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36-673: The deltoid's fibres are Pennate muscle . However, electromyography suggests that it consists of at least seven groups that can be independently coordinated by the nervous system . It was previously called the deltoideus (plural deltoidei ) and the name is still used by some anatomists. It is called so because it is in the shape of the Greek capital letter delta (Δ). Deltoid is also further shortened in slang as " delt ". A study of 30 shoulders revealed an average mass of 191.9 grams (6.77 oz) in humans, ranging from 84 grams (3.0 oz) to 366 grams (12.9 oz). From this extensive origin

72-594: A number of highly respected authorities in the sport as the premier event in strength athletics. The concept behind 'The World's Strongest Men', as it was originally named, was developed in 1977 for CBS by Langstar Inc. David Webster , a Scot who later received an OBE for his services to sport, was the head coordinator of the competition from its inception. Dr Douglas Edmunds , seven-times Scottish shot and discus champion and twice world caber champion, worked with Webster. When Webster retired from his position, Edmunds took over. These two men were responsible for inviting

108-406: A pennate muscle, PCSA is always larger than ACSA. In a non-pennate muscle, it coincides with ACSA. The total force exerted by the fibers along their oblique direction is proportional to PCSA. If the specific tension of the muscle fibers is known (force exerted by the fibers per unit of PCSA), it can be computed as follows: However, only a component of that force can be used to pull the tendon in

144-453: A person carries heavy loads. The function of abduction also means that it would help keep carried objects a safer distance away from the thighs to avoid hitting them, as during a farmer's walk . It also ensures a precise and rapid movement of the glenohumeral joint needed for hand and arm manipulation. The intermediate fibers are in the most efficient position to perform this role, though like basic abduction movements (such as lateral raise) it

180-584: A type of skeletal muscle with fascicles that attach obliquely (in a slanting position) to its tendon. This type of muscle generally allows higher force production but a smaller range of motion. When a muscle contracts and shortens, the pennation angle increases. The term "pennate" comes from the Latin pinnātus ("feathered, winged"), from pinna ("feather, wing"). In skeletal muscle tissue, 10-100 endomysium -sheathed muscle fibers are organized into perimysium -wrapped bundles known as fascicles . Each muscle

216-421: Is an exceedingly rare condition related to mechanical stress. Conversely, deltoideal acromial enthesopathy is likely a hallmark of seronegative spondylarthropathies and its detection should probably be followed by pertinent clinical and serological investigation. The Deltoid Muscle is tested by asking the patient to abduct the arm against resistance applied with one hand, and feeling for the contracting muscle with

252-399: Is assisted by simultaneous co-contraction of anterior/posterior fibers. The deltoid is responsible for elevating the arm in the scapular plane and its contraction in doing this also elevates the humeral head. To stop this compressing against the undersurface of the acromion the humeral head and injuring the supraspinatus tendon , there is a simultaneous contraction of some of the muscles of

288-473: Is composed of a number of fascicles grouped together by a sleeve of connective tissue, known as an epimysium . In a pennate muscle, aponeuroses run along each side of the muscle and attach to the tendon. The fascicles attach to the aponeuroses and form an angle (the pennation angle) to the load axis of the muscle. If all the fascicles are on the same side of the tendon, the pennate muscle is called unipennate (Fig. 1A). Examples of this include certain muscles in

324-410: Is no set rule about what specific events will occur in a contest, except that to prevent single-event specialists from gaining an advantage, each event will be different (a single contest will not include two squat events, or two overhead lifting events, for example). Normally, a strongman contest comprises five or six events, though at the top level of competition, seven or eight events may be held. Among

360-526: Is practically convenient to compute PCSA based on volume or mass and fiber length, PCSA (and therefore the total fiber force, which is proportional to PCSA) is not proportional to muscle mass or fiber length alone. Namely, the maximum ( tetanic ) force of a muscle fiber simply depends on its thickness (cross-section area) and type . By no means it depends on its mass or length alone. For instance, when muscle mass increases due to physical development during childhood, this may be only due to an increase in length of

396-422: Is provided by the total area of the cross sections perpendicular to the muscle fibers (green lines in figure 1). This measure is known as the physiological cross sectional area (PCSA), and is commonly calculated and defined by the following formula (an alternative definition is provided in the main article ): where ρ is the density of the muscle: PCSA increases with pennation angle, and with muscle length. In

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432-743: Is the collection of strength sports which measure physical strength, based on both: non-standard and historical implements as seen in Strongman and Highland games , and standardized and calibrated equipment as seen in Powerlifting and Weightlifting . Some of the disciplines have similarities to each other and although it is very difficult to master more than one, some athletes participate in several of them and perform at world class levels. Weightlifting consists of two main lifts ( snatch and clean & jerk ) and powerlifting consists of three main lifts ( squat , bench and deadlift ) where all test

468-550: The Braemar Highland Games. In the 18th and 19th centuries, circus strongmen lent sensationalism to their acts such as bending iron bars, breaking iron chains worn around their chests, and lifting heavy objects. Famous strongmen from this era included Thomas Topham , Eugen Sandow , Louis Cyr , Thomas Inch , Arthur Saxon , Angus MacAskill , and Alexander Zass . In the 20th century, strength sports such as weightlifting and powerlifting were popularized through

504-582: The Olympic Games . However, feats of strength akin to the circus performances also gained in popularity. David Prowse (who played Darth Vader in Star Wars ) was initially famous in 1964 for his lifting the famed 733 pounds (332 kg) Dinnie Stones , the first man to do so since Donald Dinnie himself a century earlier. Perhaps the most famous event is the World's Strongest Man competition, still described by

540-488: The axilla , such as for breast cancer . It may also be injured by anterior dislocation of the head of the humerus. Structures under deltoid When all its fibers contract simultaneously, the deltoid is the prime mover of arm abduction along the frontal plane. The arm must be medially rotated for the deltoid to have maximum effect. This makes the deltoid an antagonist muscle of the pectoralis major and latissimus dorsi during arm adduction. The anterior fibers assist

576-448: The hand . If there are fascicles on both sides of the central tendon, the pennate muscle is called bipennate (Fig. 1B). The rectus femoris , a large muscle in the quadriceps , is typical. If the central tendon branches within a pennate muscle, the muscle is called multipennate (Fig. 1C), as seen in the deltoid muscle in the shoulder . One advantage of pennate muscles is that more muscle fibers can be packed in parallel, thus allowing

612-406: The orangutan , which engage in brachiation and possess the muscle mass needed to support the body weight by the shoulders. In other apes, like the common chimpanzee , the deltoid is much larger than in humans, weighing an average of 383.3 gram compared to 191.9 gram in humans. This reflects the need to strengthen the shoulders, particularly the rotatory cuff, in knuckle walking apes for

648-492: The pectoralis major to flex the shoulder. The anterior deltoid also works in tandem with the subscapularis , pecs and lats to internally (medially) rotate the humerus. The intermediate fibers perform basic shoulder abduction when the shoulder is internally rotated, and perform shoulder transverse abduction when the shoulder is externally rotated. They are not utilized significantly during strict transverse extension (shoulder internally rotated) such as in rowing movements, which use

684-622: The rotator cuff : the infraspinatus and subscapularis primarily perform this role. In spite of this there may be still a 1–3 mm upward movement of the head of the humerus during the first 30° to 60° of arm elevation. The most common abnormalities affecting the deltoid are tears, fatty atrophy, and enthesopathy . Deltoid muscle tears are unusual and frequently related to traumatic shoulder dislocation or massive rotator cuff tears. Muscle atrophy may result from various causes, including aging, disuse, denervation , muscular dystrophy , cachexia and iatrogenic injury . Deltoidal humeral enthesopathy

720-473: The thoracoacromial artery (acromial and deltoid branches), the circumflex humeral arteries, and the profunda brachii artery (deltoid branch). The deltoid is innervated by the axillary nerve . The axillary nerve originates from the anterior rami of the cervical nerves C5 and C6, via the superior trunk, posterior division of the superior trunk, and the posterior cord of the brachial plexus . Studies have shown that there are seven neuromuscular segments to

756-668: The bulk of the strength athletics domain, owing to involving both standardized and non standardized tests of strength, as well as for its highly diversified nature. Strength competitions pre-date written history. The first Olympics (running, throwing, jumping) were believed to be held in 776 BCE. There are records in many civilizations of feats of strength performed by great heroes, perhaps mythological, such as Heracles , Goliath , Orm Storolfsson and Milo of Croton . Competitions that modern strongman events are modeled on, Scottish Highland Gatherings , were formalized around 1820 by Sir Walter Scott . In 1848, Queen Victoria attended

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792-531: The competitors and choosing the events. They selected men who had shown prowess in the mainstream fields of strength sports and field athletics events, such as shot put , American football , powerlifters , bodybuilders and wrestlers . The idea was to create a spectacle that would test competitors against one another. The show was enough of a success that it began to be replicated in other countries, such as Britain's Strongest Man (1979). Competitors began shifting from unpaid amateurs to professional strongmen. By

828-408: The contraction of a pennate muscle, thus requiring the fibers to rotate as they shorten. However, recent work has shown this is false, and that the degree of fiber angle change varies under different loading conditions. This dynamic gearing automatically shifts in order to produce either maximal velocity under low loads or maximal force under high loads. Farmer%27s walk Strength athletics

864-448: The deltoid muscle. Three of these lie in the anatomical anterior head of the deltoid, one in the anatomical middle head, and three in the anatomical posterior head of the deltoid. These neuromuscular segments are supplied by smaller branches of the axillary nerve, and work in coordination with other muscles of the shoulder girdle include pectoralis major and supraspinatus. The axillary nerve is sometimes damaged during surgical procedures of

900-409: The desired direction. This component, which is the true muscle force (also called tendon force ), is exerted along the direction of action of the muscle: The other component, orthogonal to the direction of action of the muscle (Orthogonal force = Total force × sinΦ) is not exerted on the tendon, but simply squeezes the muscle, by pulling its aponeuroses toward each other. Notice that, although it

936-492: The end of the 20th century, and in to the 21st, other strongman programs and events were created such as Strongman Championship hosted by Errol Silverman. Other competitions have been televised, such as the World Muscle Power Championships , World Strongman Challenge , Arnold Strongman Classic , Giants Live , Highlander World Championships , World Strongman Federation , and Europe's Strongest Man . There

972-423: The fibers converge toward their insertion on the deltoid tuberosity on the middle of the lateral aspect of the shaft of the humerus ; the intermediate fibers passing vertically, the anterior obliquely backward and laterally, and the posterior obliquely forward and laterally. Though traditionally described as a single insertion, the deltoid insertion is divided into two or three discernible areas corresponding to

1008-416: The larger the pennation angle is, the shorter are the fibers. The speed at which a muscle fiber can shorten is partly determined by the length of the muscle fiber (i.e., by N ). Thus, a muscle with a large pennation angle will contract more slowly than a similar muscle with a smaller pennation angle. Architectural gear ratio, also called anatomical gear ratio, (AGR) is a feature of pennate muscle defined by

1044-621: The maximal strength (one rep max output). Highland games consists of up to about ten different disciplines (including stone put , Scottish hammer throw , weight throw , weight over bar , caber toss , keg toss and sheaf toss ) while strongman span across more than thirty different lifts and events (including deadlift , vehicle pull , log lift , axle press , stonelifting , stone carrying , circus dumbbell press , yoke carry , farmers walk , squat , basque circle , loading medleys and grip events ), testing both maximal strength and physical endurance. At present day, Strongman takes

1080-402: The muscle fibers, with no change in fiber thickness (PCSA) or fiber type. In this case, an increase in mass does not produce an increase in force. In a pennate muscle, as a consequence of their arrangement, fibers are shorter than they would be if they ran from one end of the muscle to the other. This implies that each fiber is composed of a smaller number N of sarcomeres in series. Moreover,

1116-399: The muscle to produce more force, although the fiber angle to the direction of action means that the maximum force in that direction is somewhat less than the maximum force in the fiber direction. The muscle cross sectional area (blue line in figure 1, also known as anatomical cross section area, or ACSA) does not accurately represent the number of muscle fibers in the muscle. A better estimate

Deltoid muscle - Misplaced Pages Continue

1152-403: The muscle's three areas of origin. The insertion is an arch-like structure with strong anterior and posterior fascial connections flanking an intervening tissue bridge. It additionally gives off extensions to the deep brachial fascia . Furthermore, the deltoid fascia contributes to the brachial fascia and is connected to the medial and lateral intermuscular septa . The deltoid is supplied by

1188-422: The other hand. Site of the intramuscular injection in deltoid: The intramuscular injections are commonly given in the lower half of the deltoid to avoid injury to the axillary nerve, which winds around the surgical neck of the humerus. The deltoid is also found in members of the great ape family other than humans. The human deltoid is of similar proportionate size as the muscles of the rotator cuff in apes like

1224-420: The posterior fibers. The posterior fibers assist the latissimus dorsi to extend the shoulder. Other transverse extensors, the infraspinatus and teres minor , also work in tandem with the posterior deltoid as external (lateral) rotators, antagonists to strong internal rotators like the pecs and lats. An important function of the deltoid in humans is preventing the dislocation of the humeral head when

1260-401: The purpose of supporting the entire body weight. The deltoid muscle is a main component of both the bat and pterosaur wing musculature, but in crown-group birds it is strongly reduced, as they favour sternum attached muscles. Some Mesozoic flying theropods, however, had more developed deltoideus. Pennate muscle A pennate or pinnate muscle (also called a penniform muscle ) is

1296-432: The ratio between the longitudinal strain of the muscle and muscle fiber strain. It is sometimes also defined as the ratio between muscle- shortening velocity and fiber-shortening velocity: AGR = ε x /ε f where ε x = longitudinal strain (or muscle-shortening velocity) and ε f is fiber strain (or fiber-shortening velocity). It was originally thought that the distance between aponeuroses did not change during

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