The document describes the anatomy of the anterior compartment of the arm. It contains the coracobrachialis, biceps brachii, and brachialis muscles. The brachial artery and musculocutaneous, median, ulnar, and radial nerves also pass through this compartment. It provides details on the origin, insertion, nerve supply, and actions of the coracobrachialis and biceps brachii muscles. Additionally, it discusses the course and branches of the musculocutaneous nerve.

1. THE ARM
ANTERIOR COMPARTMENT

2. INTRODUCTION
• The arm extends from
the shoulder joint till
the elbow joint. The
skeleton of the arm is a
solo bone, the
humerus.

3. • The arm or brachium is
enveloped by a sleeve of
deep fascia (brachial
fascia),which projects
into its interior as medial
and lateral inter-
muscular septa and
divides the arm into an
anterior or flexor
compartment and a
posterior or extensor
compartment.
• These septa are well
defined in the lower part
of the arm and provide
additional areas for the
attachments of muscles.

4. ANTERIOR COMPARTMENT
CONTENTS
Muscles – Coracobrachialis,
• Biceps brachii
• Brachialis

5. Artery – Brachial
artery
Nerve-
Musculocutaneous
nerve
• Median nerve
• Ulnar nerve
• Radial nerve

6. CORACOBRAC
HIALIS
• ORIGIN: tip of
coracoid process
• INSERTION: the
medial border of
the middle of the
shaft of humerus

7. NERVE SUPPLY :
musculo-
cutaneous nerve
ACTION: flexes
forearm at elbow
joint

8. BICEPS BRACHII
• It is an elongated
fusiform muscle and
arises by two
tendinous heads, short
and long.
• ORIGIN:
1. SHORT HEAD –tip of
the coracoid process
2. LONG HEAD – arises
from supraglenoid
tubercle of scapula
and from glenoid
labrum.

9. INSERTION:
Short head – posterior
rough part of radial
tuberosity.
Long head – tendon
gives off an
extension called
bicipital
aponeurosis. This
merge with deep
fascia of forearm

10. ACTION:
1. It is strong supinator when
the forearm is flexed, all
screwing movements are
done with it.
2. It is flexor of elbow
3. The short head is flexor of
arm
4. Long head prevents upwards
displacement of head of
humerus

11. BRACHIALIS
ORIGIN:
1. lower half of front of humerus,
including both Antero-medial and
antero-lateral surfaces and
anterior border.
2. Superiorly It embraces the
insertion of deltoid
3. Medial and lateral intermuscular
septa
INSERTION:
1. Ulnar tuberosity
2. Rough anterior surface of
coronoid process of ulna

12. NERVE SUPPLY:
musculo-
cutaneous
nerve( motor)
Radial nerve is
proprioceptive.
ACTION: It flexes
forearm at the
elbow joint.

13. CORACOBRACHIALIS
MORPHOLOGY :
The coracobrachialis represent an
adductor muscle of the arm, but such
action insignificant in man.
• In some animals it is tricipital in origin.
In man upper two heads are fused to
take origin from the coracoid process
and enclose the musculo-cuteneous
nerve between them.

14. The lower head is usually
suppressed in man. sometime
it is represented by a fibrous
band, the ligament of
Struthers, which extend from
trochlear spine to medial
epicondyle of humerus
Median nerve or brachial
artery may pass below the
ligament which compresses
upon them producing
vascular spasm or median
nerve palsy

15. ANATOMICAL EVENTS AT THE LEVEL OF THE INSERTION OF
CORACOBRACHIALIS:
• Bone:
the
circular
shaft
becomes
triangular
below
this level.

16. Fascial septa: the
medial and lateral
inter-muscular
septa become
better defined
from this level
down.
ANATOMICAL EVENTS AT THE LEVEL OF THE INSERTION OF
CORACOBRACHIALIS:

17. Muscles:
i. Deltoid and
coracobrachialis
are inserted at
the same level.
ii. Origin of
brachialis .
iii. Origin of the
medial head of
triceps brachii.

18. ARTERIES:
• The brachial
artery passes
from the
medial side of
the arm to its
anterior
aspect.

19. • The profunda
brachii artery
runs in the
spiral groove
and divides
into its
anterior
descending(
radial
collateral
artery) and
posterior
descending(
middle
collateral
artery)
branches.

20. • The superior
ulnar collateral
artery originate
from the
brachial artery,
and pierces the
medial inter-
muscular
septum with
the ulnar nerve.
• The nuterient
artery of the
humerus enters
the bone

21. VEINS:
i. The basilic vein pierces the
deep fascia.
ii. Two venae comitants of the
brachial artery may unite to
form one brachial vein.

22. • NERVES:
• The median
nerve crosses the
brachial artery
from the lateral
to the medial
side.
• The ulnar nerve
pierces the
medial inter-
muscular septum
with the superior
ulnar collateral
artery and goes
to the posterior
compartment.

23. • The radial nerve
pierces the lateral
inter-muscular
septum with the
anterior descending
(radial collateral)
branch of the
profunda brachii
artery and passes
from the posterior to
the anterior
compartment.
• The medial cutaneous
nerve of the arm
pierces the deep
fascia.
• The medial cuteneous
nerve of the forearm
pierces the deep
fascia.

24. Applied anatomy
• The tendon of the long head of the
biceps brachii lies within the capsule
of the shoulder joint.
• In osteoarthritis of this joint
abnormal irregular projection
develop from the bones concerned
and friction against them can lead to
inflammation. There is pain in the
shoulder.
• Damage to the tendon can end in
rupture
• The biceps tendon reflex is induced
by a tap on the biceps tendon
a) The examinar places his thumb over
the tendon and gives a tap on his
thumb.
b) There is reflex contraction of biceps

25. MUSCULO-CUTANEOUS
NERVE
• The musculo-
cutaneous nerve is the
main nerve of the front
of the arm, and
continues below as the
lateral cutaneous nerve
of the forearm.
• It is a branch of the
lateral cord of the
brachial plexus, arising
at the lower border of
the pectoralis minor
muscle(c5,c6,c7).
• ROOT VALUE: ventral
rami of c5-c7 segments
of spinal cord.

26. COURSE AND RELATIONS
• In the lower part of the axilla – the nerve initially accompanies the
third part of axillary artery ;leaves the axilla, and enters the front of
the arm by piercing the coracobrachialis.
• It has the following relations :-
Anteriorly: pectoralis major
Posteriorly: subscapularis
Medially: axillary artery and lateral root of the median nerve
Laterally :coracobrachialis

27. COURSE AND
RELATIONS
• In the arm – it runs
downward and
laterally between the
biceps and brachialis to
reach the lateral side
of the tendon of the
biceps.It ends by
piercing the fascia 2cm
above the bend of the
forearm.

28. Branches and Distribution
–
• Muscular: to the
muscles; the biceps
brachii,coracobrachialis
and brachialis.
• Articular branches: the
elbow joint through its
branches to the
brachialis
• to humerus through a
separate branch which
enters the bone along
with its nutrient artery.

29. Cutaneous:
through the lateral
cutaneous nerve of
forearm it supplies
the skin on the
front and lateral
aspect of the
forearm from the
elbow to the wrist
including the ball
of the thumb.

30. Communicating branches:
through the lateral
cutaneous nerve of forearm
communicates with the
neighbouring nerve,namely
the superficial branch of the
radial nerve,the posterior
cutaneous nerve of
forearm,and the palmar
cutaneous branch of the
median nerve.
Variations – instead of piercing
the coraco brachialis it may
pass behind it to reach
interval between biceps and
brachialis
Temporaily, it may either give
fibers to or receive fibres
from median nerve