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Shoulder girdle

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The shoulder girdle is also known as the pectoral girdle , and it is itself a bony ring, incomplete later. The shoulder girdle is made up of two sets of bones : the scapulae , located posteriorly, the clavicles anteriorly and previously completed by the manubrium of the sternum .

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What is the shoulder girdle?

The shoulder girdle is a set of bones that is responsible for connecting the upper limb with the axial skeleton on the left and right side of the body and serves as a connection for the muscles of the upper back , chest and neck .

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  • Characteristics of the shoulder girdle
  • Function
  • Muscles
  • Shoulder Girdle Joints
  • Bones
  • Movements
  • Shoulder girdle injuries
  • Training

Characteristics of the shoulder girdle

The main characteristics of the shoulder girdle are the following:

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  • The shoulder girdle is made up of the bones of the clavicle and scapula .
  • The waist extends from the base of the neck to the lower edge of the pectoralis major muscle .
  • It is divided into three different regions: anterior or axillary , middle or deltoid, and posterior or scapular .
  • It contains the greatest amount of movement of all the joints of the body.
  • It is the proximal segment of the upper limb.

Function

The shoulder girdle function is to fix the joint glenohumeral to the trunk of the human body, it is the means of communication between the upper member or torá cico and trunk . It is also responsible for connecting the upper limb with the axial skeleton.

Muscles

The muscles that are located in the shoulder girdle are the following:

  • Angular muscle of the shoulder blade : it begins at the vertebral edge of the scapula and its function is to stabilize the lateral movements of the body and raise the scapula.
  • Biceps brachii muscle : It has two heads: the long head and the short head. Helps the code and shoulder flex, helps shoulder separation and supination of the forearm.
  • Coracobrachialis muscle : it is a speed muscle and participates in balance.
  • Deltoid muscle : located in the upper arm and shoulder. It originates from the clavicle, acromium, and spinous process of the scapula. Participates in flexion of the shoulder and internal rotation and extension of the shoulder.
  • Latissimus dorsi muscle : it is long and wide, its fibers are ascending and it has a function of extension of the arm, of approximation and internal rotation.
  • Sternocleidomastoid muscle : it is long and goes from the thorax to the base of the skull. It originates in the mastoid process of the temporal bone and its function is to rotate the head, lateral tilt, cervical flexion, and cranial extension.
  • Infraspinatus muscle : it has an external rotator function.
  • Omohyoid muscle : reaches the base of the tongue.
  • Pectoralis major muscle : it goes from the shoulder to the sternum. It is an important muscle for adduction and anteversion of the shoulder joint.
  • Pectoralis minor muscle : its function is to bring the shoulder blade forward and down.
  • Teres Major muscle : it has the function of adductor, internal rotator and extensor.
  • Teres minor muscle : it is an external rotator.
  • Serratus Major muscle : its function is to maintain a solid point of the shoulder blade, its separation and rotation.
  • Subscapularis muscle : it acts as an internal rotator.
  • Supraspinatus muscle : it has an abductor function.
  • Trapezius muscle : it is in the area of ​​the spine . Helps move, rotate and stabilize the scapula and extend the head into the neck.

Shoulder Girdle Joints

The joints that we can find in the shoulder girdle are the following:

  • The scapulohumeral joint or glenohumeral joint : it is located between the head of the humerus and the scapula . It is shaped like a ball and is a synovial joint and allows adduction , abduction , medial and lateral rotation , flexion and extension of the arm.
  • The acromioclavicular joint : it is between the acromion of the scapula and the lateral end of the clavicle and is a synovial joint. Rotates at the acromial end of the clavicle.
  • The sternoclavicular joint : it is the articulation of the manubrium of the sternum and the costal cartilage . It is a type of spherical synovial chair . It adapts to a wide range of movements.
  • The scapulo-costal joint : It is also known as the scapulothoracic joint and is formed between the scapula and the thoracic wall . It is musculoskeletal in nature and is made up of the trapezius, rhomboids, and serratus anterior muscles. Perform sliding movements.
  • The supra humeral joint: it  is also known as the subacromial joint and is a physiological joint formed by a joint of the coracoacromial ligament and the head of the humerus . This joint acts on complex movements, while the arm is fully flexed at the shoulder joint.

Bones

The bones that make up the shoulder girdle are:

  • Clavicle : these are two long bones that run horizontally. They are very superficial and are located in the upper part of the thorax . They have double curvature and are flattened at their lateral ends. They have an anchoring function for various muscles and keep the arms in their lateral position. It is not a strong bone and is very sensitive to muscle pull .
  • Scapula : they are also called shoulder blades and are triangular shaped bones that are located posterior to the number 2 and 7 ribs. It is formed by three edges, the superior , the medial or vertebral and the lateral or axillary border . It also has three angles, the top , the side and the bottom .

Movements

There are three types of movements of the shoulder girdle, which are related to each other, and are:

  • Lateral movements that depend on the rotation of the clavicle.
  • Vertical movements .
  • Rotational movements called «bell».

Shoulder girdle injuries

Some of the most common injuries to the shoulder girdle are:

  • Clavicle dislocations
  • Shoulder dislocation
  • Elbow dislocation
  • Scapula, clavicle and humerus fractures
  • Sternoclavicular injury

Training

Some exercises that can be performed to maintain the shoulder girdle are:

  • Isometric shoulder : the arm should be stretched out and the closed hand supported in supination on a hard surface. Then you should push down and hold that position for a few seconds.
  • Fist to opposite knee : In a normal position, the fist is brought towards the opposite knee, flexing and twisting the trunk and then returning to the normal position to complete one repetition.
  • Scapular retraction : in a squat position, the arms are extended towards the knees slightly bent, the hands towards the chest extending the knees and the elbows are brought as far back as possible.

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