Human Anatomy — all lessons
Foundations of Anatomy
Anatomical terminology, planes, axes and movement directionsThe Skeletal System
Skeletal system: structure and functionsBone structure, remodelling and adaptation to loadingJoints and the Muscular System
Joint types and classificationJoint mechanics: arthrokinematics and stabilityThe muscular system: organisation and major muscle groupsMuscle architecture: pennation, length and cross-sectional areaMuscle fibre typesRegional Functional Anatomy
Spine and postureThe shoulder complexThe hip complexThe knee complexThe ankle and foot complexCore and pelvic stabilityElbow and wrist functional anatomyCervical and thoracic spine functional anatomyThe shoulder complex
Four joints working as one — glenohumeral, scapulothoracic, acromioclavicular and sternoclavicular — with the rotator cuff, scapular muscles and scapulohumeral rhythm.
Learning objectives
- Identify the four joints of the shoulder complex and their roles
- Describe the rotator cuff and scapular stabilisers and their functions
- Explain scapulohumeral rhythm and scapular dyskinesis
- Apply shoulder anatomy to pressing, pulling and overhead training
Before this lesson
Why this matters
The shoulder trades stability for range. Understanding how its joints and muscles share work underpins safe pressing, pulling and overhead training, and sensible conversations with clients who have shoulder pain.
Fundamental concepts: four articulations
| Joint | Type | Role |
|---|---|---|
| Glenohumeral (GH) | Ball-and-socket | Most of arm motion; shallow glenoid deepened by the labrum |
| Acromioclavicular (AC) | Plane | Fine-tunes scapular position |
| Sternoclavicular (SC) | Saddle | Only bony link of arm to trunk |
| Scapulothoracic | Functional (not a true joint) | Scapula glides on the ribcage |
Muscles
- Rotator cuff — supraspinatus (initiates abduction, compresses head), infraspinatus and teres minor (external rotation), subscapularis (internal rotation). Together they keep the humeral head centred in the glenoid against the upward pull of the deltoid [neumann2017].
- Scapular muscles — serratus anterior and upper/lower trapezius upwardly rotate the scapula; rhomboids and middle trapezius retract; pectoralis minor tilts it anteriorly; levator scapulae elevates and downwardly rotates.
- Prime movers — deltoid, pectoralis major, latissimus dorsi, teres major.
Scapulohumeral rhythm
During arm elevation, the scapula upwardly rotates as the humerus elevates. Classic work described an overall ratio of about 2:1 (two degrees of GH motion for each degree of scapular motion) across full elevation [inman1944]. Later studies show the ratio varies across the range, between people and with load, so it is a description, not a target.
Scapular dyskinesis
Altered scapular position or motion (dyskinesis) is common in people with shoulder pain — and in many without. The 2013 Scapular Summit consensus recommended treating it as one possible contributing factor, assessed alongside other findings, rather than as a diagnosis in itself [kibler2013].
Practical application
Common mistakes and misconceptions
Case study
A recreational climber has front-of-shoulder pain during overhead presses but full, pain-free range. A physiotherapist identifies rotator-cuff-related pain; the trainer, following the physio’s plan, reduces overhead volume, adds progressive external rotation and serratus work, then gradually reintroduces pressing — documenting pain responses session by session.
Further learning: video lessons
Video links are only marked “verified” after a human has watched them. Unverified entries open a YouTube search for that channel and topic rather than a guessed link.
Shoulder complex anatomy
Kenhub
You will understand: the bones, joints and rotator cuff
Why: Clear 3D anatomy.
Scapulohumeral rhythm explained
Physiotutors
You will understand: how scapula and humerus move together during elevation
Why: Clinically focused explanation.
Knowledge check
Knowledge check · 0/5
1. Which muscle is NOT part of the rotator cuff?
2. The only bony attachment of the upper limb to the axial skeleton is the…
3. Upward rotation of the scapula during arm elevation is produced mainly by…
4. Subscapularis mainly performs…
5. Which statement about scapular dyskinesis is best supported?
Short-answer & application questions
- Describe the force couple between deltoid and rotator cuff during arm elevation.
- Which exercises would you choose to train upward rotators, and why?
- Explain why overhead athletes often have more external and less internal rotation in their dominant shoulder.
Key takeaways
- The shoulder complex comprises the glenohumeral, acromioclavicular, sternoclavicular and scapulothoracic articulations.
- The rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis) centres the humeral head; scapular muscles position the socket.
- During arm elevation, glenohumeral and scapular motion combine roughly 2:1 overall, though the ratio varies across range and individuals.
- Scapular dyskinesis is common in people with and without pain; it is a factor to consider, not a diagnosis.
Connected topics
Shoulder
anatomyCervical and thoracic spine functional anatomy
anatomyElbow and wrist functional anatomy
racquet sportsMovement patterns unique to racquet sports
References
- Neumann DA (2017). Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation (3rd ed.). Elsevier. Textbook check pending
- Inman VT, Saunders JB, Abbott LC (1944). Observations on the function of the shoulder joint. Journal of Bone and Joint Surgery, 26(1):1–30. Classic study check pending
- Kibler WB, Ludewig PM, McClure PW, et al. (2013). Clinical implications of scapular dyskinesis in shoulder injury: the 2013 consensus statement from the ‘Scapular Summit’. British Journal of Sports Medicine, 47(14):877–885. doi:10.1136/bjsports-2013-092425 Guideline check pending
Educational content only — not medical advice. Consult a qualified clinician for diagnosis or treatment.