Week 4 Oral quiz flashcards Q5-9
Innervation of biceps brachii
Musculocutaneous n. C5-C7
Proximal attachment of biceps brachi
(short head) tip of coracoid process of scapula, (long head) supraglenoid tubercle of scapula
Distal attachment of biceps brachii
Tuberosity of radius and fascia of forearm via bicipital aponeurosis
Action of biceps brachii
supinates forearm, in supine position it flexes forearm; short head resists dislocation of shoulder
Innervation of coracobrachialis
Musculocutaneous n. C5-C7
Proximal attachment of coracobrachialis
tip of coracoid process of scapula
Distal attachment of coracobrachialis
middle third of medial surface of humerus
Action of coracobrachialis
helps flex and adduct arm; resists dislocation of shoulder
Innervation of brachialis
Musculocutaneous n. C5, C6/ Radial n. C5, C7
Proximal attachment of brachialis
distal half of anterior surface of humerus
Distal attachment of brachialis
coronoid process and tuberosity of ulna
Action of brachialis
Flexes forearm in all positions
What is the innervation of the posterior compartment of brachium?
Radial nerve
Proximal attachment of triceps brachii long head
Infraglenoid tuberosity of scapula
Distal attachement of triceps brachii
proximal end of olecranon of ulna and fascia of forearm
Action of triceps brachii
extensor of forearm, resists dislocation of humerus. Especially important during adduction
Proximal attachment of lateral head of triceps brachii
Posterior surface of humerus, superior to radial groove
Proximal attachement of medial head of triceps brachii
Posterior surface of humerus, inferior to radial groove
Proximal attachment of anconeus
lateral epicondyle of humerus
Distal attachment of anconeus
lateral surface of olecranon and superior part of posterior surface of ulna
Action of anconeus
Assists triceps in extending forearm; stabilizes the elbow joint; may abduct ulna during pronation
What are the 3 cords of the brachial plexus?
lateral, posterior, medial
Spinal level and terminal branches of lateral cord
musculocutaneous (C5-7) and median terminal branches
Spinal level and terminal branches of medial cord
axillary and radial terminal branches
Spinal level and terminal branches of posterior cord
median (C6-T1) and ulnar (C7,C8,T1) terminal branches
Injury at axilla motor deficits
Injury at the axilla is “upstream” to all muscles that the radial nerve innervates. Results in motor loss in the extension of the elbow (triceps brachii), extension of the wrist (extensor carpi radialis longus), supination of the forearm (supinator), extension of the metacarpophalangeal joints of digits two through five (extensor digitorium) and the extension (extensor pollicis longus) and abduction (abductor pollicis longus) of the thumb. Loss of innervation to the forearm extensor compartment causes “wrist-drop” (patient cannot extend wrist so it hangs flaccid).
Injury at axilla sensory deficits
Sensory loss of the posterior arm, forearm, and dorsum of the thumb
Common causes of axilla radial nerve damage
overuse of crutches, shoulder dislocation, and repetitive “windmill” motion of arm used by softball pitchers
Injury at radial groove motor deficits
Has all the same motor deficits as at the axilla except the triceps is usually not paralyzed (only weakened) because only the medial head innervation is affected and posterior arm cutaneous sensation remains intact. So elbow extension and posterior arm cutaneous sensation are spared with radial injury, because the injury occurs “downstream” of where the triceps and posterior arm skin are innervated. Sensation of posterior forearm may or may not be lost.
Injury at radial groove sensory deficits
Sensation may or may not be lost
Common causes of radial groove radial nerve damge
humeral fractures or “Saturday night palsy” (compression palsy that occurs when a patient falls asleep curled over their arm most likely while drunk)
Elbow joint biomechanics
hinge type joint located 2-3 cm interior to epicondyles of humerus
Articulations of elbow joint
humero-ulnar and humero-radial articulations
Actions of elbow joint
flexion and extension
Muscles involved in elbow flexion
Brachialis, Biceps brachii, Brachioradialis
Muscles involved in elbow extension
Triceps brachii and anconeus
What are the 9 major bony landmarks of the humerus?
- greater tubercle 2. lesser tubercle 3. deltoid tubercle 4. crest of lesser tubercle and intertubercular groove 5. crest of greater tubercle 6. distal anterior surface of humerus 7. upper one-third of the frontal humerus 8. supracondylar ridge 9. medial epicondyle
Deltoid tubercle insertion
Deltoid (origin at lateral one third of clavicle, acromion process, and spine of the scapula)
Crest of lesser tubercle and intertubercular groove insertion
Latissimus Dorsi (origin at ribs 9-12, spinous processes T7-T12, iliac crest, thoracolumbar fascia) Teres Major (origin at the lateral border of the scapula slightly superior to the inferior angle)
Crest of greater tubercle insertion
Pectoralis Major (origins at sternal body, manubrium, medial half of clavicle, costal cartiliage 1-6)
Distal Anterior Surface of the Humerus origin
Brachialis (insertion at the coronoid process of the ulna)
Insertion of upper 1/3 of frontal humerus
Coracobrachialis (origin at the coracoid process)
Supracondylar ridge origin
Brachioradialis (insertion at the styloid process of the radius)
Extensor Carpii Radialis Longus (insertion at dorsal base of the 2nd metacarpal)
Medial epicondyle origin
Pronator Teres (insertion lateral radius distal to the insertion of the supinator muscle)
