Muscles And Fasciae Of The Upper Limb part 2 Flashcards
The superior aspect of the arm communicates medially with the __.
Axilla
Inferiorly, a number of important structures pass between the arm and the forearm through the __, which is positioned anterior to the elbow joint.
Cubital fossa
The MUSCLES OF THE ARM are divided into two compartments by:
Anterior compartment
Posterior compartment
The __ contains muscles that predominantly flex the elbow joint.
Anterior compartment
The __ contains muscles that extend the joint.
Posterior compartment
3 muscles of the ANTERIOR COMPARTMENT (of the arm)
▪ Coracobrachialis
▪ Brachialis
▪ Biceps brachii - which are innervated predominantly by the musculocutaneous
nerve.
ORIGIN OF THE CORACOBRACHIALIS
Medial side of the midshaft of the humerus
INSERTION OF THE CORACOBRACHIALIS
Tip of the coracoid process of the scapula
INNERVATION OF THE CORACOBRACHIALIS
Musculocutaneous nerve Action: o flexes
the arm
Clinical: CORACOBRACHIALIS
Since the Musculocutaneous Nerve runs through the Coracobrachialis muscle, it is vulnerable to nerve compression within the muscle and this can lead to weakness of elbow flexion (loss of some Brachialis and biceps function) and
Hypesthesia of lateral forearm.
ORIGIN (Proximal) OF THE BICEPS BRACHII
o Short head - Coracoid process.
o Long head –Supraglenoid tubercle of scapula.
o The tendon of the long head passes through the
glenohumeral joint superior to the humeral
head, then passes through the intertubercular
sulcus and enters the arm.
o In the arm, the tendon joins with its muscle belly
and, together with the muscle belly of the short
head, overlies the brachialis muscle.
INSERTION (Distal) OF THE BICEPS BRACHII
o The long and short heads converge to form a single tendon, which inserts onto the radial
tuberosity.
o Comment: As its name implies, the biceps is a
fusiform muscle that has 2 heads.
o As the tendon enters the forearm, a flat sheet of connective tissue (bicipital aponeurosis) fans out from the medial side of the tendon to blend with deep fascia covering the anterior
compartment of the forearm.
ACTION OF THE BICEPS BRACHII
Flexor of the forearm at the elbow joint.
Most powerful supinator of the forearm when the elbow joint is flexed.
Because the two head cross the glenohumeral joint, it can also flex the glenohumeral joint.
INNERVATION OF THE BICEPS BRACHII
▪ Musculocutaneous nerve (C5 & C6)
▪ A ‘Tap’ on the tendon of Biceps brachii at the elbow tests predominantly spinal cord segment C6
IN THE CLINIC OF THE BICEPS BRACHII
▪ Rupture of the Biceps tendon
o The tendon that most commonly ruptures is the tendon of the long head of the biceps brachii muscle.
o In isolation, this has relatively little effect on the upper limb.
o There is an extremely prominent bulge of the muscle belly as its unrestrained fibers contract the ‘POPEYE’ sign.
▪ Treatment consists of primary repair in proximal rupture or reattachment of the tendon to the bone in case of distal rupture.
ORIGIN (Proximal) OF THE BRACHIALIS
▪ Distal half of the anterior aspect of the humerous.
▪ Adjacent parts of the intermuscular septa, particularly on the medial side.
INSERTION (Distal) OF THE BRACHIALIS
▪ It lies beneath the biceps brachii muscle, is flattened dorsoventrally, and converges to form a tendon, which attaches to the tuberosity of the ulna.
ACTION OF THE BRACHIALIS
▪ Flexes the forearm at the elbow joint.
INNERVATION OF THE BRACHIALIS
▪ Predominantly by the Musculocutaneous nerve (C5 & C6).
▪ Small component of the lateral part is innervated by the radial nerve (C7).
Clinical OF THE BRACHIALIS
Damage to the musculocutaneous nerve proximal to the Brachialis (compression injury as it passes through the Coracobrachialis muscle) can lead to weakness in the brachialis & Biceps brachii muscles, thus affecting elbow flexion.
The only muscle of the posterior compartment of the arm is the __.
Triceps brachii muscle
ORIGIN OF THE TRICEPS BRACHII
▪ Long head - Infraglenoid tubercle of the scapula
▪ Medial head - extensive area on the shaft of the humerus inferior to the radial groove
▪ Lateral head - linear roughening superior to the radial groove of the humerus
INSERTION OF THE TRICEPS BRACHII
▪ 3 heads converge to form a large tendon, which inserts on the superior surface of the olecranon of the ulna.
The anconeus inserts into the lateral aspect of the olecranon and into the upper dorsal surface of the body of the ulna.
INNERVATION OF THE TRICEPS BRACHII
▪ Branches of the Radial nerve [C6, C7, C8] A ‘tap’ on the tendon of triceps tests predominantly spinal cord segment C7
ACTION OF THE TRICEPS BRACHII
▪ Extension of the forearm at the elbow joint
▪ Long head can also extend and adduct the arm at the shoulder joint
Proximally, most major structures pass between the arm and forearm through, or in relation to, the __, which is anterior to the elbow joint
Cubital fossa
The exception is the __, which passes posterior to the medial epicondyle of the humerus
Ulnar nerve
Distally, structures pass between the forearm and the hand through, or anterior to, the __
Carpal tunnel
The major exception is the __, which passes dorsally around the wrist to enter the hand posteriorly
Radial artery
The forearm is divided into __ and __
compartments
Anterior
Posterior
The muscles of the forearm compartments are separated by:
Lateral intermuscular septum
Interosseous membrane
Attachment of deep fascia along the posterior border of the ulna
It passes from the anterior border of the radius to deep fascia surrounding the limb
Lateral intermuscular septum