Jinnah Sindh Medical University



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

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