The Nerves of the Brachial Plexus, Arm, Forearm, Wrists, and Hands

Divisions

*Anterior divisions*: Supply anterior/flexion compartment of upper limb *Posterior divisions*: Supply posterior/extension compartment of upper limb

Dermatomes of Upper Limb

*C6*: Pad of thumb *C7*: Pad of middle finger *C8*: Pad of small finger

Muscle Compartment Testing of Nerves - Arm & Forearm

*Dorsal arm & forearm*: extension, supination → Radial n. *Anterior arm*: forearm flexion → Musculocutaneous n. *Anterior forearm superficial*: wrist flexion, pronation; finger flexion at MP, PIPs → Median n. (except FCU & lateral 2 heads of FDP) *Anterior forearm deep*: finger flexion DIP 2 & 3, thumb flexion, pronation → Anterior interosseous of median n.

Muscle Compartment Testing of Nerves - Hand

*Lateral (radial) hand*: Thumb flexion, adduction, opposition; PIP extension of digits 2-3 → Recurrent branch of median n. Medial (ulnar) hand*: Small finger flexion, finger adduction & abduction, PIP extension of digits 4-5 → Ulnar n.

Cords

*Lateral Cord*: Comprised of anterior division of superior & middle trunks *Posterior Cord*: Comprised of the three posterior divisions *Medial Cord*: Continuation of anterior division of lower trunk

Tomes

*Sclerotomes*: Delineate location of pain due to spinal sensory nerve root pathology. *Dermatomes*: Delineate location of loss of sensation due to spinal sensory nerve root pathology. *Myotomes*: Delineate location of muscle weakness due to spinal motor nerve root pathology.

Muscles with Double Innervation

*Subscapularis*: Upper & lower subscapular nn. *FDP*: AIN to 2nd & 3rd digits, ulnar n. to 4th & 5th *FPB*: deep head (ulnar n.) & superficial head (median n.) *Pectoralis major*: Medial & lateral pectoral nn.

Most distally innervated muscles - KNOW THESE!!!

*Useful for testing nerve continuity.* The distal most representation of a nerve provides the physician with rapid information regarding the health of a nerve. *Radial n.*: Extensor indicies; Weak MCP extension *Median n.*: Opponens pollicis; Thumb opposition *Ulnar n.*: First dorsal interosseous; Abduction of index finger *Musculocuntaneous n.*: Brachialis; Forearm flexion *Axillary n.*: Deltoid; Shoulder abduction

Radial Nerve Clinical Correlations

1st-2nd dorsal webspace sensation + normal extensor indices function = superficial radial neuropathy distal to bifurcation at elbow. Intact 1st-2nd dorsal webspace sensation + extensor indices weakness = motor nerve injury distal to bifurcation at elbow. 1st-2nd dorsal webspace sensation + extensor indices weakness = radial nerve injury proximal to bifurcation at elbow Most typical finding of general radial neuropathy is *"wrist drop"*, since all extensors are lost or weakened. Most distal muscle is extensor indices, which produces a weak MCP extension of index finger if radial motor nerve is injured.

What muscle(s) and/or joint(s) do(es) the Radial nerve innervate?

ALL DORSAL FOREARM MUSCLES. Brachioradialis, Extensor carpi radialis longis, Extensor carpi radialis brevis, Extensor digitorum, Extensor carpi ulnaris, Supinator, Extensor pollicis longis, Extensor indices, Extensor digiti minimi, Abductor Pollicis longis, Pronator Quadratus

What muscle(s) and/or joint(s) does the Musculocutaneous nerve innervate?

ANTERIOR ARM: brachialis, biceps brachii, coracobrachialis

What divisions contribute to the posterior cord?

All 3 posterior divisions of the trunks

origin of the Ulnar nerve

An extension of the medial cord

Upper Trunk

Anterior Cord, Posterior division, suprascapular, nerve to subclavius

Lower Trunk

Anterior and Posterior Division

Middle Trunk

Anterior and Posterior Division

origin of the medial cord

Anterior division of the inferior trunk

Lateral Cord

Anterior divisions of Upper and middle trunk

origin of the lateral cord

Anterior divisions of superior and middle trunks

Medial Cord

Anterior división of lower trunk

origin of medial pectoral nerves

Arises from medial cord

origin of lateral pectoral nerve

Arises from the lateral cord

origin of cutaneous (sensory) nerve to the arm and forearm

Arises from the medial cord.

Median n. - Pathway in FOREARM

As it enters forearm, the median nerve is sitting on the anterior surface of brachialis and passes between the two heads of pronator teres (medial epicondyle and coronoid) and then between two of the heads of flexor digitorum superficialis (medial epicondyle and radius) and can become entrapped by either of these as well as by the bicipital aponeurosis.

What Nerve(s) innervate the Deltoid

Axillary

What Nerve(s) innervate the Teres Minor

Axillary

What Nerve(s) innervate the Teres minor

Axillary

Useful Testing Sites

Axillary: over lateral deltoid Musculocuntaneous: lateral forearm Median: pad of index finger Ulnar: pad of small finger Radial: first dorsal web space

origin of the terminal branch of the median nerve

Both the lateral and medial cords

What spinal nerves contribute to the Long Thoracic Nerve?

C 5, C6, and C7

Which spinal nerve is the main contributing nerve to the Subclavius nerve?

C4, C5, C6*

What spinal neves contribute to the radial nerve?

C5 - T1

What nerves make up the superior trunk of the brachial plexus?

C5 and C6

What spinal nerves contribute to the upper subscapular nerve?

C5*, C6

Which spinal nerve is the main contributing nerve to the suprascapular nerve?

C5*, C6

What spinal nerves contribute to the axillary nerve?

C5, C6

What spinal nerves contribute to the lower subscapular nerve?

C5, C6*, C7

Which spinal nerves contribute to the lateral pectoral nerve?

C5, C6*, C7

Which spinal nerves contribute to the Musculocutaneous nerve?

C5, C6, C7

Five nerve roots

C5, C6, C7, C8, and T1

What spinal nerves contribute to the thoracodorsal nerve?

C6, C7*, C8

What spinal nerves contribute to the median nerve?

C6, C7, C8, T1

What spinal nerves contribute to the medial brachial cutaneous nerve?

C8, T1

What spinal nerves contribute to the medial pectoral nerve?

C8, T1

What spinal nerves contribute to the Ulnar nerve?

C8, T1 (sometimes C7)

Lateral Antebrachial cutaneous n.

Continuation of musculocuntaneous nerve after all motor branches have been given off.

Ulnar n. - Pathway in FOREARM

Crosses fascia of flexor carpi ulnaris & becomes anterior in forearm. For distal 1/2 of forearm, travels with ulnar artery. Crosses the wrist in Guyon's canal superficial to flexor retinaculum (not in carpal tunnel). It crosses under the cover of the volar/palmar carpal ligament (from the sleeve fascia). Ulnar innervated skin is normal to pinprick in carpal syndrome Well cushioned in forearm between FDS and FDP.

Superficial radial n.

Crosses over the anatomical snuffbox superficial to tendon of extensor pollicis longus, where it separates into several branches. Clinical correlation: Can be injured traumatically by handcuffs Innervates wide areas of skin on the dorsal hand & fingers, along with cutaneous branches of median & ulnar nerves. Radial nerve is ONLY cutaneous innervation over 1st-2nd dorsal webspace (radial n. tested sensorially in this region).

Medial antebrachial cutaneous n.

Cutaneous sensory ONLY - NO MOTOR Root: C8, T1 Origin: Medial cord Reaches cutaneous destination by following veins.

Medial brachial cutaneous n.

Cutaneous sensory ONLY - NO MOTOR Root: C8, T1 Origin: Medial cord Reaches cutaneous destination by following veins.

The Axillary nerve innervates

Deltoid and Teres Minor

Course of the PIN

Distal to the radial nerve split, the main branch of the radial nerve, called the posterior interosseous nerve (PIN), pierces the supinator muscle to again reach posterior compartment of forearm, & innervates all muscles of posterior forearm. Clinical correlation: can be entrapped in a contracting supinator and is called the supinator syndrome (the fibers of the supinator are called the "Arcade of Frohse").

What Nerve(s) innervate the Rhomboid Major

Dorsal Scapular

What Nerve(s) innervate the Rhomboid Minor

Dorsal Scapular

What Nerve(s) innervate the Levator scapulae (sometimes)

Dorsal scapular

What Nerve(s) innervate the Rhomboids

Dorsal scapular

Other Muscle Weaknesses

Dorsal scapular n.: rhomboids → scapular retraction Long thoracic n.: serratus anterior → scapular protraction Suprascapular n.: Supraspinatus → Initiate shoulder abduction Pectoral nn.: Pectoralis major → Shoulder flexion Lower subscapular n.: Teres major → Internal rotation, extension Thoracodorsal n.: Latissimus dorsi → Adduction, internal rotation Axillary n.: Deltoid, Shoulder abduction (numb over lateral deltoid)

What are the pre-plexus nerves discussed? (names only)

Dorsoscapular, Long Thoracic

Median n. in wrist & hand

Enters hand through carpal tunnel. It is the most superficial structure in carpal tunnel & shares space with 9 tendons: FDP (4), FDS (4), FPL *Carpal Tunnel Syndrome*: Median nerve is compressed in carpal tunnel & causes symptoms. Sensation in 4th digit (1/2 median nerve & 1/2 ulnar n.) important in diagnosis. *Clinical Correlation*: The *recurrent branch* of the median nerve (thenar branch) is motor to the thenar eminence. It is very superficial & susceptible to injury.

Median n. - Pathway in ARM

Exits shoulder *lateral to brachial artery* & continues in medial intermuscular septum (between triceps and anterior muscles) As the biceps brachii becomes tendinous distally, the median nerve becomes anterior to the proximal attachment of brachialis. *Crosses brachial artery anteriorly to travel on medial side* at mid-arm. Proximal to elbow it lies medial to the artery and it crosses the cubital fossa deep to bicipital aponeurosis with brachial artery.

The intrinsic plus position

Finger MP flexion, PIP and DIP extension tests the ulnar nerve. Full extension of the fingers is negative for ulnar nerve palsy - positive is the ulnar claw, sometimes referred to as the Bishop's sign: PIP flexion, MP hyperextension, and the small finger is often abducted.

Muscle Compartment Testing of Nerves - Shoulder

Flexion, abduction, extension, adduction → Spinal accessory, axillary, pre-plexus nerves

Course of the radial nerve

Forms as a terminal branch of posterior cord (along with the axillary nerve) just distal to the coracoid process on anterior surface of subscapularis. Enters the posterior arm with the deep brachial artery just inferior to trees major, between the long & medial heads of the triceps and follows the radial groove. Upon exiting radial groove, it pierces the lateral intermuscular septum to enter the anterior compartment, where it lies between the brachialis & brachioradialis. It crosses anteriorly over lateral epicondyle (where it can be injured in epicondylar fractures). Just past this, the superficial radial n. splits off to go to wrist.

Lower subscapular n.

Glenohumeral & acromioclavicular joints NO CUTANEOUS Root: C5, C6 Origin: Posterior cord (distal to origin of thoracodorsal n.) Innervates: Inferior subscapularis, teres major

Upper subscapular n.

Glenohumeral & acromioclavicular joints NO CUTANEOUS Root: C5, C6 Origin: Posterior cord Innervates: Superior subscapularis Travels lateral and posterior to thoradorsal nerve between subscapularis muscle and chest wall.

Thoracodorsal n.

Glenohumeral & acromioclavicular joints NO CUTANEOUS Root: C6, C7, C8 Origin: Posterior cord (distal to the origin of the upper subscapular n.) Innervates: Latissimus dorsi On the chest wall it lies posterior to long thoracic nerve.

Lateral pectoral n.

Glenohumeral & acromioclavicular joints NO CUTANEOUS, but provides propioception & pain fibers to glenohumeral joint. Root: C5, C6, C7 Origin: Lateral cord Innervates: Pectoralis major (inferior 2/3) Lateral to axillary artery at level of clavicle. Travels anterior to the first part of axillary artery & vein. Pierces clavipectoral fascia to reach the deep surface of the inferior portion of the pectoralis major muscle.

Medial pectoral n.

Glenohumeral, acromioclavicular & sternoclavicular joints NO CUTANEOUS Root: C8, T1 Origin: Medial cord Innervates: Pectoralis minor, pectoralis major (sternocostal part) Note: Actually lateral to lateral pectoral n. (named for cord of origin) Enters deep surface of pectoralis minor & some fibers pass through to innervate part of pectoralis major

What muscle(s) and/or joint(s) do(es) the ulnar nerve innervate?

HYPOTHENAR group: abductor digiti minimi, flexor digiti minimi, opponens digiti minimi; the flexor carpi ulnaris, 1/2 of the flexor digitorum profundus, the interosseus muscles (dorsal and palmar), 1/2 of lumbricals

"Hook 'em horns" sign

If patient can extend thumb, index & small fingers, the radial nerve is intact to the brachial plexus.

What muscle does the lower subscapular nerve innervate?

Inferior subscapularis muscle and teres major muscle

branches of the superior trunk

Inferior: the nerve to subclavius Superior: Suprascapular nerve

Sensory ulnar n.

Innervates 5th digit, medial 1/2 of 4th digit, medial palm. The pad of the small finger is exclusively innervated by the unlar n.

origin of the musculcutaneous nerve

Is an extension of the lateral cord

What cords contribute to the median nerve?

Lateral Cord and the Medial Cord

What nerve branches off from the Lateral Cord of the brachial plexus? (name only)

Lateral Pectoral Nerve

What Nerve(s) innervate the Pectoralis major and minor

Lateral and Medial pectoral

What Nerve(s) innervate the Pectoralis major

Lateral pectoral

What muscle does the Thoracodorsal nerve innervate?

Latissimus Dorsi muscle

thoracodorsal nerve innervates

Lattisimus dorsi

What Nerve(s) innervate the Serratus Anterior

Long Thoracic

What Nerve(s) innervate the Serratus Anterior

Long thoracic

What Nerve(s) innervate the Teres Major

Lower Scapular

C8-T1

Lower Trunk

Dejerene Klumpke Palsy

Lower Trunk Injury (C8, T1) *Causes*: Traction on arm during childbirth, fall or pull on upper limb in adults *Signs & Symptoms*: Paralysis of intrinsic hand muscles, loss of medial hand sensation, weak wrist (with flexion stronger than extension), shoulder is "normal" & strong

What Nerve(s) innervate the Flexor Digitorum Superficialis

Medial

What nerves branch off of the medial cord of the brachial plexus? (names only)

Medial Pectoral, Medial Brachial Cutaneous, and Medial Antebrachial Cutaneous nerves

What Nerve(s) innervate the Skin on medial side of forearm

Medial antebrachial cutaneous

What Nerve(s) innervate the Skin on medial side of arm

Medial brachial cutaneous

What Nerve(s) innervate the Abductor Pollicis Brevis

Median

What Nerve(s) innervate the Extensor Carpi Radialis Longus

Median

What Nerve(s) innervate the Flexor Carpi Radialis

Median

What Nerve(s) innervate the Flexor Pollicis Brevis

Median

What Nerve(s) innervate the Flexor Pollicis Longus

Median

What Nerve(s) innervate the Opponens Pollicis

Median

What Nerve(s) innervate the Pronator Quadratus

Median

What Nerve(s) innervate the Prontator Teres

Median

What Nerve(s) innervate the Thenar muscles

Median

What Nerve(s) innervate the Lumbricals

Median and Ulnar

Common Sites of Major Nerve Entrapment

Median n. at carpal tunnel Ulnar n. at cubital tunnel, by heads of flexor carpi ulnaris PIN at supinator muscle Radial n. at radial groove of humerus

terminal brachnes of the brachial plexus

Median, Ulnar, Radial and musculocutaneous nerves

C7

Middle Trunk

What Nerve(s) innervate the Biceps Brachii

Musculocutaneous

What Nerve(s) innervate the Biceps brachii

Musculocutaneous

What Nerve(s) innervate the Brachialis

Musculocutaneous

What Nerve(s) innervate the Coracobrachialis

Musculocutaneous

Branches of Medial and Lateral Cord

Musculocutaneous, medial cutaneous of forearm and arm, ulnar, median, medial pectoral, lateral pectoral

What Nerve(s) innervate the Subclavius

Nerve to subclavius

Musculocutaneous n.

Origin: Lateral cord (terminal branch) Root: C5, C6 *Motor*: Coracobrachialis, brachialis, biceps brachii *Cutaneous sensory*: Lateral forearm

Median n.

Origin: Medial & lateral cords Root: C6-T1 (contributions from all 3 trunks) Primary nerve of flexor/anterior compartment of forearm. Supplies all the long flexor muscles of the wrist and hand/digits except FCU, and ulnar half of the FDP. Via the named branch, the "anterior interosseus nerve," it also supplies: pronator quadrates, lateral 1/2 of the FDP, and the FPL (of the deep sub-compartment). Sensory branches supply the wrist joint. Remains in anterior compartment. Crosses anterior to medial epicondyle, where it can be injured in epicondylar fractures. No branches in arm. Provides some articular supply to elbow.

Suprascapular n.

Origin: Upper trunk Innervates: Supraspinatus, infraspinatus Traverses scapular notch on its way to innervate infraspinatus m.

Musculocutaneous n. - Pathway in ARM

Originates at the split of the lateral cord. Travels inferiorly & *pierces coracobrachialis from superior-posterior-medial to inferior-anterior lateral*. It then lies between brachialis & biceps brachii.

Anterior interosseous branch of median n.

Originates deep to bicipital aponeurosis, the 3 heads of flexor digitorum superficialis, and the 2 heads of pronator teres. Innervates deep anterior compartment: flexor pollicis longus, pronator quadratus, lateral 1/2 of flexor digitorum profundus NO CUTANEOUS BRANCHES.

What portion of the skin does the sensory portion of the median nerve innervate?

Palmar Skin, from the thumb to the lateral 1/2 of the ring finger.

What muscle does the medial pectoral nerve innervate? (name only)

Pectoralis Minor muscle, some of pectoralis major

What muscle(s) do(es) the lateral pectoral nerve innervate?

Pectoralis major muscle (some minor)

Posterior Cord

Posterior division of upper, middle and lower trunks

What Nerve(s) innervate the Abductor Pollicis Longs

Radial

What Nerve(s) innervate the Anconeus

Radial

What Nerve(s) innervate the Brachioradialis

Radial

What Nerve(s) innervate the Extensor Carpi Radialis Brevis

Radial

What Nerve(s) innervate the Extensor Carpi Ulnaris

Radial

What Nerve(s) innervate the Extensor Digiti Minimi

Radial

What Nerve(s) innervate the Extensor Digitorum

Radial

What Nerve(s) innervate the Extensor Indicis

Radial

What Nerve(s) innervate the Extensor Pollicis Brevis

Radial

What Nerve(s) innervate the Extensor Pollicis Longus

Radial

What Nerve(s) innervate the Extensors of the forearm

Radial

What Nerve(s) innervate the Supinator

Radial

What Nerve(s) innervate the Triceps Brachii

Radial

What Nerve(s) innervate the Triceps brachii

Radial

What area of the skin does the musculocutaneous nerve contribute to?

Radial Forearm Skin

Important Nerve Bifurcations

Radial n. at elbow → superficial & posterior interosseous Median n. distal to elbow → anterior interosseous branch & main median n. Posterior cord → radial & axillary nn. Medial cord → ulnar & median nn. Lateral cord → musculocutaneous & median nn.

Branches of Posterior Cord

Radial, axillary, thoracodorsal, lower sub scapular, upper subscapular

What does the dorsoscapular nerve innervate?

Rhomboid Major and Minor, and Levator Scapulae muscles

dorsal scapular nerve innervates

Rhomboid major, Rhomboid minor and Levator scapulae

Dorsal scapular n.

Root: C5 Innervates: Rhomboids, levator scapulae *Pre-plexus nerve* No cutaneous branches

Long thoracic n.

Root: C5, C6, C7 Innervates: Serratus anterior *Pre-plexus nerve* No cutaneous branches

Lateral cord contribution to median n.

Root: C6, C7 *Main branch, Motor*: Pronator teres Flexor carpi radialis Palmaris longus Flexor digitorum superficialis Abductor pollicis brevis 1/2 of flexor pollicis brevis Opponens pollicis Lateral 2 lumbricals Anterior interosseous branch, Motor*: Flexor pollicis longus Lateral 1/2 of flexor digitorum profundus Pronator quadratus *Cutaneous sensory*: Sensory to radial half of palm & to lateral side of 4th digit & thumb and fingers 1 & 2.

Medial cord contribution to median n.

Root: C8, T1 *Motor main branch*: Pronator teres Flexor carpi radialis Pollicis longus Flexor digitorum superficialis Abductor pollicis longus 1/2 of flexor pollicis brevis Opponens pollicis Lateral 2 lumbricals *Motor anterior interosseous branch*: Flexor pollicis longus lateral 1/2 of flexor digitorum profundus Pronator quadratus *Cutaneous sensory*: Sensory to radial half of palm & to lateral side of 4th digit & thumb & digits 1 & 2

Ulnar n.

Root: C8, T1 Origin: Medial cord *Motor*: Flexor carpi ulnaris Medial 1/2 of flexor digitorum profundus Medial 2 lumbricals Flexor digiti minimi Abductor digiti minimi Opponens digiti minimi All 3 palmar interosseous All 4 dorsal interosseous Adductor pollicis *Cutaneous sensory*: Sensory medial half of ring finger, all of small finger

Ulnar n. - Pathway in ARM

Runs from its origin in the anterior compartment of arm, with no branches in arm, to pierce medial septum & enter posterior compartment. Crosses the elbow posterior to medial epicondyle, where it is susceptible to entrapment by flexor carpi ulnaris and injury by *medial epicondylar fractures*.

Median n. in the hand

Sensory fibers innervate lateral 3 digits & lateral 1/2 of 4th digit. Motor fibers innervate lateral 2 lumbricals & via the recurrent branch, the 3 muscles of the thenar eminence (APB, FPB, OP).

Dorsal cutaneous branch of ulnar n.

Sensory to dorsal medial 1/2 of the long, proximal 3/4 of the ring & small fingers. NO MOTOR ACTION. Originates from ulnar n. approximately halfway between wrist & elbow.

Deep ulnar n.

Separates from sensory branch in the hypothenar eminence & innervates hypothenar muscles, the medial 2 lumbricals, the deep head of flexor pollicis brevis & adductor pollicis.

What muscle(s) do(es) the Long Thoracic nerve innervate?

Serratus Anterior muscle

Which nerves are involved in the brachial plexus?

Spinal nerves C5 - T1

What muscles(s) and/or joints do(es) the subclavius nerve innervate?

Subclavius muscle, sternoclavicular joint

Erb Duchenne Palsy

Superior Trunk Injury (C5, C6) *Causes*: Usually results from excessive increase in angle between neck & shoulder from: -traction on head during delivery -seatbelt injury -fall striking head & shoulder with head laterally flexed *Signs & Symptoms*: Weak shoulder muscles (except pectoralis minor & trapezius), numb deltoid & lateral forearm

What muscle does the upper subscapular nerve innervate?

Superior subscapularis muscle

What trunk(s) contribute to the radial nerve?

Superior trunk, Middle Trunk, Inferior Trunk

What trunks contribute to the median nerve?

Superior, Middle and Inferior Trunks

What Nerve(s) innervate the Glenohumeral joint

Suprascapular

What Nerve(s) innervate the Infraspinatus

Suprascapular

What Nerve(s) innervate the Supraspinatus

Suprascapular

What two nerves branch off of the Superior trunk of the brachial plexus? (names only)

Suprascapular and Subclavius Nerves

What muscle(s) and/or joints do(es) the suprascapular nerve innervate?

Supraspinatus, Infraspinatus, Glenohumeral joint

What muscle(s) and/or joint(s) do(es) the median nerve innervate?

THENAR group: Flexor Pollicus Brevis, Abductor Pollicus Brevis, Opponens Pollicus; Anterior Forearm: Pronator Teres, Flexor Carpi Radialis, Palmaris Longis, NOT Flexor Carpi Ulnaris, NOT 1/2 of flexor digitorum profundus, 1/2 of lumbricals

What muscle(s) and/or joint(s) do(es) the Axillary nerve innervate?

Teres Minor muscle, Deltoid muscle, Glenohumeral Joint

Axillary n.

Terminal branch of posterior cord Root: C5, C6 *Motor*: deltoid, teres minor *Sensory*: over lateral deltoid Exits to the posterior axillary region through the quandrangular space accompanied by posterior circumflex humeral artery. Encircles the surgical neck of the humerus.

Radial n.

Terminal branch of posterior cord Root: C5-T1 Motor: Triceps brachii, brachioradialis, extensor carpi radialis longus Superficial radial (sensory only): Dorsal 1st-2nd webspace skin PIN (Posterior interosseous branch of radial nerve) Motor only: Extensor carpi radialis brevis Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indices

What cord(s) contribues to the axillary nerve?

The Posterior Cord

What cord(s) contributes to the radial nerve?

The Posterior Cord

What trunk(s) contribute to the axillary nerve?

The Superior trunk

What divisions contribute to the Lateral Cord of the brachial plexus?

The anterior division of the Middle Trunk and the continuation of the Superior Trunk

What skin does the sensory portion of the axillary nerve innervate?

The lateral arm skin, skin over the deltoid

What cord(s) contribute to the Ulnar nerve?

The medial cord

What does the medial brachial cutaneous nerve innervate?

The skin on the medial arm

What does the medial antebrachial cutaneous nerve innervate?

The skin on the medial forearm

origin the divisions

The splitting of the superior, middle and inferior trunks anteriorly and posteriorly

origin of the posterior chord

The three posterior divisions

What portion of the skin is specific to the sensory innervation by the radial nerve?

The web between the thumb and the index finger, dorsally

What Nerve(s) innervate the Latissimus Dorsi

Thoracodorsal

What Nerve(s) innervate the Latissimus dorsi

Thoracodorsal

What Nerve(s) innervate the Adductor Digiti Minimi

Ulnar

What Nerve(s) innervate the Adductor Pollicis

Ulnar

What Nerve(s) innervate the Adductor pollicis

Ulnar

What Nerve(s) innervate the Flexor Carpi Ulnaris

Ulnar

What Nerve(s) innervate the Flexor Digiti Minimi

Ulnar

What Nerve(s) innervate the Flexor carpi ulnaris

Ulnar

What Nerve(s) innervate the Hypothenar muscles

Ulnar

What Nerve(s) innervate the Interossei

Ulnar

What Nerve(s) innervate the Opponens Digiti Minimi

Ulnar

What Nerve(s) innervate the Flexor Digitorum Profundus

Ulnar and Median

Trunks

Upper (superior): C5, C6 Middle: C7 Lower (inferior): C8, T1

C5-C6

Upper Trunk

Subscapularis

Upper and Lower Subscapular

What Nerve(s) innervate the Subscapularis

Upper subscapular

What branch(es) come(s) off from the Posterior Cord of the brachial plexus? (names only)

Upper subscapular, Thoracodorsal, Lower subscapular nerves.

three smaller nerves the posterior cord gives rise to

Upper subscapular, thoracodorsal, and lower subscapular nerve

Roots

Ventral rami of C5-T1

origin of the middle trunk

a continuation of the C7 nerve root

Median, Ulnar, Radial and musculocutaneous nerves innervate

all muscles in the arm, forearm and hand

origin of dorsal scapular nerve

directly off C5 nerve root

origin of long thoracic nerve

directly off C5, C6, C7 nerve roots

origin of the superior trunk

joining of C5 and C6 nerve roots

origin of the inferior trunk

joining of C8 and T1 nerve roots

other name for thoracodorsal nerve

middle subscapular nerve

the musculcutaneous nerve innervates

muscles in anterior compartment of the arm

What nerves branch off of the inferior trunk of the brachial plexus?

none

medial pectoral nerves innervate

pectoralis major and pectoralis minor

two larger nerves the posterior cord gives rise to

radial nerve, axillary nerve.

long thoracic nerve innervates

serratus anterior muscle

What Nerve(s) innervate the Inferior portion of subscapularis

subscapular

What Nerve(s) innervate the Teres major

subscapular

upper subscapular nerve innervates

subscapularis

lower subscapular nerve innervates

teres major and subscapularis

Which nerve does the dorsoscapular nerve originate from?

the C5 spinal nerve

Which cord(s) contribute to the musculocutaneous nerve?

the Lateral Cord

What does the Posterior Cord turn into? (names only)

the Radial Nerve and the Axillary Nerve

Which trunk(s) contribute to the musculocutaneous nerve?

the Superior Trunk and the anterior division of the Middle Trunk

shape of the combination of the lateral and median cords

the letter M

lateral pectoral nerve innervates

the pectoralis major muscle.

What trunks make up the posterior chord of the brachial plexus?

the posterior division of the superior trunk and the posterior division of the inferior trunk

What area of the skin does the sensory portion of the ulnar nerve innervate?

the skin on the medial hand

path of long thoracic nerve

travels inferiorly along rib cage