Overview of Upper Limb Muscles

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Questions and Answers

Which of the following muscle groups are located in the shoulder girdle?

Hand Muscles

Brachial Muscles

Scapulohumeral Muscles (correct)

Forearm Muscles

Which of the following muscles is responsible for the outward rotation of the arm?

Subscapularis

Infraspinatus (correct)

Teres Minor (correct)

Supraspinatus

Which muscle is responsible for the inward rotation of the arm?

Supraspinatus

Teres Minor

Subscapularis (correct)

Infraspinatus

Which of these muscles helps to elevate the scapula?

Both A and B Signup and view all the answers

Which muscle group is primarily responsible for elbow flexion?

Brachial Muscles Signup and view all the answers

Which muscle is the primary mover of elbow extension?

Triceps Brachii Signup and view all the answers

Which muscle compartment of the forearm is responsible for wrist flexion and finger flexion?

Anterior Compartment Signup and view all the answers

Which muscle compartment of the forearm is responsible for wrist extension and finger extension?

Posterior Compartment Signup and view all the answers

Which of the following are muscles of the hand?

All of the above Signup and view all the answers

What is the origin of the pectoralis major muscle?

Medial half of the clavicle, sternum, costal cartilages of ribs 1–6, and the aponeurosis of the external oblique muscle Signup and view all the answers

What are the actions of the pectoralis minor muscle?

Protraction, depression, and assistance in downward rotation of the scapula Signup and view all the answers

What nerve innervates the pectoralis minor?

Medial pectoral nerve (C8-T1) Signup and view all the answers

What is the primary blood supply to the pectoral region?

Branches of the axillary artery (lateral thoracic and thoracoacromial arteries) and branches of the internal mammary artery Signup and view all the answers

The serratus anterior muscle is located superficial to the pectoralis minor muscle.

False Signup and view all the answers

The external intercostal muscles are responsible for depressing ribs during exhalation.

False Signup and view all the answers

What are the major components of the mammary gland?

Lobes and lobules containing milk-producing cells (alveoli) Signup and view all the answers

What structures support and enclose the mammary gland?

Connective tissue, fat, and skin Signup and view all the answers

The mammary gland is only found in females.

False Signup and view all the answers

Study Notes

Overview of Upper Limb Muscles

The upper limb muscles are categorized into groups based on their location and function.
These groups are crucial for various movements, including flexion, extension, abduction, and adduction of the shoulder, elbow, wrist, and hand.
The muscles span from the shoulder girdle to the hand, interacting with bones and joints in intricate ways to allow a wide range of motion.

Muscles of the Shoulder Girdle (Scapulohumeral Muscles)

Deltoid: A large, triangular muscle that forms the rounded contour of the shoulder. It is primarily responsible for abduction (raising the arm sideways). Different portions of the deltoid are activated for different ranges of arm movement, such as anterior, middle, and posterior deltoid.
Rotator Cuff Muscles: A group of four muscles (supraspinatus, infraspinatus, teres minor, and subscapularis). These muscles are crucial for stabilizing the shoulder joint during movement. They control the position and rotation of the humerus in the glenoid cavity.
Supraspinatus: Abducts the arm.
Infraspinatus: Externally rotates the arm.
Teres Minor: Externally rotates and adducts the arm.
Subscapularis: Internally rotates the arm.
Trapezius: A large, superficial muscle of the back that extends from the neck and upper back to the scapula (shoulder blade). It plays a role in elevating, retracting, and rotating the scapula.
Rhomboids: Located beneath the trapezius, these muscles retract the scapulae toward the spine, pulling the shoulder blades together.
Levator Scapulae: Elevates the scapula and rotates it downward.

Muscles of the Arm (Brachial Muscles)

Biceps Brachii: A major muscle of the anterior (front) aspect of the arm. It is primarily involved in flexion of the elbow joint and supination of the forearm (rotating the palm upward).
Brachialis: Lies deep to the biceps brachii and is also primarily responsible for elbow flexion.
Triceps Brachii: A large muscle of the posterior (back) aspect of the arm. It is the prime mover for extension of the elbow joint.

Muscles of the Forearm (Anterior and Posterior Compartments)

Anterior Compartment: Contains muscles primarily involved in wrist flexion and finger flexion. Key muscles include:
- Flexor carpi radialis, flexor carpi ulnaris, palmaris longus, flexor digitorum superficialis, and flexor digitorum profundus.
Posterior Compartment: Contains muscles primarily responsible for wrist extension and finger extension. These include:
- Extensor carpi radialis longus and brevis, extensor carpi ulnaris, extensor digitorum, and extensor digiti minimi.

Muscles of the Hand

The hand muscles are involved in precise movements and manipulations of objects. They are divided into several groups:
- Thenar muscles: Located at the base of the thumb; responsible for thumb movements.
- Hypothenar muscles: Located at the base of the pinky finger; responsible for little finger movements.
- Interossei (palmar and dorsal): Located between the metacarpal bones; involved in abduction and adduction of the fingers.

Summary of Muscle Actions

Flexion: Decreasing the angle between two bones.
Extension: Increasing the angle between two bones.
Abduction: Moving a limb away from the midline of the body.
Adduction: Moving a limb toward the midline of the body.
Internal Rotation: Rotating a limb medially (toward the body).
External Rotation: Rotating a limb laterally (away from the body).
Supination: Rotating the forearm so the palm faces upward.
Pronation: Rotating the forearm so the palm faces downward.

Important Considerations

The muscles listed do not encompass all the muscles of the upper limb. There are also smaller, accessory muscles that contribute to the complex movements of the region.
Synergistic muscle action is crucial. Muscles often work together to produce a desired movement (e.g., several muscles work together to flex the elbow).
Antagonistic muscle pairs are essential to control movement (e.g., biceps brachii and triceps brachii work in opposition to control elbow flexion and extension, respectively).
The understanding of muscle action is critical for understanding movement patterns.

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Description

This quiz covers the anatomy and functions of upper limb muscles, focusing on the shoulder girdle and their roles in various movements such as flexion and abduction. You'll learn about specific muscles like the deltoid and rotator cuff, which are vital for shoulder stability and mobility.