In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint and the elbow joint. The distal part of the upper limb between the elbow and the radiocarpal joint is known as the forearm or "lower" arm, and the extremity beyond the wrist is the hand.
The humerus is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes. The body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes, and 3 fossae. As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to fracture, thus often becoming the focus of surgeons.
The biceps or biceps brachii is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. Both heads of the muscle arise on the scapula and join to form a single muscle belly which is attached to the upper forearm. While the biceps crosses both the shoulder and elbow joints, its main function is at the elbow where it flexes the forearm and supinates the forearm. Both these movements are used when opening a bottle with a corkscrew: first biceps screws in the cork (supination), then it pulls the cork out (flexion).
The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb. It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.
The brachialis is a muscle in the upper arm that flexes the elbow. It lies beneath the biceps brachii, and makes up part of the floor of the region known as the cubital fossa. It originates from the anterior aspect of the distal humerus; it inserts onto the tuberosity of the ulna. It is innervated by the musculocutaneous nerve, and commonly also receives additional innervation from the radial nerve. The brachialis is the prime mover of elbow flexion generating about 50% more power than the biceps.
The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is used to describe the entire appendage of the upper limb, but which in anatomy, technically, means only the region of the upper arm, whereas the lower "arm" is called the forearm. It is homologous to the region of the leg that lies between the knee and the ankle joints, the crus.
The extensor carpi radialis longus is one of the five main muscles that control movements at the wrist. This muscle is quite long, starting on the lateral side of the humerus, and attaching to the base of the second metacarpal bone.
Wrist drop is a medical condition in which the wrist and the fingers cannot extend at the metacarpophalangeal joints. The wrist remains partially flexed due to an opposing action of flexor muscles of the forearm. As a result, the extensor muscles in the posterior compartment remain paralyzed.
The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shoulder, elbow, wrist and knuckle joints. In humans, each upper limb is divided into the arm, forearm and hand, and is primarily used for climbing, lifting and manipulating objects.
The musculocutaneous nerve is a mixed branch of the lateral cord of the brachial plexus derived from cervical spinal nerves C5-C7. It arises opposite the lower border of the pectoralis major. It provides motor innervation to the muscles of the anterior compartment of the arm: the coracobrachialis, biceps brachii, and brachialis. It provides sensory innervation to the lateral forearm. It courses through the anterior part of the arm, terminating 2 cm above elbow; after passing the lateral edge of the tendon of biceps brachii it is becomes known as the lateral cutaneous nerve of the forearm.
The triceps, or triceps brachii, is a large muscle on the back of the upper limb of many vertebrates. It consists of 3 parts: the medial, lateral, and long head. It is the muscle principally responsible for extension of the elbow joint.
The cubital fossa,chelidon or inside of elbow, is the area on the anterior side of the upper part between the arm and forearm of a human or other hormid animals. It lies anteriorly to the elbow when in standard anatomical position.
The coracobrachialis muscle is a muscle in the upper medial part of the arm. It is located within the anterior compartment of the arm. It originates from the coracoid process of the scapula; it inserts onto the middle of the medial aspect of the body of the humerus. It is innervated by the musculocutaneous nerve. It acts to adduct and flex the arm.
The pronator teres is a muscle that, along with the pronator quadratus, serves to pronate the forearm. It has two origins, at the medial humeral supracondylar ridge and the ulnar tuberosity, and inserts near the middle of the radius.
In human anatomy, the supinator is a broad muscle in the posterior compartment of the forearm, curved around the upper third of the radius. Its function is to supinate the forearm.
The fascial compartments of arm refers to the specific anatomical term of the compartments within the upper segment of the upper limb of the body. The upper limb is divided into two segments, the arm and the forearm. Each of these segments is further divided into two compartments which are formed by deep fascia – tough connective tissue septa (walls). Each compartment encloses specific muscles and nerves.
The humeroulnar joint is part of the elbow-joint. It is composed of two bones, the humerus and ulna, and is the junction between the trochlear notch of ulna and the trochlea of humerus. It is classified as a simple hinge-joint, which allows for movements of flexion, extension and circumduction. Owing to the obliquity of the trochlea of the humerus, this movement does not take place in the antero-posterior plane of the body of the humerus.
The posterior compartment of the forearm contains twelve muscles which primarily extend the wrist and digits. It is separated from the anterior compartment by the interosseous membrane between the radius and ulna.
The elbow is the region between the upper arm and the forearm that surrounds the elbow joint. The elbow includes prominent landmarks such as the olecranon, the cubital fossa, and the lateral and the medial epicondyles of the humerus. The elbow joint is a hinge joint between the arm and the forearm; more specifically between the humerus in the upper arm and the radius and ulna in the forearm which allows the forearm and hand to be moved towards and away from the body. The term elbow is specifically used for humans and other primates, and in other vertebrates forelimb plus joint is used.
Left humerus. Anterior view.
Bones of left forearm. Anterior aspect.
Front of the left forearm. Superficial muscles.
Posterior surface of the forearm. Superficial muscles.
The radial artery.
The radial and ulnar arteries.
Ulnar and radial arteries. Deep view.
Nerves of the left upper extremity.
Brachioradialis
