shoulder extension agonist and antagonistproblems with oneness theology

Antagonists are the teres minor, infraspinatus, and posterior deltoid muscles. Agonists are the prime movers while antagonists oppose or resist the movements of the agonists. Another important muscle group is the rotator cuff. The second is the inferior capsular aspect, this is the point where the capsule is the weakest. Lower trapezius: along with the serratus anterior muscle, they are a primary upward rotators of the scapula. The glenohumeral joint has a greater range of movement (RoM) than any other body joint. Conjointly as agonist and antagonist couplings, they allow for the gross motor movements of the upper quadrant. PMID: 10527095 DOI: 10.1016/s0003-9993 (99)90037-0 Abstract The muscle that is contracting is called the. gluteus medius The prime flexors of the glenohumeral joint are the deltoid (anterior fibers) and pectoralis major (clavicular fibers) muscles. [21] The scapular muscles must dynamically control the positioning of the glenoid so that the humeral head remains centered and permits arm movement to occur. The coracobrachialis, teres minor, short head of biceps, long head of triceps brachii and deltoid (posterior fibers) muscles are also active during this movement, depending on the position of the arm. Acting in conjunction with the pectoral girdle, the shoulder joint allows for a wide range of motion at the upper limb; flexion, extension, abduction, adduction, external/lateralrotation, internal/medialrotation and circumduction. [13], An imbalance in the neural activation of any one of the RC muscles could easily cause a misalignment of the humeral head thus giving rise to an impingement of the subacromial structures during movement. In any pair, the agonist muscle contracts, while the antagonist muscle relaxes, allowing for the free movement of our joints and muscles. Sports medicine. These muscles include the latissimus dorsi and posterior fibres of the deltoids, with both acting as the prime mover. adductor mangus, longus & brevis The main agonists for internal rotation are the pectoralis major, latissimus dorsi, and anterior deltoid muscle. The synchronized contractions of the RC muscles must maintain the centralized positioning of the humeral head during movements in order to avoid the physical encroachment of tissues, predominantly anteriorly or superiorly to the GH joint, which has been linked to injury and pain amongst the shoulder region. This is a stabilizing mechanism in which compression of the humerus into the concavity of glenoid fossa prevents its dislocation by translating forces. More specifically to the GH joint, the fine-tuning stabilizers are just as important to the shoulder complex as the global movers for coordinated and smooth shoulder movements. This wide ligament lies deep to, and blends, with the tendon of subscapularis muscle. Rotator cuff (RC) (collectively the following muscles: supraspinatus, subscapularis, infraspinatus, teres minor) not only abduct the shoulder, but also plays an important role as stabilizer muscles. antagonist: gluteus maximus, multifidus 2012. The AC joint is a diarthrodial and synovial joint. The deltoid muscle has a significant role as a stabilizer, and is generally accepted as a prime mover for glenohumeral joint during abduction, along with the supraspinatus muscle. Top Contributors - Amanda Ager, Kim Jackson, Abdallah Ahmed Mohamed, Naomi O'Reilly, Vidya Acharya, Claire Knott, Ayesha Arabi and Khloud Shreif. [26] Regardless of the classification, the dysfunctional shoulder mechanisms can further the progression of rotator cuff disease[27] and must therefore be understood as a neuromuscular impairment. . All content published on Kenhub is reviewed by medical and anatomy experts. \mathrm{N}T=250.N is oriented in the xxx-direction. Contraction of the deltoid muscle applies a strong superior translation force to the humerus, this is countered by the action of the rotator cuff muscles, preventing superior humeral dislocation. Then, exchange papers. All three ligaments become taut during external (lateral)rotation of humerus, while they relax in internal (medial)rotation. [18] The normal contribution of the ST joint is generally expressed as the ratio of ST movement with regards to that occurring simultaneously at the GH articulation. It is believed that the supraspinatus is important for movement initiation and early abduction, while the deltoid muscle is engaged from approximately 20 of abduction and carried the arm through to the full 180 of abduction. Resistance training exercises can promote neural and structural modifications to the shoulder complex[23][24] and can increase the sensory, biomechanical, and motor-processing patterns[25] (such as to the cervico-thoracic spine, the shoulder complex and the upper extremities as a whole). These tendons form a continuous covering called the rotator capsule. Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Biologydictionary.net Editors. [21], Exercises can be performed unilaterally, or bilaterally in unstable conditions involving an increased level of postural control (standing, planking, kneeling and laying on stability ball) and/or with external overload devices challenging motor-coordination (elastics, balls, dumbbells).[22]. Glenohumeral joint (Articulatio glenohumeralis) -Yousun Koh. The loose inferior capsule forms a fold when the arm is in the anatomical position. Chapter 17: Shoudler Pain. Complete the puzzles, and then check each other's answers. Muscles contract to move our. The inferior glenohumeral ligament is a sling-like ligament extending between the glenoid labrum and the inferomedial part of the humeral neck. quadratus lumborum An Imbalance of one or more of these muscles can cause biomechanical misalignments and contribute to shoulder dysfunctions such as: impingement disorders, bursitis, instabilities, scapular dyskinesia or chronic conditions associated with pathological wear and tear. The Agonist is the main muscle moving in an exercise ( sometimes called the prime mover). Blasier RB, Carpenter JE, Huston LJ (1994) Shoulder proprioception: effect of joint laxity, joint position and direction of motion. Explain how a synergist assists an agonist by being a fixator. . Agonist and antagonist muscle pairs An explanation of how the muscular-skeletal system functions during physical exercise Muscles are attached to bones by tendons. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537148/. The scapulohumeral and thoracohumeral muscles are responsible for producing movement at the glenohumeral joint. Antagonist = Latissimus Dorsi, A level PE- analysis of movement Contraction, The Impact Of Smoking On The Respiratory Syst, David N. Shier, Jackie L. Butler, Ricki Lewis, Andrew Russo, Cinnamon VanPutte, Jennifer Regan, Philip Tate, Rod Seeley, Trent Stephens. antagonist: illiopsoas, KINES agonists, synergists, & antagonists, Gross Anatomy Muscles (origin, insertion, act, John Lund, Paul S. Vickery, P. Scott Corbett, Todd Pfannestiel, Volker Janssen, Byron Almen, Dorothy Payne, Stefan Kostka, Eric Hinderaker, James A. Henretta, Rebecca Edwards, Robert O. Self, Chapter 4 question and answer, Chapter 5 Preb. Teres major has the same action of latissimus dorsi of adduction, extension, internal rotation. There is also a theory that the neuromuscular bundle (nerves, veins, arteries) can also contribute to static stability. The concavity of the fossa is less acute than the convexity of the humeral head, meaning that the articular surfaces are not fully congruent. Between the greater and lesser tubercles of humerus, through which the tendon of the long head of biceps brachii passes. Stretch your arms forward and point your feet. Reeducation of the rotator cuff muscles (working in rotations at various angles of elevation, scaption movements and functional activities). If the spine is seen as the bottom of a triangle and the attachment to the humerus as the apex of this triangle, it is quite easy to picture one side of the muscle. [11], Innervation of the supraspinatus: The neural supply of the supraspinatus is by the suprascapular nerve (C5, C6) from the upper trunk of the brachial plexus.[11]. I would honestly say that Kenhub cut my study time in half. The labrum acts to deepen the glenoid fossa slightly, it is triangular in shape and thicker anteriorly than inferiorly. They originate at the scapula and, like the latissimus dorsi, insert at the humerus. These bursae allow the structures of the shoulder joint to slide easily over one another. It has been suggested that the tendons of the rotator cuff muscles blend with the ligaments and the glenoid labrum at their respected sites of attachments, so that the muscle contractions can provide additional stability by tightening the static structures during movement.[38]. For smooth synchronous movement of the shoulder complex we need the force couplings of the glenohumeral and scapulothoracic joints to work in a synched timing and adequate forces to offset each other. Hip abduction muscles both contract and relax to allow for this movement; these are agonist and antagonist muscles respectively. When weakness or neuromuscular dysfunction of the scapular musculature is present, normal scapular arthrokinematics become altered,[20] and ultimately predisposes an individual to an injury of the GH joint. GUStrength. If you keep your arm at your side and swing it backwards from the shoulder, you are performing shoulder hyperextension. Joint Structure and Function; A Comprehensive Analysis. Synovial fluid filled bursae assist with the joints mobility. weakness of any muscle change normal kinematic chain of the joint. The insertion points are areas where movement is possible. Rotator cuff tendinosis in an animal model: Role of extrinsic and overuse factors. Ludewig PM, & Braman, J.P. During movements in elevation and reaching activities, it is important to consider the force-coupling which acts on the floating joint. antagonist: rectus abdominus, illiopsoas External rotation of the humerus moves the greater tubercle out from under the acromial arch, allowing uninhibited arm abduction to occur. An induction process for inflorescence development, b. The SC joint is the only bony attachment site of the upper extremity to the axial skeleton. Bony instability of the shoulder. Here the capsule arches over the supraglenoid tubercle and its long head of biceps brachii muscleattachment, thus making these intra-articular structures. The upper sides of each triangle cross the lower regions of the scapulae or shoulder blades. The first and second ribs descend, while the 4-6th ascend and the 3rd acts as an axis. https://doi.org/10.1177/1941738110362518. One small study showed that even when this muscle is completely removed, most patients encounter little difficulty with shoulder movement and can continue former activities without any problem. In transverse extension, however, like when you bring the shoulders and elbows back during rowing exercises (see below), the latissimus dorsi becomes a prime mover together with the posterior deltoid muscle. antagonist: gluteus minimus, hamstrings [Updated 2020 Mar 31]. [4][6][7], For more detailed anatomy visit Shoulder Anatomy, The natural arthrokinematics of the GH joint of the shoulder complex during an open-chain movement supports various directional glides of the humeral head within the glenoid fossa. Sometimes, the latissimus dorsi acts as a synergist. There is ample evidence describing its use for improving upper body muscular endurance, strength, hypertrophy (muscle size) and power . In the image you can see how one relaxes and the other contracts to produce movement in the elbow joint. [6][7] The space itself includes a bursa that provides lubrication for the rotator cuff (RC) tendons, the insertion for the long head of the biceps tendon, and the rotator cuff (RC) tendons themselves. Top Contributors - Khloud Shreif, Amanda Ager, Kim Jackson and Rishika Babburu. Being a synovial joint, both articular surfaces are covered with hyaline cartilage. ", Biologydictionary.net Editors. Lephart SM, Riemann BL, Fu FH. Basic biomechanics (7th ed.). Light application of water to a turfgrass, Extension of the shoulder: Synergist Muscle, Extension of the shoulders: Antagonist Muscle, Flexion of the Shoulder: Synergist & Antagoni, ABduction of the shoulder: Synergist & Antago, Extension of the Wrist: Synergist & Antagonis, Rotation of the Vertebral Column: Synergist &, Extension of the Vertebral Column: Synergist, Flexion of the Vertebral Column: Synergist &, ADDuction of the Thumb: Synergist & Antagonis, David N. Shier, Jackie L. Butler, Ricki Lewis, Anatomy and Physiology: An Integrative Approach, Michael McKinley, Theresa Bidle, Valerie O'Loughlin, Essentials of Human Anatomy and Physiology. The ST joint involves the gliding movement of the scapula along the rib cage during upper extremity movements and does not include a physical bone-to-bone attachment. Escamilla RF, Yamashiro K, Paulos L, Andrews JR. Longo UG, Berton A, Papapietro N, Maffulli N, Denaro V. Muscle and Motion. If you believe that this Physiopedia article is the primary source for the information you are refering to, you can use the button below to access a related citation statement. Two transverse waves of equal amplitude and with a phase angle of zero (at t=0)t=0)t=0) but with different frequencies (=3000rad/s(\omega=3000 \mathrm{rad} / \mathrm{s}(=3000rad/s and /3=1000.rad/s)\omega / 3=1000 . You are experiencing internal rotation of this joint. [4][5] More specifically, the subacromial canal lies underneath the acromion, the coracoid process, the AC joint, and the coracoacromial ligament. Neer CS. Semimembranosus, Rectus Femoris If you form a letter T with your arms and body and then bring one or both arms from a horizontal position back down to your sides, the downward movement is adduction. rectus femoris agonist: infraspinatus I give my consent to Physiopedia to be in touch with me via email using the information I have provided in this form for the purpose of news, updates and marketing. Last reviewed: February 27, 2023 [5][20], Neuromuscular exercises typically focus on movement quality, as guided by the supervising physical therapists. During flexing of the forearm, the triceps brachii is the antagonist muscle, resisting the movement of the forearm up towards the shoulder. Shoulder impingement: biomechanical considerations in rehabilitation. The static structures of the shoulder complex, which includes the labrum (a fibrocartilaginous ring), the capsule, cartilage, ligaments, and fascia collectively act as the physical restraints to the osseous matter and provides a deepening effect to the shallow glenoid fossa. It extends to the lesser tubercle of humerus. During right arm flexion: The upper thoracic vertebrae right side flexes, right rotates and extends. To see how useful clauses are in combining sentences, go back to a piece of writing you are working on. Kinetic chain exercises for lower limb and trunk during shoulder rehabilitation can reduce the demand on the rotator cuff, improve the recruitment of axioscapular muscles[26]. However, because of the vast range of motion of the shoulder complex (the most mobile joint of the human body), dynamic stabilizers are crucial for a strong sense of neuromuscular control throughout all movements and activities involving the upper extremities. Paine R, & Voight, M.L. The healthy movement of the scapula along the thorax during arm elevation includes protraction, posterior tilting, and lateral rotation, depending on the plane of movement (Figure 1). Palastanga, N., & Soames, R. (2012). Bushnell BD, Creighton, R.A., & Herring, M.M. 2010;2(2):10115. That is usually the journal article where the information was first stated. Can you feel the movement in your shoulder? Did you find hard to remember anatomicalstructures? TFL Curated learning paths created by our anatomy experts, 1000s of high quality anatomy illustrations and articles. It's more active during arm elevation in abduction and has a gradual linear increase in activity with the increase of abduction angle. Together these three are known as the climbing muscles, as they are powerful adductors, alternatively they can lift the trunk up towards a fixed arm. It is comprised of the supraspinatus superiorly, infraspinatus and teres minor posteriorly, subscapularis anteriorly and the long head of triceps brachii inferiorly. Lowe trapezius muscle assists with SA to upwardly rotate the scapula which helps to maintain subacromial space[15]. The glenoid fossa is a shallow pear-shaped pit on the superolateral angle of scapula. Troy Blackburn and Scott M. Lephart. Jam B. Turn on your back and press your lower back into the floor by pulling in your tummy. The rotator cuff muscles help to maintain a centralized position of the head of the humerus during static postures and dynamic movements. Biologydictionary.net Editors. The role of the sensoriomotor system in the athletic shoulder. Toussaint-Louverture. Aagaard P, Simonsen EB, Andersen JL, Magnusson P, Dyhre-Poulsen P. Neural adaptation to resistance training: changes in evoked V-wave and H-reflex responses. Kennedy JC, Alexander, I.J., & Hayes, K.C. The superior, middle and inferior glenohumeral ligaments support the joint from the anteroinferior side. Lephart. Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster. [8][9], Del Maso and colleagues have estimated that a maximum of 7.5 mm of upward translation of the humeral head may occur during range of motion movements,[9] which is not an insignificant amount of migration for a large bony structure to experience within a compact space during a dynamic task. That is why these muscles must work in pairs. Latissimus dorsi function is often described as a climbing muscle but it is also a major contributor to movements such as rowing, some swimming strokes, and handling an axe when lifting it high over the head and bringing it down. Shoulder joint position sense improves with elevation angle in a novel, unconstrained task. p. 655-669. This shoulder function comes at the cost of stability however, as the bony surfaces offer little support. In the image below you can see where the horizontal sheet of the latissimus dorsi just covers the bottom of the shoulder blades. (2018). Latissimus dorsi origin and insertion is described in more detail below. Antagonist muscles act as opposing muscles to agonists, usually contracting as a means of returning the limb to its original, resting position. As it contracts it makes the thoracic space smaller and helps to push the air in the lungs out. If the agonist contracts, the antagonist relaxes and vice versa. It also plays a role in lumbar spine extension (straightening) and sideways bending (lateral flexion). Lack of mobility of the upper extremity, cervical and thoracic neurological tissues (nerve flossing exercises as needed). Individually, each muscle has its own pulling axis that results in a certain movement (prime mover), while together they create a concavity compression. Reading time: 15 minutes. Biologydictionary.net, June 11, 2020. https://biologydictionary.net/latissimus-dorsi/. . internal oblique The main lateral rotators are the infraspinatus and teres minor muscles, with help from the posterior fibers of the deltoid muscle. It can both stabilize the joint and reduce the energy needed for the agonist to work. (2015). Activities of the arm rely on movement from not only the glenohumeral joint but also the scapulothoracic joint (acromioclavicular, sternoclavicular and scapulothoracic articulations). antagonist: opposite QL, illiopsoas Which of these is a latissimus dorsi insertion point? Lam JH, Bordoni B. Anatomy, Shoulder and Upper Limb, Arm Abductor Muscles. For patients with lower back pain, one possible cause is a stiff, shortened latissimus dorsi muscle that pulls on the spine and pelvis. [3] The surrounding passive structures (the labrum, joint capsule, and ligaments) as well as the active structures (the muscles and associated tendons) work cooperatively in a healthy shoulder to maintain dynamic stability throughout movements. For the sake of clarification, the current literature differentiates between an internal impingement and an external impingement. . These compensatory effects can lead to permanent injury. It becomes stretched, and least supported, when the arm is abducted. ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motion - Part II: shoulder, elbow, wrist and hand. In: Lephart SM, Fu FH, eds. In most cases Physiopedia articles are a secondary source and so should not be used as references. Therefore, it has a more superior line of pull which cannot offset the line of force emitted from the deltoid muscle. More specifically to the GH joint, the fine-tuning stabilizers are just as important to the shoulder complex as the global movers for coordinated and smooth shoulder movements. Comparison of 3-dimensional scapular position and orientation between subjects with and without shoulder impingement. Antagonist= Latissimus Dorsi, When shoulder joint action = Extension/hyperextension, Agonist = Latissimus Dorsi All muscles originate at one or more sites and insert into one or more other locations. The capsule remains lax to allow for mobility of the upper limb. Author: Antagonist = Latissimus Dorsi, Agonist = Latissimus Dorsi Several ligaments limit the movement of the GH joint and resist humeral dislocation. Finally, the shoulder blades also use the latissimus dorsi as synergists; more specifically it is a neutralizing synergist or stabilizer. That is usually the journal article where the information was first stated. Repeat, leaning to the opposite side. Standring, S. (2016). Muscles that have their origins in the posterior (back of) shoulder joint extend the arm. Wilk KE, Yenchak AJ, Arrigo CA, Andrews JR. Jeno SH, Varacallo M. Anatomy, Back, Latissimus Dorsi. This means that when it contracts it pulls the upper arm in the direction of the hip and back. Manual therapy, Kinesiologic considerations for targeting activation of scapulothoracic muscles: part 1: serratus anterior, Kinesiologic considerations for targeting activation of scapulothoracic musclespart 2: trapezius, http://www.youtube.com/watch?v=YbbzQs7OBoY, Scapular and rotator cuff muscle activity during arm elevation: a review of normal function and alterations with shoulder impingement, Joseph B. Myers, Ji-Hye Hwang, Maria R. Pasquale, J. Richards, J. As it is the agonist that produces the force, it is also referred to as the prime mover. What pressure must the pump provide for water to flow from the upper end of the pipeline at a rate of 5.0m/s5.0 \mathrm{~m} / \mathrm{s}5.0m/s ? The resulting waves, which travel in the positive xxx-direction, are reflected at a distant point, so there is a similar pair of waves traveling in the negative xxx-direction. Every muscle can be an Agonist, and every muscle has an antagonist paired muscle. Available from: Laitung JK, Peck F. Shoulder function following the loss of the latissimus dorsi muscle. Physiopedia is not a substitute for professional advice or expert medical services from a qualified healthcare provider. Clavicle retraction contributes to 100% of scapular external and the clavicle elevation contributes to about 75% of scapular anterior tilt and 25% of scapular upward rotation of the scapula. Struyf F, Nijs, J., Baeyens, J.P., Mottram, S., Meeusen, R. Scapular positioning and movement in unimpaired shoulders, shoulder impingement syndrome, and glenohumeral instability. The bench press is one of the most popular exercises in the fitness and sports community and is often used as a measuring stick for evaluating upper body strength (Robbins 2012; Bianco, Paoli & Palma 2014). Vastus Intermedius Thus repositioning the glenohumeral joint, and upper limb, within space. Moreover, the term sensorimotor system describes the sensory, motor, and central integration and processing components involved in maintaining joint homeostasis during bodily movements - more commonly understood to be functional joint stability. The information we provide is grounded on academic literature and peer-reviewed research. They have a stabilization role during arm elevation; latissimus dorsi via its compression force to G.H joint, pectoralis major through higher going reaction force. In particular, accessory adductor muscles serve to counter the strong internalrotation produced by pectoralis major and latissimus dorsi. Jump straight into the anatomy of the glenohumeral joint with this integrated quiz: Explore our video tutorials, quizzes, articles and atlas images of glenohumeral joint for a full understanding of its anatomy. Practically all of these activities combine extreme upper arm movement with rotation of the trunk. Latissimus dorsi action depends heavily on other muscles. Latissimus dorsi is a muscle of posterior back has an attachment to scapula and humerus. The supraspinatus muscle contributes to preventing excessive superior translation, the infraspinatus and teres minor limit excessive superior and posterior translation, and the subscapularis controls excessive anterior and superior translation of the humeral head, respectively. Mechanoreceptors can be understood as the neural sensors that provide afferent input to the central nervous system for motor processing and descending motor commands for the execution of movements. The goal is to look like Superman or Supergirl flying through the air. Scapula deviated about 35 degree anterior to the frontal plane.the concave glenoid fossa articulate with convex head of humerus to form glenohumeral joint. The cross point, defined as the point where agonist and antagonist muscle torques are equal, always occurred within the fifth 15 angle subgroup (26-40) for the shoulder flexion-extension . semimembranosus On the scapula, the capsule has two lines of attachments. Philadelphia, PA: Wolters Kluwer Health/Lippincott, Williams & Wilkins. To prevent further latissimus dorsi strain try some of the exercises further on. Study with Quizlet and memorize flashcards containing terms like Agonist, Antagonist, When Elbow joint action=flexion and more. Regarding the location of the supraspinatus muscle, it is more superior than the other three rotator cuff muscles. The additional accessory movements of spin, roll and slide (glide) are also available within the glenohumeral joint. All of these muscles work with or against each other to allow a wide range of upper extremity movement. Functional anatomy: Musculoskeletal anatomy, kinesiology, and palpation for manual therapists. Muscular timing (coordinator contractions) is a key component to focus on during shoulder rehabilitation. The function of this entire muscular apparatus is to produce movement at the shoulder joint while keeping the head of humerus stableand centralized within the glenoid cavity. Internal rotation is primarily performed by the subscapularis and teres major muscles. Hall, S. J. Long-term shortening can lead to chronic back pain as the body will try to compensate, perhaps tilting the pelvis to one side and changing how a person walks. 2016 Jun 1;19(6):438-53. Can your peer reviewer suggest variations? [12] The main role of the rotator cuff is to control the fine-tuning (smaller) movements of the head of the humerus, within the glenoid fossa (often thought of as the accessory movements). Also, there is an inferior pull of force (fx), to offset the component of the middle deltoid which is active during arm elevation, as gravity cannot balance the force around the GH joint alone. Overall, to rehabilitate the neuromuscular control of the shoulder complex, the therapist should focus on the following elements: Progression factors to consider to challenge the neuromuscular control of the shoulder complex: For more exercises for the rotator cuff complex: Myers, J.B., C.A. 2002;92(6):230918. Such muscles to consider are the serratus anterior, serratus posterior, the trapezius (upper / middle / lower), the rhomboids, teres major, the levator scapulae, the latissimus dorsi and the flexibility and mobility of the thoracolumbar fascia. For example; the deltoid muscle (middle fiber in particular) acts to stabilize the humeral head against the glenoid cavity during arm elevation, while the rotator cuff muscles (specifically the subscapularis, teres minor, infraspinatus muscles) control the fine-tuning movement of the humeral head. Effects of eccentric exercise in patients with subacromial impingement syndrome: a systematic review and meta-analysis, http://www.youtube.com/watch?v=Vez6-NTFkS8, https://www.physio-pedia.com/index.php?title=Dynamic_Stabilisers_of_the_Shoulder_Complex&oldid=323295. There are also the periscapsular muscles[4], which are very important for homogeneous shoulder movements while avoiding biomechanical misalignments, such as a shoulder impingement. The latissimus dorsi is the largest muscle of the human body but is not the strongest at less than one centimeter in thickness. Pectoralis major and latissimus dorsi act as antagonists. Muscles work in pairs, whilst one works (contracts) the other relaxes. illiopsoas Richardson E, Lewis JS, Gibson J, Morgan C, Halaki M, Ginn K, Yeowell G. Moghadam AN, Abdi K, Shati M, Dehkordi SN, Keshtkar AA, Mosallanezhad Z. Ortega-Castillo M, Medina-Porqueres I. [11] The supraspinatus muscle initiates the abduction movement of the arm by pulling the humeral head medially towards the glenoid cavity thereby creating a fulcrum for movement. This muscle does not work alone. Magee, D. J. White Lion Athletics. 2006;20:71622. Other muscles act as agonist and antagonist pairs to provide excellent range of motion in the shoulder. From Figure 1 and 2, we can consider the deltoid and rotator cuff muscles as a collective force coupling for the movements associated with the glenohumeral joint. and adaptive pectoralis minor shorting[18]. Agonist =triceps brachii Antagonist = biceps brachii.

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