Shoulder joint is regarded as the most mobile joint in the body. It has movements in 3 different planes (directions): saggital = front to back, coronal = left to right, and transverse = top to bottom. In these planes of motion, the following movements are allowed:
- Flexion (bending the shoulder upwards)
- Medial rotation
- Lateral rotation
- Horizontal abduction and adduction
Movements in the frontal/coronal plane and around the sagittal axis include:
- Flexion (Bending shoulder forwards)
- Extension (Bending shoulder backwards)
- Hyperextension (Bending shoulder backwards more than in extension)
Movements around the transverse plane around the vertical axis:
- Medial/internal rotation
- Lateral/external rotation
- Horizontal abduction (about 90 degrees from the neutral position)
- Horizontal adduction (about 90 degrees from the neutral position)
Movements in the sagittal plane and around the frontal axis:
Circumduction on its own is not a specific movement but a combination of movements.
Function of the shoulder
The shoulder's main purpose is to position the hand in the most efficient way. The shoulder and the whole upper extremities help us to accomplish tasks in need.
Apart from the movements mention above, the shoulder girdle has some other motions in the joints. The motions are linear and angular. The linear motions involved are:
- Shoulder elevation/scapular elevation: This is scapula movement that involves the shoulder blade moving upwards. This movement is mainly done by the levator scapula because it has a great vertical effect based on its angle of pull.
- Shoulder depression: This movement involves all points of the scapula moving downwards.
- Shoulder retraction: In this motion, the scapula moves towards the vertebral column. The prime mover in this motion is the middle trapezius.
- Shoulder protraction: The scapula moves away from the vertebral column.
The angular motions of the shoulder girdle include:
- Upward rotation: This movement involves the inferior border of the scapula moving up and away from the spine.
- Downward rotation: This involves the inferior border of the scapula returning back to the neutral/anatomical/resting position.
- Scapula tilting: This movement is usually noticed while hyperextending the shoulder joint. The upper end of the scapula tilts forwards(anteriorly) and the lower end tilts posteriorly(backwards). One simple real life example that portrays scapula tlting is when doing a race dive during swimming.
The shoulder complex
Figure 2: Shoulder Complex. (Adapted from Lippert, L, Clinical Kinesiology & Anatomy, 4th Edition)
When taking about shoulder movements, one must remember that shoulder movement comes from different joints and structures. All of the joints form what is callled the shoulder complex (shoulder girdle and the shoulder joint). The shoulder/pectoral girdle refers to the incomplete bony ring, formed by the clavicles and the scapulae, which supports the upper limb, attaching its appendicular skeleton to the axial skeleton, manubrium sterni (Stedman's Medical Elctronic Dictionary Ver 7.0). Muscles such as trapezius, levator scapula, rhomboids, serratus anterior and pectoralis minor are involved in shoulder girdle motions. Paralysis of serratus anterior muscle leads to a winging scapula, another shoulder girlde motion. The motions occur at sternoclavicular and acromioclavicular joints. These joint together with the muscles involved allow shoulder elevation and depression, protraction and retraction, and upward and downward
rotation. Shoulder complex consists of:
- scapula (shoulder blade)
- sternum (bone between ribs
- humerus (arm bone)
- rib cage
- sternoclavicular joints (oinnt between collar bone and the bone between ribs)
- glenohumeral joint (joint between the arm bone and shoulder blade)
- Scapulothoracic articulation
The scapulothoracic articulation is not neccessarily a joint but helps in providing flexibility and some motiont so the body.
General Assessment Guidelines
To competently manage shoulder problems, one must fully assess the shoulder to understandthe root cause of the problem that a patient or an athlete is presenting with. Shoulder assessment is complex and frightening owing to the complexity nature of the anatomical parts involved.
Despite the daunting nature of shoulder assessment, one can still crack it if a few steps are followed. These few steps will form a basic guidline on shoulder physical assessment. A general rule of physical assessment is Observe, Palpate, Move (OPM) or Look, Feel/Touch and Move.
The initial aspect of almost any physical assessment is observation. The observation includes a careful look at the landmarks of the shoulder:
- Deltoid muscle
- Supraspinatus muscle
- Infraspinatus muscle
- Teres Minor
Figure 3: Posterior Landmarks of the Shoulder
Figure 4: Anterior Landmarks of the the Shoulder
- Start with observation of the normal side.
- Take note of any scars
- Compare the shoulders if there are any asymmetry
- Is there any skin discoloration?
- Are the muscle bulk looking the same or there is muscle asymmetry?
Palpation is done for different reasons of which the common ones include:
- Reproduction of a concordant sign
- Taking note if there is muscle tightness, masses, trigger points, dislocation, etc
Range of Motion (ROM):
Range of motion can be active or passive. In active range of motion, a patient moves the limb without assistance while in passive range of motion the examiner moves the limb. Sometimes ROM can neither be active nor passive but active-assisted. In active assisted range of motion (AAROM), a patient moves the extremity with the help of an axaminer or a machine.
While testing the range of motion i.e. how far a patient can move their limb, take note if there is pain or limitation. When assessing range of motion, it is good practice to test both sides simultaneously but if the symptoms are there, iit is advisable to start with the norma side and then compare with the affected side.
- Start testing the normal side.
- Compare the range of the normal side with that of the affected side.
- Abduction: Determine if the patient can lift their arms smoothly untill tthe hands are above the head.
- Adduction and Internal rotation: Ask the patient to do Appley Scratch Test i.e. ask them to touch the tip end of the shoulder blade on the opposite side. (Touching inferior angle of the contralateral scapula). The lower border of the scapula corresponds to T7.
- Adduction and External rotation: Ask the patient to touch their spine behind the back as far as they can. Many people are able to reach C7.
- Forward Bending(Flexion) with elbows straight: Ask the patient to trace out an arc as far as they can. Take note on how much they can bend their shoulders upwards with elbows straight. Normal shoulders allow the patient to reach above their head. The normal ROM is 0 to 180 degrees.
- Extension: This is the reverse of Forward Flexion. Ask the patient to trace the arc downwards until their hands are behind their back.
Another form of range of motion (ROM) as already introduced above is passive range of motion (PROM). If AROM is pain free, you may proceed to PROM. Performing PROM helps to different if the pain was originating from contractile or non-coontractie structures in the shoulder. While performing PROM, one hand of the examiner is restd on the shoulder while the other takes the shoulder joint through the above directions, as done in the AROM above. If there is pain with PROM, you must note the movements causing it and take note if there is joint creptus too.
Pain or limitation with AROM but not with PROM may imply a structural problem with the contractil structures which are firing. This may be muscles or tendons.
Creptus while perfomring the ROM may imply presence of a degenerative joint disease (DJD).
It is important to note where and in which direction the limitation in movement is. Take not of the point of limitation in the arc and determine if the limitation is due to pain or weakness.
Compare findings of the affected side to the unaffected side and determine the cause of the problem using different orthopaedic shoulder tests here.