Muscular System: Origins, Insertions, and Actions

Vocabulary practice flashcards covering muscle names, origins, insertions, and actions from the anatomy notes.

Brachialis (anterior)

An anterior arm muscle originating halfway down the humerus, inserting $1\text{ inch}$ proximal/medial on the ulna, whose action is to flex the elbow.

Medial head of triceps brachii

A posterior arm muscle head originating $\frac{1}{2} - \frac{1}{3}$ way down the humerus, inserting $1\text{ inch}$ onto the medial ulna, whose action is to extend the elbow.

Intercostals

Thoracic muscles originating on the inferior border of the rib above (ribs $1-11$) and inserting on the superior border of the rib below; responsible for breathing by expanding and contracting the rib cage.

Serratus anterior

A muscle originating on the lateral surface of ribs $1-8$ (anterior side) and inserting on the medial border of the scapula; active at the end of a bench press.

Pectoralis minor

A chest muscle originating on the anterior surface of ribs $3-5$ and inserting on the coracoid process of the scapula; its action rotates the shoulder forward.

Pectoralis major

A large chest muscle comprising three distinct heads (clavicular head, sternal head, and abdominal head) that insert along the lateral edge of the humerus to produce diverse movements of the arm.

Pectoralis major (clavicular head)

The head of the pectoralis major originating on the medial half of the anterior edge of the clavicle and inserting on the lateral edge of the proximal humerus; allows underhand motions (e.g., bowling).

Pectoralis major (sternal head)

The head of the pectoralis major originating from ribs $1-6$ on the lateral edge of the sternum and inserting on the lateral edge of the humerus; adducts the arm across the chest (e.g., sidearm pitch in baseball).

Pectoralis major (abdominal head)

The head of the pectoralis major originating from ribs $5-7$ (fascia of abdominal muscles) and inserting on the lateral edge of the more proximal part of the humerus; pulls the arm down (e.g., volleyball strike).