Surface Anatomy of the Upper Limb

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 Surface Anatomy of the Upper Limb

AUTHOR: HANNAH MAY

 

LAST MODIFIED: MARCH 19, 2014

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The surface anatomy of the upper limb refers to the anatomical

features which are palpable and visibleto the human eye.

This includes palpable bones, visible muscles groups and pulse

points.

These features are of great clinical importance when examining

a patient. Abnormal bone projections could be a sign of fracture

non-union, or degenerative joint changes. Muscle wasting

indicates a long standing nerve lesion. From the pulse,

information can be gained about the quality of the blood supply

to the limb.

In this article, we shall look at these features of upper limb

surface anatomy.

OverviewThere are three main aspects of surface anatomy; bones,

muscles and neurovascular structures.

There are many bones that form the structure of the upper

limb – the scapula, clavicle, humerus, radius, ulna, carpals,

metacarpals and phalanges. Later in the article, we shall look at

the surface markings that they produce.

The muscle groups of the upper limb can broadly be divided

into five groups; flexors of the arm, extensors of the arm,

flexors of the forearm, extensors of the forearm, and muscles of

the hand. Again, we shall examine the surface contours

produced by the muscles and their tendons.

Lastly, we shall consider the surface anatomy of the pulse

points in the upper limb. A pulse point is where a superficial

artery can be palpated against a bony structure.

Bony LandmarksPectoral Girdle

The pectoral girdle is the name used to describe the bones that

connect the upper limb to the axial skeleton. It is formed by

the clavicle and scapula. The scapula then articulates with

the humerus – the major bone of the upper limb.

Fig 1.0 – The jugular notch, located immediately above the

sternum.

Immediately above the sternum, in the inferior neck, an

indentation known as the jugular notch is visible and

palpable. It is bordered laterally by the sternal ends of the

right and left clavicle, and inferiorly by the manubrium of the

sternum.

If you follow the length of the clavicle from the sternoclavicular

joint, you’ll be palpating the superior border of the clavicle.

Notice medially you can feel the clavicle is bending towards

your hand and laterally it bends away from your hand. The

clavicle ends over the shoulder, at the next bony prominence,

known as the acromion.Here, the two bones form

the acromioclavicular joint.

The acromion is part of the scapula, and is essentially a ledge

under which the head of the humerus articulates with the

glenoid fossa. From the acromion, trace the bone in an inferior-

medial direction around the back of the patient to follow

the spine of the scapula.

The spine of the scapula ends near the midline where it joins

the medial border of the scapula, at the level of  the T3

vertebra. From here, moving inferiorly, you reach the tip of the

scapula at the inferior angle, and moving superolaterally from

here you trace the lateral border of the scapula. It’s more

difficult to palpate the lateral border because the bone is

covered by the teres minor and major. Asking the patient to

retract their shoulder may help palpation of the scapula.

Clinical Relevance – Fractured Clavicle

Abnormal contours of the anterior aspect of the pectoral girdle

= could indicate a history of a fractured clavicle. Typically the

clavicle fractures at its weakest point – the junction of the

medial 2/3 and lateral 1/3.

Shoulder Region

The shoulder joint is an articulation between the glenoid fossa

of the scapula, and the head of the humerus. It is also known as

the glenohumeral joint. The bony structures of the joint are

covered by protective muscles and ligaments, and thus cannot

be palpated.

Fig 1.1 – The bony landmarks of the humerus.

Immediately distal to the shoulder joint, some bony landmarks

can be felt. If you ask the patient to adduct their arm, you can

palpate the lesser tubercle (more anteriorly) and the greater

tubercle of the humerus. Between the tubercles lies

the intertubercular groove, in which the tendon to the biceps

brachii is located.

The greater tubercle of the humerus and the deltoid muscle

create the characteristic rounded contour of the shoulder.

Arm

The shaft of the humerus lies deep in the arm, and is difficult

to palpate. However, it is sometimes felt through thin muscle

groups in the elderly.

Elbow Joint

In the elbow region, there is little muscle mass. Thus the bony

landmarks here can be easily palpated.

The medial and lateral epicondyles of the humerus are bony

protuberances located on the sides of the elbow joint. They

produce the distinctive shape of the elbow when its fully

extended.

On the posterior side of the elbow, the olecrannon of the ulna

can be felt, forming the ‘tip’ of the elbow. By continuing

distally, the posterior border of the ulna is palpated as it runs

the length of the forearm.

Clinical Relevance – The Ulnar Nerve

The ulnar nerve runs posteriorly to the medial epicondyle of

the humerus at the elbow joint. Here, it is located superficially,

and is vulnerable to damage.

Trauma to this region causes the tingling sensation which is

commonly referred to as hitting the ‘funny bone‘.

Forearm

In the distal forearm, the round head of the ulna can be

palpated where it becomes very superficial on the medial

aspect of the wrist, (dorsal side). From the head projects a bony

point, the ulnar styloid process.

The distal aspect of the radial shaft can be felt on the lateral

side of the forearm. Its styloid process is also visible on the

lateral surface of the distal forearm, immediately before the

wrist joint.

Wrist joint

The wrist joint is made from the articulation of the radius and 3

proximal carpal bones: scaphoid, lunate and triquetrum.

These structures are difficult to palpate.

The pisiform and hook of hamate are two carpal bones

which are particularly easy to palpate, on the medial, palmar

side of the hand. The pisiform is a ball shaped prominence

proximal to the hypothenar eminence, and distal to this, when

you press firmly over the skin, you can feel the hook of hamate.

Hand

The bony structures of the hand are covered on the palmar side

by various muscle groups and a thickened layer of fascia –

the palmar fascia. However, on the dorsal aspect of the hand,

the metacarpals can be felt.

When you clench your fist, you expose the heads of

the metacarpals, as well as the heads of the distal and middle

phalanges at the interphalangeal joints.

Muscle Groups and Tendons

Fig 1.2 – The axillary fossa, bounded on either side by the

axillary folds.

Axilla

The axillary fossa (the armpit) lies between two muscular

projections:

The pectoralis major forms the anterior

axillary fold.

The latissimus dorsi and teres

major form the posterior axillary fold.

Arm

In the arm, there are three major muscles that visible and

palpable – the deltoid, biceps brachii and triceps brachii

muscles.

The deltoid muscle helps to form the contour of the shoulder,

and its insertion is clearly visible on the superolateral region of

the arm. Wasting of the deltoid is a sign of long term axillary

nerve damage.

In the anterior arm, the biceps brachii forms a large muscle

bulk, particularly on flexion of the arm at the elbow joint.

Similarly all 3 heads of the triceps brachii are palpable

posteriorly, upon extension of the arm.

Cubital Fossa

The cubital fossa is a visible, triangular-shaped hollow on the

anterior surface of the elbow joint.

The biceps brachii tendon passes through the cubital fossa,

lateral to the brachial artery (where a brachial pulse may be

taken). Flexing the arm at the elbow joint will enable you to

palpate the tendon, and even follow the proximal part of its

course to become the biceps aponeurosis.

Forearm

There are three muscular features of note in the forearm:

The flexor-pronator muscles, originating

from the medial epicondyle, are visible on

the anterior aspect of the forearm.

The extensor-supinator muscles,

originating from the lateral epicondyle, are

seen on the posterior aspect of the forearm.

The brachioradialis muscle is visible on

the anterior aspect of the forearm, despite

belonging to the posterior forearm

compartment.

Wrist

Fig 1.3 – The palmaris longus tendon is visible in midline of the

wrist.

At the wrist, the various tendons passing into the hand are

visible, and can be palpated. The palmaris longus muscle

tendon is a good example. It is visible on the anterior wrist

when the hand is flexed at the wrist and a clenched fist is

made. It is particularly prominent because the tendon is

positioned superficially to the flexor retinaculum.

(Note that the palmaris longus muscle is absent in some

people).

Hand

On the palmar aspect of the hand,

the thenar and hypothenar eminencesare visible – these are

projections formed by the muscles of the thumb and little finger

respectively.

On the back of the hand, the tendons of the extensor

digitorum muscles are pronounced during wrist

extension. Also on the dorsum of the hand a triangular

depression known as the anatomical snuffboxcan be seen.

(Read more about the anatomical snuffbox here).

Pulse Points and their Clinical UsesAn arterial pulse refers to a palpable expansion of the arteries,

produced by contraction of the heart. A pulse may palpated

wherever an artery is superficial and close to a firm surface

such as a bone or muscle tendon.

There are three major pulse points in the upper limb:

Brachial pulse – Place two fingers over

medial region of cubital fossa, immediately

medial to the tendon of the biceps brachii.

Here, it is auscultated during blood

pressure measurement, and can be

palpated to assess the character and

volume of blood flow to the upper limb.

Radial pulse – Place three fingers over the

lateral aspect of the anterior wrist, lateral to

the flexor carpi radialis tendon. The radial

pulse is often palpated to assess heart rate

and rhythm, and to test for radial-radial

delay.

Ulnar pulse – Place 3 fingers over the

medial aspect of the anterior wrist, lateral

to the flexor carpi ulnaris tendon.

Fig 1.4 – The major pulse points in the upper limb.

Superficial Veins

Fig 1.5 – Superficial veins of the upper limb.

The basilic and cephalic veins are the main superficial veins

of the upper limb. They can accessed easily, and are common

points of entry into the vascular system (e.g for drug

administration).

They originate from the dorsal venous network on the back

of the hand:

The cephalic vein arises on the lateral

aspect of the wrist, ascends the lateral part

of the forearm and arm, and drains into the

axillary vein.

The basilic vein originates on the medial

aspect of the wrist, ascends the medial part

of the forearm and arm, and becomes the

axillary vein.

In the cubital fossa, the median cubital vein connects the

cephalic and basilic veins. The median cubital vein is often used

in venepuncture.