Anatomy Brachial Plexus

What skin does the radial nerve innervate?

the strip of skin on the back of the arm

What are the non terminal nerve that branch from the superior trunk?

suprascapular nerve (superior), subclavian nerve (inferior)

Which nerves will be completely inhibited if a person has erb's palsy?

suprascapular nerve, axillary nerve, subclavian nerve, upper and lower sub scapular nerves.

What does LLOAF stand for?

Lateral 2 Lumbricals Opponens pollicis Abductor pollicis brevis Flexor pollicis brevis

What are cords in terms of the brachial plexus?

The point where divisions in the plexus unite to make a lateral, medial, and posterior section. This part is is in the axilla.

Where does the dorsal scapular nerve come from?

The root of C5 (can't see in current dissection)

Which important nonterminal nerves branche from the superior trunk?

subclavian nerve and suprascapular nerve

What are the terminal branches of the medial cord?

ulnar nerve, 1/2 of medial nerve

What type of injury could cause damage to the posterior cord?

using crutches incorrectly, inferior dislocation of humerus, falling asleep with arm over head

Are brachial plexus composed of dorsal or ventral rami?

ventral rami (dorsal rami only go to muscles of the deep back)

From which spinal cord segments does the brachial plexus originate?

C5-T1

What all does the axillary nerve innervate?

deltoideus, teres minor, and superior lateral brachial cutaneous nerve

What does a lower plexus injury look like anatomically?

digits 4 and 5 curl like a claw because they have lost use of their flexor muscles.

What happens to trunks as they head toward the terminal end of the plexus?

division section, divided into anterior and posterior parts. allows for increased mixing of the trunks

Which groups of muscles are partially lost from a serious upper plexus injury?

flexor muscles from the arm and supinators of the forearm.

What does the median nerve stimulate?

flexors forearm (all but 1.5), in the hand LLOAF, and in the skin the lateral hand

Which muscles are completely lost from a serious upper plexus injury?

infraspinatus, teres minor (lateral rotators), deltoideus and supraspinatus (abductors), subscapula and teres major (adductors)

What part of the plexus is usually injured during a lower plexus injury?

C8 and T1. Most commonly it is seen in T1

What roots pass through medial cord?

C8, T1

Where in the plexus is the long thoracic nerve found?

Along the roots of C5,6,7, down towards the serratus anterior.

Where is an upper plexus injury?

At the upper/superior trunk. C5,6

Where do nonterminal nerves that branch off of cords all go to? What are the exceptions?

Axilla associated muscles because its located in the axilla. Exceptions are medial cutaneous nerves.

What important axillary structure are the cords named relatively to?

Axillary artery

What important structures from the axilla come through the quadrangular space?

Axillary nerve and posterior circumflex humeral artery

Which muscles does the musculocutaneous nerve stimulate?

Biceps, Coracobrachialis, brachialis, lateral antebrachial cutaneous nerve

What are the roots of a prefixed plexus?

C4 to C8 (rather than C5-T1)

What roots pass through lateral cord?

C5, C6, C7

What roots pass through posterior cord?

C5-T1

What are the roots of a postfixed plexus?

C6-T2 (rather than C5-T1)

What types of muscles does the radial nerve innervate?

Extensors of both the arm and forearm

What muscles does the ulnar nerve stimulate?

In the forearm: flexor carpi ulnaris and 1/2 of flexor digitorum profundis hand: all but 5 intrinsic muscles in hand (LLOAF) and medial skin

What are three other names for a lower plexus injury?

Lower trunk palsy, klumpke's paralysis, or klumpke dejerine paralysis.

Do the extremities receive both sympathetic and parasympathetic innervation?

No, sympathetic only

What are the terminal branches of the posterior cord?

Radial nerve (big), axillary nerve

Starting with ventral rami, what are the different sections of a plexus?

Roots>>Trunks>>Divisions>>Cords>>Terminal Branches

What muscles is the brachial plexus found between?

Scalenus Anterior and Scalenus Medius

What does an upper plexus injury result from?

Serious blow to the side of the head, a fall on the shoulder, or pulling a baby out hard. (violent separation of the head and shoulder.

What are the major contributing rami called in a plexus? What do we need to be sure to not confuse them with?

They are called roots. Be careful not to confuse them with dorsal and ventral root portions of spinal nerves

Which nerves are lost during a lower plexus injury?

Ulnar nerve, medial pectoral nerve, medial cutaneous nerve of the arm and forearm. (median nerve partially)

What nerves would be affected by a posterior cord injury?

Upper middle and lower sub scapular nerves, radial nerve, axillary nerve

What are three other names for an upper plexus injury?

Upper trunk palsy, erb's palsy, and erb-duchenne palsy.

What are the three different trunks formed by the roots?

Upper/superior, middle, lower/inferior

What is the expression (in human's anatomy) of an upper plexus injury?

Waiters tip hand. arm rotates medially, forearm is pronated, hand is supinated. (sensory loss offer lateral side of hand)

What are the manifestations of a posterior cord injury?

Wrist drop (extension and flexion is weakened), shoulder abduction (deltoids), lateral rotation (subscapularis), loss of sensation in posterior forearm and lateral hand

Which roots enter the upper/superior trunk?

a union of ventral rami C5 and C6

Which roots enter the lower/inferior trunk?

a union of ventral rami C8 and T1

What are the non terminal branches of the lateral nerve?

lateral pectoral nerve

Which nerves will be partially inhibited by a sharp separation of the head and neck (erb's palsy)?

lateral pectoral nerve, musculo cutaneous nerve, median nerve, thoracodorsal nerve, radial nerve

What are the non terminal branches of the peripheral cord?

lower subscapular, thoracodorsal nerve, and upper subscapular

What are the non terminal branches of the medial nerve?

medial cutaneous nerve of the anti brachium, medial cutaneous nerve of the brachium, medial pectoral nerve

What are the terminal branches of the lateral cord?

musculocutaneous nerve and 1/2 of median nerve

Which roots enter the middle trunk?

only a continuation of C7

Which muscles are if a person falls out of a window and holds on to something at the last minute to save their lives?

p.minor, part of p.major. part of flexordigitorum profundus, all but 5 intrinsic hand muscles