Muscle Anatomy and Actions

Vocabulary flashcards covering muscle terminology, muscle actions, and muscle compartments of the upper and lower extremities along with their main actions and innervations.

Origin

The stationary attachment site where a muscle starts.

Insertion

The movable attachment site where a muscle attaches and pulls.

Action of the Muscle

The movement produced with muscle contraction.

Innervation

The nerve that stimulates the muscle.

Appendicular Region Origin Rule

In the appendicular region, the muscle origin is likely proximal to its insertion.

Isotonic Contraction

A muscle contraction that changes the length of the muscle, such as during bicep curls.

Concentric Contraction

An isotonic contraction in a shortened position where point A and point B come closer.

Eccentric Contraction

An isotonic contraction in a lengthening position where point A and point B go further apart.

Isometric Contraction

A muscle contraction that does not change the length of the muscle while still activating muscles, such as holding a plank.

Joint Crossing Rule

A rule stating that a muscle must cross a joint in order to move it.

Compartment Action Rule

A rule stating that opposing actions cannot occur in the same compartment (e.g., shoulder muscles doing flexion cannot also do extension at the same time).

Anterior Arm

Arm compartment whose main action is elbow flexion and is innervated by the musculocutaneous nerve.

Posterior Arm

Arm compartment whose main action is extension of shoulder and elbow and is innervated by the radial nerve.

Anterior Forearm

Forearm compartment whose main action is wrist and finger flexion and is innervated by the ulnar nerve and median nerve.

Intrinsic Hand Muscles and Extrinsic Muscles

Muscles innervated by the ulnar nerve and median nerve.

Posterior Forearm

Forearm compartment whose main action is wrist and finger extension and is innervated by the radial nerve.

Anterior Thigh

Thigh compartment acting on the hip and knee whose main actions are knee extension and hip flexion, innervated by the femoral nerve.

Medial Thigh

Thigh compartment whose main action is thigh and hip adduction, innervated by the obturator nerve.

Posterior Thigh

Thigh compartment whose main action is knee flexion and hip extension, innervated by the sciatic nerve.

Anterior Leg

Leg compartment whose main action is dorsiflexion of ankles and extension of toes, innervated by the deep fibular nerve.

Posterior Leg

Leg compartment whose main action is plantar flexion of ankle and flexion of toes, innervated by the tibial nerve.

Lateral Leg

Leg compartment whose main action is eversion, innervated by the superficial fibular nerve.

Intrinsic Foot Muscles

Muscles of the foot innervated by the lateral plantar nerve and medial plantar nerve.