Under what conditions will two forces form a couple?
If there are two forces which are equal and opposite they form a couple. Couple: When two forces of equal magnitude opposite in direction and acting along parallel straight lines, then they are said to form a couple. The perpendicular distance between the two force forming a couple is called the arm of the couple.
What joint is the shoulder girdle?
The shoulder girdle is composed of the clavicle and the scapula, which articulates with the proximal humerus of the upper limb. Four joints are present in the shoulder: the sternoclavicular (SC), acromioclavicular (AC), and scapulothoracic joints, and glenohumeral joint.
What are the 3 shoulder joints?
The shoulder is made up of three bones: the scapula (shoulder blade), clavicle (collarbone) and humerus (upper arm bone). Two joints in the shoulder allow it to move: the acromioclavicular joint, where the highest point of the scapula (acromion) meets the clavicle, and the glenohumeral joint.
How do I strengthen my shoulder girdle?
Bilateral External Rotation: Stand tall with shoulders down and back drawing the belly in towards the spine. With elbows at 90-degrees and resistance band in hands, gently open arms out to sides against resistance. Don’t let shoulders tilt forward — keep them down and back. This strengthens the rotator cuff muscles.
What is the difference between shoulder girdle and shoulder joint?
The shoulder is not a single joint, but a complex arrangement of bones, ligaments, muscles, and tendons that is better called the shoulder girdle. The primary function of the shoulder girdle is to give strength and range of motion to the arm. The shoulder girdle includes three bones—the scapula, clavicle and humerus.
How many ligaments are in your shoulder?
There are three glenohumeral ligaments which provide some support to the front of the shoulder joint; the superior, middle and inferior glenohumeral ligaments. The superior glenohumeral ligament works in conjunction with the coracohumeral ligament to stabilise the humeral head.
What is the main function of the shoulder?
The shoulder joint is the most mobile joint in the body. It moves the shoulder forward and backward. It also allows the arm to move in a circular motion and to move up and away from the body.
What are the 4 main ligaments of the shoulder?
Glenohumeral Ligaments (GHL): In the shoulder, the joint capsule is formed by a group of ligaments that connect the humerus to the glenoid. These ligaments are the main source of stability for the shoulder. They are the superior, middle and inferior glenohumeral ligaments.
What are the primary stabilizers of the shoulder?
The supraspinatus is the principal supporting and kinetic muscle of the shoulder. The primary function of the rotator cuff muscles is to stabilize the GH joint so that the larger shoulder movers (eg, deltoid, latissimus dorsi) can carry out their function without significant motion of the humeral head on the glenoid.
Which joint of the shoulder complex is the weakest?
The weakest area of the shoulder joint capsule is just anterior to the attachment of the long head of the triceps at the infraglenoid tubercle, and disloca- tions are most frequent in this inferior anterior region.