The torso or trunk is an anatomical term for the central part or core of many animal bodies from which extend the neck and limbs. The torso includes: the thoracic segment of the trunk, the abdominal segment of the trunk, the perineum. Most critical organs are housed within the torso. In the upper chest, the heart and lungs are protected by the rib cage, the abdomen contains most of the organs responsible for digestion: the stomach, which breaks down digested food via gastric acid; the pelvic region houses both the male and female reproductive organs. The torso harbours many of the main groups of muscles in the body, including the: pectoral muscles abdominal muscles lateral muscle epaxial muscles The organs and other contents of the torso are supplied by nerves, which originate as nerve roots from the thoracic and lumbar parts of the spinal cord; some organs receive a nerve supply from the vagus nerve. The sensation to the skin is provided by: Lateral cutaneous branches of torso|Lateral cutaneous branches Dorsal cutaneous branches Belly cast Waist Belvedere Torso
The anterior division of the twelfth thoracic nerve is larger than the others. It runs in front of the quadratus lumborum, innervates the transversus, passes forward between it and the obliquus internus to be distributed in the same manner as the lower intercostal nerves, it communicates with the iliohypogastric nerve of the lumbar plexus, gives a branch to the Pyramidalis. It gives off a lateral cutaneous branch that supplies sensory innervation to the skin over the hip. Subcostal artery subcostal vein This article incorporates text in the public domain from page 948 of the 20th edition of Gray's Anatomy posteriorabdomen at The Anatomy Lesson by Wesley Norman glutealregion at The Anatomy Lesson by Wesley Norman Atlas image: abdo_wall70 at the University of Michigan Health System - "Posterior Abdominal Wall, Anterior View" Anatomy figure: 40:07-00 at Human Anatomy Online, SUNY Downstate Medical Center - "Muscles and nerves of the posterior abdominal wall." Anatomy image:8982 at the SUNY Downstate Medical Center
The crunch is one of the most popular abdominal exercises. It works the rectus abdominis muscle and works the obliques. A crunch begins with lying face up on feet planted on the ground; the movement begins by curling the shoulders towards the pelvis. The hands crossed over the chest. Injury can be caused by pushing against the neck with hands; the difficulty of the crunch can be increased by lying on a declined bench or holding a weight under the chin, on the chest or behind the head. Crunch exercises may be performed on exercise balls. Increasing the distance will increase the load on the abdominals due to leverage; the curl-up is taught by spine biomechanics professor Stuart McGill, he considers it to be a safer alternative to the crunch, which differs from the sit-up. McGill has done extensive research on the effects of crunch exercises on the back, which can be harmful for those rehabilitating their backs from an injury; the New York Times Health blog referencing McGill in 2009 stated: An approved crunch begins with you lying down, one knee bent, hands positioned beneath your lower back for support.
"Do not hollow your stomach or press your back against the floor", McGill says. Lift your head and shoulders and relax back down. Strength exercises such as sit-ups and crunches do not cause the spot reduction of fat. Achieving "six pack abs" requires both abdominal muscle hypertrophy training and fat loss over the abdomen—which can only be done by losing fat from the body as a whole. Unlike the sit-up, in a proper crunch, the lower back stays on the floor; this is said by scientific literature to eliminate any involvement by the hip flexors, make the crunch an effective isolation exercise for the abdominals. The reverse crunch is a crunch done with the upper back on the floor and lifting the hips up instead; the twisting crunch is performed by lifting one shoulder at a time. More emphasis is placed on the obliques; the Thai crunch is performed by hitting the stomach after full contraction. This variation is used by Muay Thai fighters to condition the core to take hits from punches or knees; the cable crunch is performed while kneeling upright by curling the body to pull down on a cable machine.
The hips are kept motionless. Some experts in exercise science doubt whether crunches are necessary for sports training, others say that as few as 6–8 crunches per set are enough. Plank Sit-up Preparation Guide for the US Marine Corps Physical Fitness Test To Crunch or Not to Crunch: An Evidence-Based Examination Strength & Conditioning Journal: August 2011, Volume 33, Issue 4, pp 8–18
Aponeurosis of the abdominal external oblique muscle
The aponeurosis of the abdominal external oblique muscle is a thin but strong membranous structure, the fibers of which are directed downward and medially. It is joined with that of the opposite muscle along the middle line, covers the whole of the front of the abdomen. In the middle line, it interlaces with the aponeurosis of the opposite muscle, forming the linea alba, which extends from the xiphoid process to the pubic symphysis; that portion of the aponeurosis which extends between the anterior superior iliac spine and the pubic tubercle is a thick band, folded inward, continuous below with the fascia lata. The portion, reflected from the inguinal ligament at the pubic tubercle is attached to the pectineal line and is called the lacunar ligament. From the point of attachment of the latter to the pectineal line, a few fibers pass upward and medialward, behind the medial crus of the superficial inguinal ring, to the linea alba. In the aponeurosis of the external oblique above the pubic crest, is a triangular opening, the superficial inguinal ring, formed by a separation of the fibers of the aponeurosis in this situation.
This article incorporates text in the public domain from page 410 of the 20th edition of Gray's Anatomy "Anatomy diagram: 25466.086-1". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014-01-01. Cross section image: pelvis/pelvis-e12-2—Plastination Laboratory at the Medical University of Vienna Anatomy photo:35:07-0102 at the SUNY Downstate Medical Center - "Anterior Abdominal Wall: The External Abdominal Oblique Muscle" Anatomy image:7028 at the SUNY Downstate Medical Center
Rectus abdominis muscle
The rectus abdominis muscle known as the "abdominal muscle" or "abs", is a paired muscle running vertically on each side of the anterior wall of the human abdomen, as well as that of some other mammals. There are two parallel muscles, separated by a midline band of connective tissue called the linea alba, it extends from the pubic symphysis, pubic crest and pubic tubercle inferiorly, to the xiphoid process and costal cartilages of ribs V to VII superiorly. The proximal attachments are the pubic symphysis, it attaches distally at the xiphoid process of the sternum. The rectus abdominis muscle is contained in the rectus sheath, which consists of the aponeuroses of the lateral abdominal muscles. Bands of connective tissue called the tendinous intersections traverse the rectus abdominis, which separates this parallel muscle into distinct muscle bellies; the outer, most lateral line, defining the "abs" is the linea semilunaris. In the abdomens of people with big muscles and low body fat, these muscle bellies can be viewed externally and are referred to as "four", "six", "eight", or "ten packs", depending on how many are visible.
The rectus abdominis is a long flat muscle, which extends along the whole length of the front of the abdomen, is separated from its fellow of the opposite side by the linea alba. Tendinous intersections further subdivide each rectus abdominis muscle into a series of smaller false muscle bellies. Tensing of the rectus abdominis causes the muscle to expand between each tendinous intersection, resulting in the characteristic six or eight pack observed in individuals with low body fat; the upper portion, attached principally to the cartilage of the fifth rib has some fibers of insertion into the anterior extremity of the rib itself. It is around 10 mm thick, or 20 mm thick in young athletes such as handball players. Typical volume is around 300 cm³ in non-active individuals, or 500 cm³ in athletes; the rectus abdominis has many sources of arterial blood supply. Classification of the vascular anatomy of muscles: First, the inferior epigastric artery and vein run superiorly on the posterior surface of the rectus abdominis, enter the rectus fascia at the arcuate line, serve the lower part of the muscle.
Second, the superior epigastric artery, a terminal branch of the internal thoracic artery, supplies blood to the upper portion. Numerous small segmental contributions come from the lower six intercostal arteries as well; the muscles are innervated by thoraco-abdominal nerves, these are continuations of the T7-T11 intercostal nerves and pierce the anterior layer of the rectus sheath. Sensory supply is from the 7-12 thoracic nerves The sternalis muscle may be a variant form of the pectoralis major or the rectus abdominis; some fibers are connected with the costoxiphoid ligaments, the side of the xiphoid process. The rectus abdominis is an important postural muscle, it is responsible for flexing the lumbar spine, as. The rib cage is brought up to where the pelvis is when the pelvis is fixed, or the pelvis can be brought towards the rib cage when the rib cage is fixed, such as in a leg-hip raise; the two can be brought together when neither is fixed in space. The rectus abdominis assists with breathing and plays an important role in respiration when forcefully exhaling, as seen after exercise as well as in conditions where exhalation is difficult such as emphysema.
It helps in keeping the internal organs intact and in creating intra-abdominal pressure, such as when exercising or lifting heavy weights, during forceful defecation or parturition. An abdominal muscle strain called a pulled abdominal muscle, is an injury to one of the muscles of the abdominal wall. A muscle strain occurs; when this occurs the muscle fibers are torn. Most a strain causes microscopic tears within the muscle, but in severe injuries, the muscle can rupture from its attachment. A rectus sheath hematoma is an accumulation of blood in the sheath of the rectus abdominis muscle, it causes abdominal pain without a mass. The hematoma may be caused by a muscular tear. Causes of this include anticoagulation, pregnancy, abdominal surgery and trauma. With an ageing population and the widespread use of anticoagulant medications, there is evidence that this benign condition is becoming more common and more serious. On abdominal examination, people may have a positive Carnett's sign. Most hematomas resolve without treatment.
The rectus abdominis is similar in most vertebrates. The most obvious difference between animal and human abdominal musculature is that in animals, there are a different number of tendinous intersections. Divarication of rectus abdominis muscles Anatomy figure: 04:04-07 at Human Anatomy Online, SUNY Downstate Medical Center – "Muscles of the anterior chest wall with the pectoralis major muscles removed." Anatomy photo:18:01-0115 at the SUNY Downstate Medical Center – "Thoracic Wall: The Anterior Thoracic Wall" Anatomy figure: 35:06-07 at Human Anatomy Online, SUNY Downstate Medical Center – "Incision and reflection of the external abdominal oblique muscle." Anatomy figure: 35:07-01 at Human Anatomy Online, SUNY Downstate Medical Center – "Incision and reflection of the internal abdominal oblique muscle." Anatomy photo:35:10-0100 at the SUNY Downstate Medical Center – "Anterior Abdominal Wall: The Rectus Abdominis Muscle" Cross section image: pembody/bo
Abdominal internal oblique muscle
The internal oblique muscle is a muscle in the abdominal wall that lies below the external oblique and just above the transverse abdominal muscles. Its fibers run perpendicular to the external oblique muscle, beginning in the thoracolumbar fascia of the lower back, the anterior 2/3 of the iliac crest and the lateral half of the inguinal ligament; the muscle fibers run from these points superiomedially to the muscle's insertions on the inferior borders of the 10th through 12th ribs and the linea alba. In males, the cremaster muscle is attached to the internal oblique; the internal oblique is supplied by the lower intercostal nerves, as well as the iliohypogastric nerve and the ilioinguinal nerve. The internal oblique performs two major functions. Firstly as an accessory muscle of respiration, it acts as an antagonist to the diaphragm, helping to reduce the volume of the chest cavity during exhalation; when the diaphragm contracts, it pulls the lower wall of the chest cavity down, increasing the volume of the lungs which fill with air.
Conversely, when the internal obliques contract they compress the organs of the abdomen, pushing them up into the diaphragm which intrudes back into the chest cavity reducing the volume of the air-filled lungs, producing an exhalation. Secondly, its contraction causes ipsilateral side-bending, it acts with the external oblique muscle of the opposite side 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. For this reason, the internal obliques are referred to as "same-side rotators." Abdominal exercise Moore, Keith L. Lippincott Williams and Wilkins. ISBN 0-7817-3639-0. Abdominal, unm.edu Anatomy figure: 35:07-05 at Human Anatomy Online, SUNY Downstate Medical Center - "Incision and reflection of the internal abdominal oblique muscle." Anatomy image:7526 at the SUNY Downstate Medical Center
The inguinal ligament is a band running from the pubic tubercle to the anterior superior iliac spine. It forms the base of the inguinal canal; the inguinal ligament runs from the anterior superior iliac crest of the ilium to the pubic tubercle of the pubic bone. It is formed by the external abdominal oblique aponeurosis and is continuous with the fascia lata of the thigh. There is some dispute over the attachments. Structures that pass deep to the inguinal ligament include: Psoas major, pectineus Femoral nerve and vein Lateral cutaneous nerve of thigh Lymphatics The ligament serves to contain soft tissues as they course anteriorly from the trunk to the lower extremity; this structure demarcates the superior border of the femoral triangle. It demarcates the inferior border of the inguinal triangle; the midpoint of the inguinal ligament, halfway between the anterior superior iliac spine and pubic tubercle, is the landmark for the femoral nerve. The mid-inguinal point, halfway between the anterior superior iliac spine and the pubic symphysis, is the landmark for the femoral artery.
It is referred to as Poupart's ligament, because François Poupart gave it relevance in relation to hernial repair, calling it "the suspender of the abdomen". It is sometimes termed the Fallopian ligament. Colles' ligament is reflex ligament not inguinal ligament. Pelvis Anatomy figure: 12:03-02 at Human Anatomy Online, SUNY Downstate Medical Center - "Deep muscles of the anterior thigh." Anatomy photo:35:os-0107 at the SUNY Downstate Medical Center - "Anterior Abdominal Wall: Osteology and Surface Anatomy " Anatomy photo:35:08-0100 at the SUNY Downstate Medical Center - "Anterior Abdominal Wall: The Inguinal Ligament" Anatomy image:7179 at the SUNY Downstate Medical Center Anatomy image:7431 at the SUNY Downstate Medical Center Diagram at gensurg.co.uk