The latissimus dorsi () is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the

trapezius The trapezius is a large paired trapezoid-shaped surface muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae of the human spine, spine and laterally to the spine of the scapula. It moves the scapula and ...

on the back near the midline. The word latissimus dorsi (plural: ''latissimi dorsi'') comes from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

and means "broadest uscleof the back", from "latissimus" () and "dorsum" (). The pair of muscles are commonly known as "lats", especially among

bodybuilder Bodybuilding is the practice of progressive resistance exercise to build, control, and develop one's muscles via hypertrophy. An individual who engages in this activity is referred to as a bodybuilder. It is primarily undertaken for aesthetic ...

s. The latissimus dorsi is responsible for extension,

adduction Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

, transverse extension also known as horizontal abduction (or horizontal extension), flexion from an extended position, and (medial)

internal rotation Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

of the

shoulder joint The shoulder joint (or glenohumeral joint from Greek ''glene'', eyeball, + -''oid'', 'form of', + Latin ''humerus'', shoulder) is structurally classified as a synovial joint, synovial ball-and-socket joint and functionally as a diarthrosis and m ...

. It also has a

synergistic Synergy is an interaction or cooperation giving rise to a whole that is greater than the simple sum of its parts (i.e., a non-linear addition of force, energy, or effect). The term ''synergy'' comes from the Attic Greek word συνεργία ' f ...

role in extension and lateral flexion of the lumbar spine. Due to bypassing the scapulothoracic joints and attaching directly to the spine, the actions the latissimi dorsi have on moving the arms can also influence the movement of the scapulae, such as their downward rotation during a pull up.

Structure

Variations

The number of dorsal vertebrae, to which it is attached, varies from four to eight; the number of costal attachments varies; muscle fibers may or may not reach the crest of the ilium. A muscle 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 The biceps or biceps brachii (, "two-headed muscle of the arm") is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. Both heads of the muscle arise on the scapula and join to form a single muscle bell ...

. This axillary arch crosses the

axillary artery In human anatomy, the axillary artery is a large blood vessel that conveys oxygenated blood to the lateral aspect of the thorax, the axilla (armpit) and the upper limb. Its origin is at the lateral margin of the first rib, before which it is c ...

, just above the spot usually selected for the application of a ligature, and may mislead a surgeon. It is present in about 7% of the population and may be easily recognized by the transverse direction of its fibers. Guy ''et al.'' extensively described this muscular variant using MRI data and positively correlated its presence with symptoms of neurological impingement. A fibrous slip usually passes from the upper border of the tendon of the Latissimus dorsi, near its insertion, to the long head of the

triceps brachii The triceps, or triceps brachii (Latin for "three-headed muscle of the arm"), is a large muscle on the back of the upper limb of many vertebrates. It consists of three parts: the medial, lateral, and long head. All three heads cross the elbow jo ...

. This is occasionally muscular, and is the representative of the dorsoepitrochlearis brachii of

ape Apes (collectively Hominoidea ) are a superfamily of Old World simians native to sub-Saharan Africa and Southeast Asia (though they were more widespread in Africa, most of Asia, and Europe in prehistory, and counting humans are found global ...

s. This muscular form is found in ~5% of humans and is sometimes termed the latissimocondyloideus. The latissimus dorsi crosses the inferior angle of the

scapula The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...

. A study found that, of 100 cadavers dissected: * 43% had "a substantial amount" of fibers in the latissimus dorsi originating from the scapula. * 36% had few or no muscular fibers, but a "soft fibrous link" between the scapula and the latissimus dorsi * 21% had little or no connecting tissue between the two structures.

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 The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superolateral margin of the greater pelvis. Structure The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the posterio ...

, and its floor by the obliquus internus abdominis. * Another triangle is situated behind the scapula. It is bounded above by the

, 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

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 Auscultation (based on the Latin verb ''auscultare'' "to listen") is listening to the internal sounds of the body, usually using a stethoscope. Auscultation is performed for the purposes of examining the circulatory system, circulatory and resp ...

. The space is therefore known as the ''

triangle of auscultation The triangle of auscultation is a relative thinning of the musculature of the back, situated along the medial border of the scapula which allows for improved listening to the lungs. Boundaries It has the following boundaries: * medially, by the ...

''. *The latissimus dorsi can be remembered best for insertion as "A Miss Between Two Majors". As the latissimus dorsi inserts into the floor of the intertubercular groove of the

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

it is surrounded by two major muscles. The teres major inserts medially on the medial lip of the intertubercular groove and the pectoralis major inserts laterally onto the lateral lip.

Nerve supply

The latissimus dorsi is innervated by the sixth, seventh, and eighth

cervical nerves A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into ...

through the thoracodorsal (long subscapular) nerve.

Electromyography Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to produce a record called an electromyogram. An electromyo ...

suggests that it consists of six groups of muscle fibres that can be independently coordinated by the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

Function

The latissimus dorsi assists in depression of the arm with the teres major and pectoralis major. It adducts, extends, and internally rotates the shoulder. When the arms are in a fixed overhead position, the latissimus dorsi pulls the trunk upward and forward. It has a

role in extension (posterior fibers) and lateral flexion (anterior fibers) of the lumbar spine, and assists as a muscle of both forced expiration (anterior fibers) and an accessory muscle of inspiration (posterior fibers). Most latissimus dorsi exercises concurrently recruit the teres major, posterior fibres of the

deltoid Deltoid (delta-shaped) can refer to: * The deltoid muscle, a muscle in the shoulder * Kite (geometry), also known as a deltoid, a type of quadrilateral * A deltoid curve, a three-cusped hypocycloid * A leaf shape * The deltoid tuberosity, a part o ...

, long head of the

, among numerous other stabilizing muscles. Compound exercises for the 'lats' typically involve elbow flexion and tend to recruit the

, brachialis, and

brachioradialis The brachioradialis is a muscle of the forearm that flexes the forearm at the elbow. It is also capable of both pronation and supination, depending on the position of the forearm. It is attached to the distal styloid process of the radius by way ...

for this function. Depending on the line of pull, the

muscles can be recruited as well; horizontal pulling motions such as rows recruit both latissimus dorsi and trapezius heavily.

Training

The power/size/strength of this muscle can be trained with a variety of different exercises. Some of these include: * Vertical pulling movements such as pull-downs and pull-ups (including chin-ups) * Horizontal pulling movements such as bent-over row, T-bar row and other rowing exercises * Shoulder extension movements with straight arms such as straight-arm lat pulldowns and pull-overs *

Deadlift The deadlift is a strength training exercise in which a weight-loaded barbell is lifted off the ground to the level of the hips, with the torso perpendicular to the floor, before being placed back on the ground. It is one of the three powerlifting ...

Clinical significance

Tight latissimus dorsi has been shown to be a contributor to chronic shoulder pain and chronic back pain.Arnheim, D.D., Prentice, W.E., Principles of athletic training. 9th ed. McGraw Hill, pp 570-574, 1997. Because the latissimus dorsi connects the spine to the

, tightness in this muscle can manifest as either sub-optimal

glenohumeral joint The shoulder joint (or glenohumeral joint from Greek ''glene'', eyeball, + -''oid'', 'form of', + Latin ''humerus'', shoulder) is structurally classified as a synovial ball-and-socket joint and functionally as a diarthrosis and multiaxial joint ...

(shoulder) function which leads to chronic pain or

tendinitis Tendinopathy is a type of tendon disorder that results in pain, swelling, and impaired function. The pain is typically worse with movement. It most commonly occurs around the shoulder ( rotator cuff tendinitis, biceps tendinitis), elbow ( tenn ...

in the tendinous fasciae connecting the latissimus dorsi to the thoracic and

lumbar spine The lumbar vertebrae are located between the thoracic vertebrae and pelvis. They form the lower part of the back in humans, and the tail end of the back in quadrupeds. In humans, there are five lumbar vertebrae. The term is used to describe t ...

.Francis, P., Applied anatomy and kinesiology, supplemental materials. KB Books., p 19-25, 1999. The latissimus dorsi is a potential source of muscle for

breast reconstruction Breast reconstruction is the surgical process of rebuilding the shape and look of a breast, most commonly in women who have had surgery to treat breast cancer. It involves using autologous tissue, prosthetic implants, or a combination of both wi ...

surgery after mastectomy (e.g., Mannu flap) or to correct pectoral

hypoplastic Hypoplasia (; adjective form ''hypoplastic'') is underdevelopment or incomplete development of a Tissue (biology), tissue or Organ (biology), organ.Poland's syndrome. An absent or hypoplastic latissimus dorsi can be one of the associated symptoms of Poland's syndrome.

Cardiac support

For heart patients with low cardiac output and who are not candidates for cardiac transplantation, a procedure called '' cardiomyoplasty'' may support the failing heart. This procedure involves wrapping the latissimus dorsi muscles around the heart and electrostimulating them in synchrony with ventricular systole.

Injury

Injuries to the latissimus dorsi are rare. They occur disproportionately in baseball pitchers. Diagnosis can be achieved by visualization of the muscle and movement testing. MRI of the shoulder girdle will confirm the diagnosis. Muscle belly injuries are treated with rehabilitation while tendon avulsion injuries can be treated surgically, or with rehab. Regardless of treatment, patients tend to return to play without any functional losses.

Additional images

File:Latissimus dorsi muscle animation.gif, Position of the latissimus dorsi muscle (shown in red). Animation. File:LumbarTriangle.jpg, Lumbar triangle File:Slide9111.JPG, Latissimus dorsi File:2019-05-24 Budapest Cup training pommel horse (Martin Rulsch) 466.jpg, Clearly visible ''latissimus dorsi muscle'' of an artistic gymnast on

pommel horse The pommel horse, also known as vaulting horse, is an artistic gymnastics apparatus. Traditionally, it is used by only male gymnasts. Originally made of a metal frame with a wooden body and a leather cover, the modern pommel horse has a metal bo ...

. File:Deutsche Jugendmeisterschaften Gerätturnen männlich Training at Internationales Deutsches Turnfest Berlin 2017 (Martin Rulsch) 0857.jpg, Contraction of the ''latissimus dorsi muscle'' of another artistic gymnast on still rings.

References

External links

* —"Superficial layer of the extrinsic muscles of the back." * {{DEFAULTSORT:Latissimus Dorsi Muscle Muscles of the upper limb Shoulder adductors Shoulder extensors Shoulder flexors Shoulder medial rotators Spine lateral flexors