ANTERIOR COMPARTMENT OF ARM
Learning objectives
At the end of the lecture the student will able:
To define the compartment of the arm.
To describe the content of the anterior content of the arm.
To discuss the neurovascular structure of the anterior arm.
To correlate the clinical anatomy of the anterior arm.
FASCIAL COMPARTMENTS OF THE UPPER ARM
CONTENTS OF ANTERIOR FASCIAL COMPARTMENT
Muscles
Blood vessels
Nerves
Are the structures passing through the compartment
MUSCLES OF ANTERIOR COMPARTMENT
MUSCLES OF ANTERIOR COMPARTMENT
Biceps brachii
Origin
: Short head; Coracoid process
: Long head;Supraglenoid
tubercle
Insertion : Radial tuberosity, bicipital aponeurosis
Action
: Supination, flexes elbow
Nerve
: Musculocutaneous nerve
THE BICEPS BRACHII
•
The biceps functions primarily as strong supinator of the forearm. This action, which is aided by
the supinator muscle, requires the elbow to be at least partially flexed.
•
The biceps also functions as an powerful flexor of elbow joint, particularly when the forearm is
supinated. Functionally, this action is performed when lifting an object, such as a bag of
groceries or when performing a biceps curl.
•
Both these movements are used when opening a bottle with a corkscrew: first biceps unscrews
the cork (supination), then it pulls the cork out (flexion).
•
If the elbow joint is fully extended, supination is then primarily carried out by the supinator
muscle.
•
Weak flexor of shoulder joint.
Coracobrachialis
Origin
: Coracoid process
Insertion : Humerus, middle of body,medial
Action : Flexion (flexes shoulder)
Nerve : Musculocutaneous nerve
Cont….
The coracobrachialis draws the humerus forward (shoulder flexion) and towards the torso (shoulder
adduction).
Brachialis
Origin : Humerus, ant. surface distal 1/2
Insertion : Ulna, coronoid process, ulnar tuberosity
Action : Flexes elbow
Nerve : Musculocutaneuos n. & radial n.
Brachialis
The brachialis muscle is innervated by the musculocutaneous nerve, which runs on its superficial
surface, between it and the biceps brachii.
Part of it is also innervated by the radial nerve (proprioceptive branch).
Action: Most powerful flexor at elbow joint
When the forearm is in pronation, the brachialis, brachioradialis, and supinator function to flex the
forearm, with minimal contribution from the biceps brachii.
STRUCTURES PASSING THROUGH ANTERIOR FACIAL COMPARTMENT
RELATIONS OF BRACHIAL ARTERY
Anteriorly: Superficial in the upper part, overlapped laterally by coracobrachialis and biceps.
Upper part; Medial cutaneous nerve of forearm
Middle part; Median nerve
Lower part; bicipital aponeurosis
Posteriorly: Triceps, coracobrachialis, brachialis
`
Laterally: Upper part: Median nerve, coracobrachialis and biceps.
Lower part: tendon of biceps
Medially: Upper part: ulnar nerve, basilic vein
Lower part: Median nerve
NERVES OF THE ANTERIOR COMPARTMENT
MUSCULOCUTANEOUS NERVE
Origin
Course in arm
Branches:
1. Muscular
2. Cutaneous
3. Articular
MUSCULOCUTANEOUS NERVE
Main nerve that supply the front of arm.
• Branch of lateral cord of brachial plexus
• Root Value – C5, C6, C7.
Course In Axilla – Arises from Lateral Cord – Lies lateral to 3rd part of Axillary Artery Relation in Axilla
• Anteriorly – Pectoralis Major
• Posteriorly – Subscapularis
• Medially – Axillary artery – Lateral root of Median Nerve
• Laterally – Coracobrachialis
• Leaves the axilla and enters front of arm by piercing the coracobrachialis.
In Arm :
Runs downward and laterally between the biceps and brachialis
• Reaches lateral side of the tendon of the biceps piercing the deep fascia 2cm above the bent of fore
arm
• Continues as lateral cutaneous nerve of forearm
Muscular Branches
– Coracobrachialis
– Biceps
– Brachialis
• Cutaneous Branches – Through lateral cutaneous nerve of fore arm it supplies the skin of lateral side
of fore arm from elbow to wrist.
• It also supplies elbow joint through its branch to brachialis.
MEDIAN NERVE
Origin
Course:
Branches:
Vasomotor branches to brachial artery
ULNAR NERVE
Origin
Course in arm: pierces the medial intermuscular septum and passes behind the medial epicondyle
Branches: None
RADIAL NERVE
Origin
Course: in posterior the compartment of arm and enters the anterior compartment just above the
lateral epicondyle by piercing the lateral intermuscular septum
Branches:
1. Muscular
2. Articular branches to elbow joint
CLINCAL ASPECT
TENOSYNOVITIS OF BICEPS TENDON
COMPARTMENT SYNDROME
BICEPS JERK
DISUSE ATROPHY OF MUSCLES
TENOSYNOVITIS OF BICEPS TENDON
Inflammation of a tendon.
Symptoms : pain with motion and tenderness with palpation.
Chronic deterioration or inflammation of the tendon or tendon sheath can cause scars that restrict
motion.
Diagnosis is clinical, sometimes supplemented with imaging.
Treatment includes rest, NSAIDs, and sometimes corticosteroid injections.
COMPARTMENT SYNDROME
Symptoms resulting from increased pressure within a limited space
compromising
circulation
function
CAUSES:
Increased Volume - internal : hemmorhage, fractures, swelling from traumatized tissue, increased fluid
secondary to burns, post-ischemic swelling
Decreased volume - external: tight casts, dressings
Most common cause of hemmorhage into a compartment: fractures of the tibia, elbow, forearm or
femur
Muscle Ischemia
4 hours - reversible damage
8 hours - irreversible changes
4-8 hours - variable
Treatment
THE ONLY EFFECTIVE WAY TO DECOMPRESS AN ACUTE COMPARTMENT SYNDROME IS BY SURGICAL
FASCIOTOMY!!! (unless missed compartment syndrome)
BICEPS JERK
DISUSE ATROPHY OF MUSCLES
Disuse atrophy of muscles can occur after prolonged immobility such as extended bed-rest, or having a
body part in a cast.
This type of atrophy can usually be reversed with exercise
THANK YOU