Maximus Gage
The humerus is a long bone in the upper arm that provides structural support and serves as an insertion point for many important muscles. The muscles surrounding the humerus include the deltoids, brachioradialis, coracobrachialis, pronator teres, teres major, brachialis, and common flexor and extensor tendons. The rotator cuff muscles at the shoulder connect to the humerus to stabilize the glenohumeral joint, which is highly movable but unstable and prone to dislocation and rotator cuff injury. The pectoralis major and latissimus dorsi muscles attach at the intertubular sulcus, or groove, in the head of the humerus, helping to rotate the humerus. The humerus is the only bone in the upper arm, and injuries to it often result in damage to the muscles and nerves attached to it.
| Characteristics | Values |
|---|---|
| Muscles surrounding the humerus | Deltoids, Brachioradialis, Coracobrachialis, Pronator Teres, Teres Major, Brachialis, Supraspinatus, Infraspinatus, Subscapularis, Latissimus Dorsi, Pectoralis Major, Triceps, Biceps Brachii, Flexor Muscles of the Forearm, Supinator, Extensor Muscles, Forearm Extensor Muscles |
| Number of muscles attached to the humerus | 13 |
| Function of the muscles | Provide motion for the arm and upper body, help rotate the humerus, stabilize the glenohumeral joint, coordinate upper limb movement, transmit forces from the shoulder to the forearm |
| Nerves | Axillary, Radial, Ulnar, Median, Anterior Interosseous |
| Arteries | Brachial, Profunda Brachii, Posterior Circumflex, Radial |
| Veins | Basilic |
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What You'll Learn
Muscles that attach to the humerus
The humerus is the only bone in the upper arm. It is connected to 13 muscles that help the arm move, flex, and rotate. The humerus also helps to stabilise the arm, including the elbow and hand.
The humerus serves as an attachment site for several muscles, including the supraspinatus, infraspinatus, and teres minor, which contribute to the coordinated actions of the upper limb. The greater tuberosity is located laterally on the humerus and is an attachment site for three rotator cuff muscles: the supraspinatus, infraspinatus, and teres minor. These muscles attach to the superior, middle, and inferior facets of the greater tuberosity, respectively. The lesser tuberosity is smaller and more medially located on the bone, providing attachment for the subscapularis muscle, the fourth rotator cuff muscle.
The deltoid muscle covers the lateral aspect of the greater tuberosity, giving the shoulder its normal rounded shape. The deltoid muscle is also involved in abducting the arm. The lateral side of the humeral shaft has a roughened surface where the deltoid muscle attaches. The coracobrachialis, brachialis, and pronator teres muscles attach to the anterior side of the humeral shaft, while the medial and lateral heads of the triceps attach to the posterior side.
The radial groove, or "spiral groove," is a shallow depression on the posterior surface of the humerus, parallel to the deltoid tuberosity. The radial nerve and profunda brachii artery lie within this groove. The deltoid tuberosity, a roughened surface on the lateral shaft of the humerus, serves as the insertion site for the deltoid muscle. The teres major muscle attaches to the crest of the lesser tubercle, while the coracobrachialis muscle attaches just below it. The medial head of the triceps brachii muscle attaches to the posterior lip of the lesser tubercle, and the medial intermuscular septum attaches to an intermediate ridge.
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Rotator cuff injuries
The humerus is the only bone in your upper arm. It is connected to 13 muscles, including the rotator cuff muscles, and helps you move your arm. The rotator cuff muscles at the shoulder connect to the humerus to stabilise the glenohumeral joint, which is freely movable but also highly unstable and prone to dislocation and rotator cuff injury. The rotator cuff is a group of four muscles that come together as tendons to form a covering around the head of the humerus. The greater tuberosity is located laterally on the humerus and serves as an attachment site for three of the rotator cuff muscles: supraspinatus, infraspinatus, and teres minor. The lesser tuberosity is smaller and located more medially on the bone, providing attachment for the last rotator cuff muscle, the subscapularis.
There are two main causes of rotator cuff tears: acute injury and wear or degeneration. Tears can occur suddenly, such as from falling on an outstretched arm or lifting something heavy, or they can develop slowly over time due to overuse. Most tears occur in the supraspinatus tendon, but other rotator cuff tendons may also be involved. Tears can be partial or full, and they may cause pain and arm weakness, making daily activities like combing hair or getting dressed difficult and painful.
Treatments for rotator cuff injuries depend on the patient's age, the severity of the injury, and whether it was sudden or from wear and tear. Treatment options include ultrasound therapy, electrical stimulation, and surgery for more severe or persistent cases. Early treatment is important to prevent mild rotator cuff injuries from becoming more serious.
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Dislocated shoulders
The humerus is the only bone in your upper arm. It runs from the shoulder to the elbow and is connected to 13 muscles, helping you move your arm. The humerus is one of the longest bones in the body, which makes it more prone to fractures. It provides structural support and serves as an insertion point for many important muscles, including the pectoralis major, latissimus dorsi, rotator cuff muscles, deltoids, brachioradialis, coracobrachialis, pronator teres, teres major, brachialis, and common flexor and extensor tendons.
A dislocated shoulder happens when the head of the humerus is pushed out of the socket in the shoulder blade or scapula. The shoulder joint is the most mobile joint in the human body, allowing us to position our hands in multiple positions. However, this advantage also makes the shoulder an easy joint to dislocate. The shoulder can dislocate by sliding forward (anterior) or backward (posterior). This usually occurs when the arm is raised away from the body, but it can also happen when the arm is in front of the body, as in a seizure.
Shoulder dislocations can be complete or partial. In a complete dislocation, the joint surfaces are completely separated, while in a partial dislocation, they are only partially separated. A partial dislocation is also called a subluxation. Healthcare providers classify dislocations depending on how far the bones in the joints were moved. A complete dislocation may tear the ligaments and/or tendons in the shoulder and/or damage nerves, while a partial dislocation can continue to happen over time if the ligaments never heal. Repeated dislocations can lead to chronic shoulder instability.
Falls, sports injuries, and car accidents are the most common causes of dislocated shoulders. If you think your shoulder is dislocated, do not try to force it back into place. Keep your arm still and close to your side and go to the emergency room. Immobilization is an important treatment for a dislocated shoulder, and you may need to wear a splint or sling to hold your injured shoulder in place. You may also need to ice your shoulder and do light exercises to prevent your shoulder from tightening or freezing.
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Radial nerve damage
The radial nerve is a major peripheral nerve of the upper limb. It descends down the arm, travelling in a shallow depression within the surface of the humerus, known as the radial groove. The nerve wraps around the humerus laterally and supplies a branch to the medial head of the triceps brachii. The radial nerve innervates the muscles located in the posterior arm and posterior forearm.
More severe radial nerve injuries may require surgery. If the damage is too extensive for a doctor to reconstruct the nerve, they may recommend a functional muscle transfer, a procedure that replaces a nonworking muscle with a "donor muscle" from elsewhere in the body. Radial nerve injuries can lead to radial nerve palsy, causing pain and a loss of function in the arm, wrist, hand, and fingers.
The humerus is a long bone located in the upper arm, between the shoulder and elbow joints. It is connected to 13 muscles, including the deltoids, coracobrachialis, brachialis, and common flexor and extensor tendons. The humerus provides structural support and serves as an insertion point for many important muscles. It is also connected to several nerves, including the radial nerve and the axillary nerve.
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Humerus fractures
The humerus is a long bone located in the upper arm, between the shoulder joint and the elbow joint. It is the only bone in the upper arm and is one of the longest bones in the body. It provides structural support and serves as an insertion point for many important muscles, tendons, ligaments, and parts of the circulatory system. Due to its length, the humerus is prone to fractures upon impact.
The treatment for humerus fractures depends on the type and severity of the break. Non-operative treatments include the use of a sling, brace, splint, or cast. Rehabilitation involves gradually increasing activities to restore muscle strength, joint motion, and flexibility. Surgical treatments may be necessary if the bone fragments are displaced or in cases of severe fractures with previous arthroscopy. Surgery typically involves fixation of the fracture fragments with plates, screws, or pins.
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Frequently asked questions
The humerus is the upper arm bone, connecting the shoulder to the elbow.
The humerus is connected to 13 muscles, including the supraspinatus, infraspinatus, and teres minor.
The supraspinatus, infraspinatus, and teres minor attach to the greater tuberosity. The subscapularis attaches to the lesser tuberosity.
The most common injuries to the muscles surrounding the humerus include rotator cuff injuries, dislocated shoulders, and radial nerve damage.
Axillary nerve damage results in paralysis of the deltoid and teres minor muscles.
