Anatomy of shoulder movement and muscles

Biceps Brachii

Flexion

Corocbrachialis

Flexion

Pectoralis Major

Flexion Extension Horizontal extension Adduction Internal rotation

Anterior Deltoid

Flexion Horizontal adduction Internal rotation

The alignment of articulation surface at the humeral joint promotes what action

Flexion Shape at the end of these bones - distal end of humerus rotates anteriorly 30 degree and the proximal end of ulna rotates posteriorly 30 degreee combination promotes flexion

Posterior deltoid

External rotation Extension Horizontal abduction

Teres minor

External rotation Horizontal adduction

infraspinatus

External rotation Horizontal adduction

The lateral deviation of the ulna in relation to the humerus is sometimes known as what?

Lateral Valgus deviation

What is the carry angle

Ulna and humerus are not perfectly aligned lateral deviation of the ulna Deviation is 10-15 degree, valgus lateral deviation

Which 2 joints of the elbow complex participate in flexion and extension?

Ulna humeral articulation

What are three ways that the muscles of the rotator cuff may contribute to stability at the glenohumeral joint.

1 - Contracting creating a medial force to the humerus to compress the articular surface 2 - contraction causes tightening of the capsuloligamentous structure 3 - Contraction acting as a barrier (Roadblock)

What is the key feature of the sternoclavicular compared to the other joints of the shoulder complex?

1- Saddle shape but function as a ball and socket 2- intraaarticular disc improves concurrency, reduces stress and increases surface area 3 - wants to displace medially and superiorly

Why does the wrist extend as the fingers flex

As it places the flexors at an optimal length to be able to produce force.

An increase in the grasp force is accompanied by what 3 features

A larger Volar arch Flexion of the fingers, particularly the MCP joint Increase in contact in the contact area between teh object and the fingers and palm.

Supraspinatus

Abduction

Pectoralis minor

Abduction Downwards rotation Depression

Deltoid

Adbuction

Rhomboids

Adduction Elevation Depression

Teres major

Adduction Extension Internal rotation

Latissimus Dorsi

Adduction Extension internal rotation

What are three actions that pectoralis major responsible for producing at the glenohumeral head?

Adduction, internal rotation, horizontal flexion

Which 2 ligaments are critical for medial - lateral stability at the elbow

Anterior band of collateral ligament Lateral ulna colateral ligament

Which ligament prevents lateral and distal displacement of the head of he radius

Anuala ligament will help stabilise and the brachioradialis will also help stabilise

Which elbow flexor is called the work horse of elbow flexion and for what reason?

Brachialis due to its ability to flex in supination, semipronated position and elbow flexion with pronation. Universal flexor of the elbow

Which muscle may also help to resist distraction load on radius

Brachioradialis

What is the synergist relationship between flexor carpi radialis and flexor carpi ulnaris

Cancel out radial and Ulna deviation

At radiohumeral joint contact loads are experienced over a large area during which action

Contact area increases therefore the stress of the joint decreases

Why is radial deviation so limited

Due to the radial styloid process being more distal

Levator scapulae

Elevation Downwards rotation

How is the arm returned from full glenohumeral abduction back to neutral?

Gravity acts as a primover and the same muscles act as before only controlling in a eccentric action

Approximately how much glenohumeral elevation may be lost with scapulathoracic immobility.

Half, due to scapulothoracic rhythm

What are two ways that pronation - supination may occur? Describe how they occur

Hand free is space - distal radius rotates around fixed ulna. Fixed in space - Ulna moves posteriorly, laterally anteriorly back in the position the radius was.

What type of joint is the ulna humeral articulation

Hinge joint

What are 2 passive contraints of the glenohumeral joint?

Labrum, joint capsule and ligaments

Subscpularis

Internal rotation

How does the interosseous membrane help to distribute loads acting on the radius? How does this reduce the stress on the humerus?

Interosseous membrane pulls the ulna proximally allowing the redistribution of the load to the ulna. the load is spread over a larger contact area of the humerus and stress to elbow is decreased.

What is active insufficiency, give an example of when active insufficiency might occur at the hand.

It occurs at a multi joint muscle reaches a length where it can no longer apply effective force, this happens when the wrist is in a flexed position and you try and flex your fingers.

What other muscle (apart from rotator cuff) may assist in providing stability to the glenohumeral joint (particularly during overhead movement)

Long head bicep brachii

The primary structure that retrains elbow from extension

Olecranon

When the scapula thoracic joint upward rotates what happens at the SC and AC joint

SC Elevates and AC upward rotates

What type of joint is the proximal radioulna joint

Pivot joint - spins no translation

Total wrist motion in flexion - extension requires substantial movement at which 2 joints?

Radiocarpal and midcarpal joints

When the scapula thoracic joint Depresses what happens at the SC and AC joint

SC - Depression and AC upward rotates

When the scapula thoracic joint Elevates what happens at the SC and AC joints

SC - Elevates and AC Downward rotates

When the scapula thoracic joint abducts what happens at the SC and AC joints

SC - Protracts and AC internally rotates

When the scapula thoracic joint adducts what happens at the SC and AC joints

SC - Retraction and AC Externally rotates

Elevation of scapula is accompanied by what movement at the SC and AC joints

SC - elevation AC - downward rotation

When the scapula thoracic joint downward rotates what happens at the SC and AC joint

SC Depresses and the AC downward rotates

Describe how serratus anterior and trapezius work together during humeral abduction

Serratus anterior - Abducts scapula Trapezius - upward rotates and elevates scapula

The concave anterior surface of the scapula is seperated from the convex external surface of the thorax by which two muscles? These muscles glide over each other during movement.

Subscapularis and Serratus anterior

Although the muscles of the rotator cuff are well suited to their role as stabilizers, they can also produce actions at the glenohumeral joint. Name on action produced by each of these muscles.

Supraspinatus - Abduction Infraspinatous - external rotation Teres minor - external rotation Subscapularis - Internal rotation

Describe in detail how humeral abduction occurs through the coordinated actions at each of the joints of the shoulder complex.

Supraspinatus intiates first 30 degree Teres minor, subscap and infra stabilise humeral head in a inferior angle Deltoid takes over until full capacity is reached at 90 degree Upward rotation occurs at the ST joint via Serratus anterior and Traps. SC joint protracts AC joint internally rotates to allow full abduction

In what way are pectoralis major and latissimus dorsi different from the other muscles that act on the shoulder.

They control the position of the humerus at the glenohumeral head, they both cross the glenohumeral joint from axial skeleton

Which ligament protects against medially directed forces on the AC joint that may result from a fall or blow to the shoulder.

Trapezoid ligament

Serratus Anterior

Upwards rotation Adbuction

Overhead activities like throwing increase what type stress at the elbow? Which muscles can help to provide some stability to the medial aspect of the elbow.

Valgus stress wants to deviate the forearm laterally in relation to the humerus Dynamic stability - Wrist flexors , pronators, this is because they attach on the medial epicondyle of he humerus , so they run over the medial aspect of the medial aspect of the elbow. When fatigue is present this imposes load back on the medial ligament complex.

What stress is caused from carrying angle and where is it experienced

Valugs stress Medial aspect of elbow

Which 2 ligaments are critical for medial lateral stability of the elbow joint during flexion and extension

lateral ulna collateral ligament anterior fibers of the medial collateral ligament

When is pinch grip used

precise manipulation

What is the difference between flexi digitorum superficialis and profundus in terms of the insertion

profundus is deeper and distal, superficialis is shallow and proximal

Which joint of the elbow complex participate in pronation and supernation?

proximal radioulna joint

2 actions the radiohumeral joint participate in

supination and pronation flexion and extension of the radiohumeral

What is scapulohumeral rhythm?

the relationship between movement of the scapula and movement of the humerus during humeral elevation, a ration of 1:2 I degree of Scapulathoracic joint that 2 degree of Glenohumeral joint.

Trapezius

upward rotation adduction elevation Depression