Logan Steele
Rectus muscles are straight muscles that are part of the core muscles in the body. There are several rectus muscles, including the rectus abdominis, which is a pair of segmented skeletal muscles on the abdomen, and the four rectus muscles of the eyeball: inferior, medial, lateral, and superior recti. Rectus muscles play a crucial role in various functions, such as assisting with breathing, keeping internal organs intact, and providing stability during movement.
| Characteristics | Values |
|---|---|
| Definition | Rectus means straight, and the rectus muscle is any of several straight muscles, usually referring to the abdomen. |
| Other Names | Rectus Abdominis, Abdominal Muscle, Abs |
| Location | Abdomen/Midriff |
| Function | Assists with breathing, increases intra-abdominal pressure, keeps internal organs in place, and stabilises the body during movement. |
| Blood Supply | Inferior and superior epigastric arteries, lower intercostal arteries, subcostal and deep circumflex artery |
| Nerve Supply | Thoraco-abdominal nerves, anterior divisions of the 7th to 11th lower intercostal nerves |
| Core Muscles | Rectus Abdominis, Transversus Abdominis, Erector Spinae, Obliques |
| Separation | Diastasis Recti Abdominis is a condition where the left and right sides of the rectus abdominis muscles separate. |
| Eye Muscles | The rectus muscles are also four extraocular muscles that move the eyes about the longitudinal and vertical axes of the body. |
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What You'll Learn
Rectus Abdominis Muscle Anatomy
The rectus abdominis muscle, from the Latin for "straight abdominal", is a pair of segmented skeletal muscles on the front of a person's abdomen or "midriff". The rectus abdominis is one of the five main abdominal muscles, along with the pyramidalis, external obliques, internal obliques, and transversus abdominis. These muscles together form the core muscles, acting like a natural weight belt to protect the lower back from injury.
The rectus abdominis muscle assists with breathing and plays an important role in respiration when exhaling forcefully, such as after exercise or in conditions where exhalation is difficult, like emphysema. It also helps keep internal organs intact and creates intra-abdominal pressure, which is necessary for processes such as forceful breathing, labour, defecation, and micturition. The muscle is contained in the rectus sheath, which is formed by the merging of the aponeurosis of the transversus abdominis, external and internal oblique abdominal muscles.
The paired muscle is separated at the midline by a band of dense connective tissue called the linea alba, which divides the muscle into two segments. The connective tissue defining each lateral margin of the rectus abdominis is called the linea semilunaris. The muscle extends from the pubic symphysis, pubic crest, and pubic tubercle inferiorly, to the xiphoid process and costal cartilages of the 5th–7th ribs superiorly.
The rectus abdominis muscle is supplied with blood by several vessels, predominantly the inferior and superior epigastric arteries. Additionally, small terminal branches of the lower three posterior intercostal arteries, the subcostal artery, and the deep circumflex artery contribute to its blood supply. The muscle is innervated by thoraco-abdominal nerves, which are continuations of the T7-T11 intercostal nerves. The sensory supply is from the 7-12 thoracic nerves.
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Rectus Abdominis Functions
The rectus abdominis muscle, often referred to as the "abdominal muscle" or "abs", is a pair of segmented muscles that run down the abdomen, on either side of the middle of the body, from the rib cage to the pubic bone. These muscles are separated by a band of connective tissue called the linea alba.
The rectus abdominis has several functions. Firstly, it assists with breathing and plays a role in respiration, particularly during forceful exhalation, such as after exercise or in conditions like emphysema. It also helps to increase intra-abdominal pressure, which is important for processes like forceful defecation, childbirth, and lifting heavy weights.
Secondly, the rectus abdominis is part of the core muscles, which include the transversus abdominis, erector spinae, and obliques. These muscles act like a natural weight belt, providing stability and protecting the lower back and spine from injury. This stability helps to maintain balance and allows for movements like walking, sitting down, standing up, or twisting from side to side.
Thirdly, the rectus abdominis holds internal organs in place, ensuring they are protected. This includes organs such as the stomach, intestines, pancreas, liver, and gallbladder.
Finally, the rectus abdominis is responsible for flexing the spinal column and tensing the anterior wall of the abdomen. In those with low body fat, this muscle can be visibly seen as a "six-pack".
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Rectus Abdominis Blood Supply
The rectus abdominis muscle, also known as the abdominal muscle or abs, is a pair of segmented skeletal muscles found on the ventral aspect of a person's abdomen. The rectus abdominis has many sources of arterial blood supply.
The first of these sources is the inferior epigastric artery, which runs superiorly on the posterior surface of the rectus abdominis, enters the rectus fascia at the arcuate line, and serves the lower part of the muscle. The second source is the superior epigastric artery, a branch of the internal thoracic artery, which supplies blood to the upper portion of the muscle. Additionally, there are numerous small segmental contributions from the lower six intercostal arteries. The venous drainage of the muscles mirrors the arterial supply.
The rectus abdominis muscle is contained within the rectus sheath, which consists of the aponeuroses of the lateral abdominal muscles. The nerves and vessels enter the muscle on the lateral aspect, which allows for surgical procedures such as a caesarean section, where the muscle can be moved laterally without interrupting its neurovascular supply.
The rectus abdominis muscle 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, and the sensory supply is provided by the 7-12 thoracic nerves. The muscle plays a crucial role in respiration, assisting with forceful exhalation, and helps to keep the internal organs intact by creating intra-abdominal pressure during activities such as exercise, lifting weights, or childbirth.
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Rectus Abdominis Muscle Strains
The rectus abdominis muscle, commonly known as the "'six-pack', runs vertically down the front of the abdomen and is responsible for flexing the trunk. It assists with breathing and plays a role in respiration during forceful exhalation. The rectus abdominis also helps keep internal organs intact and creates intra-abdominal pressure during activities such as heavy lifting, forceful defecation, and childbirth.
Symptoms of a rectus abdominis muscle strain may include abdominal pain, swelling, bruising, and difficulty moving or bending. In more severe cases, there may be a rupture of the muscle from its attachment, resulting in a rectus sheath haematoma, which is an accumulation of blood in the sheath of the muscle.
Treatment for a rectus abdominis muscle strain typically involves rest, ice, compression, and elevation (RICE) to reduce pain and swelling. Pain medication and physical therapy may also be recommended. Surgery may be necessary in severe cases to repair a torn muscle. To prevent rectus abdominis muscle strains, it is important to strengthen the abdominal and core muscles.
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Rectus Abdominis and the Eyes
The rectus abdominis muscle, or "abdominal muscle", is a pair of segmented skeletal muscles found on the front of a person's abdomen. It assists with breathing and plays a crucial role in respiration during forceful exhalation, such as after exercise or in conditions like emphysema. It also helps maintain internal organs in place and generates intra-abdominal pressure during activities like exercising, lifting heavy weights, or childbirth.
Now, when we talk about the eyes, there are four rectus muscles: the inferior, medial, lateral, and superior recti. These muscles originate from a fibrous ring encircling the optic nerve and are attached to the sclera. They work together with the ciliary muscles to enable vision by moving the eyeball in various directions: superiorly (upward), inferiorly (downward), laterally (backward), or medially (forward).
The medial rectus, for instance, is responsible for eye adduction, moving the eye from side to side in coordination with the lateral rectus, an abductor. Esotropia, a condition where the cornea deviates nasally, can be caused by medial rectus palsy or lesion. This can be corrected by vertically transposing the rectus muscles.
The lateral rectus muscle, on the other hand, is one of seven extraocular muscles that control eye movement. It abducts the eye, allowing people to look to the right. However, lateral rectus myositis, a rare inflammatory disorder, can cause issues with this muscle. Sixth nerve palsy, or abducens palsy, can result in diplopia or double vision when looking in the direction of the affected muscle.
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Frequently asked questions
Rectus muscles are straight muscles, usually referring to the abdomen or eyeballs.
Rectus abdominis muscles, also known as "abdominal muscles" or "abs", are a pair of segmented skeletal muscles that run down the abdomen.
Rectus abdominis muscles help with breathing, increase intra-abdominal pressure, keep internal organs in place, and stabilise the body during movement.
Rectus muscles in the eyeball are four extraocular muscles that move the eyes about the longitudinal axis of the body, either superiorly, inferiorly, laterally, or medially.
