Normal Anatomy of the Shoulder Joint
The shoulder is the most flexible joint in the body making it the most susceptible to instability and injury. It is a ‘ball-and-socket’ joint. A ‘ball’ at the top of the upper arm bone, humerus, fits neatly into a ‘socket’, called the glenoid, which is part of the shoulder blade, scapula.
The shoulder joint is made up several bones and soft tissues. It has three bones, the collarbone (clavicle), scapula, and humerus.
Humerus provides attachment to muscles of the upper arm. Scapula is the bone that connects the upper arm bone with the collarbone. It is a flat bone and roughly triangular in shape and provides attachment to the muscles of back and neck.
The clavicle is an S-shaped short bone that connects the shoulder girdle to the body (trunk). It supports the shoulder in a functional position with the axial skeleton so that the arm has maximum range of movement. It also protects major underlying nerves and blood vessels as they pass from the neck to the axilla.
The coracoid process is the extension of the scapula around the shoulder joint at the front portion of the scapula. The acromial process is the extension of scapula around the shoulder joint at the back that forms a roof, acromion.
Glenoid is the smooth shallow depression at the end of scapula that forms the socket of shoulder joint.
The soft tissues of shoulder joint include:
- Rotator cuff – A group of 4 tendons make rotator cuff and it holds the head of the humerus in the socket.
- Biceps Tendon – The biceps tendon is a long cord-like structure which attaches the biceps muscle to the shoulder and helps to stabilize the joint.
- Caraco Clavicular Ligament – This ligament connects the clavicle with the corocoid process of the scapula.
- Acromio Clavicular Ligament – It connects the clavicle with the acromion process.
- Glenoid Labrum – The Glenoid labrum is a ring of fibro cartilage surrounding the cavity of the scapula for stabilization of the shoulder joint.
- Articular Cartilage or the Capsule – It is a capsule that surrounds the shoulder joint and helps to keep the ball and socket normally aligned.
The term arthritis literally means inflammation of a joint, but is generally used to describe any condition in which there is damage to the cartilage. Damage of the cartilage in the shoulder joint causes shoulder arthritis.
The shoulder joint is a ball and socket joint. A 'ball' at the top of the upper arm bone (the humerus) fits neatly into a 'socket', called the glenoid, which is part of the shoulder blade (scapula). The term SLAP (superior –labrum anterior-posterior) lesion or SLAP tear refers to an injury of the superior labrum of the shoulder. The labrum is a ring of fibrous cartilage surrounding the glenoid for stabilization of the shoulder joint.
The shoulder joint (glenohumeral joint) is a ball and socket joint, where the head of the upper arm bone (humerus) attaches to the shoulder socket (glenoid cavity). The shoulder socket is extremely shallow and therefore needs additional support to keep the shoulder bones from dislocating.
Shoulder Injuries in the Throwing Athlete
Shoulder injuries in baseball players are usually associated with pitching. While this overhand throwing activity can produce great speed and distance for the ball, when performed repeatedly, it can place a lot of stress on the shoulder.
Acromioclavicular joint (AC joint) dislocation or shoulder separation is one of the most common injuries of the upper arm. It involves separation of the AC joint and injury to the ligaments that support the joint. The AC joint forms where the clavicle (collarbone) meets the shoulder blade (acromion).
The forearm is made up of 2 bones namely the radius and ulna. The primary function of your forearm is rotation i.e., the ability to turn your palms up and down. The fracture of the forearm affects the ability to rotate your arm, as well as bend and straighten the wrist and elbow. The breaking of the radius or ulna in the middle of the bone requires a strong force and it is most commonly seen in adults. In most of the cases, both bones are broken during a forearm fracture.
Shoulder instability is a chronic condition that causes frequent dislocations of the shoulder joint.
A dislocation occurs when the end of the humerus (the ball portion) partially or completely dislocates from the glenoid (the socket portion) of the shoulder. A partial dislocation is referred to as a subluxation whereas a complete separation is referred to as a dislocation.
Rotator Cuff Tear
Rotator cuff is the group of tendons in the shoulder joint providing support and enabling wider range of motion. Major injury to these tendons may result in tear of these tendons and the condition is called as rotator cuff tear. It is one of the most common causes of shoulder pain in middle aged adults and older individuals.
Shoulder impingement is the condition of inflammation of the tendons of the shoulder joint. It is one of the most common causes of pain in the adult shoulder. The shoulder is a 'ball-and-socket' joint. A ‘ball' at the top of the upper arm bone, humerus, fits neatly into a 'socket’, called the glenoid, which is part of the shoulder blade, scapula. Shoulder impingement is also called as swimmer’s shoulder, tennis shoulder, or rotator cuff tendinitis.
Rotator Cuff Repair
Rotator cuff is the group of tendons in the shoulder joint providing support and enabling wider range of motion. Major injury to these tendons may result in tear of these tendons and the condition is called as rotator cuff tear. It is one of the most common causes of shoulder pain in middle aged adults and older individuals. It may occur with repeated use of arm for overhead activities, while playing sports or during motor accidents.
Shoulder instability is a chronic condition that causes frequent dislocations of the shoulder joint. A dislocation occurs when the end of the humerus (the ball portion) partially or completely dislocates from the glenoid (the socket portion) of the shoulder. A partial dislocation is referred to as a subluxation whereas a complete separation is referred to as a dislocation.
The shoulder joint provides a wide range of movement to the upper extremity but overuse or trauma can cause instability to the joint. The Latarjet procedure is a surgical procedure performed to treat shoulder instability by relocating a piece of bone with an attached tendon to the shoulder joint.
Arthroscopy is a minimally invasive diagnostic and surgical procedure performed for joint problems. Shoulder arthroscopy is performed using a pencil-sized instrument called an Arthroscope. The arthroscope consists of a light system and camera to project images to a computer screen for your surgeon to view the surgical site. Arthroscopy is used to treat disease conditions and injuries involving the bones, cartilage, tendons, ligaments, and muscles of the shoulder joint.
Shoulder Joint Replacement
The shoulder is a highly movable body joint that allows various movements of the arm. It is a ball and socket joint, where the head of the humerus (upper arm bone) articulates with the socket of the scapula (shoulder blade) called the glenoid. The two articulating surfaces of the bones are covered with cartilage, which prevents friction between the moving bones.