| Shoulder | |
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| Diagram of the human shoulder joint | |
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| Capsule of shoulder-joint (distended). Anterior aspect. | |
| Latin | articulatio humeri |
| Gray's | subject #81 313 |
| Dorlands/Elsevier | a_64/12161240 |
In human anatomy, the shoulder joint comprises the part of the body where the humerus attaches to the scapula. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Introduction ( Joints or Articulations Sutural ligament Fibrocartilages Elsevier, the world's largest Publisher of Medical and Scientific literature, forms part of the Reed Elsevier group Human anatomy, which with physiology and biochemistry is a complementary basic medical science is primarily the scientific study of the morphology of the adult Human body The humerus is a Long bone in the Arm or Forelimb that runs from the Shoulder to the Elbow. In Anatomy, the scapula, omo, or shoulder blade, is the Bone that connects the Humerus (arm bone with the Clavicle (collar [1] The shoulder refers to the group of structures in the region of the joint. [2]
It is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) as well as associated muscles, ligaments and tendons. In Anatomy, the scapula, omo, or shoulder blade, is the Bone that connects the Humerus (arm bone with the Clavicle (collar The humerus is a Long bone in the Arm or Forelimb that runs from the Shoulder to the Elbow. The articulations between the bones of the shoulder make up the shoulder joints. A joint is the location at which two or more Bones make contact The shoulder must be flexible for the wide range of motion required in the arms and hands and also strong enough to allow for actions such as lifting, pushing and pulling. The compromise between these two functions results in a large number of shoulder problems not faced by other joints such as the hip. Shoulder problems, including Pain, are one of the more common reasons for physician visits for musculoskeletal symptoms
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Joints of the shoulder
There are three joints of the shoulder: The glenohumeral, acromioclavicular, and the sternoclavicular joints. A joint is the location at which two or more Bones make contact The glenohumeral joint, commonly known as the Shoulder joint, is a synovial Ball and socket joint and involves articulation between the The acromioclavicular joint, or AC joint, is a Joint at the top of the Shoulder. The sternoclavicular articulation is a double arthrodial Joint composed of two portions separated by an Articular disc.
Glenohumeral joint
The glenohumeral joint is the main joint of the shoulder and the generic term "shoulder joint" usually refers to it. The glenohumeral joint, commonly known as the Shoulder joint, is a synovial Ball and socket joint and involves articulation between the It is a ball and socket joint that allows the arm to rotate in a circular fashion or to hinge out and up away from the body. A ball and socket joint ( enarthrosis, spheroidal joint) is a Joint in which the distal bone is capable of motion around an indefinite number of axes It is formed by the articulation between the head of the humerus and the lateral scapula. The "ball" of the joint is the rounded, medial anterior surface of the humerus and the "socket" is formed by the glenoid fossa, the dish-shaped portion of the lateral scapula. On the lateral angle of the Scapula is a shallow Pyriform, Articular surface the glenoid cavity (or glenoid fossa of scapula from Greek The shallowness of the fossa and relatively loose connections between the shoulder and the rest of the body allows the arm to have tremendous mobility, at the expense of being much easier to dislocate than most other joints in the body. Joint dislocation (Latin luxatio) occurs when bones in a Joint become displaced or misaligned
The capsule is a soft tissue envelope that encircles the glenohumeral joint and attaches to the scapula, humerus, and head of the biceps. An articular capsule (or joint capsule) is an envelope surrounding a Synovial joint. In Anatomy, the scapula, omo, or shoulder blade, is the Bone that connects the Humerus (arm bone with the Clavicle (collar The humerus is a Long bone in the Arm or Forelimb that runs from the Shoulder to the Elbow. In Human anatomy, the biceps brachii is a Muscle located on the upper Arm. It is lined by a thin, smooth synovial membrane. Synovial membrane (or synovium) is the soft tissue that lines the non- cartilaginous surfaces within Joints with cavities ( Synovial joints This capsule is strengthened by the coracohumeral ligament which attaches the coracoid process of the scapula to the greater tubercle of the humerus. There are also three other ligaments attaching the lesser tubercle of the humerus to lateral scapula and are collectively called the glenohumeral ligaments.
There is also a ligament called semicirculare humeri which is a transversal band between the posterior sides of the tuberculum minus and majus of the humerus. In Anatomy, the term ligament is used to denote three different types of structures Fibrous tissue that connects Bones to other bones This band is one of the most important strengthening ligaments of the joint capsule. An articular capsule (or joint capsule) is an envelope surrounding a Synovial joint.
Acromioclavicular joint
The acromioclavicular (AC) joint is located between the acromion process of the scapula (part of the scapula that forms the highest point of the shoulder) and the distal end of the clavicle. The acromioclavicular joint, or AC joint, is a Joint at the top of the Shoulder. The acromion process, or simply the acromion (from Greek akros, "highest" ōmos, "shoulder" is an anatomical feature
The capsule of this joint is reinforced by the coracoclavicular ligament between the scapula and clavicle at the point of articulation. The coracoclavicular ligament in further detail is created by the conoid ligament, medial from the coracoid process of the scapula and inserts on the conoid tubercle of the clavicle. Lateral to the conoid ligament is the trapezoid ligament, which runs from the coracoid process of the scapula to the trapezoid line of the clavicle. One more ligament, the coracoacromial ligament, running from the coracoid process to the acromion of the scapula contributes to the integrity of the acromioclavicular joint.
Sternoclavicular joint
The sternoclavicular occurs at the medial end of the clavicle with the manubrium or top most portion of the sternum. The sternoclavicular articulation is a double arthrodial Joint composed of two portions separated by an Articular disc. The manubrium (from Latin manubrĭum, "a handle" or manubrium sterni is the broad upper part of the Sternum. The clavicle is triangular and rounded and the manubrium is convex the two bones articulate. The joint consists of a tight capsule and complete intra-articular disc which ensures stability of the joint. The costoclavicular ligament is the main limitation to movemnet, therefore, the main stabiliser of the joint. A fibrocartilaginous disc present at the joint increases the range of movement. Sternoclavicular subluxation is rare, however can be caused by direct trauma.
Movements of the shoulder
The muscles and joints of the shoulder allow it to move through a remarkable range of motion, making it the most mobile joint in the human body. Range of motion or ( ROM) as used in the Biomedical and Weightlifting communities is the measurement of the achievable distance between the flexed position The shoulder can abduct, adduct (such as during the shoulder fly), rotate, be raised in front of and behind the torso and move through a full 360° in the sagittal plane. Abduction, in functional anatomy is a movement which draws a limb away from the median ( Sagittal) plane of the body Adduction is a movement which brings a limb — Arm or Leg — closer to the sagittal plane of the body A fly (or flye) is a Strength training exercise in which the Hand and Arm move through an arc while the Elbow is kept at Torso is an anatomical term for the central part of the many animal bodies (including that of the human from which extend the neck and limbs A sagittal plane of the human body is an imaginary plane that travels from the top to the bottom of the body dividing it into left and right portions This tremendous range of motion also makes the shoulder extremely unstable, far more prone to dislocation and injury than other joints. Joint dislocation (Latin luxatio) occurs when bones in a Joint become displaced or misaligned
Major muscles
The muscles that are responsible for movement in the shoulder attach to the scapula, humerus, and clavicle. The muscles that surround the shoulder form the shoulder cap and underarm. The axilla (or armpit, underarm, or oxter) is the area on the human body directly under the joint where the Arm connects to the Shoulder
| Name | Attachments | Function |
| serratus anterior | Originates on the surface of the upper eight ribs at the side of the chest and inserts along the entire anterior length of the medial border of the scapula. The serratus anterior is a muscle that originates on the surface of the upper eight ribs at the side of the chest and inserts along the entire anterior length of the medial border of the In Vertebrate Anatomy, ribs ( Latin costae) are the long curved Bones which form the ribcage. The medial border of the Scapula ( vertebral border, medial margin) is the longest of the three borders and extends from the medial to the | It fixes the scapula into the thoracic wall and aids in rotation and abduction of the shoulders. |
| subclavius | Located inferior to the clavicle, originating on the first rib and inserting (penetrating) on the subclavian groove of the clavicle. The Subclavius is a small triangular muscle placed between the Clavicle and the First rib. The first rib is the most curved and usually the shortest of all the Ribs; it is broad and flat its surfaces looking upward and downward and its borders inward and outward On the medial part of the Clavicle is a broad rough surface the costal tuberosity (rhomboid impression rather more than 2 cm | It depresses the lateral clavicle and also acts to stabilize the clavicle. |
| pectoralis minor | Arises from the third, fourth, and fifth ribs, near their cartilage and inserts into the medial border and upper surface of the coracoid process of the scapula. The Pectoralis minor is a thin triangular muscle situated at the upper part of the Chest, beneath the Pectoralis major. The coracoid process is a small finger-like structure on the upper lateral corner of the Scapula. | This muscle aids in respiration, medially rotates the scapula, protracts the scapula, and also draws the scapula inferiorly. |
| sternocleidomastoid | Attaches to the sternum (sterno-), the clavicle (cleido-), and the mastoid process of the temporal bone of the skull. In Human Anatomy, the sternocleidomastoid (pronounced /ˌstɚ The sternum (from Greek στέρνον sternon, "chest" or breastbone) is a long flat Bone located in the center of the thorax (chest The Mastoid process is a conical prominence projecting from the undersurface of the Mastoid portion of the temporal bone. The temporal bones are situated at the sides and base of the Skull. | Most of its actions flex and rotate the head. In regards to the shoulder, however, it also aids in respiration by elevating the sternoclavicular joint when the head is fixed. |
| levator scapulae | Arises from the transverse processes of the first four cervical vertebrae and inserts into the vertebral border of the scapula. The levator scapulae is situated at the back and side of the neck In Vertebrates cervical vertebrae (singular vertebra) are those vertebrae immediately behind (posterior to the Skull. The medial border of the Scapula ( vertebral border, medial margin) is the longest of the three borders and extends from the medial to the | It is capable of rotating the scapula downward and elevating the scapula. |
| rhomboid major and rhomboid minor (work together) | They arise from the spinous processes of the thoracic vertebrae T1 to T5 as well as from the spinous processes of the seventh cervical and first thoracic vertebrae. The rhomboid major is a muscle on the back that connects the Scapula with the Vertebrae of the Spinal column. The Rhomboideus minor arises from the lower part of the Ligamentum nuchæ and from the Spinous processes of the Seventh cervical and first Thoracic The spinous process of a Vertebra is directed backward and downward from the junction of the laminae (in humans and serves for the attachment of Muscles The 12 thoracic vertebrae compose the middle segment of the Vertebral column, between the Cervical vertebrae and the Lumbar vertebrae. They insert on the medial border of the scapula, from about the level of the scapular spine to the scapula's inferior angle. The inferior angle of the Scapula, thick and rough is formed by the union of the vertebral and axillary borders its dorsal surface affords attachment to the Teres major | They are responsible for downward rotation of the scapula with the levator scapulae, as well as adduction of the scapula. |
| trapezius | Arises from the occipital bone, the ligamentum nuchae, the spinous process of the seventh cervical, and the spinous processes of all the thoracic vertebrae, and from the corresponding portion of the supraspinal ligament. In Human anatomy, the trapezius is a large Superficial Muscle which extends longitudinally from the occipital bone to the lower thoracic vertebrae The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoid in shape and curved on itself The Nuchal ligament ( Ligamentum Nuchae in Latin) is a fibrous membrane which in the neck represents the Supraspinal ligaments of the lower vertebræ The supraspinal ligament ( supraspinous ligament) is a strong fibrous cord which connects together the apices of the Spinous processes from the Seventh cervical It inserts on the lateral clavicle, the acromion process, and into the spine of the scapula. The acromion process, or simply the acromion (from Greek akros, "highest" ōmos, "shoulder" is an anatomical feature The spine of the scapula is a prominent plate of Bone, which crosses obliquely the medial four-fifths of the dorsal surface of the Scapula at its upper part and separates | Different portions of the fibers perform different actions on the scapula: depression, upward rotation, elevation, and adductions. |
| deltoid, anterior fibers | Arises from the anterior border and upper surface of the lateral third of the clavicle. In Human anatomy, the deltoid muscle is the Muscle forming the rounded contour of the Shoulder. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species | The anterior fibres are involved in shoulder abduction when the shoulder is externally rotated. The anterior deltoid is weak in strict transverse flexion but assists the pectoralis major during shoulder transverse flexion / shoulder flexion (elbow slightly inferior to shoulders). The Pectoralis major (popularly known as pecs) is a thick fan-shaped muscle situated at the upper front ( Anterior) of the Chest wall |
| deltoid, middle fibers | Arises from the lateral margin and upper surface of the acromion. In Human anatomy, the deltoid muscle is the Muscle forming the rounded contour of the Shoulder. The acromion process, or simply the acromion (from Greek akros, "highest" ōmos, "shoulder" is an anatomical feature | The middle fibres are involved in shoulder abduction when the shoulder is internally rotated, are involved in shoulder flexion when the shoulder is internally rotated, and are involved in shoulder transverse abduction (shoulder externally rotated) -- but are not utilized significantly during strict transverse extension (shoulder internally rotated). |
| deltoid, posterior fibers | Arises from the lower lip of the posterior border of the spine of the scapula, as far back as the triangular surface at its medial end. In Human anatomy, the deltoid muscle is the Muscle forming the rounded contour of the Shoulder. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species The spine of the scapula is a prominent plate of Bone, which crosses obliquely the medial four-fifths of the dorsal surface of the Scapula at its upper part and separates | The posterior fibres are strongly involved in transverse extension particularly since the latissimus dorsi muscle is very weak in strict transverse extension. 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 Trapezius on its median The posterior deltoid is also the primary shoulder hyperextensor. |
Rotator cuff
The rotator cuff is a structure composed of tendons that, with associated muscles (supraspinatus, infraspinatus, teres minor and subscapularis), holds the ball at the top of the humerus in the glenoid socket and provideoulder joint. The rotator cuff (rotor cuff is an anatomical term given to the group of Muscles and their Tendons that act to stabilize the Shoulder. The rotator cuff (rotor cuff is an anatomical term given to the group of Muscles and their Tendons that act to stabilize the Shoulder. The supraspinatus is a relatively small muscle of the upper limb that takes its name from its origin from the Supraspinous fossa superior to the spine of the Scapula The Infraspinatus muscle is a thick triangular Muscle, which occupies the chief part of the Infraspinatous fossa. The Teres minor is a narrow elongated muscle of the Rotator cuff. The Subscapularis is a large triangular muscle which fills the Subscapular fossa. The tendons of the rotator cuff muscles also connect to the capsule of the glenohumeral joint.
Two filmy sac-like structures called bursae permit smooth gliding between bone, muscle, and tendon. A bursa (plural bursae or bursas; Latin: Bursa synovialis) is a small fluid-filled sac made of white fibrous tissue and lined with Synovial They cushion and protect the rotator cuff from the bony arch of the acromion.
Measurement of shoulder loads
For understanding normal and pathologic shoulder function knowledge of forces in the glenohumeral joint is essential. It forms the basis for performing fracture treatment or joint replacement surgery, for optimizing implant design and fixation and for improving and verifying analytical biomechanical models of the shoulder. With instrumented shoulder implants developed at the Julius Wolff Institut (Charité Berlin) the joint contact forces and moments can be measured in vivo[3] during different activities.
Additional images
 The left shoulder and acromioclavicular joints, and the proper ligaments of the scapula. |
Medical problems
See also
References
- ^ eMedicine/Stedman Medical Dictionary Lookup!. Shoulder problems, including Pain, are one of the more common reasons for physician visits for musculoskeletal symptoms Rotator cuff tears are tears of one or more of the four Tendons of the Rotator cuff muscles The phrase "having a chip on one's shoulder " means having a harboured grievance and being quick to take offence Retrieved on 2008-01-17. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 38 BC - Octavian marries Livia Drusilla. 1287 - King Alfonso III of Aragon invades Minorca
- ^ eMedicine/Stedman Medical Dictionary Lookup!. Retrieved on 2008-01-17. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 38 BC - Octavian marries Livia Drusilla. 1287 - King Alfonso III of Aragon invades Minorca
- ^ Instrumented shoulder implant, Julius Wolff Institut, Berlin
- Calais-Germain, Blandine. "Anatomy of Movement", Eastland Press, 1993. ISBN 0-939616-17-3
- Martini, Frederic; Timmons, Michael; McKinnley, Michael. "Human Anatomy", 3rd Edition, Prentice-Hall, 2000. ISBN 0-13-010011-0
The Chip-on-the-shoulder is what happens when people get in car-crashes, and their shoulders chip or flake in abnormal ways, and prohibit the normal functioning of the shoulder and its associated muscles.
External links
- Video of the shoulder carriage in motion
- NIH (article includes text from this source)
- Video of shoulder surgery, showing interior anatomy of shoulder
Dictionary
shoulder
-noun
- (anatomy) The joint between the arm and the torso, sometimes including the surrounding area.
- A part of a road where drivers may stop in an emergency; a hard shoulder (UK)
-verb
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