Logan Steele
Muscle excursion refers to the distance between a muscle's maximum elongation and maximum shortening. Excursion is important in regulating sarcomere number, which is proportional to muscle excursion and/or contraction velocity. In tendon transfer surgery, there is usually a discrepancy in excursion between the muscle being replaced and the transferred muscle. For example, in patients with radial palsy, the pronator terres (PT) muscle is used to replace the wrist extensors, but the excursion of the PT is less than that of the extensor of the wrist, so it needs to double its length to allow for full wrist movement.
| Characteristics | Values |
|---|---|
| Definition | The distance between maximum elongation and maximum shortening of a muscle |
| Muscle Excursion and Sarcomere Number | Serial sarcomere number is proportional to muscle excursion and/or contraction velocity |
| Muscle Excursion and Tendon Transfer | In tendon transfer surgery, there is often a discrepancy in excursion between the muscles to be replaced and the transferred muscle |
| Muscle Excursion and Tendon Rupture | Tendon rupture leads to muscle contracture, decreased muscle mass, contractile function, and number of sarcomeres |
| Muscle Excursion and Collagen Content | Passive skeletal muscle excursion after tendon rupture is correlated with increased collagen content |
| Muscle Excursion and Timing of Tendon Repair | The recovery of muscle excursion after tendon repair is influenced by the timing of the repair |
| Muscle Excursion and Joint Movement | Muscle excursion allows the joint to move through its entire range of motion |
| Muscle Excursion and Length-Tension Curve | Muscle excursion is determined by the range of muscle lengths where the muscles generate active tension |
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What You'll Learn
- Muscle excursion is the change in muscle length to produce a full range of joint motion
- Tendon rupture causes muscle contracture, decreased muscle mass, and contractile function
- Muscle excursion is important in regulating sarcomere number
- Excursion training is a method used to improve the usable excursion of the transferred muscle-tendon unit
- Muscle excursion is proportional to contraction velocity
Muscle excursion is the change in muscle length to produce a full range of joint motion
Muscle excursion refers to the change in muscle length required to produce a full range of joint motion. It is the distance between a muscle's maximum elongation and maximum shortening. Generally, a muscle is capable of being shortened to about half of its normal resting length and stretched to about twice its normal resting length.
Muscle excursion is important in regulating sarcomere number, which is the number of contractile units within a muscle. In growing animals, an increase in muscle excursion results in an increased sarcomere number, while a decrease in muscle excursion has the opposite effect. This relationship has been observed in studies involving tendon transfer surgery, where the muscle excursion of the transferred muscle was significantly lower than that of the original muscle, despite an increase in sarcomere number.
The concept of muscle excursion is particularly relevant in tendon transfer (TT) surgery, where there is often a discrepancy in excursion between the original and transferred muscles. For example, in patients with radial palsy, the pronator terres (PT) muscle may be used to replace the wrist extensors. However, the excursion of the PT is less than that of the wrist extensors, so it needs to double its length to allow for a full range of wrist movement. Therapists can employ excursion training methods to improve the usable excursion of the transferred muscle-tendon unit.
Additionally, muscle excursion plays a role in understanding and treating tendon rupture, a common injury resulting from trauma or degenerative disease. After a tendon rupture, the connecting muscle contracts, leading to muscle contracture and a loss of normal resting tension. This results in decreased muscle mass, contractile function, and the number of capillaries and sarcomeres. By understanding the pathologic changes that occur after tendon rupture, clinicians can determine the optimal timing and technique for surgical treatment, such as direct repair, grafting, or tendon transfer.
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Tendon rupture causes muscle contracture, decreased muscle mass, and contractile function
Muscle excursion refers to the distance between a muscle's maximum elongation and maximum shortening. Generally, a muscle can be shortened to about half of its normal resting length and stretched about twice its normal resting length.
Tendon rupture is a common injury resulting from trauma or degenerative disease. When a tendon ruptures, the attached muscle contracts, and muscle contracture occurs if repair is delayed. The loss of normal resting tension inside the muscle causes a decrease in muscle mass, contractile function, the number of capillaries, and sarcomeres. There is also an increase in muscle fibre necrosis and the amount of connective tissue in the muscle. These changes negatively impact the clinical outcome of tendon repair.
The biceps muscle is a common site of tendon rupture, particularly in middle-aged or older men. Proximal ruptures occur where the biceps attaches at the top of the shoulder, while distal ruptures are extremely rare. Although surgical correction is not always necessary, it is recommended for active individuals who desire near-normal strength and power in plantarflexion.
In summary, tendon rupture leads to muscle contracture, decreased muscle mass, and impaired contractile function due to the loss of normal resting tension in the muscle. These changes are further compounded by increased muscle fibre necrosis and connective tissue formation.
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Muscle excursion is important in regulating sarcomere number
Muscle excursion is the distance between a muscle's maximum elongation and maximum shortening. Typically, a muscle can be shortened to about half of its resting length and stretched twice as long as its resting length. Muscle excursion is important in regulating sarcomere number, which refers to the number of sarcomeres in series in skeletal muscle fibres or fascicles. Sarcomeres are the contractile units within a muscle, and the force generated by a muscle depends on the amount of overlap between thin and thick myofilaments.
Several studies have investigated the relationship between muscle excursion and sarcomere number. Some research suggests that increasing muscle excursion leads to an increase in sarcomere number, while decreasing muscle excursion has the opposite effect. These adaptations in sarcomere number appear to produce optimal sarcomere lengths relative to the immobilized muscle length. In one study, immobilizing adult skeletal muscle in stretched or shortened positions resulted in increases or decreases in sarcomere number, respectively. Similarly, in growing animals, muscle excursion may play a role in regulating sarcomere number. However, it is important to note that the relationship between muscle excursion and sarcomere number is complex and not fully understood.
In tendon transfer surgery, there is often a discrepancy in excursion between the original muscle and the transferred muscle. For example, in patients with radial palsy, the pronator teres (PT) muscle may be used to replace the wrist extensors. However, the excursion of the PT is less than that of the wrist extensors, so it needs to double its length to allow for a full range of wrist movement. This has led to questions about whether the PT can increase its fibre length after transfer and how therapy can enhance the usable excursion of the transferred muscle-tendon unit.
While chronic skeletal muscle stretch is typically associated with an increase in sarcomere number, experimental evidence has not always supported this relationship. In one study, muscle excursion was found to be significantly lower in a transferred muscle compared to controls, despite an increase in sarcomere number. This disconnect between functional and structural muscle properties highlights the complex nature of muscle physiology and the need for further research to fully understand the relationship between muscle excursion and sarcomere number.
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Excursion training is a method used to improve the usable excursion of the transferred muscle-tendon unit
Muscle excursion refers to the distance between a muscle's maximum elongation and maximum shortening. Typically, a muscle can be shortened to about half of its resting length and stretched to about twice its resting length. Excursion training is a method used to improve the usable excursion of the transferred muscle-tendon unit.
In tendon transfer (TT) surgery, there is often a discrepancy in excursion between the replaced muscle and the transferred muscle. For example, in patients with radial palsy, the pronator teres (PT) muscle is often used to replace the wrist extensors. However, the excursion of the PT is less than that of the extensor, so it needs to double its length to allow for a full range of wrist movement.
Therapists can employ excursion training to address this issue and improve the usable excursion of the transferred muscle-tendon unit. This may involve familiarizing themselves with new methods and evaluating the results of TT. By doing so, they can help improve the range of motion in patients with tendon transfers.
Additionally, muscle excursion plays a role in regulating sarcomere number, which is related to muscle function. Increasing muscle excursion results in increased sarcomere addition, while decreasing excursion has the opposite effect. This relationship is particularly evident in growing animals, and adaptations in sarcomere number can impact muscle force-length and force-velocity properties.
Understanding the relationship between muscle excursion and sarcomere number can help inform clinical practices, especially in the management of patients with tendon injuries or transfers. By manipulating muscle excursion through exercises such as passive stretching and plyometrics, clinicians can optimize muscle function and improve patient outcomes.
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Muscle excursion is proportional to contraction velocity
Muscle excursion refers to the distance between a muscle's maximum elongation and maximum shortening. A muscle typically has sufficient excursion to allow the joint to move through its entire range. The greater the number of cross-bridges attached to the actin filaments, the larger the contraction force.
Muscle excursion is important in regulating sarcomere number in growing animals. In such cases, muscle excursion may be defined as the change in muscle length required to produce the full range of joint motion. Studies have shown that immobilizing adult skeletal muscle in stretched or shortened positions produces increases or decreases in sarcomere number.
For normal skeletal muscle, there is strong support for the idea that serial sarcomere number is proportional to muscle excursion and/or contraction velocity. However, these relationships have only been experimentally measured in normal muscles. In the case of tendon transfer surgery, there is usually a discrepancy in excursion between the muscle(s) to be replaced and the transferred muscle(s).
Tendon rupture is a common injury resulting in the connecting muscle contracting and muscle contracture occurring with a delay in repair. This loss of normal resting tension inside the muscle decreases muscle mass, contractile function, and the number of capillaries and sarcomeres. Passive skeletal muscle excursion after tendon rupture has been found to correlate with increased collagen content in muscle.
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Frequently asked questions
Muscle excursion is the change in muscle length required to produce the full range of joint motion. The distance between maximum elongation and maximum shortening is referred to as excursion.
Serial sarcomere number is proportional to muscle excursion and/or contraction velocity. Increasing excursion results in increased serial sarcomere addition, while decreasing excursion results in the opposite.
Tendon rupture is a common injury resulting in the connecting muscle contracting and muscle contracture occurring with a delay in repair. This leads to decreased muscle mass, contractile function, and the number of capillaries and sarcomeres. Studies have shown that the recovery of muscle excursion after tendon repair is influenced by the timing of the repair and the muscle excursion at the time of repair.
Tendon transfer (TT) surgery involves replacing a muscle with another muscle from elsewhere in the body. As the excursion of the transferred muscle may differ from the original muscle, it may need to change in length to allow for full joint movement. Excursion training may be required post-surgery to improve the range of motion.
