Pectoral Girdle: Description, Anatomy, Function, Diagram

What Is the Pectoral Girdle?

The pectoral girdle, also known as the shoulder girdle, is composed of clavicles and scapulae. The structure it forms provides for attaching the upper limbs to the trunk. Thus, it becomes a vital part of human anatomy that provides attachments for muscles to facilitate arm movements and ranges of motion required for activities of the upper limbs. For activities that involve arm and shoulder mobility, what is essential is merely the basic structure of the pectoral girdle, providing freedom for movement in all directions.

Anatomy Of The Pectoral Girdle

The pectoral girdle has two general bones. These are:

Clavicle (Collarbone)

• S-shaped bone between the sternum and the scapula.

• Acts as a strut to hold the scapula in place, thereby providing for movement of the arm.

• Common Injuries: Fractures; most commonly as the result of falls or direct blows.

Scapula (Shoulder Blade)

• Flat, triangular bone on the posteri¬or side of the ribcage.

• Offer attachment points for a good number of muscles involved actively in the movements of the arm.

• Common injuries includes dislocations.

Joints of the Pectoral Girdle

The joints of the pectoral girdle include:

Sternoclavicular Joint

• Synovial articulation between the sternum and clavicle.

• Allow swinging motion of the clavicle in multiple planes.

Acromioclavicular Joint

• The articulation between the acromion of the scapula and the clavicle.

• It helps in the movement of the scapula, thus providing flexibility to the shoulder.

Glenohumeral (Shoulder) Joint

• Ball and socket joint between the scapula and the humerus.

• Allow for a large range of motion for the arm.

• Allows maximum range of movement including flexion, extension, abduction, adduction and rotation.

Muscles Articulating at the Pectoral Girdle

Among the long list of muscles articulating at the pectoral girdle, one finds the following:

• Pectoralis major and minor

• Deltoid

• Trapezius

• Serratus Anterior

• Rhomboid Major and Minor

These muscles offer stability and maintenance of the position of the scapula and clavicle during upper limb movements.

Nerve Supply of The Pectoral Girdle

The nerve supply to the pectoral girdle allows muscle function and sensation. These include:

Major Nerves

• Brachial Plexus

• Suprascapular Nerve

• Axillary Nerve

• Long Thoracic Nerve

Blood Supply to the Pectoral Girdle

Blood supply to the pectoral girdle allows for the delivery of oxygen and nutrients to the bones and muscles. These include:

Major Arteries

• Subclavian Artery

• Axillary Artery

• Brachial Artery

Biomechanics of The Pectoral Girdle

The biomechanics of the pectoral girdle provide for complex motions around the upper limb:

• Flexion, Extension, Abduction, Adduction

• Rotation (Medial and Lateral)

• Role in activities like lifting, pushing, and pulling.

• Coordination between the muscles and joints in the pectoral girdle is essential for forming energetic and powerful movements.

Common Disorders And Injuries

The pectoral girdle is susceptible to various forms of disorders and injuries, which include:

Injuries

• Clavicle fractures: This is the most common type and is generally caused by falls or direct impacts.

• Shoulder dislocation: Most commonly caused by trauma or through the excessive application of force excessively.

• Rotator cuff tears: Generally, this kind of injury occurs because of overuse or acute injury.

Disorders

• Shoulder impingement syndrome: It is essentially the compression of rotator cuff tendons.

• Frozen Shoulder (adhesive capsulitis): Stiffness and pain in the shoulder joint.

• Bursitis: The bursa becomes inflamed; this is usually the result of repetitive motion.

Pectoral Girdle NEET MCQs (With Answers & Explanations)

Important questions asked in NEET from this topic are:

• Major components of skeletal system

• Physiology of skeletal system

Practice Questions for NEET

Q1. The collar bone is also known as

1. Pollex

2. Phallanges

3. Clavicle

4. Scapula

Correct answer: 3) Clavicle

Explanation:

The clavicle is another name for the collarbone. Between the scapula (shoulder blade) and the sternum (breastbone), this long, S-shaped bone acts as a strut. The clavicle permits the arm's complete range of motion and aids in shoulder stabilization. Because of its location and role in supporting the shoulder joint, it is one of the most often fractured bones in the body.

Hence, the correct answer is option c)Clavicle.

Q2. The scapula is a large triangular flat bone situated in the dorsal part of the thorax between

1. Second and seventh rib

2. Third and fourth rib

3. Fifth and sixth rib

4. Second and fifth rib

Correct answer: 1) Second and seventh rib

Explanation:

The scapula, also known as the shoulder blade, is a large, triangular, flat bone situated in the dorsal part of the thorax, typically between the second and seventh ribs. It forms a part of the pectoral girdle, connecting the upper limb to the trunk. The scapula has several important features, including the spine, which divides the posterior surface into two regions, and the acromion, a bony prominence that forms the highest point of the shoulder. It also has the coracoid process, which serves as an attachment point for muscles and ligaments. The glenoid cavity is a shallow depression where the humerus (upper arm bone) articulates with the scapula, forming the shoulder joint. The scapula provides attachment for muscles involved in arm movement, such as the deltoid, supraspinatus, infraspinatus, and others. Its mobility and structure are essential for a wide range of shoulder movements, including raising the arm, rotation, and lifting.

Hence, the correct answer is option 1, second, and seventh rib.

Q3. The large, flat, triangular bone present in two halves of the pectoral girdle is

1. Scapula

2. Ulna

3. Clavicle

4. Radius

Correct answer: 1) Scapula

Explanation:

The pectoral girdle is made of two bones. These are the clavicle and the scapula. The scapula is the large triangular flat bone located on the dorsal aspect of the thorax between the second and seventh ribs. A ridge known as the spine gives off to the acromion. The clavicle articulates with the acromion and is termed the collarbone. The glenoid cavity lying beneath the acromion forms the shoulder joint by articulating with the humerus.

Hence, the correct answer is Option (1) Scapula.

Q3. A large triangular flat bone called a scapula is situated in the dorsal part of the thorax between

1. 2nd and 7th ribs

2. 5th and 9th ribs

3. 8th and 10th ribs

4. 2nd and 11th ribs

Correct answer: 1) 2nd and 7th ribs

Explanation:

The pectoral girdle consists of two bones: the clavicle and the scapula. The clavicle is a slender, S-shaped bone that connects the arm to the body, while the scapula is a flat, triangular bone that provides attachment points for muscles and supports the shoulder joint.

Hence, the correct option is 1) 2nd and 7th ribs.

Also Read:

• MCQs on Pectoral Girdle

• Human Body and Its Movements

• 5 major functions of the skeletal system

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