Shoulder Region Intrinsic Muscles Flashcards
The intrinsic muscles connect?
Scapula to humerus
Name the muscles that connect scapula to humerus?
- Deltoid
- Supraspinatus
- Infraspinatus
- Teres minor
- Teres major
- Subscapularis
Name the rotator cuff muscles?
- Supraspinatus
- Ifraspinatus
- Teresminor
- Subscapularis
Rotator cuff muscles attach to which part of shoulder joint?
Capsule
Shape of deltoid?
Triangular
Parts of deltoid? And origin of deltoid?
- Clavicular fibres - originates from lateral 3rd of clavicle
- Acromial fibres - originate from the acromion of scapula
- Spinal fibres - originate from spine of scapula
Insertion of deltoid?
Deltoid Tuberosity on lateral aspect of humerus
Nerve supply of deltoid muscle?
Axillary nerve
Axillary nerve arises from which part of brachial plexus?
Posterior cord of brachial plexus
Vascular supply of deltoid?
- Thoracoacromial artery
- Anterior and posterior humeral circumflex artery
- Subscapular artery
- Deltoid branch of profunda brachii artery
All arise from axillary artery except profunda brachii which arises from brachial artery
Action of deltoid?
Anterior (clavicular) fibres:
Flex and medially rotate the arm
Posterior (spinal) fibres:
Extend and laterally rotate the arm
Acromial (middle) fibres
Abduct the arm (takes over from from supraspinatus which abduct the first 15°)
In relation to trapezius, supraspinatous lies?
Deep to it
Origin of supraspinatus muscle?
Insertion?
Originates from Supraspinatus fossa of scapula
Runs under acromion
Inserts on the greater tubercle of humerus
How many facets of greater tubercle of humerus ?
And which muscles inserts on them?
3 facets:
1. Superior facet - supraspinatus
2. Middle facet - infraspinatus
3. Inferior facet - teres minor
Which nerve supplies supraspinatus muscle?
Suprascapular nerve
Nerve supply for infraspinatus?
Suprascapular
Function of supraspinatus?
Abducts the arm
Stability to shoulder joint
Infraspinatus muscle originates from?
Infraspinatus fossa of scapula
Action of infraspinatus?
laterally rotates the humerus at glenohumeral joint
Stabilizes shoulder joint
Origin of teres minor?
Upper two thirds of the lateral border of scapula
Location of teres minor?
Just below infraspinatus
And just above teres major
Insertion of teres minor?
Inferior facet of greater tubercle of humerus
Function of teres minor?
Same as infraspinatus:
Laterally rotates the arm
Stabilizes the joint
Nerve supply of teres minor?
Axillary nerve
Axillary nerve supplies which 2 muscles?
Deltoid and teres minor
Origin of teres major?
Lower 3rd of lateral border of scapula
Insertion of teres major?
medial lip of intertubercular groove of humerus
Action of teres major?
Adducts the arm
Medially rotates it
What function do the lady (latissimus dorsi) and two majors (pectoralis major and teres major) have in common?
Adduct the arm
Medially rotate it
Extend it
Teres major is supplied by which nerve?
Lower subscapular nerve
Nerve supply of rotator cuff mucles?
- Supraspinatus and
- Infraspinatus ——— Suprascapular nerve
- Teres minor—–axillary nerve
- Subscapularis—-upper and lower subscapular nerve
The lower subscapular nerve originates from which part of brachial plexus?
posterior cord of brachial plexus
Origin of subscapularis muscle?
Subscapularis fossa of scapula
Insertion of subscapularis muscle?
On lessor tubercle of humerus
Action of subscapularis?
Same as teres major (as have same nerve supply from subscapularis nerve)
Medially rotate the arm
Stabilizes shoulder joint
Insertion of rotator cuff muscles is on?
humerus
3 on greater tuberosity of humerus
1 on lesser
The largest and strongest rotator cuff muscle?
Subscapularis
Rotator cuff syndrome? Rotator cuff tendonitis?
Inflammation
Injury
Degeneration of rotator cuff
Muscle tear/tendinitis
Common in young atletes
E.g when bowling in cricket
Main affected muscle is supraspinatus
As it gets pinched underneath acromion
What is subacromial impingement syndrome?
Associated with rotator cuff injuries
Subacromial impingement syndrome is a condition where the tendons and bursa in the shoulder become compressed and irritated, causing pain, weakness, and limited range of motion in the shoulder.
Supraspinatus Tendonitis
Subacromial Bursitis
What is bursa?
Fluid filled sac that reduce friction between surfaces
Origin of deltoid?
Lateral 3rd of clavicle
Acromion
Spine of scapula
The initial abduction (first 15°) of arm is done by which muscle?
Supraspinatus
Which muscle forms the inferior border of quadrangular space?
Teres major
What muscle forms superior border of quadrangular space?
Teres minor
What is on the lateral side of quadrangular space?
Surgical neck of humeus
What is on the medial side of quadrangular space?
Long head of triceps
What passes through the quadrangular space?
- Axillary nerve
- Posterior humeral circumflex artery
What is the basic purpose of rotator cuff muscles?
Pull humeral head into glenoid fossa
Additional stability to glenohumeral joint
Treatment of rotator cuff tendinitis?
Rest , analgesia (pain relief without losing consciousness by painkillers)
Steroid injection or surgery
Which harmone is in steroid injection?
Steroid injections contain synthetic versions of the hormone cortisol,
which is a type of steroid hormone produced by the adrenal gland.
Cortisol has anti-inflammatory and immunosuppressive effects, which is why it is used in steroid injections to reduce inflammation and swelling in various parts of the body.
