Upper Extremity 

Rotator Cuff 

The proximal part (glenoid) of the shoulder joint is formed by the scapula and clavicle. The head of the humerus fits into the glenoid. The rotator cuff which holds the glenoid and humerus together is formed by four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis. These muscles from a cuff around the shoulder joint (it’s not a cup). Their main goal is to provide glenohumeral (shoulder) joint stability. However, they do have individual actions which we will explore here. You will commonly hear about these muscles being injured.

Deltoid

The deltoid is a large shoulder muscle. It is a common site for injections.

Serratus Anterior 

The serratus anterior is a muscle that runs from your ribs to your shoulder blade. It is an important muscle to help move your scapula (shoulder blade) as you raise your arm.

Pectoralis Major

The pectoralis major is a large muscle on the chest wall. It is the largest muscle in the pectoral region, hence pectoralis major. We do have a pectoralis minor but we will not study it in this course.

Latissimus Dorsi

The latissimus dorsi are often called the ‘lats’. You have probably seen a lat pull-down machine at the gym.

Triceps Brachii 

Triceps refers to three origins. Brachii refers to the arm (brachium).

Biceps Brachii 

Biceps refers to two origins. Brachii refers to the arm (brachium). The biceps get a lot of glory when doing bicep curls but this muscle is not your strongest elbow flexor (cliffhanger…).

Brachialis

The brachialis is your strongest elbow flexor. You didn’t have to wait long to get the answer to which muscle is the strongest elbow flexor (cliffhanger from biceps brachii). This muscle lies underneath the biceps brachii, so you don’t see it much from the surface, and therefore, it doesn’t get much glory.

Brachioradialis

The brachioradialis is named for its attachments. It originates on the brachium (arm) and inserts on the radius.

Wrist Flexors 

There are multiple muscles, which we will group together, that cause flexion at the wrist. We are grouping them for simplicity but you should understand that these are multiple, separate muscles with slightly varying origin and insertion.

Wrist Extensors 

Just like the wrist flexors, we have multiple muscles that cause extension at the wrist. Most of these share some common attachments and actions. We are grouping them for simplicity but you should understand that these are in reality separate muscles with slightly varying origin and insertion.