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The rectus muscle is a part of the human body's muscular system. Rectus muscles can be found in the abdomen, head, and neck. Rectus abdominis, also known as the abs muscle, is a long muscle that extends from the rib cage to the pubic bone. It is divided into two segments by a muscle called the linea alba. Rectus abdominis holds internal organs in place and stabilizes the body during movement. The rectus abdominis may form bumps sometimes called a “six-pack” when someone has a trim, fit abdomen. The superior rectus is one of the seven extraocular muscles and is involved with elevating the eye, causing the cornea to move superiorly. The rectus muscle also moves the eyes about the longitudinal axis of the body, superiorly, inferiorly, laterally, or medially, according to their position relative to the eyeball.
| Characteristics | Values |
|---|---|
| Common name | Abs muscle |
| Location | Abdomen |
| Shape | Long and flat |
| Function | Holds internal organs in place, keeps the body stable during movement, assists with breathing and plays an important role in respiration when forcefully exhaling |
| Innervation | Thoraco-abdominal nerves |
| Blood supply | Inferior epigastric artery, superior muscular branches of the ophthalmic artery, anterior ciliary arteries |
| Tendons | Two; one larger tendon attached to the pubic crest, and one smaller, medial tendon attached to the pubic symphysis |
| Core muscles | Rectus abdominis, transversus abdominis, erector spinae, obliques |
| Thickness | Typically around 10 mm, but can be up to 20 mm in athletes |
| Volume | 300 cm3 in non-active individuals, 500 cm3 in athletes |
| Strains | Can occur due to overstretching or overuse |
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What You'll Learn
- The rectus abdominis muscle is a long, flat muscle that extends along the front of the abdomen
- It is innervated by thoraco-abdominal nerves and plays a role in core stability
- The rectus abdominis assists with breathing and is responsible for flexing the lumbar spine
- The muscle is interrupted by fibrous bands called tendinous intersections, dividing it into segments
- Rectus sheath haematoma is an injury to the rectus abdominis muscle causing abdominal pain
The rectus abdominis muscle is a long, flat muscle that extends along the front of the abdomen
The rectus abdominis muscle specifically runs vertically down the abdomen, starting from the rib cage and extending to the pubic bone. It is separated into two segments by a band of connective tissue called the linea alba, which runs vertically between the two halves of the muscle. The muscle is further subdivided into smaller muscle bellies by tendinous intersections, also known as intersectiones tendineae. These fibrous bands create a grid-iron 'six-pack' shape in individuals with low body fat.
The rectus abdominis muscle plays a crucial role in core stability and posture. It assists with breathing and is responsible for flexing the lumbar spine during movements such as crunches and leg-hip raises. The muscle also helps to hold internal organs in place and maintain consistent internal pressure within the abdomen.
Injuries to the rectus abdominis muscle can occur, such as strains or tears, commonly referred to as a "pulled abdominal muscle." In more severe cases, a rectus sheath hematoma may develop, causing abdominal pain. Additionally, the rectus abdominis muscle is used in breast reconstruction surgery, where a segment of the muscle is incised and raised along with the inferior epigastric artery.
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It is innervated by thoraco-abdominal nerves and plays a role in core stability
The rectus abdominis muscle, informally known as the abs muscle, is a long muscle that extends along the whole length of the front of the abdomen. It is innervated by thoraco-abdominal nerves, which are continuations of the T7-T11 intercostal nerves. These nerves pierce the anterior layer of the rectus sheath, with the sensory supply coming from the 7-12 thoracic nerves.
The rectus abdominis is a paired muscle that runs vertically down both sides of the abdomen, separated by the linea alba, a band of connective tissue. The muscle fibres extend and insert into the xiphoid process of the sternum and the costal cartilages of the 5th, 6th, and 7th ribs. The upper portion is attached to the cartilage of the 5th rib, and in some cases, it can extend to the 3rd and 4th ribs.
The thoraco-abdominal nerves play a crucial role in the functioning of the rectus abdominis muscle. These nerves provide the necessary stimulation for the muscle to contract and relax, allowing it to perform its functions effectively.
The rectus abdominis is an important postural muscle and plays a significant role in core stability. It assists in flexing the lumbar spine and helps bring the rib cage and pelvis closer together. Along with other core muscles like the transversus abdominis, erector spinae, and obliques, the rectus abdominis acts like a natural weight belt, providing support and protection to the lower back. This muscle group helps to stabilise the trunk and maintain consistent internal pressure within the abdomen.
Weak abdominal muscles can lead to spinal problems and make individuals more susceptible to injuries. Therefore, maintaining the strength and health of the rectus abdominis and other core muscles is essential for overall stability and injury prevention.
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The rectus abdominis assists with breathing and is responsible for flexing the lumbar spine
The rectus abdominis 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 individuals with low body fat. The rectus abdominis is an important postural muscle that plays a crucial role in core stability, protecting the spine, and keeping the body stable and balanced during movement.
This muscle assists with breathing and is responsible for flexing the lumbar spine. During forceful exhalation, such as after exercise or in certain medical conditions, the rectus abdominis aids in respiration. Additionally, it helps bring the rib cage towards the pelvis or vice versa, depending on which is fixed in space. This movement is achieved through flexion of the lumbar spine, as seen in exercises like crunches and leg-hip raises.
The rectus abdominis is innervated by thoraco-abdominal nerves, specifically the T7-T11 intercostal nerves, which pierce the anterior layer of the rectus sheath. It receives a sensory supply from the 7-12 thoracic nerves. The muscle is interrupted by tendinous intersections, also known as intersectiones tendineae, which further subdivide it into smaller muscle bellies. These intersections create the characteristic ""six-pack"" appearance.
The rectus abdominis also plays a role in maintaining internal abdominal pressure. Along with other abdominal muscles, it helps hold internal organs in place, ensuring their stability and protection. This muscle is paired and runs vertically down both sides of the abdomen, separated by the linea alba, a band of connective tissue. The muscle fibres attach to the ribs and the pubic bone, providing structural support and facilitating movement.
Injuries to the rectus abdominis can occur, such as strains or tears, which can lead to abdominal pain. In some cases, a rectus sheath haematoma may develop, causing a potentially serious accumulation of blood in the muscle's sheath. Maintaining strong abdominal muscles through exercises like sit-ups and trunk raises is important for overall health and stability.
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The muscle is interrupted by fibrous bands called tendinous intersections, dividing it into segments
The rectus muscle is a part of the core muscles and plays a role in core stability. The rectus abdominis is a long flat muscle that extends along the whole length of the front of the abdomen. It is separated from its fellow on the opposite side by the linea alba. The rectus abdominis muscle is interrupted by fibrous bands called tendinous intersections, dividing it into segments. These fibrous bands are also called intersectiones tendineae. There are three tendinous intersections in the rectus abdominis muscle. One of these horizontal intersections is present at the level of the umbilicus, another at the level of the xiphoid process, and the third midway between them. These fibrous bands divide the muscle into segments, resulting in a grid iron 'six-pack' shape in those with low body fat. The upper portion of the rectus abdominis is attached principally to the cartilage of the fifth rib, and usually has some fibres of insertion into the anterior extremity of the rib itself.
The rectus muscle is also one of the four muscles that move the eyes about the longitudinal axis of the body, i.e., superiorly (upward) or inferiorly (downward), or about a vertical axis, i.e., laterally (backward) or medially (forward), according to their position relative to the eyeball. The rectus muscles arise from a fibrous ring that encircles the optic nerve at the optic foramen, the opening through which the nerve passes, and are attached to the sclera. The superior rectus is one of the seven extraocular muscles. The superior rectus has a primary action of elevating the eye, causing the cornea to move superiorly. The superior tendon is involved with the entire superior rectus muscle as well as portions of the medial rectus and lateral rectus muscles.
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Rectus sheath haematoma is an injury to the rectus abdominis muscle causing abdominal pain
The rectus abdominis is a long, flat abdominal 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. The rectus abdominis is an important postural muscle, responsible for flexing the lumbar spine and assisting with breathing and respiration.
A rectus sheath haematoma is an injury to the rectus abdominis muscle that causes abdominal pain. It occurs when there is bleeding into the rectus sheath, the connective tissue that supports the abdominal muscles. This bleeding is usually due to a rupture of an epigastric artery or its perforating branches within the rectus muscle. The blood supply to the rectus abdominis comes from the superior and inferior epigastric arteries. When the superior epigastric artery is injured, the resulting haematoma is typically smaller and can be quickly contained within the rectus sheath. However, a rupture of the inferior epigastric artery can lead to a larger and more clinically significant haematoma due to the lack of a posterior sheath.
The most common symptom of a rectus sheath haematoma is sudden, sharp, severe, and persistent abdominal pain, which may worsen with movement or flexion of the abdominal muscles. Other symptoms include nausea, vomiting, a palpable abdominal mass, fast heart rate (tachycardia), and low blood pressure (hypotension). The Carnett sign indicates that the pain originates from the abdominal wall, while the Fothergill sign refers to a palpable abdominal mass that does not cross the midline, indicating a rectus sheath haematoma.
Rectus sheath haematomas are typically diagnosed through an ultrasound of the abdominal wall, which can reveal fluid collection and the size of the haematoma. A CT scan with contrast can also be used to identify the location of the rupture and is highly sensitive and specific for detecting rectus sheath haematomas.
Most rectus sheath haematomas do not require medical treatment and can be managed with ice, rest, and over-the-counter pain relievers. However, in some cases, more advanced treatment, such as angioembolization, may be necessary.
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Frequently asked questions
The rectus muscle is a part of the core muscles and is also known as the abdominal muscle or the "abs muscle". It is a long, flat muscle that extends along the front of the abdomen, from the rib cage to the pubic bone.
The rectus abdominis muscle is responsible for holding internal organs in place, keeping the body stable during movement, assisting with breathing, and playing a role in respiration during forceful exhalation. It also helps with movement between the rib cage and pelvis, allowing the trunk to be in constant motion.
There are four rectus muscles: inferior, medial, lateral, and superior recti.
