Brachial Plexus Flashcards
Where does the spinal cord run from and to?
Brainstem to conus medalluris (L1/L2)
Why is the white matter of the spinal cord white?
Contains many myelinated axons
What structure branches from an emerging spinal nerve to contribute to the brachial plexus?
Ventral/Anterior Rami
Where is the brachial plexus located?
Neck and the axilla
What region of the body does the brachial plexus supply peripheral nerves to?
Shoulder and upper limbs
Where is the Axilla?
Area underneath the Glenohumeral joint at the junction of the upper limb and thorax
What is the function of the Axilla?
Provides passage way for blood vessels and nerves to reach the upper limb
What are the 4 boundaries of the Axilla?
Pectoralis major (anterior)
Latissimus dorsi + teres major (posterior)
Serrated anterior (medial)
Humerus (lateral)
What is the anterior border of the Axilla?
Pectoralis major
What is the posterior border of the Axilla?
Lattissimus dorsi wraps around teres major
What is the medial border of the Axilla?
Serratus anterior which is the muscle which overlies the rib cage
What is the lateral border of the Axilla?
Humerus (intertrabecular groove)
What is the phrase used to remember the order/arrangement of nerves of the brachial plexus?
Real Teens Drink Cold Beer
What is the order in the Brachial plexus remembered by “Real Teens Drink Cold Beer”?
Roots
Trunks
Divisions
Cords
Branches/peripheral nerves
What are the spinal nerve roots that make up the Brachial plexus?
C5 - T1
C5, C6, C7, C8 and T1
What are the 5 main peripheral nerves/branches formed by the brachial plexus?
Musculocutaneous nerve
Median nerve
Ulnar nerve
Radial nerve
Axillary nerve
What are the 3 trunks in the Brachial Plexus?
Superior
Middle
Inferior
What divisions does each trunk give off?
An anterior division + A posterior division
What 2 nerve roots form the Superior Trunk?
C5 + C6
What nerve root forms the middle trunk?
C7
What nerve roots forms the inferior trunk?
C8 + T1
What are the 3 cords in the Brachial Plexus?
Lateral cord
Posterior cord
Medial cord
What cord do all of the posterior divisions Fromm the 3 trunks all go on to form?
Posterior cord
What type of divisions go onto form the lateral and medial cords?
Anterior divisions
What anterior divisions form the lateral cord?
Anterior division from SUPERIOR trunk + Anterior division from MIDDLE trunk
What anterior division forms the medial cord?
Anterior division from the INFERIOR trunk
What are the 3 cords names based on?
Position of cord relative to the Axillary artery
What is the main peripheral nerve that branches from the lateral cord?
Musculocutaneous nerve
What is the main peripheral nerve that branches from the medial cord?
Ulnar nerve
What 2 cords form the Median nerve?
Lateral Cord + Medial Cord
What 2 main peripheral nerves branch from the posterior cord?
Axillary nerve
Radial nerve
What are the other important nerves found in the brachial plexus?
Long Thoracic nerve
Lateral pectoral nerve
Medial Pectoral nerve
What are the nerve roots of the Long Thoracic nerve?
C5, C6, C7 (First 3 in plexus)
What gives off the lateral pectoral nerve?
Lateral cord
What gives of the medial pectoral nerve?
Medial cord
What are the spinal nerve roots of the Lateral pectoral nerve?
C5, C6
What are the spinal nerve roots of the Medial pectoral nerve?
C8, T1
What does the Long thoracic nerve supply?
Serratus anterior
What does damaged to the long thoracic nerve lead to?
Winged scapula
What does the Lateral pectoral nerve supply?
Pectoralis Major
What does the Medial pectoral nerve supply?
Pectoralis Major
Pectoralis Minor
How do you remember the nerve roots that contribute to the 5 main peripheral nerves of the brachial plexus?
What is the sentence/story used to remember the nerve roots?
Use your hand
Number your fingers as the nerve roots (C5 = thumb - T1 = little finger)
3 Musketeers Assassinated (2 finger gun) 5 Rats 5 Mice and 2 Unicorns (Lowest 2 fingers)
What are the spinal nerve root contributions to the Musculocutaneous nerve?
3 Musketeers = First 3 fingers
C5, C6, C7
What are the spinal nerve root contributions to the Axillary nerve?
Assassinated = First 2 fingers
C5, C6
What are the spinal nerve root contributions to the Radial nerve?
5 Rats = All 5 fingers
C5, C6, C7, C8, T1
What are the spinal nerve root contributions to the Median nerve?
5 Mice = All 5 fingers
C5, C6, C7, C8, T1
What are the spinal nerve root contributions to the Ulnar nerve?
2 Unicorns = Last 2 fingers
C8, T1
Where is the motor innervation from the Musculocutaneous nerve?
Anterior compartment of arm
What is the Anterior compartment muscles of the arm?
Remember BBC
Biceps brachii (2 heads)
Brachialis
Coracobrachialis
What sensory nerve does the Musculocutaneous nerve become?
What is the sensory region of this nerve?
Lateral cutaneous nerve of the forearm
Lateral forearm extending slightly past the wrist but doesn’t reach the thumb
Where is the motor innervation from the Axillary nerve?
Shoulder muscles
What are the shoulder muscles innervated by the Axillary nerve?
Deltoid
Teres Minor
What is the sensory region supplied by the Axillary Nerve?
Regimental badge area (Area military would have badges on arm)
Lateral aspect of superior arm
Where is the motor innervation from the Median nerve?
Anterior forearm (majority)
Thenar muscles
What is the sensory region supplied by the median nerve?
Radial/lateral 3.5 digits of Palmar aspect of hand
Tips of the same 3.5 digits on the Dorsum of the Hand
What is the Ulnar border of the upper limb?
The medial side
Think the Ulnar nerve runs to the medial epicondyle of the humerus and if you bang this it’s referred to as hitting your funny bone
What is the Radial border of the upper limb?
Lateral side
(Side thumb is on)
Where is the motor innervation from the Radial nerve?
Posterior arm
Posterior forearm
What is the sensory region supplied by the radial nerve?
4 branches……..
Come back to this
Where is the motor innervation from the Ulnar nerve?
2 muscles in anterior forearm
Intrinsic muscle of the hand EXCEPT LOAF
What is the sensory region of the Ulnar nerve?
Ulnar 1.5 digits of the hand on both the dorsum and plantar surfaces
If somebody has an UPPER brachial plexus injury, what part of the brachial plexus is affected?
So what spinal nerve roots are affected?
Superior trunk
C5 and C6
If somebody has an LOWER brachial plexus injury, what part of the brachial plexus is affected?
So what spinal nerve roots are affected?
Inferior trunk
C8 and T1
What is the other term for an Upper Brachial plexus injury?
Erb’s Palsy
What myotomes and Dermatomes are affected in Erb’s palsy/Upper brachial plexus injury?
C5 and C6
What are the 2 common ways that lead to Upper Brachial Plexus injury/Erb’s Palsy?
Fall onto neck leading to excess lateral Flexion
Obstetric complication called Shoulder Dystocia leading to excess lateral Flexion of neck
What is shoulder dysocia?
When babies shoulders get stuck in the birth canal
What is the characteristic position of Erb’s Palsy?
Waiters Tip Position
What is the position of the arm in Erb’s palsy (Waiters Tip Position)?
Arm = Adducted + Internally rotated
Elbow = Extended + Pronated + Wrist flexed
Why is the upper limb in the position it is in Erb’s Palsy?
Muscles have a natural resting tone. If a myotome is lost e.g elbow Flexion, it means the opposite natural tone of the elbow extensors goes unopposed leading to the opposite movement occurring compared to the myotomes functions that were lost
In Erb’s Palsy what is the function of the 2 myotomes that are lost?
C5 = Shoulder abduction + Shoulder Rotation
C6 = Elbow Flexion, wrist extension and supination
What is a Lower Brachial Plexus injury called?
Klumpkes Palsy
What dermatomes and myotomes are affected as a result of the inferior trunk being damaged in a lower brachial plexus injury?
C8 and T1
How can Lower Brachial plexus injuries occur?
Obstetrician pulls out baby by extended arm
Fall out of tree and grab on to branch
What is commonly seen in Klumpke’s Palsy?
Claw hand
(REVIEW ONCE DONE FOREARM AND HAND MUSCLES)
