Muscles of the shoulder Flashcards
Origin of the Supraspinatus
supraspinous fossa of the scapula
Insertion of the Supraspinatus
1) greater tubercle
2) superior aspect of the capsule of the shoulder joint
Actions of the supraspinatus
1) Stabilises the shoulder joint by reinforcing the capsule
2) Assists the deltoid in abduction (together they abduct the shoulder about 120 degrees)
Origin of the infraspinatus
Infraspinous fossa
Insertion of the Infraspinatus
Greater tubercle (posterior surface)
Insertion of Teres minor
greater tubercle (below infraspinatus)
Origin of teres minor
Scapula (lateral border)
What tendons fuse with the capsule of the shoulder joint?
Tendons of the: Infraspinatus Teres minor Supraspinatus Subscapularis
Function and components of rotator cuff?
Function: Stabilise shoulder joint
Made up of 4 muscles: Infraspinatus Supraspinatus Teres Minor Subscapularis
Origin of Pectoralis major
CLAVICULAR HEAD - Medial 1/3 of clavicle
STERNOCOSTAL HEAD - sternum and costal cartilages
Nerve supply of pectoralis major muscle
Lateral and medial pectoral nerves
Action of pectoralis major muscle
large muscle that connects the upper part of the chest wall to the upper extremity
Clavicular fibres flex the humerus
Sternocostal fibres adduct and medially rotate humerus at shoulder joint
If upper limb is abducted and fixed, it can act as an accessory muscle of respiration
Test for the pectoralis major
CLAVICULAR HEAD - ask patient to push arm forward (flex) against resistance
STERNOCOSTAL HEAD - abduct the arm 60 degrees and adduct it against resistance. Contracting heads can be seen and felt.
Origin of Pectoralis minor (P minor lies deep to P major)
3rd-5th rib / 2nd-4th rib
Insertion of pectoralis minor
Coracoid process of the scapula
Nerve supply of pectoralis minor
Medial pectoral nerve
Action of pectoralis minor
Draws the scapula (and hence the arm) forwards - PROTRACTION of the shoulder. Also depresses shoulder
Origin of serratus anterior
series of digitation from the upper 8 ribs
Insertion of serratus anterior
Costal surface of the scapula along its medial border (the muscle forming the medial wall of the axilla lies between the scapula and the chest wall before reaching its insertion
Nerve supply of serratus anterior
Long thoracic nerve from the roots of the brachial plexus
Action of serratus anterior
Protraction (forward movement) of scapula e.g. pushing, punching
Origin of the trapezius
EXTERNAL OCCIPITAL PROTUBERANCE + SUPERIOR NUCHAL LINE
LIGAMENTUM NUCHAE - fibroelastic tissue connecting the muscles to the spines of the cervical vertebrae
SPINOUS PROCESSES OF C7 - T12
Shape and general position of trapezius
triangular muscle (muscle on two sides together has the form of a trapezium) Covers the back and most of the trunk and connects the trunk to the upper extremity. Contributes to the wide range of movements of the shoulder
Insertion of the trapezius
Upper fibres = lateral 1/3 of clavicle
Middle fibres = acromion
Lower fibres = spine of scapula
Nerve supply of trapezius
Spinal part of accessory nerve
Actions of the trapezius
Rotates scapula so that gleanoid fossa faces upwards (with help of serratus anterior). Important for raising the arm above the level of the shoulder.
Upper fibres = elevate shoulder e.g. shrugging
All fibres of muscle help to retract scapula
origin of latissimus dorsi
Large superficial muscle in lower half of back. Wraps around chest wall, contributes to posterior axillary fold
Inferior T + L vertebrae
Sacrum
Iliac crest
9th-12th ribs
Insertion of Latissimus Dorsi
Bicipital groove of humerus
Nerve supply of latissimus dorsi
thoraco dorsal nerve (C6,7, 8) from posterior cord of brachial plexus
Actions of latissimus dorsi
Extension, medial rotation and adduction of shoulder (e.g. scratching the opposite scapula)
Nerve supply of latissimus dorsi
thoracodorsal nerve (C6,7, 8) from posterior cord of brachial plexus
Actions of latissimus dorsi
Extension, medial rotation and adduction of shoulder (e.g. scratching the opposite scapula)
Actions of latissimus dorsi
Extension, medial rotation and adduction of shoulder (e.g. scratching the opposite scapula)
Insertion of rhomboid major and minor
medial border of the scapula (rhomboids lie deep to the trapezius)
Origin of the Deltoid
Lateral 1/3 of clavicle
Acromion
Spine of scapula
Insertion of deltoid
deltoid tuberosity at the middle of the shaft of the humerus
Action of deltoid
Anterior fibres = help pectorals major to flex shoulder
Lateral fibres = combine with supraspinatus to abduct the shoulder
Posterior fibres = extend joint (along with latissimus doors and teres major)
Test of deltoid
Hold the arm in the abducted position against resistance. Inability to do so suggests paralysis of the muscle
Nerve supply of deltoid
Axillary nerve - branch of the posterior cord of the brachial plexus, passing through the quadrangular space, round the posterior neck of the humerus to enter the muscle
What are the superficial flexors of the forearm? (anterior muscles)
1) Pronator teres
2) Flexor carpi radialis
3) Palmaris longus
4) Flexor digitorum superficialis
5) Flexor carpi ulnaris
What are the deep flexors of the forearm? (anterior muscles)
Flexor digitorum profundus Flexor pollicis longus Pronator quadratus (underneath)
What are the superficial extensors of the forearm? (posterior muscles)
1) Extensor carpi radialis longus
2) Extensor carpi radialis brevis
3) Extensor digitorum
4) Extensor digiti minimi
5) Extensor carpi ulnaris
What are the deep extensors of the forearm? (posterior muscles)
Supinator Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis
Nerve supply of the arm
Arm flexors (anterior) = musculocutaneous Arm extensors (posterior) = radial Forearm flexors (anterior) = median EXCEPT Flexor Carpi Ulnaris + 1/2 Flexor digitorum profundus 9both ulnar) + Brachioradialis (radial) Hand flexors = ulnar EXCEPT LLOAF
