PECTORAL , BACK AND SCAPULAR REGION Dr.Lubna Nazli

OBJECTIVES At the end of the lecture students should know: Muscles of the pectoral region. Clavipectoral fascia. Muscles of the back – layer 1 layer 2 4. Muscles attached to scapula 5. Rotator cuff 6. Quadrangular space &Triangular spaces. 7. Nerves of scapular region. 8. Arteries of scapular region. 9. Anastomosis around the scapula. 10. Applied anatomy.

Pectoral region Muscles of the Pectoral Region pectoralis major pectoralis minor subclavius And Serratus anterior.

Pectoralis major ORIGIN medial half of clavicle sternum, costal cartilages aponeurosis of external oblique muscle INSERTION lateral lip of intertubercular groove of humerus ACTION flexes, adducts, and rotates arm medially NERVE medial and lateral pectoral nerves of brachial plexus

Pectoralis minor ORIGIN ribs 3-5 INSERTION coracoid process of the scapula ACTION draws the scapula forward, medialward, and downward NERVE medial pectoral nerve of brachial plexus

Subclavius ORIGIN junction of the 1st rib with its costal cartilage INSERTION inferior surface of clavicle ACTION pulls clavicle towards the sternum NERVE nerve to subclavius of brachial plexus

Serratus anterior ORIGIN ribs 1-8 or 9 INSERTION medial border of the scapula on its costal (deep) surface ACTION it draws the scapula forward NERVE long thoracic nerve (from ventral rami C5-C7) IMP: a lesion of long thoracic nerve will cause winging of the scapula

Clavipectoral fascia The deep fascia which extends between subclavius, coracoid process and pectoralis minor muscles The structures passing through the clavipectoral fascia Cephalic vein Thoracoacromial artery Lateral pectoral nerve Lymphatics

Clavipectoral fascia

Muscles of the back are arranged in 2 layers Layer 1 – trapezius latissimus dorsi Layer 2 – levator scapulae rhomboid minor rhomboid major

TRAPEZIUS ORIGIN Medial third superior nuchal line, ligamentum nuchae, spinous processes and supraspinous ligaments to T12 INSERTION Upper fibers to lateral third of posterior border of clavicle; lower to medial acromion and superior lip of spine of scapula. ACTION laterally rotates, elevates and retracts scapula. NERVE Spinal accessory nerve (C1-5)

LATISSIMUS DORSI ORIGIN Spine T7, spinous processes and supraspinous ligaments of all lower thoracic, lumbar and sacral vertebrae, lumbar fascia, posterior third iliac crest, last four ribs and inferior angle of scapula INSERTION Floor of bicipital groove of humerus. ACTION Extends, adducts and medially rotates arm. NERVE Thoracodorsal nerve (C6, 7, 8) (from posterior cord)

LEVATOR SCAPULAE ORIGIN Posterior tubercles of transverse processes of C1-4 INSERTION Upper part of medial border of scapula ACTION Raises medial border of scapula NERVE Anterior primary rami of C3 and C4 and dorsal scapular nerve (C5)

RHOMBOID MINOR ORIGIN Lower ligamentum nuchae, spines of C7 and T1 INSERTION On posteromedial border of scapula at level of spine, below levator scapulae ACTION Retracts scapula. NERVE Dorsal scapular nerve (C5) (from root)

RHOMBOID MAJOR ORIGIN Spines of T2-T5 and supraspinous ligaments INSERTION Lower half of posteromedial border of scapula, from angle to upper part of triangular area at base of scapular spine ACTION Retracts scapula. NERVE Dorsal scapular nerve (C5) (from root )

Revise

Identify these muscles

Muscles attached to scapula The muscles which join the scapula to the humerus are: Deltoid Supraspinatus Infraspinatus Teres minor Teres major Subscapularis

DELTOID ORIGIN Lateral third of clavicle, acromion, spine of scapula to deltoid tubercle.(multipennate muscle) INSERTION Middle of lateral surface of humerus (deltoid tuberosity) ACTION Abducts arm, anterior fibers flex and medial rotate, posterior fibers extend and lateral rotate NERVE Axillary nerve (C5, 6) (from posterior cord) IMPORTANCE Site of intramuscular injection.

SUPRASPINATUS ORIGIN Medial three quarters of supraspinous fossa of scapula. INSERTION Superior facet on greater tuberosity of humerus and capsule of shoulder joint ACTION Abducts arm and stabilizes shoulder joint NERVE Suprascapular nerve (C5, 6)(from upper trunk)

INFRASPINATUS ORIGIN Medial three quarters of infraspinous fossa of scapula. INSERTION Middle facet of greater tuberosity of humerus and capsule of shoulder joint ACTION Laterally rotates arm and stabilizes shoulder joint NERVE Suprascapular nerve (C5, 6 ) (from upper trunk)

TERES MINOR ORIGIN Middle third lateral border of scapula above teres major INSERTION Inferior facet of greater tuberosity of humerus (below infraspinatus) and capsule of shoulder joint ACTION laterally rotates arm and stabilizes shoulder joint NERVE Axillary nerve (C5, 6) (from posterior cord)

TERES MAJOR ORIGIN Oval area on lateral side of inferior angle of scapula below teres minor. INSERTION Medial lip of bicipital groove of humerus ACTION Medially rotates and adducts arm. Stabilizes shoulder joint NERVE Lower subscapular nerve (C5, 6) (from posterior cord)

SUBSCAPULARIS ORIGIN Medial two thirds of subscapular fossa INSERTION Lesser tuberosity of humerus. ACTION Medially rotates arm and stabilizes shoulder joint NERVE Upper and lower subscapular nerves (C5,6) (from posterior cord)

Revise :

ROTATOR CUFF ( Musculotendinous cuff ) The tendons of four muscles form the rotator cuff. The muscles are: Supraspinatus. Infraspinatus. Teres minor. Subscapularis.

Intermuscular spaces Quadrangular space Triangular spaces Boundaries of quadrangular space: Above: teres minor & subscapularis Below: teres major Medially: long head of triceps Laterally: surgical neck of humerus Transmits: axillary nerve & posterior circumflex humeral vessels.

Triangular space ( upper ) bounded by: Above: teres minor Below: teres major Laterally: long head of triceps Transmits: circumflex scapular vessels Triangular space ( lower ) bounded by: Above: teres major Medially: long head of triceps Laterally: medial head of triceps Transmits: radial nerve and profunda brachii artery

Nerves of scapular region Upper subscapular nerve – supplies subcapularis. Lower subscapular nerve – supplies subscapularis and teres major. 3. Suprascapular nerve – supplies supraspinatus & infraspinatus. 4. Axillary nerve – supplies deltoid & teres minor.

Arteries of scapular region The arteries seen are: Transverse cervical artery. Suprascapular artery.

Anastomosis around the scapula: The scapular anastomosis connects subclavian artery and the axillary artery, forming an anastomosis around the scapula. It allows blood to flow past the joint regardless of the position of the arm.

Applied anatomy A rotator cuff injury is an injury to 1 or more of the 4 muscles in the shoulder. It can be associated with a fall. The type of injury can range from an inflammation of the muscle without any permanent damage, such as tendinitis, to a complete or partial tear of the muscle that might require surgery to fix it.