1. Upper Limb
Arm & Forearm

2. Arm Cross Section
The intermuscular septum and the humerus divide the arm into anterior and posterior compartments
Anterior Compartment:
Flexor’s
“3” muscles
Musculocutaneous nerve
Brachial artery
Posterior Compartment:
Extensor’s
“3” muscles
Radial nerve
Deep brachial artery

3. Posterior Compartment
Triceps brachii
Lateral head
Posterior surface of humerus – superior to radial grove
Long head
Infraglenoid tubercle
Radial nerve
Deep brachial a.
All three heads have a common distal attachment on the olecranon
Medial head
Posterior surface of humerus – inferior to radial grove

4. Muscles of the Arm - Posterior
Long head: Power assist for elbow extension
Medial head : primary extensor
Active throughout elbow extension
Triceps Brachii
Primary elbow extensor

5. Anterior Compartment coracobrachialis Biceps brachii brachialis
Corocoid process to mid way along the medial humerus
Long head – supraglenoid tubercle
Short head- corocoid process
brachialis
Common insertion: tuberosity of the radius
Anterior surface of humerus to coronoid process and tuberosity of the ulna
Brachial a
Musculocutaneous n.

6. Muscles of the Arm - Anterior
Biceps Brachii
Primary forearm supinator
Power assist for elbow flexion
Brachialis
Primary elbow flexor
Active throughout elbow flexion
Coracobrachialis
Action at the GH joint for flexion & adduction

7. Elbow Joint- A “Hinge” Joint
Humero-ulnar
joint
Humero-radial
joint
Enclosed in a single joint capsule (along with the superior radioulnar joint)

8. Distal Humerus (right)
In full flexion, the rim of the radial head slides in the capitulotrochlear groove and enters the radial fossa
Medial
Lateral
The trochlear ridge of the olecrenon rides in the trochlear groove
(right)
Lenangie 8-1

9. Bones of the Elbow Anterior view Posterior view
The lower end of the humerus flairs out as epicondyles. These provide a mechanical advantage to the forearm muscle groups that attach at these sites.
Lateral
lateral
Medial
Medial
extensors
flexors
capitulum
trochlea
Attachment
of the biceps
Attachment of the brachialis
Anterior view
Posterior view

10. Elbow Xray O = olecranon T = trochlea of the humerus
CP = coronoid process of the ulna
HR = head of the radius
C = capitulum

11. Carrying Angle of the Elbow
Formed by the vertical axis of the humerus and the vertical axis of the forearm
The angulation is due to the configuration of the bony articulating surfaces
Males = 5o
Females = 10o - 15o

12. Transverse Axis Includes the humeroulnar and humeroradial joints
Flexion and extension
Flexors:
Biceps, brachialis, brachioradialis
Extensors:
Triceps,
anconeus

13. Elbow Flexors
In addition to the biceps and brachialis, the brachioradialis also functions as a flexor of the elbow
Each functions at differing degrees of supination and pronation of the forearm

14. Collateral Ligaments medial
Increase stability and joint apposition
Annular ligament
Ulnar collateral
“MCL”
medial
Fibers of the radial collateral ligament attach to the annular ligament
Capitulum
Radial head
lateral
Radial collateral
“LCL”
Annular ligament

15. Annular Ligament
Annular ligament acts like a sling holding the radial head close to the ulna bone
Annular ligament offers support but allows rotation (spin) as well as glide of the radial head during supination/ pronation
Radial collateral
Synovial fold

16. Radioulnar Joint Motion
supination
pronation

17. Radioulnar Joint
Complex joint with 2 articulations connected by the interosseous membrane
Superior (annular ligament)
Inferior – with capsule and disc

18. Vertical Axis Humeroradial and radioulnar joints
Forearm supination and pronation

19. Muscles of Supination/Pronation
Supinator &
biceps brachii
Pronator teres &
pronator quadratus

20. Forearm Cross Section
The interosseus membrane and radius and ulna divide the forearm in to anterior and posterior compartments

21. Innervation rule
All muscles of the anterior compartment are supplied by the median nerve Or Ulnar nerve
All muscles of the posterior compartment are supplied by the radial nerve.

22. Superficial Muscles of the Anterior Forearm
From the common flexor tendon arising from the medial condyle of the humerus
Cross the elbow but have minimum function at that joint

23. Surface Anatomy - Anterior Forearm
lateral
medial
Thumb = pronator teres
5th digit (tucked under) = flexor digitorum superficialis
2nd digit = flexor carpi radialis
3rd digit = palmaris longus
4th digit = flexor carpi ulnaris

24. Deep Muscles of the Anterior Forearm
Thumb
Fingers
Wrist
Arise from the ulna (pronator quadratus, flexor digitorum profundus) and radius (flexor pollicis longus)

25. Superficial muscles of the posterior forearm
extensor carpi radialis longus E
superficial
extensor carpi radialis brevis
extensor carpi ulnaris
Extensor carpi ulnaris
Extensor carpi radialis brevis
Extensor carpi radialis longus
3 Superficial Muscles

26. Intermediate muscles of the posterior forearm
2 Int Muscles
Extensor digiti minimi muscle
Extensor digitorum

27. Deep muscles of the posterior forearm
Abductor pollicis longus
Extensor pollicis brevis
Extensor pollicis longus
Supinator
Extensor indices

28. Median Nerve
All forearm muscles are innervated by the MEDIAN nerve EXCEPT:
1 ½ muscles
flexor carpi ulnaris
ulnar side of the flexor digitorum profundus
Plus: All thenar mm except adductor pollicis

29. Brachial Artery in Situ
Posterior circumflex humeral a. runs with the axillary nerve
Deep brachial a. runs with radial nerve
Superior ulnar collateral a. runs with the ulnar nerve

30. Brachial Artery Anastomoses

31. Radial & Ulnar Arteries
lateral
medial
Radial artery
Ulnar artery
Common interosseous
Anterior
Posterior
Dorsal and palmer carpal branches
Dorsal and palmer carpal branches
Deep (superficial) palmar arches
superficial (deep)palmar arches

32. Injuries
Cubital tunnel syndrome – contraction of the flexor carpi ulnaris causes nerve compression
Stretch of the MCL during throwing
Loss of IR & ER rotation of the shoulder may lead to excessive pronation of supination of the forearm and subsequent muscle strain

33. Injuries
Nursemaid’s elbow – radial head subluxed from the annular ligament in an unexpected pull
Fall on the outstretched hand may lead to fracture of the elbow