Thumb muscles

Summary

This tutorial explores the muscles of the thumb, focusing on their attachment to bones, movements, and functions. It distinguishes between intrinsic and extrinsic muscles, explains thumb movements like flexion, extension, abduction, and opposition, and highlights the importance of these muscles in everyday grip and dexterity.

Takeaways

• 👍 The thumb is unique and crucial for almost every grip, emphasizing its importance in hand function.
• 🦴 The thumb has two phalanges and attaches to the metacarpal bone, trapezium, scaphoid, and other carpal bones, which are essential for its movement.
• 💪 Intrinsic muscles of the thumb are located within the hand, specifically in the thenar eminence, and are responsible for fine movements and dexterity.
• 💪 Extrinsic muscles of the thumb are located in the forearm, providing more power and strength through their tendons for gripping.
• 🔍 The movements of the thumb are named based on the actions they cause, such as flexion, extension, abduction, adduction, opposition, and reposition.
• 🤔 Understanding the thumb's movements is crucial for identifying and understanding the functions of the muscles that move the thumb.
• 🤲 The thenar eminence contains three intrinsic muscles (abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis) that are innervated by the median nerve.
• 🤚 The adductor pollicis, a muscle that adducts the thumb, is innervated by the ulnar nerve and is the only muscle responsible for thumb adduction.
• 🏋️‍♂️ The flexor pollicis longus in the forearm is a powerful muscle that flexes the thumb and is innervated by the median nerve, similar to the thenar muscles.
• 🤞 There are two extensor muscles (extensor pollicis brevis and extensor pollicis longus) in the forearm that extend the thumb, with the longus muscle having a more extended tendon due to its origin on the ulna and interosseous membrane.

Q & A

What is the significance of the muscles around the thumb?

The muscles around the thumb are crucial for thumb function, which is essential in almost every grip we perform. Understanding these muscles helps in identifying functional deficits when a nerve is injured.

How many phalanges does the thumb have?

The thumb has two phalanges, unlike the other fingers which have three.

What are the bones at the base of the thumb?

At the base of the thumb, there is the trapezium bone, followed by the scaphoid bone. The trapezium is connected to the scaphoid and trapezoid bones.

What are the intrinsic and extrinsic muscles of the thumb?

Intrinsic muscles of the thumb are within the hand, such as those in the thenar eminence. Extrinsic muscles are in the forearm and provide more power and strength through tendons.

Why is the thumb crucial in grips?

The thumb is crucial in grips because it provides the necessary dexterity and fine movement. It is involved in almost every grip we perform, making it essential for normal thumb function.

What are the movements of the thumb?

The thumb can flex, extend, abduct, adduct, oppose, and reposition. These movements are essential for understanding the function of the thumb muscles.

What is the term for the muscle that causes abduction of the thumb?

The muscle that causes abduction of the thumb is called the abductor pollicis brevis.

What is the role of the thenar eminence in the hand?

The thenar eminence is a muscular mass at the base of the thumb that contains muscles responsible for moving the thumb. It is innervated by the median nerve.

What is the anatomical snuff box and why is it significant?

The anatomical snuff box is a depression on the back of the wrist, formed by the tendons of the thumb. It is significant because it houses the scaphoid bone, which is commonly fractured.

How are the muscles of the thumb innervated?

The intrinsic muscles of the thumb in the thenar eminence are innervated by the median nerve, while the adductor pollicis is innervated by the ulnar nerve. The extrinsic muscles in the forearm are innervated by the radial nerve.

What is the function of the flexor pollicis longus muscle?

The flexor pollicis longus muscle is an extrinsic muscle located in the anterior compartment of the forearm. It is responsible for flexing the thumb and is innervated by the median nerve.