Nerve Supply Of The Upper Limb Flashcards
Major nerve network that supplies the upper limb
Begins in the neck and extends into the axilla
Brachial Plexus
Brachial Plexus is formed by the union of the:
Anterior rami of the last four cervical (C5-C8) first thoracic (T1) nerve roots
Where is the brachial plexus located (during dissection)?
Posterior Triangle of the Neck
Posterior Triangle of the Neck
Surface Landmarks
Anterior: Sternocleidomastoid
Posterior: Trapezius
Inferior: Middle third of the clavicle
Brachial plexus together with the subclavian artery emerges between the anterior and middle __.
Scalene muscles
Five Major Segments of the Brachial Plexus
Ro-Tun-Da Cu-Bao
Reach To Drink Cold Beer
Roots Trunks Divisions Cords Branches
Root anatomy
Dorsal root:
Sensation
Root anatomy
Ventral root:
Motor
The C5-C7 nerve roots are located __.
Above their corresponding vertebral body
Root
C8 is located __.
Below the C7 vertebral body
Root
T1 is located below the __.
T1 vertebral body
Root
C5 Motor
Shoulder Abduction Elbow Flexion (palm up)
Root
C5 Sensory
Lateral aspect of the arm
Root
C5 Reflex
Biceps
Root
C6 Motor
Elbow flexion (thumb up) Wrist extension
Root
C6 Sensory
Lateral forearm and thumb
Root
C6 Reflex
Brachioradialis
Root
C7 Motor
Elbow extension
Wrist flexion
Root
C7 Sensory
Middle and ring finger
Root
C7 Reflex
Triceps
Root
C8 Motor
Finger flexion, thumb extension
Root
C8 Sensory
Medial aspect of forearm and inferior arm
Root
T1 Motor
Finger abduction (Interossei)
Root
T1 Sensory
Medial aspect of the superior arm and skin of the axilla
Branches that arise at the root level
- Long Thoracic Nerve (C5-C6-C7)
2. Dorsal Scapular Nerve (C5)
Long Thoracic Nerve (C5-C6-C7)
Innervates the:
Serratus anterior
Long Thoracic Nerve (C5-C6-C7)
Abducts the:
Scapula
Long Thoracic Nerve (C5-C6-C7)
Injury:
Scapular Winging
Dorsal Scapular Nerve (C5)
Innervates the:
Major and minor rhomboids
Dorsal Scapular Nerve (C5)
Action:
Draws scapula to the spine
Formed by roots after they emerge from the scalenes
Trunks [3]
Trunk
C5+C6:
Superior Trunk
Trunk
C7:
Middle Trunk
Trunk
C8+T1:
Inferior Trunk
Nerves that arise at the Trunk level:
- Suprascapular Nerve
2. Subclavian Nerve
Suprascapular Nerve
Superior trunk (C5-C6)
Innervates:
- Supraspinatus (shoulder abduction)
* Infraspinatus (shoulder external rotation)
Subclavian Nerve
•Superior trunk (C5-C6)
Innervates:
The subclavius muscle and sternoclavicular joint
Each trunk (superior, middle and inferior) gives rise to two divisions:
Anterior and posterior division
Divisions Occur at the level of the:
Clavicle
Anterior divisions supply the __ of the upper limb
Anterior (flexor) compartments
Posterior divisions supply the:
Posterior (extensor) compartments
Three cords labelled according to their position relative to the axillary artery:
- Lateral cord
- Medial cord
- Posterior cord
Formed by the 💡anterior divisions of the 💡superior and 💡middle trunks
Lateral Cord
Continuation of the 💡anterior division of the 💡inferior trunk
Medial Cord
Formed by the union of the 💡posterior divisions of all three trunks
Posterior Cord
Nerves that arise at the Cord level:
Lateral Pectoral Nerve Medial Pectoral Nerve Thoracodorsal Nerve Upper Subscapular Nerve Lower Subscapular Nerve
Lateral Pectoral Nerve from:
Lateral Cord (C5)
Lateral Pectoral Nerve Innervates:
Clavicular head of pectoralis major
Lateral Pectoral Nerve Action:
Adducts and Internally Rotates shoulder
Medial Pectoral Nerve from:
Medial Cord (C8)
Medial Pectoral Nerve Innervates:
Sternal head of pectoralis major and pectoralis minor
Medial Pectoral Nerve Action:
Adducts shoulder
Thoracodorsal Nerve from:
Posterior Cord (C5)
Thoracodorsal Nerve Innervates:
Latissimus dorsi
Thoracodorsal Nerve Action:
Adducts and internally rotates the shoulder
Upper Subscapular Nerve from:
Posterior Cord (C5)
Upper Subscapular Nerve Innervates:
Subscapularis
Upper Subscapular Nerve Action:
Internally rotates shoulder
Lower Subscapular Nerve from:
Posterior Cord (C6)
Lower Subscapular Nerve Innervates:
Subscapularis, and teres major
Lower Subscapular Nerve Action:
Internally rotates shoulder
Terminal Branches /Peripheral Nerves [5]
Axillary Nerve (from posterior cord)
Musculocutaneous Nerve (from lateral cord)
Radial Nerve (from posterior cord)
Median Nerve (from lateral and medial cord)
Ulnar Nerve (from medial cord)
Axillary Nerve From:
Posterior cord (C5-C6)
Axillary Nerve Exits the:
Axillary fossa posteriorly
Axillary Nerve Passing through the
Quadrangular space with the posterior circumflex humeral artery
Axillary Nerve Gives rise to
Superior lateral brachial cutaneous nerve
Axillary Nerve Winds around
Surgical neck of the humerus deep to the deltoid
Axillary Nerve Structures Innervated:
Teres Minor and Deltoid (Flexion, abduction, external rotation of the Shoulder)
Glenohumeral (Shoulder) Joint
Axillary Nerve Sensory Innervation:
Skin of superolateral arm (over inferior part of deltoid)
Spaces of the Posterior Shoulder
Spaces in between muscles through which arteries and nerves pass through
- Quadrangular Space
- Triangular Interval
- Triangular Space
Quadrangular space Borders:
Superior: Teres minor
Lateral: Lateral head of triceps
Medial: Long head of triceps
Inferior: Teres major
Quadrangular space Contents:
Posterior circumflex artery
Axillary nerve
Triangular Interval Borders:
Superior: Teres major
Lateral: Lateral head of triceps
Medial: Long head of triceps
Triangular Interval Contents:
Profunda brachii
Radial nerve
Triangular space Borders:
Superior: Teres minor
Inferior: Teres major
Lateral: Long head of triceps
Triangular space Contents:
Circumflex scapular artery
Terminal branch of the lateral cord
C5-C7
Musculocutaneous Nerve
Musculocutaneous Nerve
Exits axilla by piercing the:
Coracobrachialis
Musculocutaneous Nerve
Descends between:
Biceps brachii and brachialis
Musculocutaneous Nerve Continuous as the:
Lateral antebrachial cutaneous nerve of the forearm
Musculocutaneous Nerve Structures innervated:
Coracobrachialis, biceps brachii, brachialis (Elbow flexion)
Musculocutaneous Nerve Sensory innervation:
Skin at lateral aspect of the forearm
Arises from the 💡Posterior cord (C5-T1) and the 💡largest branch of the brachial plexus
Radial Nerve
Radial Nerve Exits:
Axillary fossa posterior to axillary artery
Radial Nerve
Passes posterior to:
Humerus in radial groove with deep brachial artery in the triangular interval between the lateral and medial heads of the triceps
Radial Nerve Perforates:
Lateral intermuscular septum as it exits the posterior compartment of the arm
Radial Nerve Enters:
Cubital fossa, dividing into superficial (cutaneous) and deep (motor) radial nerves
Radial Nerve
Branches in the forearm and wrist:
- Posterior interosseous nerve
- Superficial branch of the radial nerve
- Posterior cutaneous nerve of the forearm
Radial Nerve
Structures innervated:
All muscles of the posterior compartments of the arm (e.g. triceps) and forearm (e.g. brachialis, extensor carpi radialis longus)
Radial Nerve:
Sensory Innervation
- Skin of the posterior and inferolateral arm
- Posterior forearm
- Dorsum of the hand lateral to the axial line of the ring finger
Arises from the 💡lateral cord (C6, C7) and 💡medial cord (C8, T1)
Median Nerve
Median Nerve exits the cubital fossa by passing between the heads of the
Pronator teres
Median Nerve runs deep to palmaris longus tendon as it approaches the flexor retinaculum to traverse the
Carpal tunnel
Median Nerve
Branches:
- Anterior interosseous nerve
2. Palmar cutaneous branch of the median nerve
Median Nerve
Structures innervated
•Muscles of the anterior forearm compartment (except for the flexor carpi ulnaris and the ulnar half of flexor digitorum profundus)
•Five intrinsic muscles in the thenar half of the palm (OAF+2) 1. 1st and 2nd lumbricals 2. Opponens pollicis 3. Abductor pollicis brevis 4. Flexor pollicis brevis
Median Nerve Provides sensation to the:
Thenar half (radial 3 ½ digits) of the palmar skin
Ulnar nerve Arises from the:
Medial cord (C7 –T1)
Ulnar nerve
Passes posterior to the
Medial epicondyle of the humerus
Ulnar nerve
Branches:
- Palmar cutaneous branch of the ulnar nerve
2. Dorsal cutaneous branch of the ulnar nerve
Ulnar nerve
Structures innervated:
- Flexor carpi ulnaris and ulnar half of the flexor digitorum profundus (forearm)
- Most of the intrinsic muscles of the hand (hypothenar muscles, lumbricals and interossei)
Ulnar nerve
Provides sensation:
•Skin of the ulnar side of the hand along the ring and small finger
Occur during difficult deliveries in infants
Obstetric Brachial Plexus Palsy
Obstetric Brachial Plexus Palsy Two Types:
- Erb-Duchenne Palsy
2. Klumpke’s Palsy
Most common type, upper lesion
Mechanism of injury: lateral flexion of the head
towards the contralateral shoulder with depression of the ipsilateral shoulder causing traction in infants
PE: Adducted, internally rotated shoulder; pronated forearm, extended elbow (💡Waiter’s Tip)
Prognosis and Treatment: Observation, best prognosis for spontaneous recovery
Erb-Duchenne Palsy
C5,C6
Rare type
Mechanism of injury: Arm presentation with subsequent traction/abduction from trunk
PE: deficit of all of the small muscles of the hand (ulnar and median nerves)
💡“Claw Hand” deformity
• Wrist in 💡extreme extension because of the unopposed wrist extensors
• 💡Hyperextension of the MCP and 💡flexion of the IP joints due to 💡loss of hand intrinsics
Prognosis: Poor for spontaneous recovery
Klumpke’s Palsy
C8, T1
Muscles in the posterior compartment of
the forearm are paralyzed
💡“Wrist Drop” – inability to extend the wrist and fingers at the metacarpophalangeal joints
Radial Nerve Palsy
Humerus Fracture
Results from any lesion that significantly reduces the size of the carpal tunnel, increases the size of the structures or their coverings that pass through it
Causes: inflammation of synovial sheaths, fluid retention, infection, tumors
Carpal tunnel syndrome
Most sensitive structure in carpal tunnel
Median nerve
Carpal tunnel syndrome
Signs and symptoms:
- Paresthesia (tingling), hypoesthesia (diminished sensation), or anesthesia (absence of sensation) may occur in the lateral three and a half digits.
- Inability to oppose the thumb
- Atrophy of the thenar eminence (thenar muscles)
Carpal tunnel syndrome
Treatment:
Rest and splint immobilization,
steroid injection or carpal tunnel release