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)
Describe the Peripheral Nerve Motor Innervation of the Neck?
Neck postural muscles (posterior rami of cervical spinal nerves) strap muscles (cervical plexus)
Diaphragm (phrenic nerve: C3,4,5 – from the cervical plexus)
Sternocleidomastoid & trapezius (CN XI)
Muscles of the pharynx (mainly CN X)
Intrinsic muscles of the larynx (CN X)
Peripheral Nerve Motor Innervation of Trunk?
Intercostal muscles (intercostal nerves)
Anterolateral abdominal wall muscles (thoracoabdominal nerves)
Peripheral Nerve Motor Innervation of Back?
Erector spinae & transversospinalis (posterior rami of spinal nerves)
List the main peripheral nerves innervating the upper limb
Axillary Nerve
Musculocutaneous Nerve
Medial Nerve
Radial Nerve
Ulnar Nerve
What is the spinal origin of the Axillary Nerve and what does it innervate?
C5, C6
deltoid & teres minor
Innervation of Musculocutaneous Nerve?
C5, C6, C7
-ALL of the anterior compartment of arm
biceps brachii
coracobrachialis brachialis
Innervation of Median Nerve?
(C5), C6, C7, C8, T1
muscles of the anterior compartment of forearm:
the pronator muscles (teres & quadratus)
flexor carpi radialis
palmaris longus
flexor digitorum superficialis
lateral half of flexor digitorum profundus
flexor pollicis longus
muscles of the hand:
thenar muscles
lumbricals 1&2
Innervation of Radial Nerve?
(C5), C6, C7, C8, T1
- Muscle of the posterior compartment of arm: triceps brachii
- Muscles of the posterior compartment of forearm: brachioradialis supinator
- ALL the extensors of the carpus, arm & digits
- Abductor pollicis longus
Innervation of Ulnar Nerve?
(C7), C8, T1
-Muscles of the anterior compartment of forearm:
flexor carpi ulnaris medial
half of flexor pollicis longus
adductor pollicis
- Muscles of the hand: hypothenar muscles, lumbricals 3 & 4
- ALL the interossei (dorsal & palmar)
List the main peripheral nerves innervating the lower limb
Femoral Nerve Tibial Nerve (sciatic)
Common Fibular Nerve (sciatic)
Superficial Fibular Nerve
Deep Fibular Nerve
Obturator Nerve
Innervation of the Femoral Nerve?
L2, L3, L4
Quadriceps femoris
Sartoius
Pectineus
Innervation of the Sciatic Nerve, Tibial part?
L4 - S3
-Muscles of the posterior compartment of leg:
Semimembranosus
Semitendinosus
Long head of biceps femoris
-Muscles of the posterior compartment of leg:
Gastrocnemius
Soleus
Plantaris
Popliteus
Tibialis posterior
-Muscles of the sole of the foot:
Flexor digitorum
Flexor hallucis longus
ALL intrinsic muscles of the sole of the foot
Innervation of the sciatic nerve, Common fibular part?
L4-S2
short head of biceps femoris
Innervation of Common Fibular Nerve, Superficial Branch?
-Muscles of the lateral compartment of leg:
Fibularis longus
Fibularis brevis
Innervation of the Common Fibular Nerve, deep fibular branch?
-Muscles of the anterior compartment of leg:
fibularis longus
fibularis brevis
-Muscles of the dorsum of the foot:
Extensor digitorum brevis
Extensor hallucis brevis
Innervation of the Obturator Nerve?
L2, L3, L4
ALL of the medial compartment of thigh
ALL adductors (brevis/longus/magnus)
Gracilis
