What is the structure and function of the shoulder joint?
The glenohumeral joint is what most people think of as the shoulder joint. It's the major joint in the shoulder, where the rounded top, or head, of the humerus, nestles into a rounded socket of the scapula, called the glenoid. This ball-and-socket construction allows for circular movement of the arm.
What is the action of the shoulders?
The shoulder's main motions are flexion, extension, abduction, adduction, internal rotation, and external rotation. Muscles of the shoulder. Encyclopædia Britannica, Inc. Shoulder flexion is movement of the shoulder in a forward motion.
Where is the shoulder joint?
The shoulder joint is where the humerus (upper arm bone) meets the scapula (shoulder blade). Muscles and ligaments help make up the joint. They attach to the shoulder blade and upper arm bone. At the top of the shoulder blade are two bony knobs called the acromion and coracoid process.
What type of joint is shoulder joint?
ball-and-socket synovial jointThe glenohumeral joint is a highly moveable ball-and-socket synovial joint that is stabilized by the rotator cuff muscles that attach to the joint capsule, as well as the tendons of the biceps and triceps brachii. The humeral head articulates with the glenoid fossa of the scapula.
How do you remember shoulder actions?
Mnemonic: Interlock the 2 fingers of both hands as shown in the fingure above. 2 fingers oriented upwards represent Humerus and Triceps long head. 2 fingers oriented laterally represent Teres minor and Teres major. Remember that all these 3 muscles attach on the lateral border of dorsal scapula.
What muscles do shoulder flexion?
The muscles involved in the flexion movement include the anterior deltoid, pectoralis major and coracobrachialis. For a shoulder extension, your body uses the latissimus dorsi, teres major and minor and posterior deltoid muscles.
What is shoulder flexion?
Shoulder flexion Flexion is a movement that decreases the angle between the two parts that the joint is connecting. If you hold your arms straight and palms against your sides and raise your arms in front of your body to point your hands at something in front of you, you're practicing flexion.
What muscles rotate shoulders?
The teres minor muscle externally rotates the shoulder; It is considered a fusiform muscle. The teres major provides internal rotation, extension, and adduction of the shoulder; it's considered a fusiform muscle.
What is GH joint?
Glenohumeral Joints (GH Joints) are right synovial diarthrodial joints with the ball and socket, which are responsible for the connection of the upper part of the body trunk. This joint formed by an attachment of humeral head and the glenoid fossa of the scapula. Remember that the glenoid fossa is flat, while the humerus bone is a large and round hemisphere. This bone conformation, combined with a highly mobile scapula, allows for full movement in all three planes but does not increase high-level stability.
What is the joint that covers the glenoid socket?
A flexible joint called the ball, and socket joints formed by humerus and scapula. This joint gets lined with cartilage that covers the face of the glenoid socket and the humeral head. The joint stabilize by a fibrous cartilage ring (labrum) around the glenoid socket.
What is shoulder joint?
Shoulder joints are an extraordinary combination of healthy bones, flexible ligaments and tendons, and healthy cartilage and muscles . It’s very flexible and allows lots of motions in a wide range. However, this complex structure also tends to wear out quickly, causing arthritis pain and possible injury to one of the structures.
What is the sternoclavicular joint?
The sternoclavicular joint (SC joint) forms by the articulation of the medial aspect of the clavicle and the sternum manubrium. This joint is the only direct attachment of bone to the upper body to the axial skeleton, and the connection must be stable at the same time while allowing high mobility.
Is the scapula a right or left connection?
Although this is a scapulothoracic joint, the articulation between the scapula and the thorax is not a right connection because it does not have the characteristics of fibrous, cartilage or synovial joints. It is an articulation of the anterior aspect of the scapula in the posterior thorax.
What are the bursae around the shoulder?
The most important bursae around the shoulder joint are subacromial and subscapular bursae. The subacromial bursae support the muscles around it, like deltoid and supraspinatus, while the subscapular bursae reduce the muscular damage around the shoulder joint during the joint mobility. 6. Nervous and Blood Supply.
What is the function of the rotator cuff?
The rotator cuff connects humerus to scapula in such a way, so as to fit the humeral head strong against the small glenoid socket of scapula. The rotator cuff not only helps with the stabilization of the shoulder joint anatomy, but also helps to prevent the damage caused by the shoulder joint dislocation.
What are the bones of the shoulder?
Below we will reveal the shoulder joint anatomy. 1. Bones. The humerus and scapula are two main bones forming the shoulder joint anatomy. The ball-like head of humerus gets loosely fit into the glenoid socket of the scapula, which is attributed mainly to the larger size of the head of humerus in comparison to the glenoid socket of scapula.
How many ligaments are there in the shoulder?
Ligaments around the shoulder joint further stabilize the joint anatomy and the movements around it. There are three glenohumeral ligaments and one coracoacromial ligament. The later joins the coracoids process of scapula to the humerus as the name suggests.
What is the most important cartilage in the shoulder joint?
2. Cartilage. Labrum, the most important articular cartilage, lies between the humerus head and glenoid fossa of the shoulder joint.
What is the most important joint in the human body?
Shoulder Joint Anatomy. The shoulder joint is one of the most important and freely moveable joints between the axial and the upper appendicular part of human body. Two main joints—the glenohumeral joint and the acromioclavicular joint in the shoulder help with the smooth motion for arms. The glenohumeral joint is responsible for most shoulder ...
What is joint capsule?
The joint capsule is a fibrous sheath the bounds and embeds the joint structures, which extends from the neck of humerus to the edges of glenoid cavity. The joint capsule is loosely attached so as to provide maximum movement around the shoulder joint.
How many heads does the bicep have?
The biceps actually has two (i.e. bi ceps) heads and thus two attachments around the shoulder. The short head of the biceps comes from the coracoid process. The long-head of the biceps tendon runs in the groove between the two tuberosities of the humerus on the front of the shoulder and attaches to the upper end of the glenoid labrum inside the glenohumeral joint (see joint anatomy below). The biceps attaches to the radius bone in the forearm and allows us to bend our elbow and bring our hand from a palm-down position to a palm-up position (supination).
What are the layers of the shoulder?
Starting with what is deepest, it goes: bone, then ligaments of the joint capsule, with tendons and muscles on top. There are many nerves and blood vessels that supply the muscles and bones of the shoulder. Nerves are like electrical wires that carry signals from the brain to the muscles to allow for movement of the shoulder. They also carry signals from the shoulder back to the brain about pain, pressure and temperature.
Which ligaments help stabilize the shoulder joints?
These are the main ligaments that help to stabilize the joints of the shoulder: Acromioclavicular ligaments ( several) and coracoclavicular ligaments (there are two: trapezoid and conoid).
Where does the short head of the biceps tendon come from?
The short head of the biceps comes from the coracoid process. The long-head of the biceps tendon runs in the groove between the two tuberosities of the humerus on the front of the shoulder and attaches to the upper end of the glenoid labrum inside the glenohumeral joint (see joint anatomy below).
What is the most complex of the shoulder bones?
The scapula is the most complex of the shoulder bones. It floats on the rib cage and is attached to it only by muscles. There are three important landmarks on the scapula: the spine of the scapula, the acromion, and the coracoid process.
Which joint is the most important for shoulder motion?
Of these, the glenohumeral joint is the most important for shoulder motion. It is this joint that most people commonly think of as the shoulder joint. The glenohumeral joint (GH) – a ball-and-socket type joint where the head of the humerus (ball) meets the glenoid (socket) on the scapula.
What is the function of 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.
