A&P Chapters 10 &11

Muscle Function
External Intercostals Elevates ribs; inspiration
Internal Intercostals Depresses ribs; expiration
Diaphragm Inspiration; depresses floor of thorax
Trapezius Elevates, depresses, retracts, rotates and fixes scapula; extends neck
Serratus Anterior Roates and protracts scapula; elevates ribs
Pectoralis Minor Depresses scapular or elevates ribs
Latissimus Dorsi Adducts and medially orates arm; extends shoulder
Pectoralis Major Flexes shoulder; adducts and medially rotates arm; extends shoulder from flexed position
Deltoid Flexes and extends shoulder; abducts and medially and laterally rotates arm
Teres Major Extends and medially rotates humerus; swings the arm
Subscapularis Medially rotates arm; holds head of humerus in place
Infraspinatus Laterally rotates arm; holds head of humerus in place
Supraspinatus Abducts arm; holds head of humerus in place
Teres Minor Laterally rotates ad adducts arm; hold head of humerus in place
External Obliques Flexes and rotates vertebral column; compresses abdomen; depresses thorax
Internal Obliques Flexes and rotates vertebral column; compresses abdomen; depresses thorax
Transversus Abdominis Compresses abdomen
Rectus Abdominis Flexes vertebral column; compresses abdomen
Splenius Capitus Extends, rotates, and laterally flexes head
Sternocleidomastoid 1) Laterally flexes head and neck to same side AND rotates head and neck to opposite side

2) Flexes neck

Frontalis Moves scalp and elevates eyebrows
Orbicularis Oculi Closes eyelids
Orbicularis Oris Closes lips
Masseter Elevates and protracts mandible
Buccinator Retracts angle of mouth; flattens cheeks
Biceps Brachii Flexes shoulder and elbow; supinates forearm and hand
Origin of Biceps Brachii Short head: coracoid process of scapula
Long head: glenoid cavity
Insertion of Biceps Brachii Radial Tuberosity
Brachialis Flexes elbow
Flexor Digitorum Superficialis Flexes fingers
Triceps Brachii Extends elbow; extends shoulder and adducts arm
Origin of Triceps Brachii Scapula, Posterior shaft of humerus
Insertion of Triceps Brachii Olecranon process of Ulna
Extensor Digitorum Extends fingers and wrist
Extensor Carpi Ulnaris Extends and adducts wrist
Pronator Teres Pronates forearm and hand
Supinator Supinates forearm and hand
Iliopsoas Flexes hip
What makes up the Iliopsoas Iliacus and Psoas Major
Tensor Fascia Lata Flexes hip; abducts and medially rotates thigh; stabilizes femur on tibia when standing
Sartorius Flexes hip and knee; rotates thigh laterally and leg medially
Rectus Femoris Extends knee and flexes hip
Origin of Rectus Femoris Anterior inferior iliac spine
Insertion of Rectus Femoris Tibial tuberosity via patellar ligament
Vastus Lateralis Extends knee
Origin of Vastus Lateralis Greater trochanter and line Aspera of femur
Insertion of Vastus Lateralis Tibial tuberosity via patellar ligament
Vastus Intermedius Extends knee
Vastus Medialis Extends knee
Gracilis Adducts thigh; flexes knee
Adductor Magnus Adducts thigh and flexes hip
Adductor Longus Adducts, laterally rotates thigh; tilts pelvis
Biceps Femoris Flexes knee; laterally rotates leg; extends hip
Origin of Biceps Femoris Ischial tuberosity and linea aspera of femur
Insertion of Biceps Femoris Head of fibula and lateral condyle of tibia
Semitendinosus Flexes knee; medially rotates leg; extends hip
Semimembranosus Flexes knee; medially rotates leg; tenses capsule of knee joint; extends hip
Gastrocnemius Plantar flexes foot; flexes knee
Extensor Digitorum Longus Extends four lateral toes; dorsiflexes and everts foot
Peroneus Longus/fibularis longus Everts and plantar flexes foot
Peroneus/fibrous Brevis Everts and plantar flexes foot
Tibialis anterior Dorsiflex and inverts the foot
Zero position Anatomical position
Flexes Decreases a joints angle
Extends Returns a body part to the zero position
Hyperextension Extension beyond zero position
Elevate Raises a body part vertically (shoulder shrug)
Depress Lower a body part vertically (release a shoulder shrug)
Retracts Posterior movement of a body part in a horizontal plane (rowing a boat)
Protracts Anterior movement of a body part in a horizontal plane (rowing a boat)
Abducts Moves a body part away from the midline of the body (jumping jacks)
Adducts Moves a body part towards the midline of the body (jumping jacks)
Muscle Compartments A Group of functionally related muscles enclosed and separated from others by connective tissue fascia
What does the muscle compartments contain Nerves, blood vessels that supply the muscle group
Example of muscle compartments Thoracic, abdominal walls, limbs
Indirect attachment to bone Tendons
Tendons Bridge the gap between muscle ends and bony attachment
Examples of tendons Biceps brachii, achilles tendon
Characteristics of tendons Collagen fibers of the endo-, peri-, and epimysium continue into the tendon
From there into the periosteum and the matrix of bone
Very strong structural continuity from muscle to bone
Direct (fleshy) attachment to bone characteristics Little separation between muscle and bone
Muscle seems to immerse directly from bone
Examples of direct attachments Margins of brachial is, lateral head of triceps brachii
Origin Bony attachment at stationery end of muscle
Belly Thicker, middle region of muscle between origin and insertion
Insertion Bony attachment to mobile end of muscle
Which muscles do not insert on bone but the fascia or tendon of another muscle or on collagen fibers of the dermis Distal tendon of the biceps brachia inserts on the fascia of the forearm
Fascial muscles insert on the skin
Action The effects produced by a muscle
– To produce or prevent movement
What are the four categories of action Prime mover (agonist), synergist, antagonist, fixator
Prime mover (agonist) Muscle that produces most of the force during a joint action
Synergist Muscle that aids the prime mover
-Stabilizes the nearby joint
-Modifies the direction of movement
Antagonist Opposes the prime mover
-Relaxes to give prime mover control over an action
-Preventing excessive movement and injury
Fixator Muscle that prevents movements of bone
Example of Prime mover (agonist) Brachialis
Example of Synergist Biceps Brachii
Example of Antagonist Triceps brachii
Example of Fixator Muscle that holds scapula firmly in place
Intrinsic muscles Entirely contained within a region, such as the hand
-Both origin and insertion
Extrinsic muscles Act on a designated region, but has its origin elsewhere
-Fingers: extrinsic muscles in the forearm
Blood supply to muscles Muscular system receives about 1.24L of blood per minute at rest (1/4 of the blood pumped by the heart)
Hernias Any condition in which the viscera protrudes through a weak point in the muscular wall of the abdominopelvic cavity
Compartment Syndrome Fasciae of arms and legs enclose muscle compartments very snugly
What happens if a blood vessel in a compartment is damaged Blood and tissue accumulate in the compartment
Example of fusiform muscle Biceps brachii
Example of parallel muscle Rectus abdominis
Example of triangular muscle Pectoralis major
Example of unipennate muscle Palmar interosseous
Example of bipennate muscle Rectus femoris
Example of multipennate muscle Deltoid
Example of circular muscle Orbicularis Oculi