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Regions of the upper limb

Recommended video: Regions of the upper limb [17:55]
Regions of the upper limb seen from the anterior and posterior views.

The upper limb is essential for our daily functioning. It enables us to grip, write, lift and throw among many other movements. The upper limb has been shaped by evolution, into a highly mobile part of the human body. This contrasts with the lower limb, which has developed for stability.

Maybe the most convenient way to study the anatomy of the upper limb is to do it topographically. In that manner of speaking, we will go through certain regions of the upper limb, where each of them has its own most dominant function.

Key facts
Scapular region Bone: scapula
Muscles: supraspinatus, infraspinatus, rhomboids, trapezius, levator scapulae, teres major, teres minor
Joint: scapulothoracic (physiological joint with the posterior thoracic wall supported by rhomboids and trapezius muscles)
Vascularization: transverse cervical, dorsal scapular, subscapular arteries
Innervation: subscapular nerve
Shoulder region Bones: humerus, scapula, clavicle
Muscles: rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis), deltoid, teres major muscles
Joints: glenohumeral (humerus with scapula), acromioclavicular (scapula with clavicle), sternoclavicular (clavicle with sternum)
Vascularization: axillary artery and its branches (medial and lateral circumflex), transverse cervical, suprascapular arteries
Innervation: branches of the brachial plexus (C5-C6)
Arm Bone: humerus, radius, ulna
Muscles: triceps brachii (posterior compartment); biceps brachii, brachialis, coracobrachialis (anterior compartment)
Joints: elbow joint
Vascularization: brachial artery
Innervation: musculocutaneous nerve (branch of the brachial plexus)
Forearm Bones: radius, ulna
Muscles: Anterior compartment superficial layer - flexor carpi radialis, palmaris longus, flexor carpi ulnaris, pronator teres, flexor digitorum superficialis; 
Anterior compartment deep layer - flexor digitorum profundus, flexor pollicis longus, pronator quadratus;
Posterior compartment superficial layer - brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris;
Posterior compartment intermediate layer - extensor digitorum, extensor digiti minimi;
Posterior compartment deep layer - abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis, supinator, anconeus
Joints: elbow, proximal radioulnar, distal radioulnar, wrist joints
Vascularization: ulnar artery, radial artery
Innervation: median nerve (mostly), ulnar nerve
Hand Bones: scaphoid, lunate, triquetral, pisiform, trapezium, trapezoid, capitate, hamate (carpal bones); 5 metacarpal, 5 proximal phalanx, 4 middle phalanx, 5 distal phalanx
Muscles: thenar, hypothenar, interosseous, lumbrical muscles
Joints: wrist, interphalangeal (hinge), metacarpophalangeal, intercarpal joints
Vascularization: ulnar and radial arteries
Innervation: radial, median, ulnar nerves
Clinical relations Winged scapula, fractures of the bones, paralyses of the nerves, carpal tunnel syndrome

In this article we will discuss the regions of the upper limb, as well as the individual components and essential functions. This will be joint by joint, with other structures mentioned throughout.

  1. Scapular region
    1. Muscles
    2. Scapulothoracic joint
  2. Shoulder region
    1. Glenohumeral joint
    2. Acromioclavicular joint
    3. Sternoclavicular joint
  3. Arm (brachium)
  4. Forearm
  5. Wrist
  6. Hand
  7. Clinical points
    1. Winged scapula
    2. Clavicular fracture
    3. Radial nerve palsy/Saturday night palsy
    4. Carpal tunnel syndrome
    5. Scaphoid fracture
    6. Dupuytren’s contracture
  8. Sources
+ Show all

Scapular region

The scapula bone is otherwise known as the shoulder blade. Although the scapula is located on the posterior side of the body, it is not a part of the human back. It is classified as a part of the upper limb as it is so important for its functioning.


The scapula has a spine, as well as two fossae that lie above and below it. These form the origin of the supraspinatus and infraspinatus respectively. Supraspinatus is a rotator cuff muscle that increases the stability of the humeral head, as well as an abductor of the shoulder. The infraspinatus is a lateral rotator of the shoulder.

The scapular muscles allow us to elevate our arm beyond 90 degrees of abduction. The wing-nut like movement of the scapula allows us to elevate our upper limb above our heads. The rotation of the scapula occurs through precise and coordinated contraction of several muscles including the rhomboids (which are attached to its medial border) in addition to trapezius and levator scapulae among others (both of which are attached to the superior border). The lateral border of the scapula also gives rise to teres major and minor. These muscles are adductors of the humerus.

This region has a rich blood supply via the anastomosis of several arteries including the transverse cervical, dorsal scapular and subscapular. The nerve supply is from the suprascapular nerve as well as the upper and lower subscapular nerves.

Scapulothoracic joint

This is a physiological joint, as the scapula has no bony attachments posteriorly, and is held in place purely by muscles. These include the rhomboids and trapezius among others. The rotation and elevation of the scapula is essential for the abduction of the upper limb.

Shoulder region

The shoulder region must be seen as a complex of several joints, rather than an individual joint. Classically the glenohumeral joint is what anatomists mean when referring to the shoulder joint.

Glenohumeral joint

This is clearly a joint designed for mobility rather than stability. The glenoid fossa is a shallow dish like surface, deepened by the labrum that is attached at its periphery. The labrum is said to provide a suction effect to the head of the humerus, as well as deepening the joint socket and therefore increasing stability. The joint is supplied by the medial and lateral circumflex arteries, which branch from the brachial arteries.

Acromioclavicular joint

This joint is formed between the thin surface of the clavicle laterally and the acromion process of the scapula. It is a gliding synovial joint, which ensures functional continuity between the scapula region and the thoracic wall.

Learning point: The rounded side of the clavicle is the medial surface, and its thin side is the lateral surface. The underside is marked laterally by the conoid tubercle and trapezoid line which give rise to their respective ligaments.

Sternoclavicular joint

The manubrium is the superior part of the sternum and is attached to the clavicle laterally. It is a highly mobile synovial joint that allows for both anterior posterior and medial lateral movement. This enables the upper limb to reach a large area.

All these joints are best seen as a continuous functional unit rather than a series of isolated joints. They influence each other and work in coordination to mobilize the upper limb effectively.

Arm (brachium)

In a colloquial sense, the termarm’ refers to the whole upper limb. In an anatomical sense, it refers to the proximal part of the free upper limb only i.e. above the elbow, which consists of various muscles. The brachial artery, a direct continuation of the axillary artery, supplies the region. It becomes the brachial artery at the lower border of the teres major muscle.

The elbow joint refers to the articulation of the humerus and the two forearm bones. The ulna articulates with the medial condyle of the humerus known as the trochlear. The ulna has the pronounced olecranon process on its posterior surface, which fits into the olecranon fossa of the humerus posteriorly to limit extension. The triceps brachii muscle is the three-headed muscle that extends the elbow.

The head of the radius articulates with the capitulum of the humerus. The neck of the radius also forms part of the proximal radioulnar joint, which is where supination and pronation of the hand occurs. The radius acts as a wheel, and the annular ligament that encircles the radial neck and attaches it to the ulna holds it in place when both movements occur. There are named muscles that perform these movements i.e. pronator teres, supinator and pronator quadratus. Anconeus is a small muscle at the back of the elbow that abducts the ulna in pronation.


The forearm is the region between the elbow and wrist joint. It comprises two bones, the radius and the ulna. The brachial artery divides into the radial and ulnar, which run down the forearm on their respective sides. The ulnar artery also gives rise to the anterior and posterior interosseus arteries that supply the deep muscles of the flexor and extensor compartment. The nerve supply is from the ulnar and median nerves (mainly median).

The proximal part of the radius is the head, and the distal part is the base, and vice versa for the ulna. A tough interosseus membrane connects the two bones and distributes the load. The fibers of this membrane are very tough as well as flexible, and are orientated in an obliquely downward direction. There is also a fibrous structure called the oblique cord, which is thought by some to be vestigial, but does offer some structural advantage in connecting the bones.


The wrist joint can be divided into three main parts. There is the radiocarpal joint, the ulnocarpal joint, and the midcarpal joints. The joints derive their arterial supply from the dorsal and palmar carpal arches.

The radius articulates with the scaphoid laterally and the lunate medially. The ulna articulates with a triangular pad of fibrocartilage, which is interposed between it and the triquetrum bone. When extended, the wrist joint creates torque for the long flexors to perform their movements with higher strength. The mid carpal joint is between the proximal and distal row of carpals. It is active in early flexion and extension as well as radial and ulnar deviation. In late flexion and extension, the scaphoid bridges the proximal and distal carpal rows, which consequently move in unison.


The hand is an exquisite example of engineering. The complexity of its movements, as well as its functional use make it perfect for working with tools. The blood supply is derived from the superficial and deep palmar arches from the ulnar and radial arteries respectively. The nerve supply is from the ulnar and median nerves (mainly ulnar).

The carpometacarpal joints are simple synovial joints. But the first carpometacarpal joint is more unique. It is a saddle joint that allows the thumb to oppose with the other fingers. It also enables the thumb to move with a great deal of freedom. Our thumb is much longer when compared to other primates, which signifies the move our ancestors made from the trees to the planes of the African savannah. Climbing was no longer as useful, and throwing, hammering and gripping generally were of more use to our species. The elongated, powerful and highly mobile thumb reflects this.

The other joints to consider are the metacarpophalangeal (MCP) and interphalangeal (IP) joint. The MCP joints allow for flexion, extension, abduction and adduction. The IP joints, however, only allow for flexion and extension. The proximal and distal interphalangeal joints are connected by a collateral ligament, which means that extending or flexing your DIP causes your PIP to move in the same way.

Understood everything? Test your knowledge about the regions of the upper limb with this quiz.

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