the Upper Limb
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Main Anatomy Index | The
Last updated 30 March 2006
Bones of the Upper Limb
This contains the bones of the superior appendicular skeleton:
- The clavicle and scapula (pectoral girdle)
- Humerus (arm)
- Ulna and radius (forearm)
- Carpal bones (wrist)
- Metacarpals (hand)
- Phalanges (fingers)
Bones of the Pectoral Girdle
- This bone extends laterally and almost horizontally
across the root of the neck. It extends from the
manubrium of the sternum to the acromion of the scapula.
- The clavicle (L. little key) connects
the upper limb to the axial skeleton and the
- The triangular-shaped medial (sternal) end of the
clavicle articulates with the sternum at the sternoclavicular
- The medial two-thirds of the body (shaft) of the clavicle
are convex anteriorly, whereas the lateral one-third is
flattened and concave anteriorly.
- Its curvature increases its resilience. The broad lateral
(acromial) end of the clavicle articulates with the
acromion of the scapula at the acromioclavicular
The clavicle has three functions:
- To act as a strut for
holding the upper limb free from the trunk so it may have
maximum freedom of action;
- To provide attachments for muscles;
- To transmit forces from the upper
limb to the axial skeleton.
The Scapula (p.
- This flattened, triangular bone lies on the
posterolateral aspect of the thorax, covering parts of
the 2nd to 7th ribs.
- The scapula connects the clavicle to the humerus. It is
highly mobile and has a head, neck,
- The body is thin and translucent.
- The scapula has a concave costal or anterior surface (subscapular fossa) and a
convex posterior surface from which the spine of the scapula projects.
- The smaller part, which is superior to the spine, is
called the supraspinous fossa,
and the larger part, which is inferior to the spine, is
called the infraspinous fossa.
- The spine continues laterally into a flattened process
called the acromion. It
projects anteriorly and articulates with the clavicle.
- Superolaterally, the scapula has a shallow glenoid fossa for articulation
with the head of the humerus. This part of the scapula,
called the head, is
connected to its blade-like body by a short neck.
- The coracoid process,
like a bird's beak, arises from the superior border of
the head and projects superoanteriorly.
- The scapular notch is in
the superior border.
The Bone of the Arm
The Humerus (p.
- The humerus is the largest bone in the upper limb.
- Its smooth, ball-like head articulates with the glenoid
fossa of the scapula.
- Close to the head are the greater
and lesser tubercles for the insertion of the
muscles that surround and move the shoulder
- The lesser tubercle is separated from the greater
tubercle by the intertubercular
groove (sulcus), from which lies the tendon of
the long head of biceps brachii
- The anatomical neck
separates the head and tubercles.
- Distal to the anatomical neck is the surgical
neck. This is where the bone narrows to become
the shaft. The region is called the surgical neck because
it is the most frequent fracture site of the proximal end
of the humerus.
- The body, or shaft, of the humerus is easy
to palpate, as are its medial and lateral epicondyles.
Its superior half is cylindrical.
- Anterolaterally, there is a roughness know as the deltoid tuberosity for the
insertion of the deltoid muscle.
- There is a shallow, oblique radial
groove for the radial nerve that
extends inferolaterally on the posterior aspect of the
- The distal end of the humerus is expanded from side to
side. The trochlea (L.
pulley) fits into the trochlear
notch of the ulna, which swings on this pulley
when the elbow is flexed.
- Just proximal to the trochlea are the coronoid
fossa and the olecranon
fossa, which accommodate corresponding parts
of the ulna.
- Adjoining the lateral part of the trochlea is a rounded
ball of bone called the capitulum
(L. little head).
- A prominent process, the medial
epicondyle, projects from the trochlea, and
the lateral epicondyle
projects from the capitulum. The epicondyles being
subcutaneous are easily felt. The medial epicondyle is
- From each epicondyle, a bony ridge runs proximally; these
are know as the medial and lateral supracondylar
Fractures to the Humerus
- Fractures of the surgical neck
are common in elderly persons
and usually from falls on the elbows when the arm is
- The fracture line occurs superior to the insertion of the
pectoralis major, teres major and latissimus dorsi
- Because nerves are in contact with the humerus, the axillary, radial, and ulnar nerves may be
injured in fractures of the humerus.
- Traumatic separation of the proximal epiphysis of the
humerus can occur in young persons because this epiphysis
does not fuse with the body of the humerus until about 18
years of age in females and 20 years of age in males.
- Fracture-separation of the proximal
epiphysis occurs in children because the
articular capsule of the shoulder joint is stronger than
the epiphyseal cartilaginous plate.
of the Forearm
The Radius (p.
- This is the shorter of the two forearm bones.
- It was given its name because it resembles the spoke of a
wheel (in Latin).
- The proximal end of the radius has a disc-shaped head, a smooth cylindrical neck, and an oval prominence
or tuberosity, distal to
- The body (shaft) of the
radius increases in size from its proximal to its distal
end; it has a slight lateral convexity or bowing.
- The body is concave anteriorly in its proximal
three-fourths and flattened in its distal one-fourth.
- The anterior oblique line
of the radius runs obliquely across the body from the
region of the radial tuberosity to the area of greatest
- The medial aspect of the body has a sharp interosseous border for
attachment of the interosseous
membrane. Its lateral border is rounded.
- The distal end of the radius has a medial ulnar notch into which the
head of the ulna fits, forming the distal
- Laterally the distal end of the radius tapers abruptly
into a prominent pyramidal styloid
- The inferior surface of the distal end of the radius is
smooth and concave where it articulates with the wrist or
- Posteriorly there is a prominent dorsal
tubercle on the distal end of the radius.
Fractures of the Radius
- A fall on the outstretched hand may result in a fracture of the distal end of the radius.
- Sometimes there is also a fracture of the styloid process
of the ulna.
- In the common Colle's fracture,
the distal fragment of the radius is displaced posterior.
The result is the radial and ulna styloid processes being
at approximately the same horizontal level which is an
abnormal condition (dinner fork
The Ulna (pp. 555,
- The ulna (L. elbow) is the longer bone of the forearm.
- This prismatic bone looks somewhat like a pipe wrench,
with the olecranon
resembling the upper jaw, the coronoid
process the lower jaw, and the trochlear notch the mouth.
- The olecranon and coronoid processes clasp the trochlea
of the humerus; somewhat like a pipe wrench clasps a
- The proximal "wrench-like" end of the ulna is
larger that the small, rounded distal end called the head.
- The lateral side of the coronoid
process has a small, shallow radial notch for the
disc-shaped head of the radius.
- Inferior to the radial notch is the triangular supinator fossa, which
provides an attachment for the supinator muscle.
This fossa is bounded posteriorly by a distinct supinator crest.
- The irregular anterior surface of the coronoid
process is rough and ends distally in a tuberosity onto which the brachialis, the
chief flexor muscle of the forearm, inserts.
- The body (shaft) of the
ulna is thick proximally. Its prominent lateral edge, the
interosseous border, is
where the interosseous membrane attaches.
- The small, slender distal end of the ulna has a rounded head and a conical styloid
process. The styloid process
projects distally, about 1 cm proximal to the styloid
process of the radius.
- The distal end of the ulna has a convex articular surface
on its lateral side for articulation with the ulnar notch
of the radius.
Bones of the Wrist and Hand
The Carpus (pp.
- The eight small bones of the wrist, called carpal bones are referred to
collectively as the carpus
- They are arranged in proximal and distal rows, each
containing four bones.
- The proximal row of carpal bones
(lateral to medial) consists of the scaphoid (navicular),
lunate, triquetrum, and pisiform.
- The boat-shaped scaphoid
is the largest bone of the proximal row and was given its
name because of its resemblance to a rowboat (G. scaphe).
- The lunate is
- The pea-shaped pisiform
(L. pisum, pea) is included in the proximal row,
even though it is a sesamoid bone in the tendon of flexor
ulnaris muscle. The pisiform bone is a clinically
important landmark that is easily palpable.
- The distal row of carpal bones
(lateral to medial) consists of the trapezium, trapezoid,
capitate, and hamate.
- The hamate can be
identified by its prominent process, the hook of the hamate, which
- The capitate has a
rounded head (L. caput).
- The carpal bones articulate with each other at synovial intercarpal joints and are
bound together with ligaments to form a compact mass.
- The carpus has an anterior concavity known as the carpal groove (sulcus). The
groove is converted into an osseofibrous carpal tunnel (canal) by the flexor retinaculum), which is
attached to the scaphoid and trapezium laterally and to
the pisiform and the hook of the hamate bone medially.
- The carpal tunnel is filled with tendons and the median nerve.
- Compression of the median nerve in the carpal tunnel
produces the carpal tunnel syndrome.
Metacarpus (pp. 561, 565)
- The five metacarpal bones
are miniature long bones.
- They extend from the carpus (wrist) to the digits (thumb
and fingers) and are numbered from the lateral side.
- The first metacarpal is much shorter than the others.
- Although covered with tendons, the metacarpals can easily
be palpated throughout their whole length on the dorsum
of the hand.
- The heads of the metacarpals
are at their distal ends, where they articulate with the phalanges (bones of the
- They form knuckles of the hand
that become visible when the fist is clenched.
- On the dorsal surface of each head is a small tubercle on
each side for attachment of collateral ligaments and
- The bodies (shafts) of the
metacarpal are slightly concave on their
medial and lateral sides, where the dorsal interosseous
- The bases of the metacarpals
are arranged in a fan-shaped manner from the distal row
of carpal bones.
- Each phalanx (bone of a digit) is a miniature long bone,
which consists of a body
(shaft), a larger proximal end or base,
and a smaller distal end or head.
- The thumb (first digit) has two phalanges (proximal and
distal) and each finger (second to fifth digits) has
three phalanges (proximal, middle and distal). The
phalanges in the first digit are shorter and broader than
those in the other digits.
- The proximal phalanges are the longest and the distal
ones are the shortest.