Download Unit 9: Joints of the Upper Limb

Unit 9:
Joints of the Upper Limb
Dissection Instructions:
The joints are only to be done on one limb.
In this unit, the soft tissues are to be removed to expose the joints. If this is done in a systematic
way, an excellent review can be accomplished at the same time.
Note the insertion of the pectoralis major muscle on the greater tubercular crest of the humerus
and the insertion of the pectoralis minor on the coracoid process of the scapula. Now find the medial and
lateral pectoral nerves from the medial and lateral cords of the brachial plexus. Remove the muscles by
cutting their insertions.
In the axilla, locate the axillary nerve and posterior humeral circumflex vessels. Trace them
through the quadrangular space, note the nerve to the teres minor and follow the neurovascular bundle
into the deltoid muscle. Remove the deltoid muscle. Trace the thoracodorsal nerve and vessels into the
latissimus dorsi muscle, then follow the tendon of the muscle into the intertubercular sulcus. Cut the
tendon near its insertion and remove the muscle. The tendon of the long head of the biceps brachii is held
in the sulcus by the pectoralis major muscle and the transverse ligament. Find the lower subscapular
nerve and trace it to the subscapularis and teres major muscles. Review the origin and insertion of the
teres major and then remove the muscle. Locate the upper subscapular nerve and follow it into the
subscapularis muscle. The subscapularis, teres major and latissimus dorsi muscles make up the posterior
wall of the axilla and they are all innervated by branches off the posterior cord of the brachial plexus.
Locate the musculocutaneious nerve from the lateral cord of the brachial plexus and find its
branches to the coracobrachialis and biceps brachii muscles. Review the origins and insertion of the
biceps brachii muscle. Cut the long head of the biceps brachii where the tendon joins the belly of the
muscle. Review the coracobrachialis muscle, then remove it and the short head of the biceps brachii from
the coracoid process. Detach the coracobrachialis from the humerus and cut the tendon of insertion of the
biceps brachii.
Note the course of the radial nerve from the posterior cord of the brachial plexus between the
humerus and the long and lateral heads of the triceps brachii muscle to the lateral intermuscular septum of
the arm. Detach the long head of the triceps brachii from the infraglenoid tubercle of the scapula and the
lateral head from the humerus. Note that the deep brachial vessels travel with the radial nerve in the
radial groove of the humerus. Find the two branches of the radial nerve to the medial head of the triceps
brachii and note that the proximal branch, the ulnar collateral nerve, is accompanied by the superior
ulnar collateral artery and the second branch goes with the middle collateral artery. Follow the latter
structures through the medial head of the triceps brachii to the anconeus muscle. Very carefully remove
the triceps brachii from the olecranon process of the ulna without damaging the capsule of the elbow
joint, which is fused to its deep surface.
Note that the plane of the acromioclavicular joint space is nearly in a sagittal plane. Saw
through the scapular spine where it becomes the acromion process. Carefully clean the oracoclavicular
ligament consisting of conoid and trapezoid parts (Plates 406; 6.43, 6.46). Identify the
coracoacromial and coracohumeral ligaments.
Unit 9 - 1
Review the subscapularis, supraspinatis, infraspinatis and teres minor muscles forming the
rotator cuff of the shoulder joint (Plates 408, 409; 6.45, 6.46, Table 6.5, p. 397). Trace the
suprascpular nerve and vessels to the supraspinous muscle. Cut the muscles opposite the neck of the
scapula (proximal to the glenoid surface) and follow the suprascapular neurovascular bundle to the
infraspinous fossa. Free the muscles from the capsule of the shoulder joint before cutting them from their
bony attachments on the humerus.
Turn to the back of the shoulder joint and make a vertical incision down the back of the joint
capsule so the humerus can be rotated away from the glenoid fossa of the scapula. Note the glenoid
labrum. It is a fibrocartilagenous lip which deepens the glenoid fossa. Locate the tendon of the long
head of the biceps brachii muscle and follow it to the supraglenoid tubercle. Note that part of the origin
is from the glenoid labrum. Now locate the communication between the joint space and the supscapular
bursa. Between the biceps tendon and the opening of the bursa is the superior glenohumeral ligament.
Bordering the inferior margin of the opening of the subscapular bursa is the middle glenohumeral
ligament. Below this and running downward and lateralward is the inferior glenohumeral ligament
(Plates 406; 6.41 - 6.45).
Locate the radial nerve above the elbow and review the nerves to the extensor muscles of the
forearm. The brachioradialis and extensor carpi radialis longus are innervated from the main trunk, the
extensor carpi radialis brevis and supinator from the deep branch and the rest of the extensors after the
nerve exits the supinator. Remove the extensor muscles that attach to the lateral epicondyle and
supracondylar ridge of the humerus after the insertions have been reviewed.
Note the relationship between the median nerve and the brachial artery. The nerve has no
branches until it reaches the cubital fossa. The artery has many branches, most of which are unnamed
muscular branches. Trace the ulnar nerve through the arm, behind the medial epicondyle of the humerus
and between the heads of the flexor carpi ulnaris muscle. Locate its branch to this muscle and to the
flexor digitorum profundis. Review the origins and insertions of the flexor muscles of the forearm, then
remove those that arise from the medial epicondyle of the humerus. Identify the end of the brachial
artery, the radial and ulnar arteries and the common interosseous artery. Now find the radial recurrent,
interosseious recurrent and anterior and posterior ulnar recurrent arteries.
Carefully remove the brachialis from the anterior surface of the elbow joint (the capsule is very
thin and fused to the muscle) after reviewing its origin and insertion.
The elbow joint is formed by the humerus radius and ulna (Plates 421; 6.52, 6.54 - 6.57). Within
the elbow joint is the proximal radioulnar joint. The proximal end of the had of the radius articulates with
the capitulum of the humerus while the circumference of the head of the radius articulates with the radial
notch of the ulna. The trochlear fossa of the ulna articulates with the trochlea of the humerus. The main
stability of the joint is maintained by this trochlea-trochlear fossa relationship.
On the medial side of the elbow joint, clean the ulnar collateral ligament and identify the
anterior, posterior and oblique parts. Clean the radial collateral ligament on the lateral side of the elbow
joint. Notice that it attaches inferiorly to the annular ligament. This ligament attaches to the ulna and
circles the neck and lower part of the head of the radius. The anterior and posterior part of the elbow joint
capsule is weak.
Open the elbow joint by making a horizontal incision through the front of the joint capsule at the
level of the radial head-capitulum atriculation. Alternately pronate and supinate the hand and watch for
movement of the annular ligament. It should be noted that the annular ligament does not move, but the
capsule distal to the annular ligament is loose and allows for the movement. Note that the tissue between
Unit 9 - 2
the radius and ulna below the annular ligament also is loose. That portion of the capsule is known as the
quadrate ligament.
Find the insertion of the flexor carpi ulnaris on the pisiform bone, then cut the tendon proximal to the
bone. Review the insertions of the flexor pollicis longus, flexor digitorum superficialis and profundis and
detach them. Locate the flexor carpiradialis insertion and then cut its tendon. Review the anatomy of the
median and ulnar nerves in the hand and the superficial and deep palmar arterial arches. Review the muscles
of the hand.
Review the extensor retinaculum, identify the tendons passing under it and trace them to their
insertions. Review the blood supply to the dorsal aspect of the forearm and hand. Now, remove the muscles
that cross the wrist and hand joints, but not the metacarpophalangeal and interphalangeal joints.
Clean the interosseous ligament between the radius and ulna (Plate 422; 6.58). This makes up the
middle radioulnar articulation. It is a syndesmosis, a fibrous joint.
The distal radioulnar joint is a separate synovial joint between the head of the ulna and the ulnar
notch of the radius (Plates 422, 438; 6.85 -6.89). Alternately supinate and pronate the hand and note the
movement at the distal radioulnar joint. At the distal end of the ulna is a fibrocartilagenous disk which
separates the ulna from the carpal bones.
Remove the areolar tissue covering the wrist joint and identify the dorsal and palmar radiocarpal
ligaments (Plates 437, 438; 6.85, 6.86) Note that they come from the distal end of the radius and pass distally
and medialward as they cross the wrist joint. On the sides of the joint are the radial and ulnar collateral
ligaments of the wrist.
The pisiform bone articulates with the triquetral by a plane synovial joint. The other seven carpal
bones articulate with each other through the mid-carpal joint (Plates 438; 6.85, 6.89). This is a single
complex synovial joint. Distally the carpal bones articulate with the metacarpal bones through three joint
cavities. The first metacarpal bone forms a saddle joint with the trapezium bone. The second and third
metacarpals and the third and fourth metacarpals have synovial joints with the adjacent carpal bones.
The metacarpophalangeal joints (Plates 441; 6.89) are condylar joints except for the first one,
which is a hinge joint. They all have radial and ulnar collateral ligaments. The palmar part of the
capsules is very tough and is connected by the deep transverse metacarpal ligament. The dorsal aspect of
the joints is formed primarily by the extensor tendon expansion (hood). The interphalangeal joints are
hinge joints and their capsules are similar to those of the metacarpophalangeal joints (Plates 44; 6.90).
Unit 9 - 3
Be sure to identify all of the following:
acromioclavicular joint
coracoclavicular ligament (conoid & trapezoid)
coracoacromial ligament
coracohumeral ligament
rotator cuff of shoulder joint
subscapularis muscle
supraspinatus muscle
infraspinatus muscle
teres minor muscle
glenoid fossa
glenoid labrum
tendon of long head of biceps brachii muscle
superior glenohumeral ligament
middle glenohumeral ligament
inferior glenohumeral ligament
ulnar collateral ligament (elbow)
radial collateral ligament (elbow)
annular ligament
quadrate ligament
interosseous ligament
dorsal radiocarpal ligament
palmar radiocarpal ligament
radial collateral ligament (wrist)
ulnar collateral ligament (wrist)
Unit 9 - 4