controls what motion?
None
91
The lateral femoral cutaneous nerve offers sensation for what areas?
Anterior, lateral, posterior aspect of thigh
92
The femoral nerve, anterior division nerves consist of what roots?
L2, L3, L4
93
The lateral femoral cutaneous nerve innervates what muscles?
Sartorius Pectineus
94
The femoral nerve, anterior division nerve controls what motion?
- Medical aspect of lower thigh - Adduction of thigh
95
The femoral nerve, anterior division nerve offers sensation for what areas?
Anterior medical skin of thigh
96
The femoral nerve, posterior division nerves consist of what roots?
L2, L3, L4
97
The femoral nerve, posterior division nerve innervates what muscles?
Quadriceps
98
The femoral nerve, posterior division nerve controls what motion?
- Knee extension - Patellar movements
99
The femoral nerve, posterior division nerve offers sensation for what areas?
Anterior thigh hip and knee
100
The obturator nerve, anterior division nerves consist of what roots?
L2 - L4
101
The obturator nerve, anterior division nerve innervates what muscles?
- Gracilus - Adductor longus - Adductor brevis - Pectineus
102
The obturator nerve, anterior division nerve controls what motion?
Thigh adduction
103
The obturator nerve, anterior division nerve offers sensation for what areas?
- Anterior thigh hip and knee
104
The obturator nerve, posterior division nerves consist of what roots?
L2-L4
105
The obturator nerve, posterior division nerve innervates what muscles?
Adductor magnus Obturator externus
106
The obturator nerve, posterior division nerve controls what motion?
Knee
107
The superior gluteal nerves consist of what roots?
L4, L5, S1
108
The superior gluteal nerve innervates what muscles?
Gluteus medius Gluteus minimus Tensor fasciae latae (TFL)
109
The superior gluteal nerve controls what motion?
Hip abduction (gluteus medius/minimus) Medial rotation of the hip (gluteus medius/minimus) Stabilization of the pelvis during gait (gluteus medius) TFL assists with hip abduction, medial rotation, and tensioning the IT band
110
The superior gluteal nerve offers sensation for what areas?
None; Purely motor
111
The inferior gluteal nerves consist of what roots?
L5, S1, S2
112
The inferior gluteal nerve innervates what muscles?
Gluteus maximus
113
The inferior gluteal nerve controls what motion?
Hip extension (especially rising from sitting, climbing stairs) External rotation of the hip
114
The inferior gluteal nerve offers sensation for what areas?
None; Purely motor
115
The posterior cutaneous nerve consists of what roots?
S1, S2, S3
116
The posterior cutaneous nerve innervates what muscles?
None; purely sensory
117
The posterior cutaneous nerve controls what motion?
None; purely sensory
118
The posterior cutaneous nerve offers sensation for what areas?
Skin of the posterior thigh Inferior cluneal nerves → skin of lower buttock Perineal branch → skin of the perineum (variable)
119
The pudendal nerve consists of what roots?
S2, S3, S4
120
The pudendal nerve innervates what muscles?
External anal sphincter External urethral sphincter Bulbospongiosus (bulbocavernosus) Ischiocavernosus Superficial transverse perineal muscle Deep transverse perineal muscle (Part of) Levator ani — specifically puborectalis and pubococcygeus portions receive contribution, but levator ani is primarily supplied by the nerve to levator ani (S3–S4).
121
The pudendal nerve controls what motion?
motion of voluntary pelvic floor muscles, especially sphincter closing (urination & defecation control) perineal contractions involved in sexual function and perineal stabilization.
122
The pudendal nerve offers sensation for what areas?
External genitalia - Penis & scrotum (via dorsal nerve of penis) - Clitoris & labia (via dorsal nerve of clitoris) Perineal skin - Posterior scrotum/labia - Perineal region around the urogenital triangle Anal region - Skin around the anus - Inferior anal canal (via inferior rectal nerves)
123
The sciatic nerve consists of what roots?
L4, L5, S1, S2, S3
124
The sciatic nerve splits into...
- The tibial nerve - Common Fibular (Peroneal)
125
The Common Fibular (Peroneal) nerve splits into...
Deep Fibular (Peroneal) Nerve Superficial Fibular (Peroneal) Nerve
126
The tibial nerve consists of what roots?
L4, L5, S1, S2, S3 (Sciatic Nerve)
127
The tibial nerve innervates what muscles?
all the muscles in the posterior compartment of the leg and most of the intrinsic foot muscles Superficial layer - Gastrocnemius (medial & lateral heads) - Soleus - Plantaris Deep layer - Popliteus - Tibialis posterior - Flexor digitorum longus - Flexor hallucis longus
128
The tibial nerve controls what motion?
1. Knee Slight knee flexion via popliteus (also unlocks the knee) 2. Ankle Plantarflexion → gastrocnemius, soleus, plantaris, tibialis posterior Inversion → tibialis posterior 3. Toes Flexion of toes → flexor digitorum longus, flexor hallucis longus, intrinsic foot muscles (via medial & lateral plantar nerves) 4. Foot Stabilization Supports the medial and lateral arches via intrinsic foot muscles
129
The tibial nerve offers sensation for what areas?
1. Medial Plantar Nerve (branch of tibial) Skin of: - Medial plantar surface of the foot - Plantar surface of toes 1–4 (medial side) - Dorsal contribution: none (plantar only) 2. Lateral Plantar Nerve (branch of tibial) Skin of: - Lateral plantar surface of the foot - Plantar surface of 5th toe and lateral half of 4th toe 3. Heel - Calcaneal branch of tibial nerve: - Skin over posterior heel
130
The deep fibular (peroneal) nerve consists of what roots?
L4, L5, S1, S2, S3 (Sciatic Nerve; Common Fibular (Peroneal) nerve)
131
The deep fibular (peroneal) nerve innervates what muscles?
1. Anterior Compartment of the Leg - Tibialis anterior - Extensor hallucis longus - Extensor digitorum longus - Fibularis (peroneus) tertius 2. Dorsal Foot Muscles - Extensor digitorum brevis - Extensor hallucis brevis
132
The deep fibular (peroneal) nerve controls what motion?
1. Ankle - Dorsiflexion → tibialis anterior, extensor digitorum longus, fibularis tertius - Inversion → tibialis anterior - Eversion → fibularis tertius (minor contribution) 2. Toes - Extension of toes 2–5 - Extension of big toe
133
The superficial fibular (peroneal) nerve consists of what roots?
L4, L5, S1, S2, S3 (Sciatic Nerve; Common Fibular (Peroneal) nerve)7
134
The superficial fibular (peroneal) nerve innervates what muscles?
Fibularis longus + Fibularis brevis
135
The superficial fibular (peroneal) nerve controls what motion?
Everts the foot Weakly plantarflexes the ankle
136
The superficial fibular (peroneal) nerve offers sensation for what areas?
dorsum of the foot (except 1st web space and lateral edge)
137
The deep fibular (peroneal) nerve consists of what roots?
L4, L5, S1, S2, S3 (Sciatic Nerve; Common Fibular (Peroneal) nerve)
138
The deep fibular (peroneal) nerve innervates what muscles?
- Tibialis Anterior - Extensor Hallucis Longus (EHL) - Extensor Digitorum Longus (EDL) - Fibularis (Peroneus) Tertius' - Extensor Digitorum Brevis - Extensor Hallucis Brevis (EHB)
139
The deep fibular (peroneal) nerve controls what motion?
Dorsiflexes ankle Inverts foot Extends great toe Extends toes 2–5 Everts foot (weak)
140
The deep fibular (peroneal) nerve offers sensation for what areas?
1st dorsal web space
141
The sural nerve offers sensation for what areas?
lateral border on the dorsum of the foot
142
The sural nerve consists of what roots?
Components from peroneal (typically L5–S1) and tibial (S1–S2) Dominant: S1–S2
143
The sural nerve innervates what muscles?
None; purely sensory
144
The sural nerve controls what motion?
None; purely sensory
145
Three upper extremity nerves monitored in IONM
Radial Median Ulnar
146
Four lower extremity nerves monitored in IONM
-Obturator - Femoral -Sciatic (and it's branches) - Pudendal
147
# Categories of skeletal muscle actions Extensor
increase the angle at a joint.
148
# Categories of skeletal muscle actions Flexor
decreases the angle at a joint.
149
# Categories of skeletal muscle actions Abductor
moves the limb Away from the midline of the body
150
# Categories of skeletal muscle actions Adductor
moves the limb toward the midline of the body.
151
# Categories of skeletal muscle actions Levator
"Moves insertion upward" AKA Elevates a body part - The origin is usually above. - The insertion (The point where the muscle attaches to the bone that moves when the muscle contracts) is below. - When the muscle contracts, it pulls the insertion upward toward the origin.
152
# Categories of skeletal muscle actions depressor
"moves insertion downward" AKA Lowers a body part - The origin is usually above. - The insertion (The point where the muscle attaches to the bone that moves when the muscle contracts) is below. - When the muscle contracts, it pulls the insertion downward
153
# Categories of skeletal muscle actions Rotator
rotates a bone along its axis
154
# Categories of skeletal muscle actions sphincter
constricts an opening.
155
# Muscle Innervation The trapezius muscle is innervated by what major nerve?
None
156
# Muscle Innervation The trapezius muscle is innervated by what spinal nerves?
C2, C3, C4, CNXI
157
# Muscle Innervation The sternocleidomastoid muscle is innervated by what major nerve?
None (on IONM notes); CNXI
158
# Muscle Innervation The sternocleidomastoid muscle is innervated by what spinal nerves?
C2, C3, C4 (+CNXI)
159
# Muscle Innervation The deltoid muscle is innervated by what major nerve?
Axillary
160
# Muscle Innervation The deltoid muscle is innervated by what spinal nerves?
C5, C6
161
# Muscle Innervation The biceps brachii muscle is innervated by what major nerve?
Musculocutaneous
162
# Muscle Innervation The biceps brachii muscle is innervated by what spinal nerves?
C5, C6
163
# Muscle Innervation The brachioradialis muscle is innervated by what major nerve?
Radial
164
# Muscle Innervation The brachioradialis muscle is innervated by what spinal nerves?
C5-C6
165
# Muscle Innervation The triceps muscle is innervated by what major nerve?
Radial
166
# Muscle Innervation The extensor carpi radialis muscle is innervated by what major nerve?
C7, C8
167
# Muscle Innervation The extensor carpi radialis muscle is innervated by what spinal nerves?
C7, C8
168
# Muscle Innervation The flexor carpi radialis muscle is innervated by what major nerve?
Median
169
# Muscle Innervation The flexor carpi radialis muscle is innervated by what spinal nerves?
C7-C8
170
# Muscle Innervation The extensor carpi ulnaris muscle is innervated by what major nerve?
Radial
171
# Muscle Innervation The extensor carpi ulnaris muscle is innervated by what spinal nerves?
C7, C8
172
# Muscle Innervation The flexor carpi ulnaris muscle is innervated by what major nerve?
Radial
173
# Muscle Innervation The flexor carpi ulnaris muscle is innervated by what spinal nerves?
C8, T1
174
# Muscle Innervation The abductor pollicis brevis muscle is innervated by what major nerve?
Median
175
# Muscle Innervation The abductor pollicis brevis muscle is innervated by what spinal nerves?
C8, T1
176
# Muscle Innervation The abductor digiti minimi muscle is innervated by what major nerve?
Ulnar
177
# Muscle Innervation The abductor digiti minimi muscle is innervated by what spinal nerves?
C8, T1
178
# Muscle Innervation The adductor muscle is innervated by what major nerve?
Obturator
179
# Muscle Innervation The adductor muscle is innervated by what spinal nerves?
L2, L3, L4
180
# Muscle Innervation The quadriceps muscle is innervated by what major nerve?
Femoral
181
# Muscle Innervation The quadriceps muscle is innervated by what spinal nerves?
L2, L3
182
# Muscle Innervation The tibialis anterior muscle is innervated by what major nerve?
Peroneal
183
# Muscle Innervation The tibialis anterior muscle is innervated by what spinal nerves?
L4, L5, S1
184
# Muscle Innervation The peroneus longus muscle is innervated by what major nerve?
Peroneal
185
# Muscle Innervation The peroneus longus muscle is innervated by what spinal nerves?
L5, S1
186
# Muscle Innervation The biceps femoris muscle is innervated by what major nerve?
Sciatic
187
# Muscle Innervation The biceps femoris muscle is innervated by what spinal nerves?
L5, S1
188
# Muscle Innervation The gastrocnemius muscle is innervated by what major nerve?
Tibial
189
# Muscle Innervation The gastrocnemius muscle is innervated by what spinal nerves?
S1, S2
190
# Muscle Innervation The abductor hallucis muscle is innervated by what major nerve?
Tibial
191
# Muscle Innervation The abductor hallucis muscle is innervated by what spinal nerves?
S2, S3
192
# Muscle Innervation The anal sphincter muscle is innervated by what major nerve?
Pudendal
193
# Muscle Innervation The anal sphincter muscle is innervated by what spinal nerves?
S2, S3, S4
194
# Muscle Innervation The urethral sphincter muscle is innervated by what major nerve?
Pudendal
195
# Muscle Innervation The urethral sphincter muscle is innervated by what spinal nerves?
Pudendal
F25 IONM pt 1
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