What is unique about the shoulder?

The shoulder is a unique and complex joint. The shoulder needs a high degree of flexibility, but it also needs to remain stable in multiple planes of motion. To accomplish this, the shoulder joint is supported by a combination of bones, ligaments, and muscles.

Why is the shoulder joint unique?

The anatomy of the shoulder is unique – it has a relatively shallow socket which results in amazing flexibility and range of motion to the shoulder joint which is unparalleled elsewhere in the body.

What are the key features of the shoulder joint?

The shoulder is made up of two joints, the acromioclavicular joint and the glenohumeral joint. The acromioclavicular joint is where the acromion, part of the shoulder blade (scapula) and the collar bone (clavicle) meet. The glenohumeral joint is where the ball (humeral head) and the socket (the glenoid) meet.

Why is the shoulder joint so important?

The glenohumeral joint, also known as the shoulder joint, is a ball-and-socket joint that connects the upper arm to the shoulder blade. This joint allows free movement of the arm so that it can rotate in a circular fashion.

Why is the shoulder the weakest joint?

The shoulder is the most movable joint in the body. But it is also an unstable joint because of its range of motion. Because the ball of the upper arm is larger than the socket of the shoulder, it is at risk of injury. The shoulder joint is supported by soft tissues.

What is abduction of the shoulder?

Shoulder abduction



Abduction occurs when you have arm movement away from the middle of your body. When you raise your arm out from the sides of your body, it’s an abduction of your shoulder. A normal range for abduction, starting with your palms at your sides, is around 150 degrees in a healthy shoulder.

What are the muscles responsible for the different movements of the shoulder joint?

The primary muscle group that supports the shoulder joint is the rotator cuff muscles. The four rotator cuff muscles are the supraspinatus, infraspinatus, teres minor, and subscapularis. Together the rotator cuff muscles form a musculotendinous cuff as they insert on the proximal humerus.

What is a shoulder?

The shoulder is the group of structures in the region of the joint. The shoulder joint is the main joint of the shoulder. 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.

Why is the shoulder so mobile?

The shoulder also has ligaments—structures that attach bone to bone, which also act to restrain movement. While these structures provide stability to the joint, the shoulder is also very dependent on what is called “dynamic stability” or in other words, stability provided by muscle contraction.

Which type of movement is unique to the forearm?

Which type of movement is unique to the forearm? Supination and pronation are unique to the forearm because of the arrangement of the radius and ulna. This allows rotation of our hand in space.

What kind of joint is the shoulder?

ball-and-socket synovial joint

The glenohumeral joint is the main articulation of the shoulder joint. It is the multiaxial ball-and-socket synovial joint formed by the articular surfaces of the glenoid cavity and the head of the humerus.

How do you get stronger shoulders?

Best Shoulder Exercises

  1. Overhead Press. Why It’s Great: All-in-one exercise for building strong shoulders. …
  2. Dumbbell Shoulder Press. Why It’s Great: Fantastic for training strength and working with greater ranges of motion. …
  3. Landmine Press. …
  4. Arnold Press. …
  5. Push Press. …
  6. Bottoms Up Kettlebell Press. …
  7. Banded/Cable Delt Raises.


Is the shoulder joint strong?

The shoulder joint is a remarkable combination of strong bones, flexible ligaments and tendons, and strong cartilage and muscles. It is designed to be incredibly flexible, enabling a wide range of motion.

What is the top of the shoulder called?

Glenohumeral joint.



This joint is considered the main joint in the shoulder and is where the rounded top, or head, of the humerus (arm bone) nestles into the shallow, rounded socket of the scapula (shoulder blade) like a golf ball on a tee.

Why is the shoulder joint so flexible?

The shoulder joint is the body’s most flexible joint: A group of four muscles holds the head of the upper arm bone in the relatively flat shoulder socket (glenoid). Each of these muscles has a tendon that attaches it to the bone. Together, this group of muscles and tendons is known as the rotator cuff.

How do shoulders work?


There are actually four joints that make up the shoulder. The main shoulder joint called the glenohumeral joint is formed where the ball of the humerus fits into a shallow socket on the scapula.

Where are your shoulders?

The shoulder joint is the junction between the chest and the upper extremity. Two joints are at the shoulder. The glenohumeral joint is the ball-and-socket junction of the top of the arm bone, and the socket of the shoulder blade.

What is the shoulder blade called?

scapula

The scapula, or shoulder blade, is a large triangular-shaped bone that lies in the upper back. The bone is surrounded and supported by a complex system of muscles that work together to help you move your arm.

How do shoulders rotate?

The teres major provides internal rotation, extension, and adduction of the shoulder; it’s considered a fusiform muscle. The subscapularis muscle internally rotates the humerus; the upper portion of the muscle influences abduction, while the lower area influences adduction. It is considered a multipennate muscle.

What is flexion of shoulder?

A shoulder flexion is when you move your arms anywhere from a resting position by your sides to straight above your head. An extension is when you move your arms and stick them out behind you. The muscles involved in the flexion movement include the anterior deltoid, pectoralis major and coracobrachialis.

What limits shoulder flexion?

Muscles that can limit shoulder flexion are: Pectoralis Major/Minor. Teres Major. Latissimus Dorsi.

What is shoulder horizontal abduction?

Reach forward to place your hands directly in front of you at shoulder height. Keep your palms down. Reach out to the sides of your body with both hands at the same time. Hold for a count of three to five seconds and repeat 10 times. Increase by three repetitions each week until you can easily do 20 repetitions.

What is shoulder horizontal flexion?

Horizontal flexion: this only happens at the shoulder joint and occurs in the transverse plane. When an arm is held out to the side parallel to the floor and then pulled across the chest, that would be horizontal flexion.

What is shoulder circumduction?

Circumduction is the orderly combination of shoulder movements so that the hand traces a circle and the arm traces a cone. In order it is produced by shoulder flexion, abduction, extension and abduction (or the reverse).

What muscles are used in adduction of the shoulder?

Adduction is accomplished primarily by the pectoralis major, latissimus dorsi, teres major, triceps, and coracobrachialis. The deltoid and the supraspinatus, a muscle that runs along the scapula in the back, are the two main abductors of the shoulder.

What is muscle under armpit called?

Pectoralis major: This large fan-shaped muscle stretches from the armpit up to the collarbone and down across the lower chest region. It connects to the sternum (breastbone). Pectoralis minor: The smaller of the pectoralis muscles, this muscle fans out from the upper ribs up to the shoulder area.

What muscle initiates abduction of the shoulder?

supraspinatus muscle

The supraspinatus muscle originates from the supraspinous fossa of the scapula, passes under the acromion, and inserts on the superior facet of the greater tubercle of the humerus. It is responsible for the initiation of arm abduction and is in control of the motion up to the first 15 degrees of abduction.