Muscle Anatomy - A&P

Epimysium

Dense irregular connective tissue encasing entire skeletal muscle, integrating with tendons to transmit contractile force and reduce friction between adjacent muscles.

Fasicles

Bundles of skeletal muscle fibers encased by perimysium, serving as structural and functional subunits within a muscle to coordinate contraction.

Perimysium

Connective tissue surrounding a fascicle.

Muscle Fiber

A single muscle cell.

Endomysium

Connective tissue surrounding a muscle cell.

Tendon

Connects muscle to bone.,

Aponeurosis

Strong sheet of tissue that acts as a tendon to attach muscles to bone.

Origin

Attachment of a muscle that remains relatively fixed during muscular contraction.

Insertion

The attachment of a muscle tendon to a moveable bone or the end opposite the origin.

Action

The specific movement a muscle produces at a joint, determined by its origin, insertion, and line of pull.

Flexion

Decreases the angle of a joint.

Extension

Increases the angle of a joint.

Hyperextension

Extension beyond anatomical position.

Abduction

Movement away from the midline of the body.

Adduction

Movement toward the midline of the body.

Rotation

Movement of a bone around its longitudinal axis within a joint, without lateral displacement.

Dorsiflexion

Bending of the foot or the toes upward.

Plantar Flexion

Bending of the sole of the foot by curling the toes toward the ground.

Agonist

Contraction that generates movement.

Antagonist

Relaxation require for movement.

Synergist

Contracts with the agonist to aid movement.

Fixator

Synergist that stabilizes joints.

Orbicularis Oculi

Closes the eyelids.

Orbicularis Oris

Closes lips.

Masseter

Elevates the mandible to close the jaw.

Temporalis

Elevates and retracts the mandible.

Sternoclei Domastoid

Rotates the head to the opposite side and tilts it to the same side; flexes neck.

Trapezius

Elevates, depresses, retracts, and rotates the scapula; rotates the arm.

Pectoralis Major

Adducts and flexes humerus.

Pectoralis Minor

Protracts and depresses scapula.

Internal Intercostals

Depresses ribs during forced expiration.

External Intercostals

Elevates ribs during inspiration.

Deltoid

Flexes, abducts, and extends the arm; medially and laterally rotates the arm.

Rectus Abdominus

Flexes the vertebral column; compresses abdominal contents.

External Oblique

Contralateral trunk rotation; lateral flexion; bilateral trunk flexion.

Internal Oblique

Ipsilateral trunk rotation; lateral flexion; bilateral trunk flexion.

Transversus Abdominis

Compresses abdominal contents; stabilizes the trunk.

Latissimus Dorsi

Extends, adducts, and medially rotates the arm; draws the shoulder downward and backward.

Humerus and scapula. (Origin)

Origin of Triceps Brachii

Olecranon Process (Insertion)

Insertion of Triceps Brachii

Triceps Brachii

Extends forearm.

Scapula. (Origin)

Origin of Biceps Brachii

Radial tuberosity. (Insertion)

Insertion of Biceps Brachii

Biceps Brachii

Flexes forearm.

Humerus (anterior distal shaft). (Origin)

Origin of Brachialis

Coronoid process of ulna. (Insertion

Insertion of Brachialis

Brachialis

Elbow flexion.

(ECRL) Extensor Carpi Radialis Longus

Extends wrist and abducts hand.

Extensor Digitorum

Extends fingers and the wrist.

Flexor Digitorum Superficialis

Flexes wrist and fingers.

Flexor Carpi Radialis (FCR)

Flexes wrist and abducts hand.

Gluteus Maximus

Extends thigh.

Gluteus Medius

Abducts and medially rotates thigh.

Sartorius

Flexes, abducts, and laterally rotates thigh at the hip; flexes knee.

Gracilis

Adducts thigh.

Quadriceps Femoris

Extends leg.

Rectus Femoris

Most superior muscle in quadriceps.

Vastus Lateralis

To the left and below the rectus femoris.

Vastus Medialis

Towards in the inwards of the midline on the thigh.

Vastus Intermedius

Intermediate-most muscle on the thigh.

Hamstrings

Flexes knee.

Biceps Femoris

Outside of posterior thigh.

Semimembranosus

Inside of posterior thigh.

Femur (Origin)

Origin of Gastrocnemius

Calcaneus (Insertion)

Insertion of Gastrocnemius

Gastrocnemius

Plantarflexes ankle; flexes knee.

Posterior tibia. (Origin)

Origin of Flexor Digitorum Longus

Distal phalanges. (Insertion)

Insertion of Flexor Digitorum Longus

Flexor Digitorum Longus

Flexes toes 2-5; plantarflexes ankle; inverts foot.

Tibia/Fibula (Origin)

Origin of Extensor Digitorum Longus

Distal phalanges. (Insertion)

Insertion of Extensor Digitorum Longus

Extensor Digitorum Longus (EDL)

Extends toes and dorsiflexes foot.

Tibia (Origin)

Origin of Tibialis Anterior

1st Metatarsal (Insertion)

Insertion of Tibialis Anterior

Tibialis Anterior

Dorsiflexes and inverts foot.