anatomy of the arm

1. The anatomy of the arm
By:
Mehrdad asgari
Ph.D of Anatomical Sciences, Department of Anatomy, School of Medicine, Guilan
University of Medical Sciences, Rasht, Iran
30 july, 2021
In The Name Of Allah

2. Arm
Region
Arm Region

3. Cutaneous Nerves of Arm
• 1- Supraclavicular nerves (C4,C5)
supply skin over shoulder & upper ½ of deltoid
• 2- Superior lateral cutaneous nerve (C5,C6)
Branch of axillary
supplies skin over lower ½ of deltoid.
3- Inferior lateral cutaneous nerve (C5,C6)
Cutaneous branch of radial nerve
Supplies skin over lower lateral arm below deltoid
• 4- Intercostobrachial nerve (T2)
Lateral cutaneous branch of second intercostal nerve
supplies skin of upper part of medial side of arm
(close to axilla).
– 5-Medial brachial cutaneous (C8-T1)
Branch of brachial plexus
supplies medial side of arm below axilla.
• 6- Posterior brachial cutaneous nerve (C5-
C8)
Branch of radial nerve
Supplies lower posterior medial arm

6. Fascia of the Arm
Superficial fascia

7. Fascia of the Arm
• Brachial fascia
deep fascia around the arm
Continuous with the antebrachial fascia of the
forearm
• Medial and lateral Intermuscular
septa
-Extend from deep surface of brachial fascia to
humerus
-Divide arm into anterior (flexor) and posterior
(extensor) compartments
• Medial septum:
medial lip of intertubercular sulcus
(superiorly) → medial epicondyle
• Lateral septum:
lateral lip of intertubercular sulcus
(superiorly) → lateral epicondyle

8. Compartment of the arm
• Medial intermuscular septa:
It is perforated by
ulnar nerve
- superior ulnar collateral artery
-posterior branch of the
inferior ulnar collateral artery
• Lateral intermuscular septa:
It is perforated by
radial nerve
radial collateral artery
branch of the profunda brachii artery

11. Muscles of the Arm
• Anterior (flexor) compartment
Biceps brachii
Flexes and supinates
Coracobrachialis:
Flexes and adducts arm
Pierced by the
musculocutaneous nerve
Brachialis:
main flexor of forearm

13. Biceps brachii Muscle
• Origin:
a) Short head; Corachoid process
b) Long head; supraglenoid tubercle
• Insertion
- Radial tuberosity
- fascia of forearm via bicipital aponeurosis
 Innervation
Musculocutaneous nerve (C5,C6)
 Action
- Supinates forearm and, when it is supine,
flexes forearm
- Weak flexion of arm

15. Coracobrachialis
• Origin:
Corachoid process
• Insertion
- Middle third of medial surface of
humerus
• Innervation
Musculocutaneous nerve (C5,C6)
• Action
Helps to flex and adduct arm

16. Brachialis Muscle
• Origin:
- Distal half of anterior surface of humerus
- med. & Lat. Intermuscular septum
Insertion
- ulnar tuberosity
- anterior aspect of Coronoid process
Innervation
- Musculocutaneous nerve (C5,C6)
- Radial nerve
Action
- Major flexor of the forearm
- flexes forearm in all positions

17. Attachments of muscles of the front of the arm
Action
Nerve
Insertion
Origin
Muscles
Flexion &
adduction of
arm
Musculocutaneu
s C5-7
The middle 5cm of
the medial border of
humerus
Corachoid
process
Coracobrachialis
Flexion &
supination of
forearm
Musculocutaneu
s C5-7
Radial tuberosity &
bicipital aponeurosis
to deep facia of the
forearm
a) Short head;
Corachoid
process
b) Long head;
supraglenoid
process
Biceps brachii
Flexion of
forearm
Musculocutaneu
s C5-7
Radial nerve
Ulnar tuberosity
Lower ½ of the
front of
humerus &
med. & Lat.
Intermuscular
septum
Brachialis

20. Posterior (extensor) compartment
• Triceps brachii
- Main extensor of arm
- Stabilizes head of humerus in
glenohumeral joint
Anconeus:
- extends arm
- resists adduction of the ulna during
pronation

21. Attachments of muscles of the back of the arm
Action
Nerve
Insertion
Origin
Muscle
Chief extensor
of forearm;
long head
steadies head of
abducted
humerus
Radial nerve
C6-8
Posterior part of
superior surface
of olecranon
process of ulna
a) Long head
infraglenoid tubercle of
scapula
b) Lateral head
posterior surface of
humerus, superior to radial
groove
c) Medial head
posterior surface of
humerus, inferior to radial
groove
triceps

27. Brachial Artery
• Continuation of the axillary artery, ends in
cubital fossa
• Lies anterior to triceps and
brachialis throughout its course
• Accompanied by median nerve,
which crosses anterior to artery
and lies medially in cubital fossa
• Divides into
ulnar and radial arteries
under bicipital aponeurosis

32. • Branches of brachial A.
• Many Muscular branches
• Profonda brachii
 Accompanies radial nerve in radial groove
 Deltoid
 Middle collateral
 Radial collateral
• Superior ulnar collateral
• Nutritional
• Inferior ulnar collateral
• Two terminal branches
( Radial & Ulnar )

33. 1-Profonda brachii

34. Anastomosis around elbow
 In front of lateral epicondyle
: between Radial collateral & radial
recurrent artery.
 Behind lateral epicondyle :
between Middle collateral branch of
profunda artery & interosseous recurrent
artery.
 In front of medial
epicondyle :
 between anterior branch of inferior ulnar
collateral artery & anterior ulnar recurrent
artery.
 Behind medial epicondyle :
between superior ulnar collateral + posterior
branch of inferior ulnar collateral artery &
posterior ulnar recurrent artery.

36. Venous Drainage of Arm
• 1- Superficial veins
(drain into axillary vein)
• Cephalic vein
- On anterolateral surface
- Enters deltopectoral groove
- Then deltopectoral triangle
• Basilic vein
- Medial side, inferior arm
- Pierces deep fascia at junction of inferior
and middle third of arm
- Runs superiorly to axillary vein

37. 2- Deep veins
Paired, accompany brachial artery
(venae comitantes)
- Form at elbow from
radial and ulnar veins
- Have valves
- Merge with basilic vein to form
axillary vein

39. Musculocutaneous nerve
• Origin : lateral cord of brachial plexus in axilla.
• Course : It descends downward and
laterally,piercing coracobrachialis muscle, and
then passes between biceps & brachialis.
• It appears at lateral margin of biceps tendon,
• piercing deep fascia above elbow, where it
descends as lateral cut. N. of forearm on the
lateral aspect of forearm.
• Branches :
•
1-muscular (biceps, coracobrachialis,
+brachialis).
•
.2-Cutaneous: lateral cutaneous nerve of forearm
to supply skin of front & lateral sides of forearm
down to the root of thumb.
3-articular : to elbow joint.

40. Median nerve
 origin : medial & lateral
Cords of brachial plexus in
axilla.
 Course : above,it descends
on lateral side of brachial
artery. -At the middle of
arm, it crosses the
brachial artery. Then it
descends on the medial side of
the artery.
- At the elbow ,it is crossed by
the biciptal aponeurosis.
 Has No branches in the upper
arm.

41. Median nerve
• supplies
Forearm flexors
(except
flexor carpi ulnaris
and the medial half of
flexor digitorum profundus)
Thenar muscles and
1st and 2end lumbricals
Skin over the lateral hand
and 3½ digits

43. Ulnar nerve
 Origin : medial cord of brachial
plexus in axilla.
 Course : above, it is covered
posteriorly by medial head of triceps.
 -it descends medial to the brachial
artery as far as the middle of the arm,
where the insertion of
coracobrachialis,
 it pierces medial facial septum ,
accompanied by superior ulnar
collateral artery to descend in the
post.
 compartment of arm, passing behind
medial epicondyle to enter forearm
bet. 2 heads of flexor carpi ulnaris.
 It has No branches in the arm.
 Only, it has articular to elbow
joint.

44. Ulnar nerve
• supplies
• Flexor carpi ulnaris
• Medial half of FDP
• Hypothenar muscles
• 3rd and 4th lumbricals
• All interossei muscles
• Skin over the medial hand
and 1½ digits

45. Radial nerve
 Origin : post.cord of brachial plexus in the
axilla.
 Course : -on leaving axilla, it passes
immediately into post. compartment of arm
where it descends in spiral groove of humerus
, accompanied by profunda brachii artery,
 deep to lateral head of triceps.
-Then,it pierces lateral facial septum above
elbow to enter anterior compartment of arm,
 between brachialis (medially) and
brachioradialis & extensor carpi radialis longus
(laterally).
 -At the front of lateral epicondyle, it
terminates into superficial & deep branches.

47.  In the axilla :
1-post.cut.N.of arm.
2-branches to long head of triceps.
 In the Spiral groove :
1-branches to lateral & medial heads of
triceps.
2-branch to anconeus.
3-lateral cut. N. of arm. 4-
post. Cut.n.of forearm.
 In anterior compartment of arm
above elbow, (
in deep groove bet. brachialis &
brachioradialis):
1-Muscular : brachialis (lateral ½),
brachioradialis, &
extensor carpi radialis longus.
2-Articular : elbow joint.
Branches of the Radial nerve

49. In front of lateral epicondyle
of humerus, it divides into two
terminal branches :
1-superficial branch.
2-deep branch
(posterior interosseous N.).

50. Radial nerve
• supplies
Triceps
Anconeus
Extensor muscles of forearm
Skin over posterior arm and
forearm

51. Axillary nerve
• Supplies
Teres minor
Deltoid
Shoulder joint
Skin over inferior deltoid

53. • Elbow region
• 1- Cubital Fossa
• 2- olecranon fossa

54. Elbow region
Cubital Fossa
Boundaries
• Superiorly:
 Imaginary line connecting medial and
lateral epicondyles of humerus
• Medially:
 Lateral border of pronator teres
 Laterally:
 medial border of Brachioradialis
• Apex:
 Site of overlap of pronator teres by
brachioradialis

56. • Roof:
1. skin
2. superficial fascia
3. Cephalic vein
4. Basilic vein
5. Median cubital vein
connecting the cephalic and
basilic veins
6. Lateral and medial
cutaneous nerves of
forearm
7. Deep fascia with bicipital
aponeurosis

58. floor
Floor
brachialis
supinator muscles of arm and forearm

59. Cubital fossa
• Contents:
1. Median nerve
2. Brachial artery dividing into
radial and ulnar arteries
3. Biceps brachi tendon
4. Radial nerve
and its two terminal branches (super
ficial and deep)

63. Olecranon Region
• Skin
• Olecranon bursa
• Anconeus muscle
• Para-olecranon grooves
• arteris

67. The elbow joint
• Humerus, radius and ulna form a hinge joint.
• Humeroradial joint
- The capitulum of the humerus articulates with the upper aspect of the head of the radius
• Humero-ulnar joint
- The trochlea of the humerus articulates with the trochlear notch of the ulna
• Proximal radio-ulnar joint

68. The elbow joint
• Flexion is done by biceps, brachialis and coracobrachialis.
• Extension is performed by triceps, particularly medial head.
• The extended ulna makes with the humerus an angle of 170 degrees.
• This is carrying angle. It is 10-15degrees It fits the elbow into the waist when
the arm is at the side
Movements

69. Capsule of Elbow Joint
 Capsule surrounds the joint:
• Anteriorly to the margins of the
coronoid and radial fossae of the humerus
• Medially and laterally just beyond the
articular margin
• Excluding the medial and lateral
epicondyles to which the common flexor
and extensor origins are attached
• Posteriorly to the margins of the
olecranon fossa
• Inferiolaterally it is inserted into the
annular ligament of the superior
radioulnar joint

71. • Medial or Ulnar Collateral Ligament
• Lateral or Radial Collateral Ligament