Upper Limb Anatomy Quiz: Practice Questions & Flashcards

Study Notes

Anatomy of the Upper Limb

The upper limb is composed of several bones, muscles, tendons, ligaments, blood vessels, and nerves that work together to allow us various actions such as lifting objects, grasping, typing, throwing, and more. Let's explore the main components of the upper limb, starting with its skeleton.

Bones of the Upper Limb

Humerus

The humerus is the largest bone in the upper limb. It is located between the shoulder and elbow joints. At the proximal end, it articulates with the scapula via the glenohumeral joint. This ball-and-socket joint allows for a wide range of motion, including flexion, extension, abduction, adduction, internal rotation, and external rotation of the arm. The distal end of the humerus articulates with the radius and ulna bones of the forearm at the elbow joint.

Forearm Bones (Radius and Ulna)

The two bones of the forearm—the radius and ulna—are essential for forearm movement and wrist stability. The radius is located on the thumb side of the forearm and is slightly shorter than the ulna. Its head articulates with the capitulum of the humerus, forming part of the elbow joint. The radius also forms part of the radiocarpal joint with the carpal bones of the hand, allowing for wrist movement. On the other hand, the ulna runs along the little finger side of the forearm and has a longer shaft than the radius. Its head articulates with the trochlea of the humerus, while its styloid process serves as one point of attachment for the wrist extensor muscles.

Hand Bones (Carpals, Metacarpals, Phalanges)

The hand is made up of 27 bones divided into three groups: carpals (wrist bones), metacarpals (hand bones), and phalanges (finger bones). The carpals include the scaphoid, lunate, triquetrum, and pisiform, which are arranged in two rows. The eight metacarpals are numbered 1 to 5 from the radial (thumb) side to the ulnar (little finger) side, and they articulate with the carpals and the proximal phalanges. The phalanges are the small bones of the fingers and toes. There are 14 phalanges in total, with three phalanges in each finger (excluding the thumb, which has only two) and two in each toe.

Muscles of the Upper Limb

The muscles of the upper limb can be categorized into three groups: flexors (which bend the limb), extensors (which straighten the limb), and rotators (which rotate the limb). The primary flexor muscles include the biceps brachii, brachialis, and brachioradialis, while the primary extensor muscles are the triceps brachii and anconeus. The rotator muscles include the supraspinatus, infraspinatus, teres minor, and subscapularis, which are located in the shoulder joint.

Tendons and Ligaments of the Upper Limb

Tendons are fibrous bands of connective tissue that connect muscles to bones, while ligaments are fibrous bands that connect bones to other bones. The ligaments of the upper limb include the medial and lateral collateral ligaments of the elbow, the ulnar collateral ligament, and the radial collateral ligament. Tendons, on the other hand, include the biceps tendon, the triceps tendon, and various flexor and extensor tendons.

Blood Vessels and Nerves of the Upper Limb

The upper limb is supplied by multiple arteries, including the brachial artery and radial artery. The brachial artery branches off from the axillary artery near the shoulder and continues down the arm until it gives rise to the ulnar and radial arteries just above the elbow joint. These arteries supply blood to the forearm and hand. For venous return, the basilic vein, cephalic vein, and median cubital vein convey deoxygenated blood back towards the heart.

Nerve supply to the upper limb comes from multiple sources, including the brachial plexus (which innervates most of the upper extremity), radial nerve (innervating the triceps, extensor digitorum communis, and extensor carpi radialis brevis muscles), ulnar nerve (innervating the flexor carpi ulnaris and flexor digitorum profundus muscles), and median nerve (supplying sensation over the palm and fingers).

In summary, the upper limb is comprised of a complex interplay of bones, muscles, tendons, ligaments, blood vessels, and nerves that enable our arms to perform intricate movements and maintain functionality. Understanding these structures and their interactions is important for medical professionals and anyone interested in human anatomy.

Description

Explore the bones, muscles, tendons, ligaments, blood vessels, and nerves that make up the upper limb and enable various actions like lifting, grasping, and throwing. Learn about the structures such as humerus, radius, ulna, carpals, metacarpals, phalanges, flexor and extensor muscles, tendons, ligaments, blood vessels like the brachial artery, and nerves like the brachial plexus and radial nerve.