BACK
Muscles of the back: 1. Trapezius 2. Latissimus dorsi 3. Levator scapulae 4. Rhomboideus major 5. Rhomboideus minor
Trapezius:
It is a triangular muscle.
Origin: Medial one-third of superior nuchal line, ligamentum nuchae, C7, T1 - T12 spines, intraspinous ligaments.
Insertion: Upper fibres on posterior border of lateral 1/3 of clavicle, middle fibres shows insertion on medial margin of acromion process and upper lip of crest of spine of scapula and lower fibres shows insertion on deltoid tubercle at medial end of spine of scapula.
Trapezius muscle of both side form diamond shape.
Nerve supply: Motor nerve is spinal part of accessory nerve and some proprioceptive fibres passes through C3 and C4 nerve.
Action: upper fibres of trapezius with levator scapulae muscle elevate scapula, middle fibres of trapezius and rhomboids muscle retract scapula, upper fibres and lower fibres of trapezius rotate scapula and help in abduction of shoulder joint beyond 90 degree.
Latissimus dorsi muscle
Origin: From T 7 to T 12 spines, aponeurotic origin from spines of lumbar vertebra and sacral vertebra, posterior one-third of outer lip of iliac crest.
Insertion: Fibres of muscles goes laterally and turn around inferior margin of teres major muscle finally shows insertion in the floor or of intertubercular sulcus.
Nerve supply: Thoracodorsal nerve C6 C7 and C8.
Action: It helps in extension at shoulder joint, adduction, medial rotation of humerus. It is a climbing muscle and it helps in elevation of trunk during climbing.
Muscles of the back: 1. Trapezius 2. Latissimus dorsi 3. Levator scapulae 4. Rhomboideus major 5. Rhomboideus minor
Trapezius:
It is a triangular muscle.
Origin: Medial one-third of superior nuchal line, ligamentum nuchae, C7, T1 - T12 spines, intraspinous ligaments.
Insertion: Upper fibres on posterior border of lateral 1/3 of clavicle, middle fibres shows insertion on medial margin of acromion process and upper lip of crest of spine of scapula and lower fibres shows insertion on deltoid tubercle at medial end of spine of scapula.
Trapezius muscle of both side form diamond shape.
Nerve supply: Motor nerve is spinal part of accessory nerve and some proprioceptive fibres passes through C3 and C4 nerve.
Action: upper fibres of trapezius with levator scapulae muscle elevate scapula, middle fibres of trapezius and rhomboids muscle retract scapula, upper fibres and lower fibres of trapezius rotate scapula and help in abduction of shoulder joint beyond 90 degree.
Latissimus dorsi muscle
Origin: From T 7 to T 12 spines, aponeurotic origin from spines of lumbar vertebra and sacral vertebra, posterior one-third of outer lip of iliac crest.
Insertion: Fibres of muscles goes laterally and turn around inferior margin of teres major muscle finally shows insertion in the floor or of intertubercular sulcus.
Nerve supply: Thoracodorsal nerve C6 C7 and C8.
Action: It helps in extension at shoulder joint, adduction, medial rotation of humerus. It is a climbing muscle and it helps in elevation of trunk during climbing.
Levator scapulae
Origin: From transverse process and posterior tubercles of transverse processes of C1 to C4 vertebrae.
Insertion: Fibres goes downwards and medially shows insertion on medial border of scapula from superior angle to apex of spine of scapula.
Nerve supply: It receives nerve supply from C3 and C4 nerves a small branch carrying C5 from dorsal scapular nerve.
Action: Helps in elevation of scapula with trapezius muscle.
Rhomboideus major
Origin: From spine of vertebrae T2, T3, T4, T5 and supra spinous ligaments.
Insertion: It shows insertion on medial boeder of scapula from inferior angle to root of spine of scapula.
Rhomboideus minor
Origin: From spine of C7 and T1 also from ligamentum nuchae.
Insertion: On medial border of scapula at apex of spine of scapula.
Nerve supply: Both muscles receives nerve supply from C5.
Action: Rhomboideus major and minor muscle retract scapula.
Applied anatomy
1. Axillary arch: It is a muscular slip from latissimus dorsi which crosses axillary vessels and nerves join pectoralis major or coracobrachialis or biceps brachii muscle.
2. Lumbar triangle: It is a small triangle boundaries are medially by lateral border of latissimus dorsi, laterally by posterior border of external oblique muscle and base inferiorly by iliac crest. Lumbar hernia can occur through this triangle because it is a weak area of abdominal wall.
3. Triangle of auscultation: It is a small trianglar area of chest wall. Boundaries are as follows medial by lateral border of trapezius, lateral boundary by medial border of scapula, below by upper border of latissimus dorsi muscle and floor of the triangle formed by sixth and seventh rib and seventh intercostal space. With stethoscope in this area respiratory sounds are heard also cardiac end of stomach lies here so that with stethoscope sound of liquids which passes through cardiac orifice of stomach are audible.
Origin: From transverse process and posterior tubercles of transverse processes of C1 to C4 vertebrae.
Insertion: Fibres goes downwards and medially shows insertion on medial border of scapula from superior angle to apex of spine of scapula.
Nerve supply: It receives nerve supply from C3 and C4 nerves a small branch carrying C5 from dorsal scapular nerve.
Action: Helps in elevation of scapula with trapezius muscle.
Rhomboideus major
Origin: From spine of vertebrae T2, T3, T4, T5 and supra spinous ligaments.
Insertion: It shows insertion on medial boeder of scapula from inferior angle to root of spine of scapula.
Rhomboideus minor
Origin: From spine of C7 and T1 also from ligamentum nuchae.
Insertion: On medial border of scapula at apex of spine of scapula.
Nerve supply: Both muscles receives nerve supply from C5.
Action: Rhomboideus major and minor muscle retract scapula.
Applied anatomy
1. Axillary arch: It is a muscular slip from latissimus dorsi which crosses axillary vessels and nerves join pectoralis major or coracobrachialis or biceps brachii muscle.
2. Lumbar triangle: It is a small triangle boundaries are medially by lateral border of latissimus dorsi, laterally by posterior border of external oblique muscle and base inferiorly by iliac crest. Lumbar hernia can occur through this triangle because it is a weak area of abdominal wall.
3. Triangle of auscultation: It is a small trianglar area of chest wall. Boundaries are as follows medial by lateral border of trapezius, lateral boundary by medial border of scapula, below by upper border of latissimus dorsi muscle and floor of the triangle formed by sixth and seventh rib and seventh intercostal space. With stethoscope in this area respiratory sounds are heard also cardiac end of stomach lies here so that with stethoscope sound of liquids which passes through cardiac orifice of stomach are audible.