Logan Steele
The abdominal muscles, also known as the abs, are essential for several bodily functions. They are located between the ribcage and the pelvis on the front of the body. There are five main abdominal muscles: pyramidalis, rectus abdominis, external obliques, internal obliques, and transversus abdominis. These muscles work together to support the spine, hold internal organs in place, and enable movement. The deepest muscle of the abs, the transversus abdominis, wraps around the waist to support the spine and can compress the abdomen, increasing abdominal pressure for essential bodily functions. This muscle is activated when you compress your stomach towards your spine.
| Characteristics | Values |
|---|---|
| Number of abdominal muscles | 5 main muscles, 4 main muscle groups |
| Names of abdominal muscles | Transversus abdominis, rectus abdominis, external obliques, internal obliques, pyramidalis |
| Location of abdominal muscles | Between the rib cage and pelvis on the front of the body |
| Function | Support the trunk, allow movement, hold organs in place, regulate internal abdominal pressure, protect the spine, stabilise the trunk, maintain posture, prevent injuries and back pain |
| Appearance | A ["six-pack"] may be visible in individuals with low belly fat and a trim, fit abdomen |
| Activation | Intentionally contracting the abdominal muscles is the only way to activate them when sitting |
Explore related products
What You'll Learn
Transversus Abdominis
The transversus abdominis is a broad paired muscular sheet found on the lateral sides of the abdominal wall. It is the deepest abdominal muscle layer and wraps around the waist to support the spine. It is also referred to as the "corset muscle" because it has the effect of pulling in what would otherwise be a protruding abdomen.
The transversus abdominis is one of the five main abdominal muscles, which include the rectus abdominis, external obliques, internal obliques, and pyramidalis. These muscles are located between the ribs and the pelvis on the front of the body. The transversus abdominis specifically lies on the lateral abdominal wall, deep to the internal abdominal oblique and external abdominal oblique muscles. It comprises the deepest layer of the lateral abdominal wall.
The transversus abdominis has several origin points:
- Lateral one-third of the superior surface of the inguinal ligament and the associated iliac fascia
- Anterior two-thirds of the inner lip of the iliac crest
- Thoracolumbar fascia between the iliac crest and the 12th rib
- Internal aspects of the lower six ribs and their costal cartilages
From these origin points, the transversus abdominis fibres course horizontally over the lateral abdominal wall towards the midline, oriented perpendicular to the linea alba. The transversus abdominis aponeurosis makes up the posterior wall of the rectus sheath, which covers the posterior upper three-quarters of the rectus abdominis.
The transversus abdominis helps to compress and retain the contents of the abdomen, providing thoracic and pelvic stability. It also assists in exhalation, contracting during the exhalation phase of respiration to force air out of the thorax. Additionally, it helps to protect the spine and keep the body stable and balanced. It is important for maintaining normal abdominal tension and increasing intra-abdominal pressure.
Piriformis Aggravators: Causes of Piriformis Muscle Pain and Discomfort
You may want to see also
Explore related products
Internal Obliques
The internal obliques, or internal abdominal oblique muscles, are broad, thin muscular sheets found on the lateral abdominal wall. They are one of the five main abdominal muscles, along with the pyramidalis, rectus abdominis, external obliques, and transversus abdominis. The internal obliques are important for several functions of the body.
Firstly, they are accessory muscles of respiration, acting as antagonists to the diaphragm. When the diaphragm contracts, it pulls the lower wall of the chest cavity down, increasing lung volume. Conversely, when the internal obliques contract, they compress the organs of the abdomen, pushing them upwards into the diaphragm, which then intrudes into the chest cavity, reducing lung volume and producing an exhalation.
Secondly, the contraction of the internal obliques causes ipsilateral rotation and side-bending. They work with the external oblique muscles to achieve this torsional movement of the trunk. For example, the right internal oblique and the left external oblique contract as the torso flexes and rotates to bring the left shoulder towards the right hip. This is why the internal obliques are referred to as "same-side rotators".
Thirdly, the internal obliques help maintain abdominal pressure and movements of the trunk, along with the other abdominal muscles. The internal obliques flex the trunk when bilaterally contracted and cause lateral flexion upon unilateral contraction. Compression of the internal obliques increases intra-abdominal pressure. Weakness in the internal obliques, along with other abdominal muscles, increases the risk of abdominal hernias.
The internal abdominal oblique muscle has multiple sites of origin, distributed along the anterolateral side of the trunk. According to their origin, the muscle fibres can be divided into the anterior, lateral, and posterior fibres. Anterior fibres arise from a deep structure known as the iliopectineal arch, passing inferomedially and arching over the inguinal canal. They then merge with the tendinous fibres of the transversus abdominis muscle to form the conjoint tendon.
Understanding CT Scans: Muscle Visibility and Imaging
You may want to see also
Explore related products
External Obliques
The external oblique muscle is one of the outermost abdominal muscles, extending from the lower half of the ribs around and down to the pelvis. The external oblique muscles cover the sides of the abdominal area, sitting on the top surface of the abdomen right below the subcutaneous fat and skin. The internal obliques are underneath the external obliques on each side of the trunk.
The external oblique is the largest and outermost of the three flat abdominal muscles of the lateral anterior abdomen. It is situated on the lateral and anterior parts of the abdomen. It is broad, thin, and irregularly quadrilateral, its muscular portion occupying the side, its aponeurosis the anterior wall of the abdomen. In most humans, the oblique is not visible due to subcutaneous fat deposits and the small size of the muscle. It arises from eight fleshy digitations, each from the external surfaces and inferior borders of the fifth to twelfth ribs (lower eight ribs).
The external oblique functions to pull the chest downwards and compress the abdominal cavity, which increases the intra-abdominal pressure as in a Valsalva maneuver. It also performs ipsilateral (same-side) side-bending and contralateral (opposite side) rotation: the right external oblique would side-bend to the right and rotate to the left, and vice versa. The internal oblique muscle functions similarly except it rotates ipsilaterally.
The external abdominal oblique is innervated by the anterior rami of the thoracic spinal nerves T7-T12. The intercostal nerves T7- T11 supply the superior-most part of the muscle and the subcostal nerve (T12) innervates the lower part. The muscle receives sensory innervation from the lumbar plexus, via the iliohypogastric nerve (L1). Blood supply to the upper two-thirds of the external abdominal oblique comes from branches of the lower posterior intercostal and subcostal arteries, while the deep circumflex iliac artery supplies the inferior third of the muscle.
The Secret to Muscle Definition Revealed
You may want to see also
Explore related products
Rectus Abdominis
The rectus abdominis is a pair of long, flat muscles that run vertically down the front of the abdomen, on either side of the linea alba, a connective tissue. The rectus abdominis is the most superficial of the abdominal muscles, and in people with low body fat, it is visible beneath the skin as a 'six-pack'.
The rectus abdominis is innervated by the thoracoabdominal nerves, which are continuations of the T7-T11 intercostal nerves. The muscle is responsible for flexing the lumbar spine, as when doing a crunch or sit-up exercise. It also assists with breathing and plays an important role in respiration when forcefully exhaling, as seen after exercise.
The rectus abdominis acts to stabilise the core, together with the transversus abdominis, erector spinae, and oblique muscles. These core muscles act like a natural weight belt to protect the lower back from injury. Weak core muscles can lead to spinal problems.
The rectus abdominis also helps to hold the internal organs in place and keep the body stable during movement. It compresses the abdominal viscera and increases intra-abdominal pressure, which is important for essential bodily functions like breathing, coughing, vomiting, and childbirth.
Understanding the Muscles Innervated by C6 Nerve Roots
You may want to see also
Explore related products
Core stability
The core is a box structure made up of the abdominal muscles at the front and sides, the paraspinal and gluteal muscles at the back, the diaphragm at the top, and the pelvic floor and hip girdle muscles at the bottom. The abdominal muscles create a rigid cylinder around the spine during movement, providing stability. The deepest abdominal muscle, the transversus abdominis, wraps around the waist to support the spine. This muscle is activated when you compress your stomach toward your spine. It also helps prevent instability and supports the lower back.
The external obliques are the V-shaped muscles that run diagonally down your sides, helping you rotate your spine. The internal obliques lie underneath the external obliques. The rectus abdominis is the straight-down-the-center muscle that can create the appearance of a six-pack.
To improve core stability, you can perform exercises that target the abdominal and back muscles. These exercises can be done anywhere and do not require specialized equipment. For example, you can lie on your back with your knees bent and feet flat on the floor. Then, lift your pelvis off the ground while keeping your feet and shoulders on the floor. This exercise can be made more challenging by lifting one foot off the ground and extending the knee. Another exercise is to balance on your hands and knees with your back flat and your arms and thighs perpendicular to the floor.
Reversing Muscle Contractures: Strategies for Improved Mobility and Flexibility
You may want to see also
Frequently asked questions
Abdominal muscles, or abs, are a set of muscles located between the rib cage and the pelvis on the front of the body. They support the trunk, allow movement, and hold organs in place by regulating internal abdominal pressure.
There are five main abdominal muscles: pyramidalis, rectus abdominus, external obliques, internal obliques, and transversus abdominis.
The transversus abdominis is the deepest abdominal muscle. It wraps around the waist to support the spine and prevent instability. This muscle is activated when you compress your stomach toward your spine.
Deep abdominal muscles are activated when the body is in motion. They can also be activated while sitting by intentionally contracting the abdominal muscles.
