Abdominal muscles cover the anterior and lateral abdominal region and meet at the anterior midline. These muscles of the anterolateral abdominal wall can be divided into four groups: the external obliques, the internal obliques, the transversus abdominis, and the rectus abdominis.
There are three flat skeletal muscles in the antero-lateral wall of the abdomen. The external oblique, closest to the surface, extend inferiorly and medially, in the direction of sliding one’s four fingers into pants pockets. Perpendicular to it is the intermediate internal oblique, extending superiorly and medially, the direction the thumbs usually go when the other fingers are in the pants pocket. The deep muscle, the transversus abdominis, is arranged transversely around the abdomen, similar to the front of a belt on a pair of pants. This arrangement of three bands of muscles in different orientations allows various movements and rotations of the trunk. The three layers of muscle also help to protect the internal abdominal organs in an area where there is no bone.
The linea alba is a white, fibrous band that is made of the bilateral rectus sheaths that join at the anterior midline of the body. These enclose the rectus abdominis muscles (a pair of long, linear muscles, commonly called the “sit-up” muscles) that originate at the pubic crest and pubic symphysis, and extend the length of the body’s trunk. Each muscle is segmented by three transverse bands of collagen fibers called the tendinous intersections. This results in the look of “six-pack abs,” as each segment hypertrophies on individuals at the gym who do many sit-ups.
The posterior abdominal wall is formed by the lumbar vertebrae, parts of the ilia of the hip bones, psoas major and iliacus muscles, and quadratus lumborum muscle. This part of the core plays a key role in stabilizing the rest of the body and maintaining posture.
Movement | Target | Target motion direction | Prime mover | Origin | Insertion |
---|---|---|---|---|---|
Twisting at waist; also bending to the side | Vertebral column | Supination; lateral flexion | External obliques; internal obliques | Ribs 5–12; ilium | Ribs 7–10; linea alba; ilium |
Squeezing abdomen during forceful exhalations, defecation, urination, and childbirth | Abdominal cavity | Compression | Transversus abdominis | Ilium; ribs 5–10 | Sternum; linea alba; pubis |
Sitting up | Vertebral column | Flexion | Rectus abdominis | Pubis | Sternum; ribs 5 and 7 |
Bending to the side | Vertebral column | Lateral flexion | Quadratus lumborum | Ilium; ribs 5–10 | Rib 12; vertebrae L1–L4 |
This article incorporates text from a free content work. Licensed under CC BY 4.0. Text taken from Anatomy and Physiology , J. Gordon Betts et al, Openstax .
The rectus abdominis muscle, also known as the "abdominal muscle" or simply the "abs", is a pair of segmented skeletal muscle on the ventral aspect of a person's abdomen. The paired muscles are separated at the midline by a band of dense connective tissue called the linea alba, and the connective tissue defining each lateral margin of the rectus abdominus is 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 transverse abdominal muscle (TVA), also known as the transverse abdominis, transversalis muscle and transversus abdominis muscle, is a muscle layer of the anterior and lateral abdominal wall, deep to the internal oblique muscle. It is thought by most fitness instructors to be a significant component of the core.
The abdominal internal oblique muscle, also internal oblique muscle or interior oblique, is an abdominal muscle in the abdominal wall that lies below the external oblique muscle and just above the transverse abdominal muscle.
The abdomen is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. The area occupied by the abdomen is called the abdominal cavity. In arthropods it is the posterior tagma of the body; it follows the thorax or cephalothorax.
In anatomy, the abdominal wall represents the boundaries of the abdominal cavity. The abdominal wall is split into the anterolateral and posterior walls.
The lumbar plexus is a web of nerves in the lumbar region of the body which forms part of the larger lumbosacral plexus. It is formed by the divisions of the first four lumbar nerves (L1-L4) and from contributions of the subcostal nerve (T12), which is the last thoracic nerve. Additionally, the ventral rami of the fourth lumbar nerve pass communicating branches, the lumbosacral trunk, to the sacral plexus. The nerves of the lumbar plexus pass in front of the hip joint and mainly support the anterior part of the thigh.
The iliohypogastric nerve is a nerve that originates from the lumbar plexus that supplies sensation to skin over the lateral gluteal and hypogastric regions and motor to the internal oblique muscles and transverse abdominal muscles.
In vertebrates, the pubis or pubic bone forms the lower and anterior part of each side of the hip bone. The pubis is the most forward-facing of the three bones that make up the hip bone. The left and right pubic bones are each made up of three sections, a superior ramus, inferior ramus, and a body.
The conjoint tendon is a sheath of connective tissue formed from the lower part of the common aponeurosis of the abdominal internal oblique muscle and the transversus abdominis muscle, joining the muscle to the pelvis. It forms the medial part of the posterior wall of the inguinal canal.
Abdominal exercises are a type of strength exercise that affect the abdominal muscles. Human abdominal consist of four muscles which are the rectus abdomens, internal oblique, external oblique, and transversus abdominis. When performing abdominal exercises it is important to understand the effects, functions, the types of exercises, and think about how to perform this exercise safely.
In human anatomy, the inguinal region refers to either the groin or the lower lateral regions of the abdomen. It may also refer to:
The pubic tubercle is a prominent tubercle on the superior ramus of the pubis bone of the pelvis.
The arcuate line of rectus sheath is a line of demarcation corresponding to the free inferior margin of the posterior layer of the rectus sheath inferior to which only the anterior layer of the rectus sheath is present and the rectus abdominis muscle is therefore in direct contact with the transversalis fascia. The arcuate line is concave inferior-wards.
The linea semilunaris is a curved tendinous intersection found on either side of the rectus abdominis muscle.
The rectus sheath is a tough fibrous compartment formed by the aponeuroses of the transverse abdominal muscle, and the internal and external oblique muscles. It contains the rectus abdominis and pyramidalis muscles, as well as vessels and nerves.
In kinesiology, core stability is a person's ability to stabilize their core. Stability, in this context, should be considered as an ability to control the position and movement of the core. Thus, if a person has greater core stability, they have a greater level of control over the position and movement of this area of their body. The body's core is frequently involved in aiding other movements of the body, such as running; thus it is known that improving core stability also improves a person's ability to perform these other movements.
The following outline is provided as an overview of and topical guide to human anatomy:
The hip bone is a large flat bone, constricted in the center and expanded above and below. In some vertebrates it is composed of three parts: the ilium, ischium, and the pubis.
In surgery, a surgical incision is a cut made through the skin and soft tissue to facilitate an operation or procedure. Often, multiple incisions are possible for an operation. In general, a surgical incision is made as small and unobtrusive as possible to facilitate safe and timely operating conditions.
The pelvis is the lower part of the trunk, between the abdomen and the thighs, together with its embedded skeleton.