Human Anatomy: Shoulder Joint

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Questions and Answers

What is the primary function of the biceps muscle?

Extension of the elbow

Abduction of the shoulder

Flexion of the elbow (correct)

Internal rotation of the shoulder

Which muscle is primarily responsible for extension of the elbow?

Deltoid

Biceps

Supraspinatus

Triceps (correct)

What group of muscles is responsible for stabilizing the shoulder joint?

Pectorals

Rotator cuff (correct)

Hamstrings

Quadriceps

Which muscle of the rotator cuff is responsible for internal rotation?

Subscapularis Signup and view all the answers

How can one determine if an image shows the posterior view of the rotator cuff?

The spine of scapula is visible across the image Signup and view all the answers

Which muscle is located superiorly on the rotator cuff and helps with abduction?

Supraspinatus Signup and view all the answers

What shape is the deltoid muscle compared to?

Triangle Signup and view all the answers

Which function does the infraspinatus muscle primarily perform?

External rotation Signup and view all the answers

What primary motion does the deltoid muscle assist with?

Abduction of the arm Signup and view all the answers

Which muscles are responsible for shoulder rotation?

Rotator cuff and deltoid Signup and view all the answers

What does a positive shear test indicate?

Injury to the AC joint Signup and view all the answers

What ratio describes the movement between the scapula and humerus during arm elevation?

1:2 Signup and view all the answers

What must happen for proper shoulder flexion and abduction?

The scapula needs to rotate Signup and view all the answers

Which type of shoulder dislocation is the most common?

Anterior dislocation Signup and view all the answers

What occurs during an anterior shoulder dislocation?

Humeral head moves forward Signup and view all the answers

Which of the following statements is true about the biceps muscle?

It also assists with shoulder flexion and supination. Signup and view all the answers

Which exercise is described as passive and aids in stretching the shoulder?

Pendulum exercise Signup and view all the answers

What characterizes chronic shoulder dislocations?

Increased force needed for dislocation over time Signup and view all the answers

What condition is referred to as an AC joint sprain?

Sprain where the acromion joins the clavicle Signup and view all the answers

Which position is associated with a posterior shoulder dislocation?

Abduction and internal rotation Signup and view all the answers

What symptom is commonly associated with acute shoulder injuries?

Nerve tingling Signup and view all the answers

What action is primarily associated with the rotator cuff?

Internal and external shoulder rotation Signup and view all the answers

Why does superior dislocation of the shoulder not occur?

There is bone preventing the humeral head from moving upward Signup and view all the answers

What happens when the humeral head is forced out of the glenoid cavity?

The shoulder becomes dislocated Signup and view all the answers

What is the primary function of a joint?

To allow the ends of two bones to make contact Signup and view all the answers

Which joint consists of the glenoid fossa and the humerus?

Glenohumeral joint Signup and view all the answers

Which of the following joints is not a true anatomical joint?

Scapulothoracic joint Signup and view all the answers

What does the acromioclavicular joint connect?

Acromion and Clavicle Signup and view all the answers

What is the role of the acromion in the shoulder joint?

It is part of the acromioclavicular joint Signup and view all the answers

Which bones make up the shoulder joint?

Scapula, Clavicle, Humerus Signup and view all the answers

Which joint allows for the separation of the shoulder commonly seen in athletes?

Acromioclavicular joint Signup and view all the answers

What are the main functions of the biceps in relation to the shoulder?

Facilitating flexion of the arm Signup and view all the answers

What is the function of the supraspinatus muscle in the rotator cuff?

Abduction of the arm Signup and view all the answers

Which type of rotator cuff injury involves a complete detachment of the tendon from the bone?

Full tear Signup and view all the answers

What primary symptom indicates impingement injury affecting the rotator cuff?

Deep pain in the shoulder Signup and view all the answers

What factor is primarily responsible for bicipital tendinitis?

Repetitive overhead movement Signup and view all the answers

Which statement is true regarding the acromion type of impingement injury?

It leads to compression of the shoulder space. Signup and view all the answers

How does a partial tear differ from a full tear in rotator cuff injuries?

A partial tear does not completely detach from the bone. Signup and view all the answers

Why do athletes experience worse pain from shoulder injuries at night?

Sleeping with arms above the head Signup and view all the answers

What main movement increases tension and irritation in the long head of the biceps tendon?

Rotating the shoulder Signup and view all the answers

Study Notes

Shoulder Joint Anatomy

The shoulder is classified as a ball and socket joint, allowing for a wide range of motion.
Major bones involved: Scapula (shoulder blade), Clavicle (collarbone), Humerus (upper arm bone).
Additional structures include the Acromion, sternum, and rib cage.

Shoulder Joints

Four main joints enable shoulder movement:
- Scapulothoracic Joint: Connects scapula and rib cage, essential for shoulder mobility.
- Acromioclavicular Joint: Connects the acromion and clavicle; common site for shoulder separations.
- Glenohumeral Joint: Joint between glenoid fossa of scapula and head of humerus; classified as a ball and socket joint.
- Sternoclavicular Joint: Joins the sternum and clavicle; one of the true joints of the shoulder.

Muscle Anatomy

Biceps Brachii: Located frontally (anterior) on the upper arm; responsible for elbow flexion and forearm supination.
Triceps Brachii: Positioned on the back (posterior) of the arm; involved in elbow extension.
Rotator Cuff: Composed of four muscles (Supraspinatus, Infraspinatus, Teres Minor, Subscapularis); crucial for shoulder stability and allowing arm rotation.

Rotator Cuff Functions

Supraspinatus: Facilitates abduction (raising arm away from body).
Infraspinatus: Allows external rotation of the shoulder.
Teres Minor: Aids in external rotation.
Subscapularis: Responsible for internal rotation.
The rotator cuff stabilizes the shoulder joint during various arm movements.

Scapulohumeral Rhythm

Coordination between scapula and humerus is vital for smooth arm elevation.
Movement ratio of scapula to humerus is 1:2; for example, during a 180-degree lift, the scapula rotates 60 degrees, while the humerus moves 120 degrees.

Common Shoulder Injuries

Acromioclavicular Joint Sprain: Characterized by a bump (step deformity) at the shoulder; tested through the shear test to assess pain and stability.
Glenohumeral Dislocation: Most commonly occurs in anterior direction. Other types include posterior (less common) and rare inferior dislocations.
Rotator Cuff Injury: Includes partial or full tears, typically caused by repetitive overhead motions, leading to instability and pain.

Impingement Injury

Occurs when subacromial space narrows, compressing the rotator cuff tendons. Pain increases upon overhead activities and can lead to deep discomfort at night.

Bicipital Tendinitis

Involves inflammation of the long head of the biceps tendon, arising from repetitive overhead activities. Symptoms include pain during shoulder rotation and overhead movement.

Key Takeaways

Understanding shoulder anatomy and biomechanics is essential for diagnosing and treating shoulder injuries.
The rotator cuff plays a critical role in maintaining shoulder stability, while joint interactions facilitate a wide range of arm motions.

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Description

This quiz focuses on the anatomy of the shoulder joint, which is classified as a ball and socket joint. You will learn about the main bones involved, including the scapula, clavicle, and humerus, as well as additional structures like the acromion. Understanding these components is essential for studying human movement and joint function.