Anatomy of Spinal Nerves Flashcards
Each pair of spinal nerves supplies?
Everything in one segment of the body wall
Spinal nerve
Mixed
Rami
Mixed
Root
Sensory/Motor
Rootlet
Sensory/Motor
What is somatic sensory?
Sensation receptors in the body wall
What sort of things do somatic sensory receptors sense?
Pain Temperature Vibration Touch Proprioception
What do somatic motor axons synapse with?
All the skeletal muscles of the body wall
Where are all sympathetic axons carried?
On spinal nerves
What do sympathetic axons control?
Glands and smooth muscle of arterioles
Describe spinal reflexes.
Segmental synapses between somatic motor and somatic sensory axons
There is no parasympathetics in the body wall
TRUE
Spinal reflex tests look at 2 things, what are they?
Dermatomes (sensory)
Myotomes (motor)
Dermatome
Area of skin supplied by one spinal nerve pair
Myotome
Skeletal muscle supplied by one spinal nerve pair
Name a common location of CVA.
Internal capsule
What does dermatome testing allow you to test?
Dorsal root
Dorsal rootlet
Spinal nerve
C1
No sensory components
C2
Back of scalp
Adam’s apple
C3
Back of neck
Jugular notch
C4
Clavicle
Shoulder tip
C5
Badge patch
C6
Thumb
C7
Middle finger
‘C seven points to heaven’
Middle finger is longest finger
C8
Little finger
T1
Medial forearm
T2
Medial arm
Sternal angle
T4
Male nipple
T10
Umbilicus
T12
Pubic symphysis
L1
Groin
‘Hands in pockets’
L2
Anterior thigh
L3
Anterior knee
L4
Medial malleolus
L5
Dorsum of foot
S1
Heel
S2
Posterior knee
S3
Buttock
S4
Perineum
S5
Perianal skin
What does posterior rami supply?
A strip of skin centrally down the back and posterior neck
What anterior rami do not contribute to a plexus?
T2-T12
What nerves supply the upper anterolateral chest wall?
Intercostal nerves
What nerves supply the lower anterolateral chest wall?
Ilioinguinal
Iliohypogastric
Anterior rami of T12 is?
Subcostal nerve
Definition of a spinal nerve.
Contains axons originating from one spinal cord level
Definition of a named nerve.
Contains axons originating from one or more spinal cord level, supplying a particular area
What spinal cord level is the femoral nerve?
L2-L4
The femoral nerve has spinal cord nerves from 3 segments. What does this mean?
The femoral nerve crosses 3 dermatomes
How can the named nerves that supply the skin to the neck be remembered?
LITTLE - lesser occipital
GOATS - greater auricular nerve
TREAD - transverse cervical nerve
SOFTLY - supraclavicular nerve
What is the posterior skin of the neck supplied by?
Posterior rami of spinal nerves C2-C8
What is the anterolateral neck skin supplied by?
Cervical plexus (C1-C4)
Lesser occipital nerve
C2
Skin to posterior ear
Greater auricular nerve
C2,C3
Skin over the angle of the mandible
Transverse cervical nerve
C2,C3
Skin over anterior neck
Supraclavicular nerve
C3,C4
Skin over clavicle and shoulder tip
What is an important area in the upper limb, for referred pain from the myocardium? (give spinal cord levels)
T1 and T2 anterior rami
What supplies cutaneous innervation to the anatomical snuffbox?
Cutaneous branches of the RADIAL nerve
Axillary nerve
C5, C6
Radial nerve
C5, C6, C7, C8, T1
Ulnar nerve
C7, C8, T1
Median nerve
C5, C6, C7, C8, T1
Cutaneous branch of musculocutaneous nerve
C5, C6, C7
Outline the series of events that occurs when a peripheral nerve is tested.
- Stimulation
- AP travels along axons of plexus
- AP continues to anterior rami
- AP reaches spinal nerve
- AP travels to posterior root
- AP travels to posterior rootlet
- AP reaches posterior horn of spinal cord
C5 myotome tests what muscle? Explain the movement.
Deltoid
Shoulder abduction
C6 myotome tests what muscle? Explain the movement
Biceps brachii
Elbow flexion
C7 myotome tests what muscle? Explain the movement
Triceps brachii
Elbow extension
C8 myotome tests what muscle? Explain the movement
Flexion digitorum superficialis
Finger flexion
T1 myotome tests what muscle? Explain the movement
Dorsals interossei
Finger abduction
L3 tests what muscle? Explain the movement
Quadriceps femoris
Knee extension
L4 tests what muscle? Explain the movement
Tibialis anterior
Ankle dorsiflexion
L5 tests what muscle? Explain the movement
Extensor hallucis longus
Great toe extension
S1 tests what muscle? Explain the movement
Gastrocnemius
Ankle plantar flexion
S2 tests what muscle? Explain the movement
Biceps femoris
Knee flexion
Outline the stages that occur when the motor function of a peripheral nerve is tested.
- AP started voluntarily by 1y somatosensory cortex
- AP’s via UMN or corticospinal tract
- AP goes along axon of anterior horn
- UMN synapses with LMN
- AP travels along spinal neve
- AP goes along either anterior/posterior rami
- AP reaches NMJ of muscle
What is a reflex?
An involuntary response to a stimuli
When the patella tendon is tapped, what fibres are stretched?
Quadriceps fibres
Cluneal nerves are the only ones that are always posterior rami
TRUE
Outline the stages of the patella tap reflex.
- Tendon tapped
- Stretches quads fibres
- Muscle initiates AP’s in anterior rami of femoral nerve
- Sensory AP conducted to dorsal horn of L3
- Axons pass to anterior horn to LMN of quads
- AP via LMN of femoral nerve travel to quads
- Muscle contracts, knee extended
UMN lesions are?
Spasticity
LMN lesions are?
Flaccidity
Biceps brachii
C5, C6
Triceps brachii
C7
Brachioradialis
C6
Knee jerk
L3
Ankle jerk
S1
A footballer presents with a 2 month history of worsening ‘pins and needles’ in his left lateral upper thigh which has been getting worse and is not completely numb. What nerve is involved? Explain this.
Lateral cutaneous nerve of the thigh L2,L3
Compression neuropathy of the right lateral cutaneous nerve of thigh by the inguinal ligament due to physiological muscle hypertrophy in an athlete
Footballers get this as they have good hip flexors which bulge and trap the nerve