What forms the brachial plexus? Where does it pass?
Formed by ventral rami of C5-T1. Has roots that pass between the anterior and middle scalene muscle and is enclosed with the axillary artery and vein in the axillary sheath
What are the branches, passage and innervation directly from the brachial roots?
1. Dorsal scapular nerve (C5 or C4 and C6): Pierces the middle scalene and descends deep to the levator scapulae and rhomboid. Innervates rhomboids and frequently the levator scapulae
2. Long thoracic nerve (C5-C7 or C5-C6): Decends behind the brachial plexus and runs on the external surface of the serratus anterior. Innervates serratus anterior
What forms the different trunks of the brachial plexus?
Anterior rami of
Superior trunk: C5-C6
Middle trunk: C7
Inferior trunk: C8-T1
What are the branches (passage and innervation) from the trunks of the brachial plexus?
Only the upper/superior trunk has branches.
1. Suprascapular nerve (C5-C6 or C4): Passes through the scapular notch under the superior transverse scapular ligament. Innervates supraspinatus, shoulder joint and infraspinatus.
2. Nerve to subclavius (C5 or C4 and C6): Descends in front of the brachial plexus and the subclavian artery, behind the clavicle. Innervates subclavius and sternoclavicular joint (Usually branches to the accessory phrenic nerve which enters the thorax to join the phrenic nerve).
What are the name of the different cords of the brachial plexus?
Lateral, medial and posterior cord
What are the branches (passage and innervation) from the lateral cord of the brachial plexus?
1. Lateral pectoral nerve (C5-C7): Accompanies the pectoral branch of the thoracoacromial artery. Innervates pectoralis major primarily, but also the pectoralis minor.
2. Musculocutaneous nerve (C5-C7): Pierces the coracobrachialis muscles and descends between the biceps brachii and the brachialis. Innervates coracobrachialis, biceps brachii and brachialis.
What are the two first branches (passage and innervation) from the medial cord of the brachial plexus?
1. Medial pectoral nerve (C8-T1): Forward between the axillary artery and veins. Innervates pectoralis minor and major.
2. Medial Brachial Cutaneous Nerve (C8-T1): Runs along the medial side of the axillary vein. Innervates the skin on the medial side of the arm.
What are the relations between the medial and lateral pectoral nerve?
Lateral pectoral nerve sends a branch over the first part of the axillary artery to the medial pectoral nerve which forms a nerve loop through which the lateral pectoral nerve conveys motor fibers to the petoralis minor.
What are the two last branches (passage and innervation) from the medial cord of the brachial plexus?
3. Medial Antebrachial Cutaneous nerve (C8-T1): Runs between the axillary artery and vein, and then runs medial to the brachial artery. Innervates skin on the medial side of the forearm.
4. Ulnar nerve (C8-T1): Runs down the medial aspect of the arm, but does not branch in the brachium.
How is the median nerve formed? Passage?
From the medial (C8-T1) and lateral cords (C5-C7) to form median nerve (C5-T1). Runs down the anteromedial aspect of the arm but does not branch in the brachium.
What are the three first branches (passage and innervation) from the posterior cord of the brachial plexus?
1. Upper subscapular nerve (C5-C6): Innervates upper portion of the subscapularis
2. Thoracodorsal nerve (C6-C8): Runs behind the axillary artery and accompanies the thoracodorsal artery. Innervates the latissimus dorsi.
3. Lower subscapular nerve (C5-C6): Runs downward behind the subscapular vessels to the teres major. Innervates teres major and lower part of subscapularis.
What are the two last branches (passage and innervation) from the posterior cord of the brachial plexus?
4. Axillary nerve (C5-C6): Accompanies the posterior circumflex humeral artery and winds around the surgical neck of the humerus. Innervates deltoid, teres minor and gives rise to the lateral brachial cutaneous nerve.
5. Radial nerve (C5-T1): Occupies the musculospiral groove on the back of the humerus with the profunda brachii artery.
Which nerves of the brachium continues into the forearm?
1. Musculocutaneous nerve (C5-C7) continues as the lateral antebrachial cutaneous nerve (to innervate skin on the lateral side of forearm).
2. Median nerve (C5-T1)
3. Radial nerve (C5-T1) (w/ posterior antebrachial cutaneous nerve)
4. Ulnar nerve (C8-T1)
5. Medial antebrachial cutaneous nerve (C8-T1)
What are the passage of the median nerve in the arm and forearm? Ends?
1. Runs in the anteromedial aspect of the arm and at the elbow it lies medial to the brachial artery between the brachialis and biceps.
2. Passes through the cubital fossa, deep to the bicipital aponeurosis.
3. Enters forearm between the humeral and ulnar heads of the pronator teres muscle.
4. Passes between the flexor digitorum superficialis and the flextor digitorum profundus muscles.
5. Then becomes superficial by passing between the tendons of the flexor digitorum superficialis and flexor carpi radialis near the wrist.
6. Enters the palm of the hand through the carpal tunnel and terminates by dividing into three common palmar digital nerves
What are the larger branches from the median nerve? Innervation and passage.
1. Anterior interosseous nerve: Branches of in the cubital fossa. Descends between the flexor digitorum profundus and the flexor pollicis longus. Passes behind the pronator quadratus. Supplies these muscles and ends in sensory endings to the wrist joint.
2. Recurrent branch (to the thenar muscles) in the hand. Innervates abductor pollicis brevis, oppones pollicis and flexor pollicis brevis.
What does the median nerve innervate?
1. All of the anterior muscles of the forearm except the flexor carpi ulnaris and the ulnar half of the flexor digitorum profundus.
2. Lateral two lumbricals
3. Skin of the lateral side of the palm + palmar side of the lateral three and one-half fingers
4. Skin of the dorsal side of the index finger, middle finger and one-half of the ring finger
Which muscles in specific does the median nerve innervate (9)?
1. Pronator teres and quadratus
2. Palmaris longus
3. Flexor carpi radialis
4. Flexor pollicis longus
5. Flextor digitorum superficialis and 1/2 of profundus
6. Abductor pollicis brevis
7. Opponens pollicis
8. Flexor pollicis brevis (superficial head)
9. First and second lumbricals
What are the passage of the radial nerve in the arm and forearm? Ends?
1. Passes inferolaterally with the profunda brachii in the radial groove on the back of the humerus between the medial and lateral heads of triceps
2. Pierces the lateral intermuscular septum to enter the anterior compartment
3. Descends anterior to the lateral epicondyle between the brachialis and brachioradialis to enter the cubital fossa
4. In the cubital fossa, it divides into superficial and deep branches.
What are the branches from the radial nerve?
1. Muscular branches
2. Articular branches
3. Cutaneous posterior brachial and cutaneous posterior antebrachial nerve
Ends as superficial and deep branch in the cubital fossa
What does the radial nerve innervate directly (5)?
2. Triceps brachii
5. Extensor carpi radialis longus and brevis
The deep ending branch of the radial nerve, passage and innervation (6)?
Enters the supinator muscles and winds laterally around the radius in the muscle. Continues as the posterior interosseous nerve. Innervates:
2. Extensor digitorum
3. Extensor carpi ulnaris
4. Extensor pollicis longus/brevis
5. Extensor indicis
6. Abductor pollicis longus
7. Extensor digiti minimi
The superficial ending branch of the radial nerve, passage and innervation?
Descends in the forearm under cover of the brachioradialis muscle. Passes posterior around the radius under its tendon. Runs distally to the dorsum of the hand were it innervate: The skin of the radial side of the hand, and the radial two and one-half digits over the proximal phalanx.
What are the passage of the ulnar nerve in the arm and forearm? Ends?
1. Runs down the medial aspect of the arm and pierces the medial intermuscular septum at the middle of the arm.
2. Descends behind the medial epicondyle in a groove or tunnel
3. Enters the forearm by passing between the two heads of the flexor carp ulnaris
4. Descends between the flexor carpi ulnaris and flexor digitorum profundus muscle
5. Enters the hand superficial to the flexor retinaculum and lateral to the pisiform bone
6. Terminates by dividing into superficial and deep branches.
The superficial ending branch of the ulnar nerve, innervation and termination?
1. Palmar bervis
2. Skin over the palmar and dorsal surfaces of the medial one-third of the hand
Terminates by dividing into three palmar digital branches, which supply the skin of the little finger and the medial side of the ring finger
The deep ending branch of the ulnar nerve, passage?
Arises and travels through the Guyon's canal.
1. Passes between the pisiform and the hook of hamate
2. Then deep to the oppones digiti minimi.
3. Curves medial to the hook of hamate
4. Turns laterally to follow the course of the deep palmar arterial arch across the interossei
5. Then runs between two heads of the adductor pollicis.
Innervation of the deep ending branch of the ulnar nerve?
1. Hypothenar muscles (abductor, short flexor and opponens digiti minimi)
2. Medial two lumbricals
3. All interossei muscles
4. Adductor pollicis
5. Usually the deep head of the flexor pollicis brevis
Which muscles does the ulnar nerve innervate directly (2) or indirectly (7)?
1. Flexor carpi ulnaris
2. Flexor digitorum profundus (ulnar 1/2)
From the superficial branch:
1. Palmaris brevis
From the deep branch:
2. Abductor digiti minimi
3. Flexor digiti minimi
4. 3rd and 4th lumbricals
5. Palmar and dorsal intersseous muscles
6. Adductor pollicis
7. Flexor pollicis brevis (deep head)