Muscles of the Body Part 1 (Q2,P4)

Question 1

Pectoralis Major

Answer 1

• Origin:
  1) Clavicular head – anterior surface of medial half of clavicle
  2) Sternocostal head – anterior surface of sternum, superior six costal cartilages, and aponeurosis of external oblique muscle
• Insertion: Lateral lip of intertubercular groove of humerus
• Action:Adducts and medially rotates humerus; draws scapula anteriorly and inferiorly
  Acting alone: clavicular head flexes humerus and sternocostal head extends it

Question 2

External Intercostals

Answer 2

Origin: Inferior border of rib above
Insertion: Superior border of rib below
Action: Elevates the ribs in breathing
Muscles of inspiration
Run UP to DOWN

Question 3

Internal Intercostals

Answer 3

Origin: Superior border of rib below
Insertion: Inferior border of rib abov

DOWN: rib below TO UP: rib above

Action: Depresses ribs in breathing
Muscles of expiration and decreases thoracic capacity
Deep to external intercostals

Question 4

Diaphragm – Phrenic Muscle

Answer 4

Separates thoracic and abdominopelvic cavities
Origin: Sternum, ribs, and vertebrae
Insertion: Central tendon
Action: Increases chest capacity

Question 5

Trapezius

Answer 5

Origin:Medial third of superior nuchal line; external occipital protruberance, nuchal ligament, and spinous processes of C7 - T12 vertebrae
Insertion: Lateral third of clavicle, acromion, and spine of scapula
Action:Elevates, retracts and rotates scapula; superior fibers elevate, middle fibers retract, and inferior fibers depress scapula; superior and inferior fibers act together in superior rotation of scapula

Question 6

Latissimus Dorsi

Answer 6

Origin:Spinous processes of inferior 6 thoracic vertebrae, thoracolumbar fascia, iliac crest, and inferior 3 or 4 ribs
Insertion:Floor of intertubercular groove of humerus
Action:Extends, adducts, and medially rotates humerus; raises body toward arms during climbing; rowing motion of humerus

Question 7

The 4 Abdominal Wall Muscles

Answer 7

Rectus Abdominis
External Oblique
Internal Oblique
Transversus Abdominis

Question 8

Rectus abdominus

Answer 8

Origin: Pubic crest and symphysis
Insertion: Xiphoid process and costal cartilages of ribs 5-7
Action: Flexes trunk
Anteromedial abdominal muscle; six pack

Question 9

External Obliques

Answer 9

Origin: By fleshy strips (short tendons) from outer surfaces of lower eight ribs
Insertion: Most fibers insert into linea alba via a broad aponeurois
Action: Compresses the abdomen
Most superficial of anterolateral abdominal muscles

Question 10

Internal Obliques

Answer 10

Origin: Iliac crest, inguinal ligament, and lumbar fascia
Insertion: Linea alba
Action: Compresses the abdomen
Intermediate or middle depth for the anterolateral abdominal muscles
Deep to external obliques, internal and external striations go in different directions

Question 11

Transversus abdominus

Answer 11

Origin: Inguinal ligament, lumbar fascia, cartilages of last six ribs; iliac crest
Insertion: Linea alba; pubic crest
Action: Compresses the abdomen
Deepest anterolateral abdominal muscle
Anterolateral= (situated or occurring in front and to the side.)

Question 12

Psoas Major

Answer 12

Origin: By fleshy strips from transverse processes, bodies, and discs of lumbar vertebrae and T12
Insertion: Medial femur; lesser trochanter of femur via iliopsoas tendon
Action: Flexes the thigh
Considered a Posterior abdominal muscle
thick, long muscle