Week 3 Anatomy

Shoulder joint

Location – upper limb joint

Bones involved – humeral head and glenoid fossa of the scapula

Type of joint – ball and socket synovial joint

Movements – flexion, extension, abduction, adduction, internal and external rotation, circumduction

Bony congruance – poor bony congruence- only 1/3 of the ball of humerus articulates with the relatively flat glenoid fossa – inherent instability of this joint

Muscle  Рrotator cuff muscles supraspinatus, infraspinatus, teres minor, and subscapularis all attach to the capsule and actively contribute to joint stability. Deltoid and Long head of triceps prevents inferior dislocation in shoulder abduction.

Ligament – glenohumeral ligaments – anteriorly, coracohumeral superiorly, extrinsic- corocoacromial arch superiorly.

Other – the fossa is deepened by the fibrocartilagenous glenoid labrum, fibrous joint capsule(anatomical neck to glenoid)

Blood supply – ant and post humeral circumflex arteries and suprascapular artery

Nerves – axillary, suprascapular and lateral pectoral nerves.

 

 

Muscular/tendinous attachments to the scapula:

Bony features attachments of rotator cuff muscles

 

supraspinatus, infraspinatus and teres minor on greater humeral tubercle.

subscapularis on lesser tubercle.

 

Contents of bicipital groove

Tendon of long head of biceps brachii, its synovial sheath

 

Proximal end of humerus

  • Head
  • Anatomical neck (above tubercles)
  • Greater(lat) and lesser tubercles(ant)
  • Intertubercular sulcus
  • Shaft
  • Deltoid tuberosity laterally
  • Radial groove posteriorly (contains radial nerve and profunda brachii artery.

 

Shoulder X-ray

wikiradiography.net

 

Brachial plexus organisation:

Roots between the scalenus anterior & scalenus medius

Trunks in the posterior triangle of the neck

Divisions behind the clavicle (at the outer border of the first rib)

Cords in the axilla (clasping the second part of the axillary artery)

Definitive nerves of supply forming in the lateral part of the axilla