SPINE

The spine has three main sections, cervical, thoracic, and lumbar. There are seven cervical vertebrae (C1-C7), twelve thoracic (T1-T12), and five lumbar (L1-L5). In addition, there are two fused vertebrae, the sacrum and the coccyx. The twelve thoracic and five lumbar vertebrae make up the thoracolumbar spine.

The cervical spine supports the head and allows anterior, posterior, and lateral flexion and extension, plus rotation of the head and neck. C2, called the axis, forms a pivot with C1, called the atlas, around which the head rotates on the cervical spine. Normal curvature is lordotic (eyes pointing up).

The thoracolumbar spine (T1-L5) has two normal curvatures, lordotic in the lumbar region and kyphotic in the thoracic region. The primary spinal functions are to maintain an erect posture, provide stability and mobility, transmit loads, absorb shocks, and protect the spinal cord.

SHOULDER

The shoulder joints consist of the glenohumeral joint, acromioclavicular joint, sternoclavicular joint and the scapulothoracic joint, which is technically not a true joint. The bony structures consist of the humerus, scapula, and clavicle. Soft tissue includes muscles, for example the rotator cuff muscles (Supraspinatus, Infraspinatus, Subscapularis, and Teres Minor), several ligaments including the coracoclavicular (trapezoid and conoid), coracohumeral, and coracoacromial ligament and others, labrum, bursas and brachial plexus nerve. The shoulder joint is the most active and complex joint of the body. The capsule and ligament act as stabilizers, while the muscles and tendons play a dynamic role. Rhythmic cooperation of the shoulder joints ensures the smooth movement in all directions.

ELBOW

Elbow joints include ulnohumeral, radiohumeral and superior radioulnar joints. Numerous ligaments surround the joint capsule. The elbow joint itself is a simple hinge joint, consisting of the humerus, ulna and radius. The humerus and ulna bone shaft form an angle, called the "carrying angle". Normal carrying range angle is about 10¡ã to 15¡ã, with a higher degree among females than males on average.

WRIST

The wrist joint is a complex structure, consisting of eight carpal bones and the distal part of the ulnar and radial bones. These are the radiocarpal and midcarpal joints. The ulnar bone doesn't directly articulate with the carpal bones. The triangular fibrocartilaginous complex (TFCC) is located between the ulna and carpals. With the disc, the radius bears 60% of loading; without the disc, the radius transmits 95% of the loading.