The upper limb runs from your deltoid to your hand,
With 6 categories of muscles under your command. Throughout the pectoral region, shoulder,
and upper arm, Your hand as well as the anterior, and posterior forearm!
There are four pectoral muscles on the anterior chest wall,
With sternal and clavicular heads, pec major is superficial!
It serves to adduct your arm or bring it towards your core,
And rotating your arm medially is its second chore!
Under it the minor forms part of the axilla’s anterior wall,
Stabilizing the scapula and, pulling it to the thoracic wall.
Nearby the serratus anterior holds the scapula to the ribcage,
It rotates the scapula, which gives your arm more range.
The subclavius runs horizontally under the collarbone,
For anchoring and depressing the collarbone it’s known.
The five extrinsic shoulder muscles go from the torso
To the clavicle, scapula, humerus, and just so you know,
The superficial ones are the trapezius and latissimus dorsi,
The deep ones are the two rhomboids, and levator scapulae!
The six intrinsic shoulder muscles, we will now discuss,
Running from the scapula or clavicle to the humerus.
The deltoid helps raise your arm, gives the shoulder joint stability,
Teres major gives arm adduction, medial rotation, see.
Four rotator cuff muscles give the shoulder joint stability,
Subscapularis and infraspinatus give humerus rotatability,
Subscapularis rotates inward and infraspinatus outward,
Teres minor helps the deltoid, supraspinatus pulls upward,
In the upper arm, four muscles are present, Including three found in the anterior compartment!
Brachialis, coracobrachialis, and biceps brachii, And in the posterior compartment is triceps brachii
The anterior compartment of the forearm bustles, With superficial, intermediate and deep muscles.
And in general these forearm muscles participate, In flexing the wrist and fingers, and making them pronate!
Superficial ones arise from the medial epicondyle of the humerus
Sharing a common tendon, they include flexor carpi ulnaris,
As well as palmaris longus and flexor carpi radialis,
And last but not least, there’s the pronator teres
The intermediate compartment has flexor digitorum superficialis,
Allowing these four fingers to flex, just like this.
At the wrist, four tendons result, from splitting of this muscle,
Attaching to four fingers after passing through the carpal tunnel
There are 3 deep compartment muscles – pronator quadratus,
Flexor pollicis longus, and flexor digitorum profundus,
Posterior compartment muscles produce extension At the wrist and fingers, and have two layers to mention,
Deep and superficial - separated by connective tissue,
There are seven superficial, and five deep muscles too!
The extensor digitorum, is the main finger extensor,
The extensor carpi ulnaris, is a wrist adductor and extensor,
The extensor digiti minimi extends the pinky and wrist,
Extensor carpi radialis longus, and brevis, help move the wrist!
From the lateral supracondylar ridge, originates the brachioradialis,
Which then attaches to the distal end of the radius!
Brachioradialis has an origin characteristic of an extensor,
But it lets you bend your elbow, so it’s actually a flexor!
The anconeus is on the elbow joint’s posterior aspect,
For extending the elbow and rotating, the forearm it’s adept.
Except the supinator, the deep muscles create motion,
In the thumb and index finger, now the others we mention:
Abductor pollicis longus, extensor pollicis brevis,
Extensor pollicis longus, and extensor indicis
Extrinsic and intrinsic muscles, hand movements equip,
Extrinsic ones are in the forearm, for crude movements and grip,
Intrinsic muscles are within the hand, and allow fine motor function,
And the remainder of this song will be their introduction!
Three thenar muscles at the thumb’s base create the thenar eminence
Controlling fine thumb movements, opponens pollicis is the largest,
Above it the abductor pollicis brevis abducts the thumb likeso,
Flexor pollicis brevis bends the thumb as we here show.
The hypothenar eminence is on the palm’s medial side,
Opponens digiti minimi inwardly rotates metacarpal five,
Abductor Digiti Minimi is most superficial and abducts the pinky
Flexor Digiti Minimi Brevis helps you flex your pinky
Four lumbricals link to fingers, and an oddity is known,
Take note that these muscles do not attach to bone!
Interossei are between metacarpals, and for their function,
Dorsal ones cause abduction, palmar ones cause adduction,
And they both assist MCP joint flexion, As well as IP joint extension!
On the hand’s dorsum, dorsal interossei are most superficial,
And originate from lateral and medial metacarpals, it’s official!
Attaching to each finger’s proximal phalanx and extensor hood,
To abduct fingers at the MCP joint, understood?
Another intrinsic muscle, your palmaris brevis ensures,
That your grip is tight, by deepening hand curvature.
Last the large triangular adductor pollicis in your palm
With two heads that let you adduct your thumb!