1. Major Skeletal Muscles of Trunk and Upper Limbs
Chapter 6 Lecture 4

2. Extend and adduct humerus
Latissimus Dorsi
Extend and adduct humerus
The latissimus dorsi is a large muscle in the back. It is often referred to as a lat. *It has origins on the vertebrae, ilium ribs and scapula. *The insertion is on the humerus. When it contracts it moves the humerus. *It can extend, adduct and rotate the arm medially. This is the main muscle used in movement such as pounding a nail with a hammer.

3. Deltoid Abducts humerus
The deltoid covers the shoulder and has the shape of a delta. *It has origins on the scapula and clavicle. *The deltoid inserts on the deltoid tuberosity of the humerus. *Contraction of the deltoid will adduct the arm. If only the anterior fibers of the muscle contract it will flex the arm. Contraction of the posterior fibers will extend the arm.

4. Adducts and flexes humerus
Pectoralis Major
Adducts and flexes humerus
The pectoralis major is a large muscle in the pectoral region of the body. *It has origins on the clavicle and sternum. *The insertion is on the greater tubercle of the humerus. *Contraction of the pectoralis major will flex the arm. It will also adduct and rotate the arm medially. The pectoralis major is used in movements such a climbing, throwing and doing pushups.

5. Biceps Brachii Flexes Elbow and supinates forearm
“Turns a corkscrew and pulls the cork”
The biceps brachii is located on the anterior side of the upper arm. It is often just called the biceps. There is a biceps femoris in the leg we will study shortly. *The biceps has two origins. One origin is on the corocoid process and the other on the Glenoid cavity of the scapula. The “bi” in biceps refers to the two origins. *It inserts on the radial tuberosity. *Contraction of the biceps will cause flexing at the elbow joint.

6. Triceps Brachii Extends Elbow
The triceps is on the back of the upper arm. *It has three origins. Two origins are on the back of the humerus and one on the scapula. *The triceps inserts on the olecranon. *Movement of the triceps will extend the elbow joint.

7. Flexes vertebral column Most Superficial
Rectus Abdominus
Flexes vertebral column
Most Superficial
Rectus abdominus is a long muscle in the abdomen. *The muscle originates on the pubis. *It inserts on the xiphoid process of the sternum and also on cartilage of the ribs. *When rectus abdominus contracts it will flex the abdomen.

8. Flexes and rotates vertebral column Superficial and lateral
External Oblique
Flexes and rotates vertebral column
Superficial and lateral
Another muscle in the abdomen is the external oblique. It has muscle fibers that run in an oblique direction across the abdomen. *Contraction of the external oblique will compress the abdomen.

9. Internal Intercostals
Depress ribs when exhale
Deep
The internal intercostals are also located between the ribs. *They will depress the ribs.

10. External Intercostals
Elevate ribs when inhale
Deep
There are two groups of muscles that run between the ribs. The first are the external intercostals. *They will elevate the ribs.

11. Erector spinae
Back extension

12. Inspiration Found below lungs
Diaphragm
Inspiration
Found below lungs
This is an inferior view of the diaphragm. This muscle separates the abdominal cavity from the thoracic cavity. *When it contracts it will cause inspiration.

13. Forearm Muscles Flexor carpi radialis—Flexes wrist
Extensor carpi—Extends wrist
Flexor digitorum—Flexes fingers
Extensor digitorum—Extends fingers
There are several muscles in the forearm that have important movements. *The flexor carpi are used to flex the wrist. *Extensor carpi extend the wrist. *Flexor digitorum flexes the fingers. *Extensor digitorum extends the fingers. *The pronator pronates. *A supinator muscle will supinate.