Logan Steele
The rectus abdominis is a long, flat muscle that extends along the front of the abdomen, commonly referred to as the six-pack. It is responsible for flexing the lumbar spine and plays a crucial role in core stability, assisting with breathing and respiration during forceful exhalation. The rectus abdominis is innervated by thoraco-abdominal nerves and has multiple sources of arterial blood supply. It is involved in various actions, including compressing the abdominal viscera and providing structural support to adjacent abdominal structures. The muscle is also associated with spinal problems and abdominal injuries, such as strains and rectus sheath hematomas.
| Characteristics | Values |
|---|---|
| Muscle type | Flat, long, strap-like, skeletal |
| Location | Abdomen, anterior abdominal wall |
| Function | Flexes the lumbar spine, assists in breathing, stabilises the pelvis, depresses the ribs |
| Innervation | Thoraco-abdominal nerves (T7-T11), continuations of the T7-T11 intercostal nerves |
| Blood supply | Inferior epigastric and superior epigastric arteries, posterior intercostal, subcostal and deep circumflex arteries |
| Layers | Three tendinous intersections, separated by linea alba |
| Attachments | Originates from the crest of the pubis bone, inserts into the xiphoid process of the sternum and the costal cartilage of ribs 5-7 |
| Thickness | Typically 10mm, up to 20mm in athletes |
| Volume | 300 cm3 in non-active individuals, 500 cm3 in athletes |
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What You'll Learn
Rectus abdominis is a long, flat muscle
The rectus abdominis is a long, flat muscle that extends along the whole length of the front of the abdomen. It is often referred to as the "abs muscle" and is responsible for the appearance of a "six-pack". This muscle is part of the core muscles, which also include the transversus abdominis, erector spinae, and obliques. Together, these muscles act like a natural weight belt, protecting the lower back from injury and stabilising the spine.
The rectus abdominis is a paired muscle, with two long muscles running vertically up the front of the abdomen, from the pubis to the xiphoid process and ribs. It is separated by the linea alba, a connective tissue, into two parallel muscles on either side of the midline of the anterior abdominal wall. The muscle is further subdivided into a series of smaller muscle bellies by tendinous intersections, also known as intersectiones tendineae. These fibrous bands divide the muscle into segments, resulting in a "six-pack" shape in individuals with low body fat.
The rectus abdominis has several functions, including flexing the spinal column, tensing the anterior wall of the abdomen, and assisting in compressing the contents of the abdomen. It also assists with breathing and plays a crucial role in respiration during forceful exhalation, such as after exercise. Additionally, it helps stabilise the pelvis during walking and depresses the ribs.
The strength of the rectus abdominis and other abdominal muscles is essential for maintaining core stability and preventing spinal problems. Various exercises, such as sit-ups, planks, and crunches, can be performed to strengthen these muscles. The sit-up exercise, for example, involves raising the trunk against gravity to the midline and slowly lowering it down in multiple sets.
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It is a voluntary muscle
The rectus abdominis is a voluntary muscle. It is a long, flat muscle that extends along the entire length of the front of the abdomen, and is often referred to as the "abs muscle". It is separated from its counterpart on the opposite side by the linea alba, a connective tissue. The rectus abdominis is responsible for the appearance of a "six-pack", which is more visible in individuals with low body fat.
The rectus abdominis is a vital postural muscle that aids in flexing the lumbar spine, as seen in exercises like crunches. It also plays a role in respiration, assisting with forceful exhalation after exercise or in certain medical conditions. This muscle is paired and runs vertically on both sides of the midline of the anterior abdominal wall. It originates from the pubic crest, specifically the pubic tubercle, and inserts into the xiphoid process of the sternum and the costal cartilages of the 5th to 7th ribs.
The muscle's strength is typically assessed by asking the patient to raise their trunk against gravity from a supine position. This movement isolates the rectus abdominis and helps therapists grade the patient's performance and ability to follow instructions. The rectus abdominis is also involved in stabilising the pelvis during walking and depressing the ribs.
The muscle receives its blood supply from various vessels, predominantly the inferior and superior epigastric arteries. It is innervated by the thoraco-abdominal nerves, which are continuations of the T7-T11 intercostal nerves. These nerves pierce the anterior layer of the rectus sheath, providing sensory input to the muscle.
In summary, the rectus abdominis is a long, flat, voluntary muscle that plays a crucial role in posture, movement, and respiration. It is an essential component of the abdominal wall and contributes to the well-known "six-pack" appearance.
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It is responsible for the appearance of six-pack abs
The rectus abdominis is a long, flat muscle that extends along the entire length of the front of the abdomen. It is separated from its fellow muscle on the opposite side by the linea alba, a connective tissue. The rectus abdominis is often referred to as the "abs muscle" or simply "abs", and it is what people think of as their "six-pack".
The rectus abdominis is responsible for flexing the spinal column and tensing the anterior wall of the abdomen. It also assists in compressing the contents of the abdomen and plays a role in core stability. The muscle is innervated by thoraco-abdominal nerves, which are continuations of the T7-T11 intercostal nerves. It has a rich blood supply from various vessels, predominantly the inferior and superior epigastric arteries.
The rectus abdominis is paired and runs vertically on either side of the linea alba, on the anterior surface of the abdominal wall. It is divided into sections by tendons, which give it the segmented "six-pack" appearance when it is well-developed. The muscle is engaged when the lumbar spine is flexed, bringing the ribs and pelvis closer together, as in a crunch or sit-up exercise.
To effectively train the rectus abdominis for a strong six-pack, it is important to understand its structure and function. Exercises that isolate the rectus abdominis, such as raising the trunk from a supine position, are effective for building strength in this muscle. Additionally, sit-up exercises that involve raising and lowering the trunk against gravity can target the rectus abdominis, especially when the knees are bent to minimise the engagement of hip flexors.
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It is an important postural muscle
The rectus abdominis muscle is an important postural muscle. It is a long, flat muscle that extends along the entire length of the front of the abdomen. It is separated from its fellow on the opposite side by the linea alba, a connective tissue. The rectus abdominis is responsible for flexing the lumbar spine, as when doing a crunch. It also assists with breathing and plays a crucial role in respiration during forceful exhalation, such as after exercise or in conditions like emphysema.
The rectus abdominis is often referred to as the "six-pack" muscle and is a key component of core stability. It helps to stabilise the trunk and protect the lower back from injury. Weak abdominal muscles can lead to poor posture, lower back pain, and other musculoskeletal issues. Therefore, it is important to focus on strengthening these muscles through exercises such as sit-ups and trunk raises.
The muscle is innervated by the thoraco-abdominal nerves, which are continuations of the T7-T11 intercostal nerves. It receives its blood supply from various vessels, predominantly the inferior and superior epigastric arteries. The rectus abdominis is paired and separated at the midline by the linea alba, with each muscle further subdivided by tendinous intersections into smaller muscle bellies.
The rectus abdominis is a vital postural muscle that helps maintain core stability, supports the spine, and facilitates movement. Its strength is crucial in preventing various musculoskeletal issues and ensuring proper posture and spinal health. By understanding the importance of this muscle, individuals can focus on strengthening their rectus abdominis through targeted exercises and maintain overall physical well-being.
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It assists with breathing
The rectus abdominis muscle is a long, flat muscle that extends along the entire length of the front of the abdomen. It is often referred to as the "abs muscle" and is visible as a "six-pack" in people with low body fat. While the rectus abdominis is not a primary respiratory muscle, it does play a role in assisting with breathing.
The rectus abdominis is involved in forceful exhalation, particularly after exercise or in conditions where there is an increased respiratory effort. During exhalation, the muscle contracts and tenses, assisting in compressing the contents of the abdomen and aiding in the expulsion of air from the lungs. This is especially noticeable during activities that require forceful or rapid exhalation, such as coughing, sneezing, or blowing air out.
The muscle's role in breathing is closely related to its function in maintaining core stability and posture. As a core muscle, the rectus abdominis works in conjunction with other muscles, such as the transversus abdominis, erector spinae, and obliques, to stabilize the spine and pelvis. This stability helps to create a solid foundation for the respiratory muscles to work efficiently.
Additionally, the rectus abdominis assists in breathing by providing structural support to the rib cage and spine. It attaches to the rib cage and the pelvis, allowing for movements that can indirectly impact breathing. For example, when performing a crunch or a leg-hip raise, the rectus abdominis flexes the lumbar spine, bringing the rib cage closer to the pelvis or vice versa. This movement can help expand or contract the thoracic cavity, facilitating inhalation or exhalation.
The involvement of the rectus abdominis in breathing becomes more pronounced during periods of increased respiratory demand or distress. In such situations, the central nervous system modulates the activity of the muscle to regulate intra-abdominal and intra-thoracic pressures. This modulation can lead to increased activation of the rectus abdominis, particularly during forceful exhalation.
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Frequently asked questions
The rectus abdominis is a long, flat muscle that extends along the front of the abdomen. It is often referred to as the "abs muscle" and is responsible for the appearance of a "six-pack".
The rectus abdominis is involved in flexing the spinal column, tensing the abdominal wall, and assisting in compressing the contents of the abdomen. It also plays a role in core stability, helping with balance and stabilising the spine.
Exercises such as planks, crunches, and sit-ups can help strengthen the rectus abdominis. To isolate the muscle, perform exercises with bent knees to minimise the engagement of hip flexors.
A strain occurs when the muscle is stretched too far, resulting in microscopic tears or, in severe cases, a rupture from its attachment. This can lead to abdominal pain and may require rest and recovery.
