Topic 9: Nerve Supply of the Lower Limb Flashcards
(116 cards)
1
Q
The Nervous System
A
- Bodies control centre+ communication network
- Senses changes, interprets changes and responds to changes
- Highly specialised cells (neurons) that are designed to transmit information around the body
o Sensory neurons transmit information about conditions inside and outside the body
o Motor neurons transmit information that controls the activity of muscles and glands - Glial/ support cells provide protection and nutrition
2
Q
The Central Nervous System
A
- Brain and co-located structures
- Spinal cord
All protected by bones of the axial skeleton
3
Q
The Peripheral Nervous System (PNS)
A
- Nerves that connect the CNS to the peripheral structures e.g. skin, muscle, glands
- cranial nerves
- spinal nerves
4
Q
Cranial Nerves
A
o Nerves that emerge directly from the brain/ brainstem
o 12 pairs, named and numbered
o Supply the musculoskeletal structures of the head and neck
o Supply the viscera of the thorax and abdomen
5
Q
Spinal Nerves
A
o Nerves that emerge from the spinal cord
o 31 pairs, each numbered according to the place where it emerges from the spinal cord and vertebral column
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
o Supply the structures of the trunk wall + limbs
- E.g. spinal nerve
6
Q
Spinal Nerve Formation
A
- Spinal cord- cut in cross section, part of the CNS
- Sensory Neurons enter at the back of SC
- The spinal nerve then divides into a dorsal (posterior) ramus, and a ventral (anterior) ramus
- motor and sensory neurons = grouped together in the spinal nerve
- motor neurons leave from the front of SC
7
Q
Ventral Ramus
A
- distributed to the muscles of the anterior + lateral trunk, and the corresponding skin
- also distributed into the limbs to supply the muscles and skin there
8
Q
Dorsal Ramus
A
Distributed to the muscles of the back, and the skin covering those muscles
9
Q
Sensory Distribution
A
- To skin – sensation e.g. hot, cold, pain, touch, pressure
- To joints – sensation of joint position (proprioception)
o General rule for supply of joints – ‘where a nerve supplies a muscle that moves a particular joint, that nerve will also supply that joint’.
10
Q
Motor Distribution
A
To muscles:
- turns the muscle on, makes it contract (might be concentric, isometric, or eccentric dependent on task requirements)
To glands:
- (usually) increases secretion from gland
- e.g. supply to sweat glands produces sweating
11
Q
Sensory Pathways
A
- Touch hot object (pain receptors in skin) –> impulse travels down arm–> dendrite of afferent neuron –> axon of afferent neuron –> cell body of interneuron - spinal cord
12
Q
Motor Pathways
A
Sensory impulse has been processed by CNS–> cell body of efferent neuron –> axon of efferent neuron –> muscle contracts and withdraws part being stimulated
13
Q
Ventral Rami form plexi
Cervical Plexus
A
C1234, supplies structures in the neck and the diaphragm
14
Q
Brachial Plexus
A
C5678, T1
Supplies the upper limbs
15
Q
Lumbar Plexus
A
L1234
Supplies the lower limb
16
Q
Lumbosacral plexus
A
L45, S123
Supplies the lower limb
17
Q
Lumbar Plexus nerve inclusions
A
Genitofemoral, lateral femoral cutaneous, femoral, obturator
18
Q
Lumbosacral Plexus nerve inclusions
A
Lumbosacral trunk, posterior femoral cutaneous, sciatic
19
Q
Femoral Nerve Root Value
A
L234
20
Q
Femoral Nerve motor distribution
A
iliacus, pectineus, sartorius, quad group
21
Q
Femoral Nerve sensory distribution
A
- Skin of anterior and medial thigh
2. knee and hip joints
22
Q
Saphenous nerve (cutaneous branch of femoral) root value
A
none as it branches off the femoral nerve
23
Q
Obturator Nerve Root value
A
L234
24
Q
Saphenous nerve (branch of femoral) motor distribution
A
none
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Saphenous nerve (branch of femoral) sensory distribution
Skin of the medial knee+ leg to base of great toe
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Obturator Nerve Motor Distribution
Pectineus, add brev, add long, 1/2 of add mag, obt ext, gracilis
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Root value definition
where the nerve originates in the SC
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Obturator Nerve Sensory Distribution
Skin of medial thigh
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Lateral Femoral Cutaneous nerve root value
none (why?)
| Is it because it comes off the fem vein?
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Lateral Femoral Cutaneous nerve motor distribution
none
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Lateral Femoral Cutaneous nerve sensory distribution
skin of the lateral thigh
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Genitofemoral nerve root value
none
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Genitofemoral Nerve motor distribution
none
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genitofemoral nerve sensory distribution
skin of the medial thigh, skin of the external genitalia
35
Muscular branches nerve motor distribution
iliacus & psoas major
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LUMBOSACRAL PLEXUS
| Posterior Femoral Cutaneous nerve root value
XXX
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Posterior Femoral Cutaneous nerve motor distribution
none
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Posterior Femoral Cutaneous nerve sensory distribution
skin of posterior thigh and leg to mid calf
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Superior gluteal nerve root value
XXX
40
Superior gluteal nerve motor distribution
gluteus Medius and minimus, TFL
41
Superior gluteal nerve sensory distribution
hip joint
42
Inferior gluteal nerve root value
XXX
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Inferior gluteal nerve motor distribution
gluteus maximus
44
Inferior gluteal nerve sensory distribution
none
45
Muscular branches nerve root value
XXX
46
Muscular branches nerve motor distribution
external rotators except obt ext
47
Muscular branches nerve sensory distribution
none
48
Sciatic nerve root value
L45S123
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Sciatic nerve motor distribution
hamstrings and hamstring (extensor) half of adductor magnus
50
Sciatic nerve sensory distribution
none
51
BRANCHES OF THE SCIATIC NERVE
| Tibial Nerve Motor distribution
gastrocs, soleus, plantaris, popliteus. TP, FHL, FDL
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BRANCHES OF THE SCIATIC NERVE
| Tibial Nerve Sensory distribution
knee and ankle joints
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BRANCHES OF THE SCIATIC NERVE (branch of tibial)
| Medial Plantar Nerve Motor distribution
AbdHall, FDB, FHB, 1st lumbrical
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BRANCHES OF THE SCIATIC NERVE (branch of tibial)
| Medial Plantar Nerve Sensory distribution
skin of the medial 3 and 1/2 digits and corresponding sole
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BRANCHES OF THE SCIATIC NERVE (branch of tibial)
| Lateral Plantar Nerve Motor distribution
FDMB, AddHall, 2nd to 4th lumbricals, intertossei, AbDM, FA
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BRANCHES OF THE SCIATIC NERVE (branch of tibial)
| Lateral Plantar Nerve Sensory distribution
skin of the lateral 1 and 1/2 digits and corresponding sole
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BRANCHES OF THE SCIATIC NERVE (branch of tibial)
| Sural Nerve Motor distribution
none
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BRANCHES OF THE SCIATIC NERVE (branch of tibial)
| Sural Nerve Sensory distribution
skin of the lateral and posterior leg, heel, and skin of the lateral side of the sole
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Common peroneal nerve motor distribution
none directly but see branches
60
BRANCH OF COMMON PERONEAL
| Superficial Peroneal motor distribution
peroneus longus and brevis
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BRANCH OF COMMON PERONEAL
| Superficial Peroneal sensory distribution
skin of lateral leg, dorsum of foot except skin between digits 1 and 2
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BRANCH OF COMMON PERONEAL
| Deep Peroneal motor distribution
TA, EHL, EDL, PT, EDB (anterior)
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BRANCH OF COMMON PERONEAL
| Deep Peroneal sensory distribution
skin between digits 1 and 2
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BRANCH OF COMMON PERONEAL
| Sural nerve* motor distribution
none
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BRANCH OF COMMON PERONEAL
| Sural nerve* sensory distribution
skin of the lateral and posterior leg, heel and skin of the lateral side of the sole
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Hilton's Law
a single nerve can supply the skin, joint, and muscles of that region. e.g. femoral nerve supplies the anterior thigh
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Innervation of hip joint
Innervated primarily by the sciatic, femoral, obturator nerves, and superior gluteal nerve
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Innervation of knee joint
Branches of the femoral nerve to vastus medialis, and also intermedius and lateralis. From the sciatic nerve by genicular branches of the tibial and common peroneal nerves
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Innervation of ankle joint
receives its nerve supply from deep peroneal, saphenous, sural and tibial nerves, occasionally the superficial peroneal nerve also supplies the ankle joint.
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Most Vulnerable Sites
1. close to skin - penetrating injury e.g. common peroneal nerve wraps around head of fibula
2. between skin and bony projection --crushing injury e.g. plaster applied too tightly
3. between retinacula and bone -- squashing injury, small amount of welling with no where to go
4. on bone -- from fracture
71
Functional loss and deformity from a lesion
can cause:
1. paralysis/ paresis
2. loss of sensation
3. seen distal to the point of the lesion.
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How does functional loss &deformity occur due to a lesion?
action potential is inhibited and stopped, meaning the message travelling along the nerve is either weakened/ prevented.
73
Femoral nerve vulnerable site
Body of psoas muscle, iliopsoas groove and at inguinal ligament = find and have movement as they lie above the inguinal ligament
74
Femoral nerve lesion effect
1. quad fem, sartorius, and pectineus experience motor loss
| 2. loss of skin sensation on the medial and anterior thigh, medial leg and foot
75
Obturator nerve vulnerable site
inferior aspect of pubic ramus and obturator foramen
76
Obturator nerve lesion effect
Weakness of thigh adduction, external rotation of thigh, small numbness of medial thigh
77
Sciatic nerve vulnerable site
from pelvis to the distal thigh, between greater sciatic notch and ischial tuberosity
78
Sciatic nerve lesion functional loss
motion and sensation of posterior, medial, and lateral leg
79
Tibial nerve vulnerable site
Popliteal fossa region, laceration of popliteal area, posterior dislocation
80
Tibial nerve lesion functional loss
numbness, pain, tingling and weakness of knee or foot
81
Common peroneal nerve vulnerable site
Posterior and lateral aspect of knee joint complex
82
Common peroneal nerve lesions functional loss
lateral and anterior function of leg, skin of upper lateral and lower posterolateral leg
83
Superficial Peroneal nerve vulnerable site
areas around the fibular head, between the tibia and fibula joint
84
Superficial Peroneal nerve functional loss
peroneus muscle skin of anterolateral aspect of the leg and greater part of dorsum of the foot
85
Deep peroneal nerve vulnerable site
Injury to the knee, fibula fracture, fibula head and neck, and lateral aspect of knee
86
Deep peroneal nerve lesion functional loss
lower leg muscles function, dorsal webspace, foot functions
87
Myotome
- a group of muscles supplied by one spinal nerve (via both its dorsal and ventral rami)
- often described in terms of the movements that these muscles bring about (e.g. hip flexion)
88
Myotome and segmental innervation
Mass of muscle innervated by a single spinal nerve
89
Lower Limb myotomes things to remember
o Two segments per movement
o Consecutive pairs of antagonistic movement
o Begin on anterior surface
o Drop a joint, drop a segment
90
Dermatomes (sensory version of myotome)
- An area of skin supplied by one spinal nerve
- Usually a long, elongated strip of skin
- Overlap and variation
- Less clinically reliable than myotomes
91
Hip Jt Mvmts in segmental innervation
Extension
| Flexion
92
Hip Jt Myotomes
Flexion - L2 L3
| Extension - L4, L5
93
Knee jt mvmts
extension
| flexion
94
Knee jt myotomes
Ext- L3,L4
| Flex- L5, S1
95
Ankle jt mvmts
Dorsiflexion
| Plantarflexion
96
Ankle jt myotomes
Dorsi- L4,L5
| Plantar- S1, S2
97
Toe jt mvmt
Ext
| Flex
98
Ankle Jt myotomes
Ext- L5, S1
| Flex- S1, S2
99
Lesions femoral nerve- at inguinal ligament
```
Motor loss in:
- quad fem
- sartorius
- pectineus
Sensory loss:
- loss of skin sensation on the middle and anterior thigh , medial leg and foot
```
100
Segmental Innervation
- the distribution of the motor and sensory neurons of the spinal neurons of the spinal nerve
- established during the embryonic period
101
Distinguishing between a spinal nerve & peripheral nerve lesion
- Example
o A patient comes to you with symptoms that include weak leg extension and tingling down the medial part of their leg into their foot
- How to distinguish is the problem due to a central, or spinal, nerve lesion or is it a peripheral nerve problem?
102
Femoral nerve motor distribution
Quad fem (hip F, knee E)
Iliacus (hip F)
Pectineus (hip F)
103
Femoral nerve sensory distribution
- skin of the anterior and medial thigh
| - skin of the medial leg and foot (via saphenous branch)
104
L4 Myotomes
- hip extension (myotomes usually described by mvmts they produce)
- knee ext
- ankle DF
105
L4 Dermatomes
- skin of the lateral thigh
- skin of the anterior knee
- skin of the medial leg & foot
106
Proving it is a spinal lesion Clinical signs (L4 vs femoral)
- Weakness in leg extension
- altered sensation in skin over medial leg & foot
From this info, not enough to make diagnosis --> need further testing LOOK FOR DIFFERENCES
107
What would I write? (L4 vs femoral)
1. i would test hip ext
2. i would test ankle df
3. i would expect to find weakness on the affected side
4. although less clinically reliable, i would also do a skin sensation test. i would expect to find altered sensation in a strip of skin over the lateral thigh/ anterior knee
108
L4 vs Common Peroneal
• Patient presents with weakness in ankle dorsiflexion and complains of numbness over their big toe. How would you prove it is an L4 lesion (Tip: for the common peroneal you have to factor in its branches)
109
L5 vs Deep Peroneal
• Patient presents with weakness in ankle dorsiflexion and toe extension, and also complains of pins and needles over the top of digits 2,3 and 4. How would you prove it is a L5 lesion?
110
L5 vs Tibial
• Patient presents with weakness in knee flexion and tingling on the medial plantar aspect of their foot. How would you prove it is a L5 lesion? (Tip: think about the branches of the tibial nerve)
111
L5 myotomes
* Hip ext
* Knee flex
* Ankle dorsi
* Toe ext
112
L5 dermatome
* Lateral fem condyle
* Anterior ankle
* Dorsal surface of the foot b/w 2nd and fourth digits
113
Tibial nerve motor dist
* Gastrocs, soleus, plantaris, TP, FHL, FDL
* Ankle plantarflexion
* Ankle inversion
* Knee flexion
* Toe flexion
114
Tibial nerve sensory dist
* Skin of the medial 3 and ½ digits and corresponding sole
* Skin of the lateral and posterior leg, heel and skin of the lateral side of the sole
* Skin of the lateral and posterior leg
115
L5 vs...
To prove that it is a L5 lesion i would test all of the not crossed off muscles (hip ext, ankle dorsi, toe ext) and expect weakness on the affected side. Although less clinically reliable I would also test the dermatomes…
116
S2 vs Tibial
• Patient presents with weakness in plantarflexion and pins and needles over the heel of their foot. How would you prove it is a S2 lesion? (Tip: think about the branches of the tibial nerve)
