Brachial Plexus Flashcards
(79 cards)
What is the range of spinal nerves involved in the brachial plexus?
C1-4, C5-T1
What is the interscalene triangle?
The space formed between the anterior and medial scalene muscles.
How is the upper trunk of the brachial plexus formed?
By the joining of nerve roots C5-6.
What forms the lower trunk of the brachial plexus?
Nerve roots C8-T1.
What is the middle trunk of the brachial plexus?
It is formed by C7, which does not join with another nerve root.
How many sections do the trunks of the brachial plexus divide into as they pass beneath the clavicle?
6 sections: 3 anterior and 3 posterior.
What are the three cords formed around the axillary artery?
Medial, lateral, and posterior cords.
What forms the posterior cord of the brachial plexus?
All trunks of the brachial plexus.
What contributes to the middle trunk of the brachial plexus?
The middle trunk sends contributions with C5-6 from the lateral cord.
What forms the medial cord of the brachial plexus?
The two remaining nerves C8-T1.
What forms the radial nerve?
The posterior cord from C5-8 and T1.
Where does the radial nerve pass?
It passes axillary wall to deltoid and teres minor, follows the brachial artery in the arm, and innervates the triceps.
What branches does the radial nerve divide into after passing over the lateral epicondyle?
Deep and superficial branches.
What is the motor function of the radial nerve?
Initially supplies all three triceps heads.
What muscles receive motor innervation from the radial nerve?
Triceps, aconeus, brachioradialis, extensor carpi radialis longus.
What does the deep branch of the radial nerve supply?
Extensor carpi radialis longus and supinator.
What muscles are innervated by the posterior interosseous nerve?
Extensor digitorum, extensor digit minimi, extensor carpi ulnaris, extensor pollicis longus, extensor pollicis brevis, extensor indicis, and abductor pollicis longus.
How is sensory supply mainly provided by the radial nerve?
Mainly by the posterior cutaneous nerve.
What area does the sensory supply of the radial nerve cover?
A strip of skin down the center and back of the forearm and elbow joint.
What does the superficial branch of the radial nerve provide sensory innervation to?
The dorsal surface of the hand and lateral 3 ½ fingers, short of nail beds, and the web between the thumb and index finger.
What may trauma to the radial nerve result in?
Motor weakness in supination and/or extension of wrist (wrist drop) and extension of fingers.
What sensory losses may occur due to radial nerve trauma?
Loss to the posterior forearm, radial side of forearm, dorsal aspect of 3 ½ digits (excluding nail beds), and web space.
How is the radial nerve strength tested?
The patient resists against applied force using extensor pollicis longus.