Latissimus dorsi

Information about Latissimus dorsi

Latissimus dorsi
Latissimus dorsi
Muscles connecting the upper extremity to the vertebral column.
Latinmusculus latissimus dorsi
subject #121 432
Origin:spinous processes of thoracic T6-T12, thoracolumbar fascia, iliac crest and inferior 3 or 4 ribs
Insertion:floor of intertubercular groove of the humerus
Artery:subscapular artery, dorsal scapular artery
Nerve:thoracodorsal nerve
Action:pulls the forelimb dorsally and caudally
Antagonist:deltoid, trapezius
Dorlands/Elsevier m_22/12549548
The latissimus dorsi (plural: latissimi dorsi) is the large, flat, dorso-lateral muscle on the trunk, posterior to the arm, and partly covered by the spinotrapezius on its median dorsal region.

Overview

The latissimus dorsi is a triangular, flat muscle, which covers the lumbar region and the lower half of the thoracic region, and is gradually contracted into a narrow fasciculus at its insertion into the humerus.

It arises by tendinous fibers from the spinous processes of the lower six thoracic vertebrae and from the posterior layer of the lumbodorsal fascia, by which it is attached to the spines of the lumbar and sacral vertebræ, to the supraspinal ligament, and to the posterior part of the crest of the ilium.

It also arises by muscular fibers from the external lip of the crest of the ilium lateral to the margin of the sacrospinalis, and from the three or four lower ribs by fleshy digitations, which are interposed between similar processes of the obliquus abdominis externus.

From this extensive origin the fibers pass in different directions, the upper ones horizontally, the middle obliquely upward, and the lower vertically upward, so as to converge and form a thick fasciculus, which crosses the inferior angle of the scapula, and usually receives a few fibers from it.

The muscle curves around the lower border of the teres major, and is twisted upon itself, so that the superior fibers become at first posterior and then inferior, and the vertical fibers at first anterior and then superior.

It ends in a quadrilateral tendon, about 7 cm. long, which passes in front of the tendon of the teres major, and is inserted into the bottom of the intertubercular groove of the humerus; its insertion extends higher on the humerus than that of the tendon of the pectoralis major.

The lower border of its tendon is united with that of the teres major, the surfaces of the two being separated near their insertions by a bursa; another bursa is sometimes interposed between the muscle and the inferior angle of the scapula.

The tendon of the muscle gives off an expansion to the deep fascia of the arm.

Actions

The latissimus dorsi is responsible for extension, adduction, transverse extension, and internal rotation of the shoulder joint. It also has a synergistic role in extension and lateral flexion of the lumbar spine.

Variations

The number of dorsal vertebræ to which it is attached vary from four to eight; the number of costal attachments varies; muscle fibers may or may not reach the crest of the ilium.

A muscular slip, the axillary arch, varying from 7 to 10 cm. in length, and from 5 to 15 mm. in breadth, occasionally springs from the upper edge of the latissimus dorsi about the middle of the posterior fold of the axilla, and crosses the axilla in front of the axillary vessels and nerves, to join the under surface of the tendon of the pectoralis major, the coracobrachialis, or the fascia over the biceps brachii. This axillary arch crosses the axillary artery, just above the spot usually selected for the application of a ligature, and may mislead the surgeon during the operation. It is present in about 7% of subjects and may be easily recognized by the transverse direction of its fibers.

A fibrous slip usually passes from the lower border of the tendon of the Latissimus dorsi, near its insertion, to the long head of the triceps brachii. This is occasionally muscular, and is the representative of the dorsoepitrochlearis brachii of apes.

Triangles

  • The lateral margin of the latissimus dorsi is separated below from the obliquus externus abdominis by a small triangular interval, the lumbar triangle of Petit, the base of which is formed by the iliac crest, and its floor by the obliquus internus abdominis.
  • Another triangle is situated behind the scapula. It is bounded above by the trapezius, below by the latissimus dorsi, and laterally by the vertebral border of the scapula; the floor is partly formed by the rhomboideus major. If the scapula is drawn forward by folding the arms across the chest, and the trunk bent forward, parts of the sixth and seventh ribs and the interspace between them become subcutaneous and available for auscultation. The space is therefore known as the triangle of auscultation.

Nerves

The Latissimus dorsi is supplied by the sixth, seventh, and eighth cervical nerves through the thoracodorsal (long subscapular) nerve.

Training

To increase the power of this muscle, the muscle can be trained with the following exercises: Most latissimus dorsi exercises concurrently recruit the teres major, posterior fibers of the deltoid, long head of the triceps brachii, among numerous other stabilizing muscles. Compound exercises for the 'lats' typically involve elbow flexion and tend to recruit the biceps brachii, brachialis, and brachioradialis for this function. Depending on the line of pull, the trapezius muscles can be recruited as well; horizontal pulling motions such as rows recruit both latissimus dorsi and trapezius heavily.

Additional images


Left humerus. Anterior view.

Right hip bone. External surface.

Muscles on the dorsum of the scapula, and the Triceps brachii.

The axillary artery and its branches.

The brachial artery.

The veins of the right axilla, viewed from in front.

The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front.

Surface anatomy of the back.

The left side of the thorax.

Lumbar triangle


External links

 •  • [ e]
Muscles of upper limbs
VERTEBRAL COLUMNtrapezius - latissimus dorsi - rhomboid major - rhomboid minor - levator scapulae
THORACIC WALLSpectoralis major - pectoralis minor - subclavius - serratus anterior
SHOULDERdeltoid - rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis) - teres major
ARManterior compartment: coracobrachialis - biceps brachii - brachialis
posterior compartment: triceps brachii - anconeus
FOREARManterior compartment: super. - pronator teres - palmaris longus - flexor carpi radialis - flexor carpi ulnaris - flexor digitorum superficialis - deep - pronator quadratus - flexor digitorum profundus - flexor pollicis longus
posterior compartment: super. - mobile wad (brachioradialis, extensor carpi radialis longus and brevis) - extensor digitorum, - extensor digiti minimi - extensor carpi ulnaris - deep - supinator - anatomical snuff box (abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus) - extensor indicis
HANDlateral volar - thenar (opponens pollicis, flexor pollicis brevis, abductor pollicis brevis, adductor pollicis)
medial volar - palmaris brevis - hypothenar (abductor minimi digiti, flexor digiti minimi brevis, opponens digiti minimi)
intermediate - lumbrical - dorsal interossei - palmar interossei
Latin}}} 
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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bold refer to the diagram at right.)

In the skull (8):
  • 1-9. cranium
  • 7. mandible
''In the middle ears (6):
  • malleus
  • incus
  • stapes
In the throat (1):
  • hyoid
In the shoulder girdle (4):
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thorax is a division of an animal's body that lies between the head and the abdomen.

In mammals, the thorax is the region of the body formed by the sternum, the thoracic vertebrae and the ribs. It extends from the neck to the diaphragm, not including the upper limbs.
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The thoracolumbar fascia (lumbodorsal fascia) is a deep investing membrane which covers the deep muscles of the back of the trunk.

Above, it passes in front of the Serratus posterior superior and is continuous with a similar investing layer on the back of the
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The crest of the ilium (or iliac crest) is convex in its general outline but is sinuously curved, being concave inward in front, concave outward behind.

It is thinner at the center than at the extremities, and ends in the anterior and posterior superior iliac spines.
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bold refer to the diagram at right.)

In the skull (8):
  • 1-9. cranium
  • 7. mandible
''In the middle ears (6):
  • malleus
  • incus
  • stapes
In the throat (1):
  • hyoid
In the shoulder girdle (4):
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The tubercles of the humerus are separated from each other by a deep groove, the intertubercular groove (bicipital groove, sulcus intertubercular), which lodges the long tendon of the Biceps brachii and transmits a branch of the anterior humeral circumflex artery to
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The humerus is a long bone in the arm or fore-legs (animals) that runs from the shoulder to the elbow. On a skeleton, it fits between the scapula and the ulna. It consists of the following three sections:
  • Upper extremity of humerus
  • Body of humerus

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Arteries are muscular blood vessels that carry blood away from the heart.[1] All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.

The circulatory system is extremely important for sustaining life.
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The subscapular artery, the largest branch of the axillary artery, arises at the lower border of the Subscapularis, which it follows to the inferior angle of the scapula, where it anastomoses with the lateral thoracic and intercostal arteries and with the descending branch of the
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The dorsal scapular artery (or descending scapular artery[1]) is a blood vessel which supplies the latissimus dorsi, levator scapulae, rhomboids, and trapezius.
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  • Accessory nerve
  • Accessory obturator nerve
  • Alderman's nerve
  • Anococcygeal nerve
  • Ansa cervicalis
  • Anterior interosseous nerve
  • Anterior superior alveolar nerve
  • Aortic plexus
  • Auerbach's plexus
  • Auriculotemporal nerve
  • Axillary nerve

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The thoracodorsal nerve (middle or long subscapular nerve), a branch of the posterior cord of the brachial plexus, derives its fibers from the sixth, seventh, and eighth cervical nerves; it follows the course of the subscapular artery, along the posterior wall of the
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Kinesiology is the scientific study of the anatomy, physiology, and mechanics of body movement, especially in humans. [1] The word kinesiology is derived the Greek "kinesis" (motion) + the suffix -ology or -logy from the greek "logos" or "logia"(meaning a field of study).
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A forelimb is an anterior limb on an animal's body. When referring to quadrupeds, the term foreleg is often instead used.

The term is not to be confused with the forearm, which refers to a segment of the arm between the elbow and the wrist.
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In anatomy, the dorsum is the upper side of animals that typically run, fly or swim in a horizontal position, and the back side of animals (like humans) that walk upright. In vertebrates the dorsum contains the backbone.
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In sciences dealing with the anatomy of animals, precise anatomical terms of location are necessary for a variety of reasons. Non-scientists often wonder why zoological and human anatomists use complex terminology to describe locations on a body, when common terms like "up",
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An antagonist is a kind of muscle that acts in opposition to the movement generated by the agonist and is responsible for returning a limb to its initial position.

Antagonistic pairs in houses

These antagonistic muscles are found in pairs called antagonistic pairs.
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In human anatomy, the deltoid muscle is the muscle forming the rounded contour of the shoulder.

It was previously called the Deltoideus and the name is still used by some anatomists. It is called so because it is in the shape of the Greek letter Delta (triangle).
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This article or section may be confusing or unclear for some readers.
Please [improve the article] or discuss this issue on the talk page. This article has been tagged since December 2006.
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Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
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This article or section may be confusing or unclear for some readers.
Please [improve the article] or discuss this issue on the talk page. This article has been tagged since December 2006.
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The humerus is a long bone in the arm or fore-legs (animals) that runs from the shoulder to the elbow. On a skeleton, it fits between the scapula and the ulna. It consists of the following three sections:
  • Upper extremity of humerus
  • Body of humerus

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The thoracolumbar fascia (lumbodorsal fascia) is a deep investing membrane which covers the deep muscles of the back of the trunk.

Above, it passes in front of the Serratus posterior superior and is continuous with a similar investing layer on the back of the
..... Click the link for more information.
The supraspinal ligament (supraspinous ligament) is a strong fibrous cord, which connects together the apices of the spinous processes from the seventh cervical vertebra to the sacrum; at the points of attachment to the tips of the spinous processes fibrocartilage is
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Ilion or Ilium may refer to:
  • Ilion or Ilium, alternative names for the legendary city of Troy
  • Ilio, Greece, a suburb of Athens, Greece, also known as Nea Liossia
  • Ilion, New York, a village in Herkimer County, New York

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The Erector spinæ (or Sacrospinalis in older texts), a bundle of muscles and tendons, and its prolongations in the thoracic and cervical regions, lie in the groove on the side of the vertebral column.
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The external oblique muscle (of the abdomen) (also external abdominal oblique muscle) is the largest and the most superficial (outermost) of the three flat muscles of the lateral anterior abdomen.
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Teres major is a muscle of the upper limb and one of six scapulohumeral muscles. It is a thick but somewhat flattened muscle.

Origin and insertion

It arises from the oval area on the dorsal surface of the inferior angle of the scapula, and from the fibrous septa
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The Pectoralis major is a thick, fan-shaped muscle, situated at the upper front (anterior) of the chest wall. It makes up the bulk of the chest muscles in the male and lies under the breast in the female.
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