Anatomy of the shoulder region

Question 1

What are the skeletal components of the shoulder region?

Answer 1

Clavicle + scapula -> pectoral girdle
Humerus
Glenohumeral joint, acromioclavicular joint

Question 2

What are the ligaments of the shoulder region and what are their functions?

Answer 2

Acromioclavicular
Coracoacromial
Coracoclavicular
Glenohumeral -> superior, middle, inferior

Question 3

What are the features of the coracoclavicular ligament?

Answer 3

Two parts, major stabilising ligament

Question 4

What are the features of the coracoacromial ligament?

Answer 4

Forms arch

Provides support for head of humerus, prevents superior dislocation

Question 5

What type of joint is the glenohumeral joint and what are its actions?

Answer 5

Highly mobile ball + socket joint
Abduction/Adduction
Flexion/Extension
Circumduction
Lateral/Medial rotation

Question 6

What are the actions of the deltoid and what is its innervation?

Answer 6

Abduction of arm, posterior fibres -> extension + lateral rotation, anterior fibres -> flexion + medial rotation. Axillary nerve

Question 7

Which muscles perform adduction of the arm?

Answer 7

Latissimus dorsi, pectoralis major

Question 8

How does abduction/adduction of the arm take place?

Answer 8

Abd: deltoid contracts -> brings arms horizontally.
upper fibres + lower fibres of trapezius and lower digitations of serratus anterior contract -> rotation of scapula.
Add: mainly gravity. rhomboids + levator scapulae contract -> scapula back towards midline.

Question 9

Which muscles are involved in flexion of the arm?

Answer 9

Biceps brachii, coracobrachialis, anterior fibres of deltoid

Question 10

Which muscles are involved in extension of the arm?

Answer 10

Long head of triceps, posterior fibres of deltoid, latissimus dorsi.
(Lateral + medial heads of triceps -> extend forearm)