Spinal Nerves Flashcards
All spinal nerves are mixed. True or false?
True
Where is a spinal nerve located?
Only within an intervertebral foramen
Spinal nerves contain sympathetic and parasympathetic divisions of the ANS. True or false?
False
- only contain sympathetic division of the ANS
How do spinal nerves connect with structures of the body wall ?
Via rami
How do spinal nerves connect with the spinal cord ?
Via roots and rootlets
How many pairs of spinal nerves are there?
31
There are 8 cervical spinal nerves. True or false?
True
There are 5 sacral spinal nerves. True or false?
True
There are 4 coccygeal spinal nerves. True or false?
False
- 1
Where do rootlets emerge from?
Dorsal and ventral aspects of each segment of the spinal cord
When dorsal (or ventral) rootlets come together they form a dorsal (or ventral) ____
Root
What is a dorsal root ganglion? and where is it located?
Enlargement of the posterior root as it passes through the intervertebral foramina
Which type of fibres does the dorsal root ganglion carry?
General sensory fibres
When dorsal and ventral roots fuse, it forms?
Mixed spinal nerve
Where do dorsal and ventral roots fuse?
Intervertebral foramen
Anterior (ventral) roots and rootlets carry only SENSORY/MOTOR fibres ?
Motor
Posterior (dorsal) roots and rootlets carry only SENSORY/MOTOR fibres?
Sensory
What does the spinal nerve split to form
Anterior and posterior rami
Which is larger: anterior or posterior rami?
Anterior rami
Sensory axons pass from
Dorsal horn of spinal cord -> Posterior rootlet -> Posterior root -> Mixed spinal nerve
Motor axons pass from
Mixed spinal nerve -> Anterior root -> Anterior rootlet -> Anterior horn of spinal cord
Rami are mixed. True or false?
True
Anterior and posterior rami of each spinal nerve have segmental innervation. True or false?
True
Each spinal nerve pair supplies a body segment with ? (name 4 things)
- sensation in all body wall structures
- somatic motor supply to underlying skeletal muscles
- sympathetic nerve supply to the skin and to the smooth muscle of arterioles
- Spinal reflexes
Name 4 somatic general sensory symptoms
Pain (neuralgia)
Paraesthesia (pins and needles)
Numbness (anasthesia)
Hot or cold
Clinical testing of spinal nerve function involves testing 3 things
Test dermatomes -> tests sensory function
Test myotomes -> tests motor function
Test spinal cord reflexes -> tests sensory and motor function simultaneously
Sensory pathway - pre-central gyrus or post-central gyrus ?
Post central gyrus
Sensations from the body wall arrive in the ANTERIOR/POSTERIOR root of a spinal nerve ?
Posterior
What are dermatomes?
Areas of skin supplied by sensory innervation from a single spinal nerve
If there is pathology in a single spinal nerve then you are unlikely to experience any numbness or abnormality at the affected level. Why?
There is a degree of overlap from other spinal nerves which are still functioning and are able to sufficiently supply that structure
Which dermatome is the male nipple ?
T4
Dermatomal testing allows you to check the integrity of dorsal roots/rootlets AND spinal nerves. True or false?
True
- but only tests the sensory component of spinal nerves
If there is sensory and motor deficit the problem will be?
Spinal nerve
If there is sensory deficit but motor function is normal, what will the problem be?
It is a dorsal root/rootlet problem
If both sides of the body are affected (abnormal dermatomal testing) then it is more likely to be a central/peripheral lesion?
Central
C2 dermatome supplies
Back of the scalp round to adams apple
C3 dermatome supplies clavicle, shoulder tip. True or false?
False
C4
Which dermatome supplies the back of the neck and jugular notch?
C3
Which dermatome supplies the badge patch area?
C5
Which dermatome supplies the thumb and index finger?
C6
Which dermatome supplies the 4th and 5th finger?
C8
Which dermatome supplies the medial forearm?
T1
Which dermatome supplies the middle finger?
C7
Which dermatome supplies the medial arm and sternal angle?
T2
Which dermatome supplies the pubic symphysis?
T12
Which dermatome supplies the groin?
L1 (hands in pockets)
Which dermatome supplies the anterior thigh?
L2
What does L3 dermatome supply?
Anterior knee
What does L4 dermatome supply
Medial malleolus
Which dermatome supplies the lateral malleolus?
S1
Which dermatome supplies the heel?
S1
Which dermatome supplies the dorsum of the foot ?
L5
Which dermatome supplies toes 4 and 5 ?
S1
Which dermatome supplies toes 1-3 ?
L5
What does S2 dermatome supply?
Posterior knee
What does S3 dermatome supply?
Buttocks
What does S4 dermatome supply?
Perineum
What does S5 dermatome supply?
Perianal skin
What do posterior rami supply?
Posterior rami supply sensation to the MEDIAL section of the back, from T2 -> L3 vertebral level
Sensation lateral/outwith the posterior rami supply section is supplied by ?
Anterior rami
Plexuses are formed by anterior/posterior rami only. True or false?
Anterior rami only
What is a plexus?
Intermingled anterior rami
Which anterior rami do NOT contribute to a plexus?
T2 -> T12 anterior rami
What is the upper anterolateral trunk wall supplied by?
Intercostal nerves
Intercostal nerves are formed from anterior rami of which spinal nerves ?
T2 -> T 11
What is the lower anterolateral trunk wall supplies by?
Iliohypogastric and ilioinguinal nerves
Iliohypogastric and ilioinguinal nerves are formed from the fabrication of the anterior rami of which spinal nerve?
L1 spinal nerve
The subcostal nerve is formed from anterior rami of which spinal nerve?
T12
Spinal nerve vs named nerver
Spinal nerve - contains axons originating from one SC level
Named nerve - contains axons originating from ONE OR MORE SC level
Named nerves follow a dermatome. True or false?
False
Named nerves - the area of cutaneous innervation of the femoral nerve crosses which 3 dermatomes?
L2, L3, L4
If patient comes in with pain in L2 dermatome region, what are the 2 options:
L2 dermatome alone is affected
OR
Femoral nerve
Therefore must check L3 and L4 dermatomes for any abnormality
C2 spinal nerve - named nerve ? what does it supply ?
Lesser occipital nerve
Supplies skin posterior to external ear
C2,C3 named nerve ? what does it supply?
Greater auricular nerve
Supplies skin over angle of mandible and some of external ear
C3,C4 named nerve? what does it supply?
Supraclavicular nerve
Supplies skin over the clavicle and shoulder tip
What are the 4 named nerves of the cervical plexus?
Lesser occipital nerve
Greater auricular nerve
Transverse cervical nerve
Supraclavicular nerve
What phrase is used to remember the nerves of the cervical plexus?
Little
Goats
Tread
Softly
Where is the nerve point of the neck located?
Posterior border of the SCM
Axillary nerve roots?
C5, C6
UMN - where is the cell body located?
Within the primary somatomotor cortex of the pre-central gyrus
Where are UMN’s found?
In brain and SC
Where are LMN’s found?
From spinal nerve roots and moving peripherally
Dysfunction in UMN results in SPASTICITY/FLACCICITY ?
Spasticity
What are myotomes
The skeletal muscles supplied with motor innervation from a single nerve
Cervical plexus roots
C1-C4
The cervical plexus supplies motor innervation to the diaphragm. True or false?
True
T2-L3 motor axons supply postural back muscles via ?
Posterior rami
T2-L3 motor axons supply intercostal muscles via ?
Anterior rami
Lumbosacral plexus roots
L1-S4
Which myotome tests shoulder abduction?
C5
Which myotome tests finger abduction?
T1
Which myotome tests elbow extension?
C7
Which myotome tests finger flexion?
C8
Which myotome tests elbow flexion?
C6
Which myotome tests great toe extension?
L5
Which myotome tests knee extension ?
L3
Which myotome tests knee flexion?
S2
Which myotome tests ankle dorsiflexion?
L5
Which myotome tests ankle plantar flexion ?
S1
Testing spinal reflexes tests sensory and motor component. true or false?
True
Reflex muscle contractions are controlled by ascending/descending pathways?
Descending
Patellar reflex - tap the patellar tendon which causes stretching of the fibres of which muscle?
Quadriceps fibres
Knee jerk reflex tests
L3
Bicepps brachi reflex tests
C5, C6
Triceps brachii reflex tests
C7
Brachioradialis reflex tests
C6
Ankle jerk reflex tests
S1
Peripheral nerve motor innervation - muscles of facial expression
CN VII
Peripheral nerve motor innervation - muscles of mastication
CN V3
Peripheral nerve motor innervation - diaphragm
Phrenic nerve (C3,4,5 - from the cervical plexus)
Peripheral nerve motor innervation - sternocleidomastoid?
CN XI
Peripheral nerve motor innervation - trapezius
CN XI
Peripheral nerve motor innervation - intercostal muscles
Intercostal nerves
Peripheral nerve motor innervation - anterolateral abdominal wall muscles
Thoracoabdominal nerves
Peripheral nerve motor innervation - intrinsic back muscles
Posterior rami of spinal nerves
Named nerve motor innervation of upper limb - axillary nerve
C5, C6
deltoid and teres minor
Named nerve motor innervation of upper limb - musculocutaneous nerve
C5, C6, C7
Named nerve motor innervation of lower limb - femoral nerve
L2, L3, L4
Named nerve motor innervation of lower limb - obturator nerve
L2, L3, L4