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1. Functional Implications of Fascicle Arrangement

Fascicle arrangement affects the range of motion and the power of a muscle. Different fascicle arrangements include:

- Parallel (e.g., sartorius): Muscles have fascicles running parallel to the long axis, providing extensive range of motion but less power.

- Pennate (e.g., rectus femoris): Fascicles attach obliquely to a central tendon. This structure allows for greater power but limits range of motion.

- Convergent (e.g., pectoralis major): Fascicles converge from a broad area to a single tendon, offering versatility in muscle movement.

- Circular (e.g., orbicularis oris): Fascicles are arranged in concentric rings, useful for closing openings like the mouth or eyes.

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2. Differentiating Muscle Roles

- Agonist (Prime Mover): The primary muscle responsible for generating a specific movement (e.g., biceps brachii for elbow flexion).

- Antagonist: The muscle that opposes the movement of the agonist (e.g., triceps brachii for elbow extension).

- Synergist: Assists the agonist by providing additional force or reducing unwanted movement (e.g., brachialis assisting the biceps brachii).

- Fixator: Stabilizes the origin of the agonist, enabling it to function more effectively (e.g., muscles of the shoulder girdle stabilizing the scapula).

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3. Locating Axial and Appendicular Muscles

The axial muscles include those located on the head, neck, and trunk, while appendicular muscles are associated with the limbs. Use models and diagrams to study the location of these muscles.

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4. Primary Actions of Identified Muscles

Head & Neck Muscles

- Occipitofrontalis (epicranius):

- Frontal belly: Raises eyebrows, wrinkles forehead.

- Occipital belly: Pulls scalp backward.

- Orbicularis oculi: Closes the eye (blinking, squinting).

- Orbicularis oris: Closes and protrudes the lips (kissing muscle).

- Levator labii superioris: Elevates upper lip (smiling).

- Zygomaticus (major and minor): Elevates the corners of the mouth (smiling).

- Depressor anguli oris: Lowers corners of the mouth (frowning).

- Depressor labii inferioris: Lowers lower lip.

- Temporalis: Elevates and retracts the mandible (chewing).

- Masseter: Elevates the mandible (chewing).

Neck & Trunk Muscles

- Sternocleidomastoid: Flexes neck, rotates head.

- Trapezius: Elevates, retracts, and rotates the scapula.

Thoracic Muscles

- External intercostals: Elevate ribs during inhalation.

- Internal intercostals: Depress ribs during forced exhalation.

- Pectoralis major: Adducts and medially rotates the arm.

- Pectoralis minor: Stabilizes the scapula by drawing it anteriorly.

- Serratus anterior: Protracts and rotates the scapula.

- Latissimus dorsi: Extends, adducts, and medially rotates the arm.

- Diaphragm: Prime mover for inhalation, contracts to flatten and enlarge the thoracic cavity.

Abdominal Muscles

- Rectus abdominis: Flexes the vertebral column.

- Linea alba: Fibrous structure running down the midline of the abdomen.

- External obliques: Flex and rotate the vertebral column.

- Internal obliques: Flex and rotate the vertebral column.

Back Muscles

- Rhomboideus major: Retracts and elevates the scapula.

- Infraspinatus: Laterally rotates the arm.

- Supraspinatus: Abducts the arm.

- Subscapularis: Medially rotates the arm.

- Teres major: Medially rotates and adducts the arm.

- Teres minor: Laterally rotates the arm.

Shoulder and Arm Muscles

- Deltoid: Abducts the arm.

- Biceps brachii: Flexes the elbow, supinates the forearm.

- Brachialis: Flexes the elbow.

- Triceps brachii: Extends the elbow.

- Brachioradialis: Flexes the forearm.

Forearm Muscles

- Extensor carpi radialis longus: Extends and abducts the wrist.

- Extensor digitorum: Extends the fingers.

- Extensor carpi ulnaris: Extends and adducts the wrist.

- Flexor carpi ulnaris: Flexes and adducts the wrist.

- Palmaris longus: Flexes the wrist.

- Flexor carpi radialis: Flexes and abducts the wrist.

- Pronator teres: Pronates the forearm.

Pelvis and Thigh Muscles

- Gluteus maximus: Extends and laterally rotates the thigh.

- Tensor fasciae latae: Abducts and medially rotates the thigh.

- Iliotibial tract: Provides stability to the knee.

Medial and Anterior Thigh Muscles

- Gracilis: Adducts the thigh.

- Sartorius: Flexes, abducts, and laterally rotates the thigh.

- Rectus femoris: Extends the knee and flexes the thigh.

- Vastus medialis: Extends the knee.

- Vastus lateralis: Extends the knee.

Posterior Thigh Muscles (Hamstrings)

- Biceps femoris: Extends the thigh, flexes the knee.

- Semitendinosus: Extends the thigh, flexes the knee.

- Semimembranosus: Extends the thigh, flexes the knee.

Lower Leg Muscles

- Tibialis anterior: Dorsiflexes and inverts the foot.

- Extensor digitorum longus: Extends the toes, dorsiflexes the foot.

- Peroneus (Fibularis) longus: Everts and plantarflexes the foot.

- Soleus: Plantarflexes the foot.

- Gastrocnemius: Plantarflexes the foot, flexes the knee.

- Calcaneal tendon (Achilles tendon): Connects the gastrocnemius and soleus to the heel bone, aiding in plantarflexion.

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