Anatomy for MSP: Muscles of the Upper Limb

Muscles connecting Upper Limb to the Thorax

Pectoralis Major Muscle

Origin: It originates from the medial third of the clavicle, sternum and upper six costal cartilages.

Insertion: It inserts at the lateral lip of bicipital groove of the humerus.

Function: Abduction and medial rotation of the arm.

Nerve Supply: Medial and Lateral pectoral Nerves from Brachial Plexus

Pectoralis Minor Muscle

Origin: It originates from the 3rd to 5th ribs.

             Insertion: It inserts at the coracoid process of the scapula.

             Function: Depression of the scapula.

             Nerve Supply: Medial Pectoral Nerve from Brachial Plexus

Subclavius Muscle

             Origin: It originates from the superior border of the 1st rib.

             Insertion: It inserts at the clavicle.

             Function: Depression of the clavicle.

             Nerve Supply: Nerve to subclavius from Upper Trunk of Brachial Plexus

Serratus Anterior Muscle

             Origin: It originates from the 1st eight ribs.

             Insertion: It inserts at the medial border of the scapula.

             Function: Upward, downward and medial rotation of the scapula.

             Nerve Supply: Long Thoracic Nerve

Muscles connecting Scapula to the Vertebral Column

Trapezius Muscle

Origin: Ocipital bone, spines of 7th cervical and all thoracic vertebrae.

             Insertion: Lateral third of clavicle, spine of scapula and acromion process.

   Function: Elevation, depression rotation of the scapula.

             Nerve Supply: Accessory nerve and C3 and C4

Latissimus Dorsi Muscle

              Origin: Iliac crest, Spines of lower six thoracic vertebrae, lower three or four ribs and inferior angle of scapula.
              Insertion: Floor of bicipital groove of Humerus.

              Function: Extention, Adduction and Medial rotation of the arm.

              Nerve Supply: Thoracodorsal Nerve

Levator Scapulae Muscle

              Origin: It originates from the transverse processes of upper three cervical vertebrae.

              Insertion: It inserts at the medial upper border of the scapula.

Function: It elevates the scapula.

              Nerve Supply: C3,C4 and Dorsal Scapular Nerve

Rhomboid Minor Muscle

Origin: It originates from the spinous processes of the 7th and T1 vertebrae.

              Insertion: It inserts on the superior medial border of the scapula.

              Function: Elevation and medial rotation of the scapula.

              Nerve Supply: Dorsal Scapular Nerve

Rhomboid Major Muscle

              Origin: It originates from the spinous processes of 2nd to 5th thoracic vertebrae.

              Insertion: It inserts on the medial lower border of the scapula.

              Function: Elevation and medial rotation of the scapula.

              Nerve Supply: Dorsal Scapular Nerve

Muscles connecting Scapula to the Humerus

Supra spinatus Muscle

Origin: It originates from the supra spinatus fossa of the scapula.

             Insertion: It inserts on the greater tubercle of the humerus.

             Function: Abduction and stabilization of the shoulder joint.

Nerve Supply: Suprascapular nerve

Infra spinatus Muscle

Origin: It originates from the infraspinatus fossa of the scapula.

Insertion: It inserts on the greater tuberosity of the humerus.

Function: Lateral rotation of the arm and stabilization of the shoulder joint.

Nerve Supply: Suprascapular nerve

Sub scapularis Muscle

              Origin: It originates from the sub scapular fossa of the scapula.

              Insertion: It inserts on the lesser tuberosity of the humerus.

              Function: Medial rotation of the arm and staabilization of the shoulder joint.

              Nerve Supply: Upper and Lower subscapular Nerves

Teres Minor Muscle

Origin: It originates from the inferior lateral border of the scapula.

Insertion: It inserts on the greater tuberosity of the humerus.

Function: Lateral rotation of the arm.

Nerve Supply: Axillary Nerve

Teres Major Muscle

Origin: It originates from the inferior lateral border of the scapula.

Insertion: It inserts on the medial lip of bicipital groove.

Function: Medial rotation of the arm and stabilization of the shoulder joint.

Nerve Supply: Lower Subscapular Nerve

Deltoid Muscle

             Origin: It originates from the lateral third of the clavicle, acromion process and spine of the scapula.

             Insertion: It inserts on the deltoid tuberosity of the humerus.

             Function: The anterior fibers flex, middle fibers abduct and posterior fibers extend the shoulder joint.

             Nerve Supply: Axillary Nerve

Muscles of the Arm

Coracobrachialis Muscle

              Origin: It originates from the coracoid process of the scapula.

              Insertion: It inserts on the medial third of the humerus.

              Function: Flexion of the arm.

              Nerve Supply: Musculocutaneous Nerve

Brachialis Muscle

              Origin: It originates from the lower 1/3 of the anterior aspect of humerus.

              Insertion: It inserts on the coronoid processs of the ulna.

              Function: Flexion of the elbow joint and supination of the forearm.

              Nerve Supply: Musculocutaneous Nerve

Bicep Brachii Muscle

              Origin: The long head of bicep muscle originates from the supra glenoid tubercle of the glenoid cavity while short head from the corocoid process of the scapula.

              Insertion: Radial tuberosity

              Function: Flexion of the elbow joint and supination of the forearm.

              Nerve Supply: Musculocutaneous Nerve

Tricep Brachii Muscle

              Origin: Long head originates from the infraglenoid tubercle of the glenoid cavity, medial head from medial side below the radial groove and lateral head from
lateral side above the radial groove.

              Insertion: Olecranon process of the ulna.

              Function: Extention of the elbow joint.

              Nerve Supply: Radial Nerve

Muscles of the Forearm

A. Anterior Surface of Forearm (flexors primarily)

1. Superficial Group

a. Pronator teres:

b. Flexor Carpi Radialis: flexes wrist and abducts hand

c. Palmaris Longus:

d. Flexor Carpi Ulnaris: flexes wrist and adducts hand

2. Intermediate Group

a. Flexor Digitorum Superficialis: flexes wrist and flexes digits 2 - 5 at the MP and PIP joints

(MP=metacarpal-phalangeal PIP=proximal interphalangeal)

3. Deep Group

a. Flexor Digitorum Profundus: flexes wrist and digits 2-5 at the MP, PIP and DIP joints (DIP=distal interphalangeal)

b. Flexor Pollicis Longus:

c. Pronator quadratus:

Innervation of Anterior compartment muscles: All the muscles are suplied by the Median nerve and its branches except the flexor carpi ulnaris and the medial part of the flexor digitorum profundus, which are supplied by the Ulnar nerve.

B. Lateral Surface of Forearm

a. Extensor Carpi Radialis Longus: extends wrist and abducts hand

b. Brachioradialis:

Nerve Supply to Lateral compartment muscles: Radial Nerve

C. Posterior Surface of Forearm (extensors primarily)

1. Superficial Group

a. Anconeus:

b. Extensor Carpi Radialis Brevis

c. Extensor Digitorum: extends wrist and extends digits 2-5 at MP, PIP, and DIP joints

d. Extensor Carpi Ulnaris:

e. Extensor digiti minimi:

2. Deep Group

a. Supinator: supinates forearm

b. Abductor Pollicis Longus:

c. Extensor Pollicis Longus: extends thumb

d. Extensor Pollicis brevis:

e. Extensor indicis:

Innervation to Posterior compartment muscles: Deep branch of radial nerve.

Selected Muscles

Brachioradialis Muscle

              Origin: Lateral supracondylar ridge of humerus.

              Insertion: Base of styloid process of radius.

              Function: Flexion of the forearm at elbow joint.

              Innervation: Radial Nerve

Anconeus Muscle

             Origin: Lateral epicondyle of humerus.

             Insertion: Lateral surface of olecranon process of ulna.

             Function: Extention of elbow joint.

             Nerve Supply: Deep branch of Radial Nerve

Supinator Muscle

              Origin: Lateral epicondyle of humerus.

              Insertion: Neck and shaft of radius.

              Function: Supination of the forearm.

             Nerve Supply: Deep branch of Radial Nerve

Pronator Teres Muscle

              Origin: Humeral head originates from the medial epicondyle of humerus and ulnar head from the medial border of coronoid process of ulna.

              Insertion: Lateral aspect of shaft of radius.

Function: Pronation and flexion of the forearm.

              Nerve Supply: Median Nerve

Pronator Quadratus Muscle

              Origin: Anterior surface of shaft of ulna.

              Insertion: Anterior surface of shaft of radius.

              Function: Pronation of forearm.

              Nerve Supply: Median Nerve

HAND MUSCLES

A. Thenar muscles: move the thumb:

Short muscles of thumb innervated by Median Nerve except adductor pollicis, which is by deep branch of Ulnar Nerve.

B. Hypothenar muscles:
Short Muscles of Little Finger are innervated by deep branch of Ulnar Nerve.

C. Midpalmar muscles

1. All of these muscles flex the MP joints and extend the PIP/DIP joints