This section describes the upper extremities and their structures.

The Upper Extremity

The following project will provide an in depth explanation of the anatomy of the upper extremity. Sections are as follows:

• Arteries
• Veins
• Bones

• humerus
• radius
• ulna

• Muscles
• Articulations

• elbow

• Lymph System

Note: Information regarding nerves of the upper extremity is contained in the brachial plexus section.

Arteries of the Upper Extremity

  Origins

The right subclavian artery branches off the brachiocephalic trunk.

The left subclavian artery arises directly from the aortic arch.

Pathway: Proximal to Distal.

Subclavian Artery

The subclavian artery passes laterally deep to the clavicle. The subclavian artery then becomes the axillary artery as it passes into the axillary region. The axillary artery is that portion between the outer border of the teres major muscle and border of the first rib. Several other branches of the axillary artery supply blood to tissues of the upper thorax and shoulder region.

Brachial Artery

The brachial artery is a continuation of the axillary artery through the brachial region. The brachial artery courses on the medial side of the humerus. A deep brachial artery branches for the brachial artery and curves posterior near the radial nerve to supply the triceps brachii muscle. Two additional branches from the brachial artery are the anterior and posterior humeral circumflex arteries. The two arteries form a continuous ring of vessels around the proximal portion of the humerus.

Radial and Ulnar Arteries

The brachial artery bifurcates proximal to the cubital fossa into the radial and ulnar arteries. They supply the blood to the forearm and a portion of the hand and digits. The radial artery courses down the lateral side of the arm where it sends many small branches to the forearm. The radial recurrent artery is the first and largest major branch of the radial artery which serves the region of the elbow. The ulnar artery extends down the ulnar side of the forearm and serves the medial side of the forearm through many small branches. The first large branch of the ulnar nerve is the ulnar recurrent artery which arises from the proximal portion near the elbow.

Arteries of Upper Extremity

From “Human Anatomy (4th ed.),” by K. Van De Graaf, 1995, p., 533.

Veins of the Upper extremity

Note: The veins of the upper extremity are classified as either deep or superficial veins. The superficial veins are highly variable and form an extensive network just below the skin. The deep veins accompany the arteries of the same region and bear similar names. A brief summary of the two types of veins follows.

Deep Veins of the Upper Extremity

The radial vein on the lateral side of the forearm and the ulnar vein on the medial side drain blood form the deep and superficial palmar arches of the hand. The radial and ulnar veins join in the cubital fossa to form the brachial vein which continues up the medial side of the brachium. The brachial then becomes the axillary vein draining portion of the biceps and trips. Finally the axillary vein becomes the subclavian vein.

Superficial Veins of the Upper Extremity

The main superficial vessels of the upper extremity are the basilic and cephalic veins. The basilic vein passes on the ulnar side of the forearm and the medial side of the arm. Near the head of the humerus, the basilic vein merges with the brachial vein and forms the axillary vein. The cephalic vein drains the superficial portion of the hand and forearm on the radial side and continues p the lateral side of the arm. In the shoulder region the cephalic vein pierces the fascia and joins the axillary vein. Another portion of the superficial vein is the median vein. It ascends from the cephalic vein on the lateral side to connect with the basilic vein on the medial side.

Superficial Veins Deep Veins

From “Human Anatomy (4th ed.),” by K. Van De Graaf, 1995, p., 542.

Bones of Upper Extremity

Humerus

The humerus is the bone of the upper arm. The smooth, dome-shaped head of the bone lies at an angle to the shaft and fits into a shallow socket of the scapula (shoulder blade) to form the shoulder joint. Below the head, the bone narrows to form a cylindrical shaft. It flattens and widens at the lower end and, at its base, it joins with the bones of the lower arm (the ulna and radius) to make up the elbow.

Condyles of the Humerus

At the lower end of the humerus (upper arm bone) and the femur, there are two smooth condyles (rounded processes of the bone): a knob-like "capitulum" on the lateral side and a pulley-shaped "trochlea" in the middle. The capitulum unites with the radius (smaller lower arm bone) at the elbow, and the trochlea is a notch which joins ligaments to the head of the ulna (larger lower arm bone). Above the condyles on either side are "epicondyles," which provide attachments for muscles and ligaments of the elbow. The one toward the center of the arm is the "medial epicondyle," and the one to the side is the "lateral epicondyle."

From “Human Anatomy (4th ed.),” by K. Van De Graaf, 1995, p.,173.

Ulna

The ulna is the longer of the two bones of the forearm; the other being the radius. When the palm faces forward, the ulna is the inner bone (the one nearest the body) running down the forearm parallel to the radius. The upper end joins with the radius and extends into a rounded projection that fits around the lower end of the humerus (the upper arm bone) to form the elbow joint. The lower end of the ulna is rounded and forms a joint with the wrist bones and lower end of the radius.

Radius

The radius is the shorter of the two long bones of the forearm. The other is the ulna. The radius is the bone on the thumb side of the arm. The shaft of the radius has a broad base that joins the lower end of the ulna and the upper bones of the wrist at a large process called the radial styloid. The disk-shaped head of the radius, which is smaller than the base, joins the lower end of the humerus (bone in the upper arm) to form the elbow joint.

From “Human Anatomy (4th ed.),” by K. Van De Graaf, 1995, p., 174.

Muscles of the Upper extremity

Biceps Brachii

Some muscles have more than one origin (immovable end) or insertion (movable end). The "biceps brachii" in the upper arm, for example, has two origins. This is shown in its name, "biceps," which means "two heads." It is attached to the scapula (shoulderblade) in two places and extends along the front surface of the humerus (upper arm bone). It is inserted by means of a tendon on the largest part of the radius (lower arm bone). When it contracts, the movable end is pulled toward the origin, and the arm bends at the elbow.

From: http://www.rad.washington.edu

Brachialis

The brachialis is a large muscle beneath the biceps brachii. It connects the shaft of the humerus (upper arm bone) to the ulna (longest) forearm bone) and is the strongest flexor of the elbow.

From: http://www.rad.washington.edu 

Brachioradialis

The brachioradalis connects the humerus (upper arm bone) to the radius (shortest lower arm bone) and aids in flexing the elbow.

From: http://www.rad.washington.edu 

Triceps Brachii

The triceps brachii has three heads (connective immovable muscle) and is the only muscle on the back of the upper arm. It connects the humerus (upper arm bone) and the scapula (shoulder blade) to the ulna (longest of the forearm bones) and is the primary extensor of the elbow. The three heads are the "lateral," the "medial," and the "long head."

From: http://www.rad.washington.edu 

Muscles of the Humerus 

From “Human Anatomy (4th ed.),” by K. Van De Graaf, 1995, p., 257

Muscles of the Forearm

The following is a list of origin, insertion points, action, innervation, and arterial supply of the forearm muscles. The forearm is made of many tiny muscles which are included in the picture.

  Extensor Carpi Radialis Brevis

From: http://www.rad.washington.edu

Extensor Carpi Radialis Longus

The extensor carpi radialis longus runs along the lateral side of the forearm, connecting the humerus (upper arm bone) to the hand. It functions to extend the wrist and assists in abducting the hand.

From: http://www.rad.washington.edu

Extensor Digitorum

From: http://www.rad.washington.edu

Extensor Digiti Minimi

From: http://www.rad.washington.edu

Extensor Indicis

From: http://www.rad.washington.edu

Extensor Pollicis Brevis

From: http://www.rad.washington.edu

Extensor Pollicis Longus

From: http://www.rad.washington.edu

Flexor Carpi Radialis

From: http://www.rad.washington.edu

Flexor Carpi Ulnaris

From: http://www.rad.washington.edu

Flexor Digitorum Profundus

From: http://www.rad.washington.edu

Forearm Muscles

From “Human Anatomy (4th ed.),” by K. Van De Graaf, 1995, p., 258.

Lymphatic System of Upper Extremity

Lymphatic Trunks

Lymphatic trunks drain lymph from the larger areas of the body, and they are named for the areas that they serve. The "lumbar trunk" drains lymph from the legs, lower abdominal wall, and the pelvic organs; the "intestinal trunk" drains organs of the abdominal cavity; the "intercostal" and "bronchomediastinal trunks" receive lymph from portions of the thorax; the "subclavian trunk" drains the arm; and the "jugular trunk" drains parts of the neck and head. These trunks then join one of two collecting ducts: the thoracic duct or the right lymphatic duct. After leaving these collecting ducts, lymph enters the veins to become part of the plasma, just before the blood returns to the right atrium of the heart.

Lymph Nodes Lymph nodes generally occur in groups along the larger lymphatic vessels. They are distributed throughout the body, but they lack the tissues of the central nervous system. All lymph nodes have the primary function of the production of lymphocytes, which help defend the body against microorganisms and against harmful foreign particles and debris from lymph before it is returned to the blood stream. The axillary region: these nodes are in the underarm region and receive lymph from vessels that drain the arm, the walls of the thorax, the breast, and the upper walls of the abdomen.

From “Principles of Human Anatomy (9 th ed.),” by G. Tortora, 2002, p., 486.

Basic Study Questions

  1.  Identify arterial blood supply to the upper extremity, proximal to distal.

  2.  Identify the main bones of the arm.

  3.  What muscle extends the forearm?

  4.  What is your olecranon?

Additional Study Questions