Origin_Insertion_Action_ (OIA) Flashcards

Tips

• Origin: Stays still during contraction (usually proximal).

• Insertion: Moves during contraction (usually distal).

• Linea alba: Not a muscle, it's connective tissue (CT) meaning "white line."

Skeletal Muscle — Shape, Striations, and Branching?

Long skinny fiber; Has striations (Yes); Does not branch (No).

Skeletal Muscle — Nuclei info (How many, Shape, Where)?

Many nuclei per cell (due to no mitosis, just more protein); Squamous/Squash flat shape; Located at the edge of the cell.

Skeletal Muscle — Intercalated discs, Control type, and Location?

No intercalated discs; Voluntary control; Attached to the skeleton.

Cardiac Muscle — Shape, Striations, and Branching?

Branched fibers; Has striations (Yes); Does branch (Yes).

Cardiac Muscle — Nuclei info (How many, Shape, Where)?

Just one nucleus; Squash flat/Round shape; Located in the middle of the cell.

Cardiac Muscle — Intercalated discs, Control type, and Location?

Yes, intercalated discs present (only type with them); Involuntary control (never stops/has pacemaker); Located around your heart.

Smooth Muscle — Shape, Striations, and Branching?

Spindle-shaped; No striations (No stripes); Branching is N/A.

Smooth Muscle — Nuclei info (How many, Shape, Where)?

Just one nucleus; Cigar-shaped nucleus; Located in the middle.

Smooth Muscle — Intercalated discs, Control type, and Location?

No intercalated discs; Involuntary control; Located in bags, tubes, blood vessels, stomach, bladder, uterus, and intestines.

Orbicularis oculi — Origin, Insertion, Action

Origin: Frontal / Maxilla

• Insertion: Skin of eyelid

• Action: Close eye, blinking

Zygomaticus — Origin, Insertion, Action

Origin: Zygomatic bone

• Insertion: Skin at the corner of the mouth

• Action: Smiling

Orbicularis oris — Origin, Insertion, Action

Origin: Maxilla / Mandible

• Insertion: Skin of the lips

• Action: Purse lips (kissing)

Buccinator — Origin, Insertion, Action

Origin: Maxilla / Mandible

• Insertion: Orbicularis oris

• Action: Sucking in cheeks

Mentalis — Origin, Insertion, Action

Origin: Mandible

• Insertion: Skin of chin

• Action: Move chin

Masseter — Origin, Insertion, Action

Origin: Maxilla, Zygomatic

• Insertion: Mandible

• Action: Chewing

Digastric — Origin, Insertion, Action

Origin: Mandible

• Insertion: Loop on hyoid

• Action: Open mouth (depress mandible)

Sternocleidomastoid — Origin, Insertion, Action

Origin: Sternum, Clavicle

• Insertion: Mastoid process of temporal bone

• Action: Rotate head, and Flex head

Temporalis — Origin, Insertion, Action

Origin & Insertion: N/A (per notes)

• Action: Chewing muscle

Deltoid — Origin, Insertion, Action

Origin: Clavicle / Scapula

• Insertion: Humerus

• Action: Arm/shoulder abduction

Pectoralis major — Origin, Insertion, Action

Origin: Sternum / Clavicle

• Insertion: Humerus

• Action: Arm flexion

Serratus anterior — Origin, Insertion, Action

Origin: Ribs

• Insertion: Scapula

• Action: Move / Stabilize the scapula

External intercostal — Origin, Insertion, Action

Origin: Ribs

• Insertion: Ribs

• Action: Breathe in (inspiration)

Internal intercostal — Origin, Insertion, Action

Origin: Rib

• Insertion: Rib

• Action: Breathe out (expiration)

Diaphragm — Origin, Insertion, Action

Origin: Sternum / Rib

• Insertion: Central tendon

• Action: $75\%$ of work of breathing

External oblique — Origin, Insertion, Action

Origin: Ribs

• Insertion: Linea alba + os coxa

• Action: Compress abdomen (Note: fibers point to groin)

Internal oblique — Origin, Insertion, Action

Origin: Os coxa

• Insertion: Linea alba

• Action: Compress abdomen (Note: fibers point to outer hip)

Rectus abdominus — Origin, Insertion, Action

Origin: Os coxa (middle pubis)

• Insertion: Sternum + ribs

• Action: Flex vertebral column (bend over) (Note: the "8 pack")

Transversus abdominus — Origin, Insertion, Action

Back: * Origin: Ribs

• Insertion: Linea alba

• Action: Compress abdomen (Note: deep layer, fibers go straight across)

Trapezius — Origin, Insertion, Action

Origin: Vertebrae

• Insertion: Scapula

• Action: Moves and stabilizes scapula

Latissimus dorsi — Origin, Insertion, Action

Origin: Vertebrae

• Insertion: Humerus

• Action: Adduct the arm (down shoulder)

Rhomboid major — Origin, Insertion, Action

Origin: Vertebrae

• Insertion: Scapula

• Action: Stabilize scapula

Rhomboid minor — Origin, Insertion, Action

Origin: Vertebrae

• Insertion: Scapula

• Action: Stabilize scapula

Levator scapulae — Origin, Insertion, Action

Origin: Cervical vertebrae

• Insertion: Scapula

• Action: Elevate scapula (shrug shoulder)

Teres major — Origin, Insertion, Action

Origin: Scapula (Note: Not a rotator cuff!)

• Insertion: Shaft of humerus

• Action: Adduct arm/shoulder

Rotator Cuff Muscles (SITS) — Name the 4 muscles, their common Origin, Insertion, and Action.

Muscles: Supraspinatus, Infraspinatus, Teres minor, Subscapularis

• Origin: Scapula

• Insertion: Head of Humerus

• Action: Rotate & Circumduct