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The humerus is the upper arm bone that runs from the shoulder to the elbow. It is the only bone in the upper arm and is the longest bone in the body after the bones in the legs. The humerus serves as an attachment site for muscles, including the supraspinatus, infraspinatus, and teres minor, which facilitate movement of the hand, elbow, and forearm. Injuries to the humerus can result in muscle and nerve damage, with fractures being one of the most common issues affecting the bone.
| Characteristics | Values |
|---|---|
| Definition | The humerus is the upper arm bone. |
| Number | There is only one humerus bone in the upper arm. |
| Location | The humerus runs from the shoulder to the elbow. |
| Shape | The humerus has a rounded end where it meets the shoulder, a long shaft in the middle, and a flatter end that forms the elbow joint. |
| Connections | The humerus is connected to 13 muscles, including the supraspinatus, infraspinatus, and teres minor. It also connects to tendons, ligaments, and parts of the circulatory system. |
| Function | The humerus helps with arm movement, flexion, and rotation. It holds the 13 muscles in place and stabilizes the arm, including the elbow and hand. |
| Injuries | Common issues affecting the humerus include fractures, osteoporosis, and damage to nerves or muscles attached to it. Injuries can be caused by trauma, such as falls or car accidents, or sports-related activities. |
| Treatment | Treatment for a fractured humerus may include surgery to repair the bone and physical therapy to regain strength and movement. |
| Physiotherapy | Physiotherapists can use their knowledge of humerus anatomy to tailor rehabilitation programs, enhance range of motion, and address functional impairments. |
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What You'll Learn
The humerus is the upper arm bone
The humerus plays a crucial role in arm movement, flexion, and rotation, as well as stabilising the rest of the arm, including the elbow and hand. It serves as an attachment point for muscles, including the supraspinatus, infraspinatus, and teres minor. These muscles contribute to the coordinated movements of the hand and elbow, facilitating overall dexterity and functionality of the upper limb.
The bone has three borders: the anterior, lateral, and medial borders. It also has three surfaces: the anterolateral, anteromedial, and posterior surfaces. The anterolateral surface is covered by the deltoid muscle, which is responsible for abduction of the arm. The deltoid inserts into the deltoid tuberosity, a roughened area on the lateral surface of the humerus shaft.
Injuries to the humerus are common, often occurring during sports, falls, or car accidents. Fractures of the humerus can lead to damage to nearby nerves and muscles, such as the radial nerve and profunda brachii artery, resulting in potential paralysis and sensory loss. Osteoporosis, a condition that weakens bones, increases the risk of fractures in the humerus. Physiotherapy plays a crucial role in rehabilitation after humerus injuries, helping to enhance the range of motion and address functional impairments.
In summary, the humerus is the upper arm bone, providing structural support and facilitating movement in the arm. It serves as an attachment site for multiple muscles and plays a crucial role in maintaining the stability and functionality of the upper limb.
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It supports 13 muscles
The humerus is the upper arm bone that runs from the shoulder to the elbow. It is the only bone in the upper arm and, other than the bones in the legs, it is the longest bone in the body. The humerus serves as an attachment point for 13 muscles, which contribute to the movement of the hand, elbow, and upper limb. These muscles include:
- Supraspinatus
- Infraspinatus
- Teres Minor
- Latissimus Dorsi
- Teres Major
- Pectoralis Major
- Deltoid
- Brachialis
- Brachioradialis
- Triceps (medial and lateral heads)
- Coracobrachialis
- Pronator Teres
Injuries to the humerus can often lead to damage to the attached muscles and nerves. Some common issues include fractures, osteoporosis, and radial nerve damage. The radial nerve helps move the elbow, wrist, hand, and fingers, so injury to this nerve can cause paralysis of the extensors of the wrist, resulting in "wrist drop". Another common injury is axillary nerve damage, which results in paralysis of the deltoid and teres minor muscles, causing difficulty in abducting the affected limb.
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Injuries to the humerus can cause nerve and muscle damage
The humerus is the bone in your upper arm, running from your shoulder to your elbow. It is the only bone in your upper arm and is the longest bone in your body, other than the bones in your legs. The humerus is connected to 13 muscles, including the supraspinatus, infraspinatus, and teres minor, and is also connected to tendons and ligaments. These muscles and tendons help your arm to move, flex, and rotate, and they stabilise the rest of your arm, including your elbow and hand.
When you injure your humerus, it is likely that the muscles and nerves attached to it will also be damaged. This damage can include rotator cuff injuries, dislocated shoulders, and radial nerve damage. The rotator cuff is a group of muscles and tendons that keep your shoulder joint stable and help it to move. A dislocated shoulder occurs when the head of the humerus is pushed out of the socket in the shoulder. Radial nerve damage can cause paralysis in the extensors of the wrist, a condition known as 'wrist drop'. Other nerves that can be damaged in a humerus fracture include the median nerve, ulnar nerve, and axillary nerve.
If you fracture your humerus, you may need surgery to repair the bone, and physical therapy to regain strength and movement in your arm. A healthcare provider will diagnose a humerus fracture with a physical exam and imaging tests, such as an X-ray, MRI, or CT scan. With proper treatment, you should be able to make a full recovery.
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Fractures are common
The humerus is a long bone in the upper arm that runs from the shoulder to the elbow. It is one of the largest bones in the human body and is essential for a range of movements, including flexion, extension, and rotation of the arm. The bone itself is thick and curved, with a rounded head that fits into the shoulder socket and a narrow shaft that tapers down to the elbow. While the bone is strong and durable, fractures of the humerus are common, especially in certain high-risk groups.
The humerus bone is prone to fractures for several reasons. Firstly, the humerus is a long bone, and longer bones are generally more susceptible to fractures. Secondly, the humerus is located in an area of the body that is often exposed to trauma, such as falls or direct impacts during contact sports. The elderly are at particular risk of humeral fractures due to age-related bone loss and a higher risk of falls. Osteoporosis, a condition that weakens the bones, is also more prevalent in older adults, further increasing the risk of fracture. In fact, fractures of the humerus are one of the most common types of bone breaks in older individuals, often occurring as a result of a fall onto an outstretched hand or a direct impact to the shoulder or arm.
In younger individuals, humeral fractures are often the result of high-energy trauma, such as motor vehicle collisions or sports injuries. Contact sports, such as football, hockey, and rugby, carry a particularly high risk of humeral fractures due to the frequent body contact and impact involved. Fractures in younger people tend to occur as a result of a direct blow to the bone, and these breaks are typically more severe, often resulting in multiple fragments.
While less common, stress fractures of the humerus can also occur, especially in those who participate in repetitive arm activities, such as throwing sports (e.g., baseball or javelin) or weight lifting. These fractures are caused by overuse and the accumulation of stress on the bone over time, rather than a single traumatic event. They are more common in athletes who have recently increased the intensity or duration of their training, as the bone may not have had sufficient time to adapt and strengthen in response to the new demands.
The treatment for a humeral fracture will depend on the location and severity of the break. Nondisplaced fractures, where the bone cracks but maintains proper alignment, may only require a sling or cast to immobilize the arm during healing. However, more severe fractures, especially those that result in bone displacement, may require surgical intervention to realign and stabilize the bone with metal plates, screws, or rods. Physical therapy also often plays a crucial role in the recovery process, helping to restore range of motion, strength, and function to the affected arm.
Overall, fractures of the humerus are relatively common, particularly in the elderly and those who participate in high-risk sports or activities. While these fractures can be painful and debilitating, prompt medical attention and appropriate treatment can effectively manage them, ensuring a successful recovery and a return to normal function.
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The humerus is crucial for arm movement
The humerus is the upper arm bone, running from the shoulder to the elbow. It is the only bone in the upper arm and, other than the bones in the leg, it is the longest bone in the body. The humerus is crucial for arm movement, as it serves as an attachment point for muscles that contribute to the movement of the hand, elbow, and forearm, and therefore the function of the upper limb.
The humerus has three borders and three surfaces. The lateral and medial borders form medial and lateral supraepicondylar ridges, with the lateral ridge being rougher. The medial is the larger of the two and extends more distally. The ulnar nerve passes in a groove on the posterior aspect of the medial epicondyle, where it can be felt. The distal portion of the humerus also includes three depressions, known as the coronoid, radial, and olecranon fossae, which accommodate the forearm bones during flexion or extension at the elbow.
The radial (or spiral) groove is a shallow depression that runs diagonally down the posterior surface of the humerus, parallel to the deltoid tuberosity. The radial nerve and profunda brachii artery lie in this groove. The muscles that attach to the humerus along its shaft include the coracobrachialis, deltoid, brachialis, and brachioradialis anteriorly, and the medial and lateral heads of the triceps posteriorly.
The humerus plays a key role in facilitating the functionality of muscles such as the supraspinatus, infraspinatus, and teres minor. It also enables flexion and extension movements of the forearm, contributing to the overall dexterity of the upper limb. The humeral head articulates with the glenoid fossa of the scapula, forming the glenohumeral joint, which is a synovial ball-and-socket joint. This joint allows for a wide range of movements, including internal and external rotation, abduction, adduction, flexion, and extension.
Injuries to the humerus can have significant impacts on arm movement and overall functionality. Humerus fractures are a common issue, often caused by trauma such as falls or sports injuries. These injuries can lead to muscle and nerve damage, affecting the radial nerve, axillary nerve, and profunda brachii artery. As a result, individuals may experience paralysis in certain muscles and sensory loss in various parts of the hand and fingers.
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