Muscular System II Lecture Notes

Practice vocabulary flashcards covering the anatomy and mechanics of the muscular system, including lever systems, muscle actions, and specific axial and appendicular muscles.

Origin

The immovable end of a muscle attachment.

Insertion

The movable end of a muscle attachment, which moves towards the origin during contraction.

Lever (bone)

A rigid rod that moves about a fixed point.

Fulcrum (joint)

The fixed point around which a lever moves.

Load

The force to be overcome in a lever system.

Effort or Work

The force required to overcome a load, supplied by skeletal muscles.

First Class Lever

A lever system where the fulcrum is between the effort and the load, exemplified by tilting the head backward.

Second Class Lever

A lever system where the load is between the fulcrum and the effort, exemplified by rising up on one’s toes.

Third Class Lever

The most common type of lever in the human body, where the effort is between the fulcrum and the load, exemplified by flexing the elbow.

Prime movers (agonists)

Muscles primarily responsible for a specific movement.

Antagonists

Muscles that oppose a specific movement.

Synergists

Muscles that help agonists perform their action.

Fixators

Specific synergists that stabilize the bone.

Sphincter

The general name for a circular muscle that surrounds external body openings.

Convergent arrangement

Muscles where the origin is broad and the fascicles converge toward a single tendon of insertion, such as the pectoralis major.

Parallel arrangement

Muscles where fascicles run parallel to the long axis; can be straplike (sternocleidomastoid) or fusiform (biceps brachii).

Pennate arrangement

Muscles where fascicles insert into a tendon; categories include unipennate, bipennate, and multipennate.

Axial musculature

Muscles that move the head, vertebral column, and thoracic cage.

Appendicular musculature

Muscles that move the appendicular skeleton, including the pectoral girdle and limbs.

Brevis

A descriptive term used in naming muscles that means short.

Teres

A descriptive term used in naming muscles that means round.

Brachii

A descriptive term used in naming muscles that means 'of the arm'.

Biceps

A descriptive term used in naming muscles that means 'two heads'.

Rectus

A descriptive term used in naming muscles that means straight.

Flexor

A descriptive term used in naming muscles that refers to a muscle that flexes.

Frontalis

Muscle originating on the occipital bone and inserting into the skin around the eye, used to raise eyebrows.

Orbicularis Oculi

Muscle originating on the frontal and maxilla bones and inserting into the eyelid, responsible for closing the eye or blinking.

Orbicularis Oris

Muscle originating near the mouth and inserting into the skin of the lip, used for closing lips or kissing.

Buccinator

Muscle originating on the maxilla and mandible that compresses cheeks and blows air out.

Zygomaticus major

Muscle originating on the zygomatic bone and inserting into the corner of the mouth, used for smiling.

Platysma

Muscle originating on the fascia of the upper chest and inserting into the mandible, used to depress the mandible for pouting.

Temporalis

Mastication muscle originating on the temporal bone and inserting onto the coronoid process of the mandible.

Masseter

Mastication muscle originating on the zygomatic bone and inserting onto the ramus of the mandible to close the jaw.

Sternocleidomastoid

Muscle originating on the sternum and clavicle and inserting into the mastoid process of the temporal bone, used to flex the neck or pull the head to one side.

Splenius

Muscle originating on the cervical and thoracic vertebrae and inserting on the occipital bone to rotate or extend the neck.

Diaphragm

The agonist muscle responsible for inhaling.

Linea alba

A central fiber-like structure in the abdominal wall where muscles like the internal and external obliques and transversus abdominis insert.

Hernias

Protrusions of visceral organs through the abdominal wall due to high pressure in the abdominal cavity.

Pelvic diaphragm

Two sheets of muscles that support the pelvic organs.

Quadriceps

A group of four muscles including the rectus femoris, vastus medialis, vastus lateralis, and vastus intermedius that extend the leg.

Hamstrings

A group of three muscles including the biceps femoris, semitendinosus, and semimembranosus that flex the leg.

Ventral gluteal site

A safe area in the gluteus medius used for intramuscular injections.