Upper Extremity Muscles

Objective 10.10

10.10.1 Give the origin, insertion, and action of the major muscles of the upper extremity.

10.10.2 Identify these muscles on a picture or image.

 

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.

An illustration showing the muscles of the rotator cuff with their attachments.

Muscle(s) Origin Insertion Primary Action(s)
Supraspinatus Scapula Humerus Shoulder Abduction
Infraspinatus Shoulder External Rotation
Teres minor Shoulder External Rotation
Subscapularis Shoulder Internal Rotation

 

Deltoid

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

An illustration highlighting the origin and insertion of the deltoid muscle.

Muscle Origin Insertion Primary
Deltoid Scapula

Clavicle

 Humerus Shoulder Abduction

 

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.

An illustration highlighting the origin and insertion of the serratus anterior muscle.

Muscle(s) Origin Insertion Primary Action(s)
Serratus Anterior Upper Ribs

(ribs 1 through 8 or 9)

 Scapula

(medial border)

 Scapular Protraction

 

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.

An illustration highlighting the origin and insertion of the pectoralis major muscle.

Muscle(s) Origin Insertion Primary Action(s)
Pectoralis major Clavicle (clavicular head)

Sternum (sternal head)

 Humerus Shoulder Adduction

Shoulder Internal Rotation

 

Latissimus Dorsi

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

An illustration highlighting the origin and insertion of the latissimus dorsi muscle.

Muscle(s) Origin Insertion Primary Action(s)
Latissimus Dorsi Thoracic Vertebrae

Lumbar Vertebrae

Sacrum

Iliac Crest

 Humerus Should Extension

Shoulder Adduction

Shoulder Internal Rotation (as in butterfly stroke)

 

Triceps Brachii 

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

An illustration highlighting the origin and insertion of the triceps brachii muscle.

Muscle Origin Insertion Primary Action(s)
Triceps Brachii

Latin: “three-headed [muscle] of arm”

 Scapula (long head)

Humerus (lateral/medial head)

 Ulna (olecranon process) Elbow Extension

Shoulder Extension

 

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…).

An illustration highlighting the origin and insertion of the biceps brachi muscle.

Muscle Origin Insertion Primary Action(s)
Biceps Brachii

Latin: “two-headed [muscle] of arm”

 Scapula Radius (radial tuberosity) Elbow Flexion

Forearm Supination

 

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.

An illustration highlighting the origin and insertion of the brachialis muscle.

Muscle Origin Insertion Primary Action(s)
Brachialis Humerus Ulna (olecranon process) Elbow Flexion

 

Brachioradialis

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

An illustration highlighting the origin and insertion of the brachioradialis muscle.

Muscle Origin Insertion Primary Action(s)
Brachioradialis Humerus Radius (styloid process) Elbow Flexion

 

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.

An illustration highlighting the origin and insertion of the wrist flexors muscle group.

Muscle(s) Origin Insertion Primary Action(s)
Wrist Flexors Humerus (medial epicondyle) Varies Wrist Flexion

 

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.

An illustration highlighting the origin and insertion of the wrist extensors muscle group.

Muscle(s) Origin Insertion Primary Action(s)
Wrist Extensors Humerus (lateral epicondyle) Varies Wrist Extension

 

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Integrated Human Anatomy and Physiology Copyright © by Travis Price; Jim Hutchins; Justin Burr; Maddison Johnston; Pamela Silberman; Jeffery Speth; Jordan West; Misty Allen; and Elizabeth Rebarchik is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License, except where otherwise noted.

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