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42 Cards in this Set
- Front
- Back
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The clavicle crosses the brachial plexus at what level?
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The cords, so the roots, trunks, and divisions are supraclavicular (Mnemonic: Clavicle at the Cords)
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What spinal roots make up the plexus?
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C5-T1. Can be prefixed and start at C4 or postfixed and continue past T1
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What forms the upper, middle, and lower trunks?
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Upper: c5-c6
Middle: c7 Lower: c8-t1 |
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What forms the posterior cord of the plexus?
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The posterior divisions from all three trunks. Note that no peripheral nerves originate from the divisions
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What 3 peripheral nerves are supraclavicular on the brachial plexus?
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Long Thoracic, Dorsal Scapular, and Suprascapular
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What does the dorsal scapular nerve innervate?
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Levator scapulae, Rhomboid major and minor
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What does the long thoracic nerve innervate?
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Serratus Anterior. lesion leads to winging of the scapula (medial winging)
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Where is Erb's point and what nerve arises there?
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Erb's point is at the confluence of the C5 and C6 roots forming the upper trunk and the suprascapular nerve arises from here
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What does the suprascapular nerve innervate?
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Supraspinatus and infraspinatus
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What is the difference between preganglionic and postganglionic nerve root injury?
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Preganglionic: Injury occurs proximal to the dorsal root ganglion; postganglionic (aka extraforaminal injury) is damage of the spinal nerve distal to the dorsal root ganglion
Preganglionic is an injury with no prospect of repair or recovery |
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What are some tests that are poor prognostic indicators following brachial plexus injury?
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- Meningocele on cervical myelography
- EMG evidence of denervation of paracervical muscles and rhomboids - Winging of scapula - Horner's syndrome - Normal histamine response |
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How do you interpret a histamine test?
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Positive test: Vasodilation, wheal, and flare is a normal response
If positive with dermatomal anesthesia - Likely preganglionic lesion If negative with dermatomal anesthesia - Likely postganglionic |
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What is horner's syndrome?
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Damage at the level of T1 which disrupts the sympathetic innervation to the head leading to PAM: (ptosis, anhidrosis, miosis)
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Infraclavicular brachial plexus injuries (damage at and distal to the cord level) are most commonly associated with what injuries?
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Associated with fractures and dislocations. Prognosis for recovery good
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The naming of the cords of the brachial plexus (lateral, posterior, and medial) are relative to what?
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Relative to their relationship with the 2nd part of the axillary artery
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Describe the path of the lateral pectoral nerve and what it innervates
What does the medial pectoral nerve innervate? |
Arises from the lateral cord of the brachial plexus. Travels lateral to the axillary artery and innervates the clavicular and superior sternal portions of the pec major
Medial pectoral nerve innervates the pec minor and the inferior portion of the sternal head of the pec major |
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What 3 peripheral nerves originate from the middle cord?
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Upper subscapular, thoracodorsal, and lower subscapular.
Thoracodorsal innervates latissimus dorsi |
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The lateral, medial, and posterior cords terminate to form what peripheral nerves branches?
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Lateral: Musculocutaneous
Posterior: Axillary & Radial Medial: Ulnar Lateral and Medial combine to form the Median |
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What are the boundaries of the axilla?
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Base: hairy skin & sub-Q fat
Apex: Clavicle Anterior wall: Pec muscles Posterior wall: Lats, teres major, subscap Medial wall: Ribs 1-4 Lateral wall: intertuburcular groove of humerus |
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Where do the nerve roots of the plexus emerge?
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From spinal canal through intervertebral foramen then exit between the anterior and middle scalenes just superior to rib 1
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Describe the formation of the axillary artery
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On the left side the subclavian artery branches directly from the aorta and on the right it branches from the braciocephalic trunk behind the SC joint. The subclavian artery passes through the anterior and middle scalenes and becomes the axillary artery when it passes over the first rib. The axillary artery is broken up into 3 parts (Mnemonic: She Tastes Like Sweet Apple Pie):
1st part: Prior to pec minor has 1 branch: Superior thoracic artery which supplies the serratus anterior and pec muscles 2nd part: posterior to pec minor has 2 branches: The thoracoacromial arch which has 4 branches: The acromial, clavicular, deltoid, and pectoral. Lateral thoracic (runs with long thoracic nerve) and The 3rd part of the axillary artery is beyond the pec minor and has 3 branches: The subscapular (branches into thoracodorsal and circumflex scapular) and anterior and posterior humeral circumflex The axillary artery continues to become the brachial artery at the lower border of the teres major |
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What are the 5 major branches of the subclavian artery broken into the 3 parts of the subclavian?
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Mnemonic: VITamin C & D
1. From origin to medial border of anterior scalene: (VIT) Vertebral arteries which enter the foramen transversarium from C6 through C1 and form the basilar artery; Internal Thoracic Artery; Thyrocervical trunk (which divides into SIT: Suprascapular artery, inferior thyroid artery, and transverse cervical artery) 2. Deep to anterior scalene: Costocervical trunk which splits into supreme thoracic and deep cervical artery 3. From lateral margin anterior scalene to 1st rib: Dorsal scapular artery (25% of the time arises from transverse cervical artery) |
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Describe the axillary vein -- And remember to find out about if lymph drainage is necessary
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Axillary vein joins with veins corresponding to all named branches of the axillary artery then becomes the subclavian vein at the lateral border of rib 1. It joins the internal jugular forming the brachiocephalic vein and empties into the superior vena cava. On the left the the thoracic duct drains into the subclavian vein at the junction of the internal jugular
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Superior trunk injuries of the brachial plexus lead to what? What is the mechanism?
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Erb's palsy which is manifested as shoulder internal rotation, elbow extension, and hand flexion (waiter's tip)
Mechanism: Forceful lateral rotation of the neck away from the affected side combined with forceful depression of the affected shoulder |
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Inferior trunk injuries (C8 and T1) result in what?
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Klumpke's Palsy: Claw hand (extension of MCPs and flexion of IPs)
Horner's syndrome may be present |
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What has a better prognosis, supra or infraclavicular brachial plexus injuries?
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Infraclavicular have almost 90% recovery
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What is the origin (nerve root), course, and innervation for the following nerve:
Dorsal scapular nerve |
- Origin: C5
- Course: Pierces middle scalene, descends deep to levator scapulae - Innervation: Levator scapulae, rhomboids |
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What is the origin (nerve root), course, and innervation for the following nerve:
Long Thoracic Nerve |
- Origin: C5-C7
- Course: Descends posterior to C8 to T1 roots, descends on external surface of serratus anterior - Innervation: Serratus Anterior |
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What is the origin (nerve root), course, and innervation for the following nerve:
Nerve to Subclavius |
- Origin: C5-C6
- Course: Descends posterior to clavicle, anterior to brachial plexus and subclavian artery - Innervation: Subclavius, SC joint |
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What is the origin (nerve root), course, and innervation for the following nerve:
Suprascapular nerve |
- Origin: C5-C6
- Course: Passes laterally through posterior triangle of the neck, traverses suprascapular notch under transverse scapular ligament - Innervation: Supraspinatus, Infraspinatus, GH joint |
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What is the origin (nerve root), course, and innervation for the following nerve:
Lateral Pectoral Nerve |
- Origin: C5-C7
- Course: Pierces clavipectoral fascia, reaches deep surface of pectoral muscle - Innervation: Pectoral major |
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What is the origin (nerve root), course, and innervation for the following nerve:
Medial pectoral nerve |
- Origin: C8-T1
- Course: Passes between axillary artery and vein, enters deep surface of pec minor - Innervation: Pec minor and major |
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What is the origin (nerve root), course, and innervation for the following nerve:
Medial brachial cutaneous nerve |
- Origin: C8-T1
- Course: Runs along medial side of axillary vein - Innervation: Skin of medial arm |
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What is the origin (nerve root), course, and innervation for the following nerve:
Medial antebrachial cutaneous nerve |
- Origin: C8-T1
- Course: Runs between axillary artery and vein - Innervation: Skin of medial forearm |
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What is the origin (nerve root), course, and innervation for the following nerve:
Upper subscapular nerve |
- Origin: C5-C6
- Course: Passes posteriorly and enters subscapularis - Innervation: Subscapularis |
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What is the origin (nerve root), course, and innervation for the following nerve:
Thoracodorsal nerve |
- Origin: C6-C8
- Course: Arises between superior and inferior subscapular nerves - Innervation: Latissimus dorsi |
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What is the origin (nerve root), course, and innervation for the following nerve:
Lower subscapular nerve |
- Origin: C5-C6
- Course: Passes inferolaterally, deep to subscapular artery and vein - Innervation: Subscapularis, Teres Major |
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What is the origin (nerve root), course, and innervation for the following nerve:
Musculocutaneous nerve |
- Origin: C5-C7
- Course: Pierces coracobrachialis, descends between biceps brachii and brachialis - Innervation: Coracobrachialis, Biceps brachii, Brachialis, Skin of lateral forearm |
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What is the origin (nerve root), course, and innervation for the following nerve:
Median Nerve |
- Origin: C6-T1
- Course: Formed from lateral cord head joining medial cord head, descends medially to biceps brachii - Innervation: Most flexor muscles in forearm, radial half of flexor digitorum profundus, thenar muscles and lumbricals 1 and 2, skin of lateral palm (LOAF muscles: Lumbricals 1&2, Opponens, Abductor pollicis brevis, flexor pollicis brevis) |
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What is the origin (nerve root), course, and innervation for the following nerve:
Ulnar nerve |
- Origin: C7-T1
- Course: Descends medial to brachial artery, runs posteriorly to medial epicondyle of humerus - Innervation: FCU, ulnar half of flexor digitorum profundus, hand intrinsics |
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What is the origin (nerve root), course, and innervation for the following nerve:
Axillary nerve |
- Origin: C5-C6
- Course: Passes through quadrangular space and winds around surgical neck of humerus - Innervation: teres Minor, Deltoid, GH joint, Skin of inferior deltoid |
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What is the origin (nerve root), course, and innervation for the following nerve:
Radial nerve |
- Origin: C5-T1
- Course: Descends posterior to axillary artery, enters radial groove with deep brachial artery, passes between long and medial heads of triceps brachii - Innervation: Triceps brachii, Anconeus, brachioradialis, Extensor muscles of forearm, Skin of posterior arm, forearm, hand |
