Clinical Testing of the Spinal Nerves Flashcards
List some somatic general sensory symptoms
pain (neuralgia)
pins & needles (paraesthesia)
numbness (anaesthesia)
sensitivity (hyperaesthesia)
temperature perceptions
loss of co-ordination/balance/clumsiness (e.g. ataxia)
List some somatic motor symptoms
muscle stiffness, tightness or spasm (cramp)
muscle floppiness or looseness (reduced tone or hypotonia)
muscular weakness (reduced power)
loss of co-ordination/balance/clumsiness (e.g. ataxia)
How to we test each spinal nerve segment?
Sensory functions - dermatomes
Motor function - myotomes
Both of the above simultaneously - spinal cord reflexes
How do we question the pathology of a spinal nerve?
Is it affecting a single dermatome / myotome? Or more than one? Which segment?
Is it part of the distribution area of a named nerve? does it contain axons from more than 1 spinal nerve?
Is it affecting either the anterior or posterior ramus? Or a single spinal nerve?
Is it affecting either posterior or anterior root?
How do we question the integrity of the CNS with respect to the pathology?
Is the pathology within a CNS ascending tract, or a CNS descending tract?
Or the primary somatosensory coretx?
Within the primary somatomotor cortex?
Label the Dermotome map with remarkable locations
Cutaneous nerve diagram
Label the periphral cutaneous nerves of the head and neck, including their spinal origins
How are the thoracic cutaneous nerves named?
T1-T12
Although the anterior T12 dermatome is innervated by the ‘subcostal nerve’ (ant. ramus T12)
Label cutaneous innervation of the upper limb
Note that spinal nerves in brackets provide some dermatomal overlaps
Label cutaneus innervation of the lower limbs
Note that spinal nerves in brackets provide some dermatomal overlaps
What muscle groups are innervated by each plexus?
- Cervical plexus
- Brachial plexus
- Thoracic
- Lumbosacral
-Cervical (C1-C4)
Neck postural & strap muscles
Diaphragm
-Brachial (C5-T1)
Muscles of the upper limb
Extrinsic back muscles
-Thoracic (T2-L3)
Postural back muscles
Intercostal muscles anterolateral
abdominal wall muscles
-Lumbosacral (L1-S4)
Muscles of the lower limb
Perineal skeletal muscles
Detail the clinical testing of the shoulder joint spinal nerves
Detail the clinical testing of the elbow joint spinal nerves
Detail the clinical testing of the finger joints spinal nerves
Detail the clinical testing of the wrist joint spinal nerves
Detail the clinical testing of the hip joint spinal nerves
Detail the clinical testing of the knee joint spinal nerves
Detail the clinical testing of the ankle joint spinal nerves
Describe the sequence of events that must be consequential to test the sensory function of a spinal nerve (right femoral nerve)
- APs in the axons of the receptors of the L2 dermatome part of the femoral nerve somatosensory distrubution
- APs conducted centrally along the same axons within the L2 anterior ramus
- the same L2 axons weave their way through the lumbar plexus to the L2 spinal nerve
- APs conducted via the same axons which are now in the L2 posterior root
- APs conducted via the same axons which are now in the L2 posterior rootlets
- APs arrive at the posterior horn of the L2 spinal cord segment
- APs are conducted via an ascending tract to the primary somatosensory cortex
Describe the sequence of events that must be consequential to test the motor function of a spinal nerve (right femoral nerve)
- APs are generated by voluntary intention in the primary somatomotor cortex
- APs are conducted via the UMN axons of the corticospinal tract
- APs reach the L3 spinal cord segment’s anterior horn
- the L3 LMNs are stimulated (synaptically)
- APs conducted along the LMN’s axons through the L3 spinal nerve then EITHER the L3 anterior ramus, or, the L3 posterior ramus (the latter for postural neck/back muscles only)
- LMN axons then often weave their way through a plexus into a named nerve
- APs arrive at the neuromuscular junction of the muscle supplied
Describe the sequence of events in a monosynapthic reflex arc (patellar reflex)
- patellar ligament tapped
- stretches quadriceps fibres
- muscle stretch receptors initiate APs in the anterior rami axons within the femoral nerve
- sensory APs conducted to dorsal horn of L4
- axons pass into anterior horn to synapse on LMNs that supply quadriceps
- APs conducted via the LMN axons in the femoral nerve to reach the quadriceps NMJ
- muscle contracts to extend knee joint
List the spinal nerves corresponding to these reflexes:
(i) Biceps
(ii) Triceps
(iii) Supinator / brachioradialis
(iv) Knee
(v) Ankle
(i) C5 (C6)
(ii) C7
(iii) C6
(iv) L4
(v) S1
Describe the Peripheral Nerve Motor Innervation of Head
Muscles of facial expression (CN VII)
Muscles of mastication (CN V)
Muscles of the tongue (CN XII)
Muscles of the soft palate (CN X/pharyngeal plexus)
