Question

Know the origin/insertion/action of the following

a.Pectoralis major

b. Deltoid

c.Trapezius

d. Latissimus dorsi

Also locate the Linea alba

Answer 1

Muscles	Origin	Insertion	Action
Pectoralis Major	Two heads:(a) Clavicular head :anterior surface of the medial half of the clavicle. (b)Sternocostal head:anterior surface of sternum and upper 6 costal cartilages and aponeurosis of external oblique muscle.	Lateral lip of intertubercular groove in humerus.	(a) Clavicular head:flexion of humerus at shoulder joint. (b)Sternoclavicular head:horizontal and vertical adduction,extension, and internal rotation of the humerus, Depression and abduction of the scapula
Deltoid	Three heads :(a)Anterior head:lateral third part of the clavicle (b)Lateral head:Acromion of scapula (c)Posterior head:Spine of scapula	Deltoid tuberosity of the humerus.	(a) Anterior head :flexion of humerus at shoulder joint. (b)Lateral head :Abduction of humerus at shoulder joint (c)Posterior head:Extenstion of humerus at shoulder joint.
Trapezius	Three parts :(a) Superior part :From superior nuchal lines,external occipital protuberance. (b)Middle part:vertebra T1-T4 (c)Inferior part:vertebrae T5-T12	Three insertions:(a)Superior part :Lateral clavicle (b)Middle part:acromion of scapula (c)Inferior part:Spine of scapla.	(a)Superior part :Elevation of scapula. (b)Middle part:Retraction of scapula. (c)Inferior part:Depression of scapula.
Latissimus dorsi	Four origins :(a)Spines of (T7-T12) (b) inferior 3-4 ribs (c)Thoracolumbar fascia (d)iliac crest	Intertubercular sulcus on humerus	Extension,adduction and internal rotation of of humerus at shoulder joint.

• Linea alba is fibrous line on anterior abdominal wall formed by fusion of rectus sheath and rectus abdomins muscles .It begins from xiphiod process and extend to pubic symphysis.