Question

actions of these muscles

Muscle                                       origin                                          insertion                            action

Latissimus dorsi	Spinous processes of T7 thru L5, lower 3 ribs, iliac crest
Rhomboids	Spinous processes of C7 thru T5
Diaphram External intercostals
Internal Intercoatals
Triceps brachii	Long head: inferior margin of glenoid cavity Lateral head: posterior humerus Medial head: distal radial groove of post. humerus
Biceps brachii	Short head: coracoid process Long head: supra-glenoid tubercle
Brachioradialis
Flexor Digitorum Longus

Answer 1

Ans- 1. Latissimus dorsi -

(i)Origin-

Vertebral part- spinous processes of vertebrae T7 to T12, thoracolumbar fascia.

Iliac part- posterior third of crest of ilium

Costal part- Ribs 9 to 12

Scapular part- inferior angle of scapula

(ii).Insertion- Intertubercular sulcus of the humerus between teres major muscle and pectoralis major muscle.

(iii)Act of the muscle- It assists in the internal rotation of the arm, arm adduction, arm extension and assists in respiration.

2. Rhomboids-

(i). Origin- nuchal ligaments, spinous processes of C7 to T5 vertebrae.

(ii). Insertion- It inserts in the medial border of the scapula.

(iii). Action- These muscles pulls the scapulae medially, rotates scapulae and holds the scapulae into thorax wall.

3. Diaphragm-

(i). Origin-

Sternal part- Posterior aspect of xiphoid process

Costal part- internal surfaces of lower costal cartilages and ribs 7-12

Lumbar part- Medial and lateral arcuate ligaments, bodies of vertebrae L1-L3, anterior longitudinal ligament.

(ii). Insertion- Central tendon of diaphragm

(iii). Action of the muscle- The muscle depresses costal cartilage, primary muscle of respiration.

4. External intercoastal muscles-

(i). Origin- Inferior border of the ribs as far back as posterior angles.

(ii). Insertion - Superior borders of the ribs below, passing obliquely downwards and backwards.

(iii). Action of the muscle- These muscles fixes intercoastal spaces during the respiration. It aids in forced inspiration by elevating ribs.

5. Internal intercoastal muscles-

(i). Origin- costal groove of ribs

(ii). Insertion- Superior border of immediate rib below

(iii). Action of the muscle- Depresses ribs during forced expiration, support intercostal spaces and thracic cage.