A quick-read guide to the Glenohumeral (GH) Joint from The Arm Doc
Why you should care
- The most mobile joint in your body lets you throw, lift, swim, and climb.
- Also, the most frequently dislocated – mobility comes at a price.
- Common conditions we treat include dislocations, rotator cuff tears, frozen shoulder, and arthritis.
Anatomy in plain English
Part | What it is | Why it matters |
Ball | Humeral head (top of upper-arm bone) | Large, round, built for big arcs of motion. |
Socket | Glenoid of the shoulder blade | Shallow – think tea-cup on a saucer. |
Labrum | Rubber-y ring around the socket | Deepens the cup; anchor for ligaments & biceps tendon. |
Capsule & ligaments | Tough envelope with “safety belts” (superior, middle, inferior GH ligaments) | Keep the ball from slipping out – especially in specific positions. |
Rotator cuff | 4 small but mighty muscles/tendons | Dynamically suck the ball into the socket so the big muscles (deltoid, pec) can power movement. |
Bursae | Tiny, fluid-filled cushions | Cut down friction under the acromion & coracoid. |
Nerves & vessels | Axillary, suprascapular, lateral pectoral; ACHA/PCHA arteries | Injured nerves = weak deltoid; injured vessels = risk to bone health. |
How the shoulder stays put
- Static guards – labrum, capsule, ligaments, “suction-cup” joint pressure.
- Dynamic guards – rotator cuff fires first, periscapular muscles position the blade, long-head biceps helps when the cuff is tired or torn.
- Position matters –
- 0° abduction ➜ Superior GH ligament & coracohumeral ligament do the heavy lifting.
- 45° ➜ Middle GH ligament kicks in.
- 90° with the arm cocked back ➜ Inferior GH ligament (anterior band) is the MVP.
Movements & muscle line-up
Move | Main drivers | Normal ROM* |
Flexion | Ant. deltoid, pec major | 0 – 180° |
Extension | Post. deltoid, lats | 0 – 60° |
Abduction | 0-15° supraspinatus → deltoid to 90° → scapular rotators past 90° | 0 – 150° |
External rotation | Infraspinatus, teres minor | Up to 90° |
Internal rotation | Subscapularis, pec major, lats | 70 – 90° |
* Figures assume a healthy cuff and good scapular motion.
Trouble spots we see every day
Condition | Red-flag symptoms | Our playbook |
Anterior dislocation | Arm held at side, can’t rotate, shoulder looks “squared off.” | Gentle reduction ➜ sling ➜ stability rehab; surgery if recurrent. |
Rotator-cuff tear / impingement | Pain or weakness lifting overhead or sleeping on the side. | Targeted PT, ultrasound-guided injections, arthroscopic repair if needed. |
Frozen shoulder | Stiffness > pain, worse at night; can’t reach bra strap or back pocket. | Stretch program, capsular injections, possible arthroscopic release. |
Arthritis | Deep ache, grind/click, reduced range. | Activity mods, biologic injections, resurfacing or total/reverse shoulder replacement. |
When to call The Arm clinic
- Shoulder slipped out (or feels like it might)
- Night-time pain or constant “dead arm” with overhead sports
- Can’t raise the arm past shoulder height after 2-3 weeks of self-care
- Post-fracture stiffness or deformity
Proven treatment philosophy
- Listen → examine → investigate only if it changes the plan.
- Rehab first – motion, cuff strength, scapular control.
- Precision procedures – small-scope repairs, modern ligament recon, tailored arthroplasty.
- Guided return to sport/work – velocity progressions, industrial-strength conditioning.
FAQs
Is cracking or popping normal?
Often yes (gas bubbles or tendon flick). Painful or catching pops deserve an exam.
Do I always need an MRI?
Not if your story and exam are crystal-clear. We use imaging to confirm, not to guess.
How long is recovery after cuff repair?
Sling 4-6 weeks, PT to month 4, most athletes throw/light-lift by month 6.
Ready to get your shoulder back?
If you have pain, book an appointment to be reviewed by Prof Imam or another member of our specialist team at The Arm Clinic. Early specialist care helps prevent long-term issues. Visit www.TheArmDoc.co.uk or book your consultation today. Phone: 020 3384 5588 | Email: Info@TheArmDoc.co.uk
(Created for patient education – not a substitute for personal medical advice.)