Shoulder, Arm, and Back Flashcards
What are the three functions of the deltoid?
- Anterior fibers from lateral 1/3 of clavicle - Arm flexion
- Middle fibers from acromion - Arm abduction
- Posterior fibers from spine of the scapula - Arm extension
What is the musculotendinous cuff, and tendons from which muscles make it up? What is its function?
Rotator cuff. Tendons from supraspinatus, infraspinatus, teres minor, and subscapular muscles make it up.
These tendons across the glenohumeral joint prevent posterior displacement of head of humerus
Tendons from which muscles form a sheath around the long head of biceps tendon?
Supraspinatus and subscapular
Where does the suprascapular artery come from?
Either directly from the subclavian artery, or a branch from the thyrocervical trunk from the subclavian artery
What is the dorsal scapular artery?
Also called the transverse cervical artery. Runs with dorsal scapular nerve, can come directly from subclavian artery but most often the thyrocervical trunk. Supplies blood to trapezius and medially to the scapula
What is the best example of collateral circulation in the shoulder?
If blood supply to the brachial artery is cut, blood can still reach the circumflex scapular artery via the suprascapular artery and the transverse cervical artery (dorsal scapular)
What are the borders of the triangular space? What runs through it?
Teres minor, teres major, long head of triceps (medial side). Circumflex scapular artery runs through (an offshoot of the subscapular artery)
What are the borders of the quadrangular space? What runs through it?
teres major, teres minor, lateral border of long head of triceps, surgical neck of humerus. Axillary nerve and posterior circumflex artery runs through
What are the borders of the triangular interval? What runs through?
Inferior border of teres major, long head of triceps (lateral), shaft of humerus. Radial nerve and profunda brachii artery run through
How are the anterior and posterior compartments of the humerus defined? What separates them?
Anterior - contains flexors innervated by musculocutaneous nerve
Posterior - contains extensors innervated by the radial nerve.
Separated by the intermuscular septa (arm’s deep fascia)
What are the origin, insertion, innervation, and action of the coracobrachialis?
Origin: Coracoid process
Insertion: Medial mid-shaft of humerus
Innervation: Musculocutaneous nerve
Weak flexor of arm
What are the origin, insertion, innervation, and action of the biceps brachii?
Origin: Long head from superglenoid tubercule, short head from coracoid process
Insertion: Radial tuberosity of radius
Innervation: Musculocutaneous nerve
Flexor of forearm, supinator of forearm, minor flexor of arm through short head
What are the origin, insertion, innervation, and action of the brachialis muscle?
Origin: Anterior aspect of distal humerus and intermuscular septum
Insertion: tuberosity of ulna
Innervation: Musculocutaneous nerve (it’s in the anterior compartment)
Flexor of forearm
What are the origins, insertion, innervation, and actions of the triceps brachii?
Origin: Long head - infraglenoid tubercule
Medial head - humeral shaft inferior to radial (spiral) groove. This head cannot be palpated
Lateral head - humeral shaft superior to radial groove
Insertion: Olecranon (of ulna)
Innervation: Radial nerve
Forearm extension, long head can also extend / adduct the arm
What defines the transition from axillary artery to brachial artery? What does it do?
It is renamed brachial artery at the inferior border of the teres major. It supplies blood to the anterior compartment.
What accompanies the radial nerve through the triangular interval and what is its function?
The profunda brachii artery. Its function is to supply blood to the posterior compartment
What accompanies the brachial artery? Where does it run?
Paired brachial veins accompany it. It joins the basilic vein medially to form the axillary vein. It runs medially to the short head of the biceps, and superficially to the brachialis muscle.
Where does the basilic vein run?
It runs medially to biceps brachii and the brachial artery, but penetrates the deep fascia
How does the musculocutaneous nerve run and what is its fate?
After piercing through the coracobrachialis muscle, it runs deep to the biceps brachii and superficially over the brachialis muscle. It emerges from under the biceps as the lateral cutaneous nerve of the forearm
How does the ulnar nerve move as it travels through the arm?
Arising from the medial cord, it accompanies the brachial artery medially and posteriorly as it travels down the distal forearm. It will pierce the IMS around the fattest portion of the brachialis muscle, before running posterior to the medial epicondyle of humerus.
How does the median nerve move as it travels through the arm.
Arising from the lateral and medial cords, it accompanies the brachial artery laterally and anteriorly as it travels down the distal forearm. Around the fattest part of the brachialis muscle, it moves anteriorly over the brachial artery to become medial to it.
How does the radial nerve move as it travels through the arm?
After passing through the triangular interval (with profunda brachii artery), it moves medially to laterally through the spiral / radial groove of the humerus. it is susceptible to injury at this time. It runs anteriorly just proximal to the elbow and runs between the brachialis and brachioradialis muscles.
