2-20_UTA_Review_SLIDES_-_Skeletal_Muscles

Page 1: Skeletal Muscle Functions

  • Skeletal Muscle Overview

    • Responsible for voluntary movements.

    • Connected to bones by tendons.

Page 2: Relationship between Muscles and Joints

  • Muscle Functionality by Joint Position

    • Muscles crossing a joint influence movements around all axes of rotation associated with that joint.

    • Locating muscles on the skeleton helps predict movements:

      • Observe direction of muscle fibers indicating contraction and shortening.

      • Identify possible movements such as flexion, extension, abduction, adduction, medial rotation, and lateral rotation.

Page 3: Mechanics of Muscle Contraction

  • Basic Mechanics

    • Muscles only pull, they do not push.

    • Example:

      • Muscle: Biceps

      • Movement Completed: Flexion at the elbow.

      • Joint: Elbow

      • Axis of Rotation: Horizontal

      • Generality: Muscles crossing the elbow joint affect forearm movement.

Page 4: General Rule of Muscle Movement

  • Function of Muscles Across Joints:

    • SC joint: Moves the shoulder.

    • Shoulder joint: Moves the arm.

    • Elbow joint: Moves the forearm.

    • Wrist joints: Move the hand.

    • Joints of the digits: Move the fingers.

    • Similar functionality applies for the lower extremity.

Page 5: Rule of Thumb in Muscle Positioning

  • Muscle Function by Location

    • Most anterior muscles serve as flexors and medial rotators.

    • Most posterior muscles function as extensors and lateral rotators.

    • Abduction and adduction depend on muscle position relative to the joint (superior or inferior).

Page 6: Divisions of the Muscular System

  • Types of Muscles:

    • Axial Muscles:

      • Associated with the head, vertebral column, and thoracic cage (60% of skeletal muscles).

    • Appendicular Muscles:

      • Linked to pectoral and pelvic girdles and limbs (40% of skeletal muscles).

Page 7: Muscle Groups of the Head and Neck

  • Types of Head and Neck Muscles:

    • Muscles of Facial Expression

    • Muscles of Mastication

    • Muscles of the Eye

    • Muscles of the Tongue

    • Muscles of the Pharynx

    • Muscles of the Larynx

    • Muscles that move the head

Page 8: Muscles of Facial Expression

  • Key Muscles:

    • Frontalis: Raises eyebrows.

    • Obicularis Oris: Puckers lips.

    • Obicularis Oculi: Closes eyes.

    • Levator Labii Superioris: Raises lips.

    • Zygomaticus: Smile muscle.

    • Buccinator: Tightens cheeks.

    • Depressor Labii Inferioris: Lowers lips.

Page 9: Muscles of Mastication

  • Key Muscles:

    • Masseter: Main muscle for chewing.

  • Muscles of the Pharynx and Larynx:

    • Control diameter of windpipe and throat.

  • Extrinsic Eye Muscles:

    • Aid in speech, pitch changes, and direct eye movement.

Page 10: Anterior Muscles of the Neck

  • Suprahyoid Muscles: Elevate hyoid bone and depress mandible.

  • Infrahyoid Muscles: Depress hyoid bone; elevate larynx & pharynx.

  • Functions include chewing, talking, swallowing, singing.

  • Sternocleidomastoid: Functions as a head/neck rotator.

Page 11: Posterior Muscles of the Neck

  • Functionality:

    • Head (neck) extensors aid in moving the head backward (looking up).

Page 12: The Vertebral Column

  • Muscle Attachment:

    • Primarily attached to spinous processes; some attach to transverse processes.

  • Function: Maintain trunk erect and extended.

  • Note: This is the most overworked muscle group; individual muscles not required to be memorized for lectures.

Page 13: Anterior Body Wall

  • Intercostal Muscles:

    • Exterior: Pull up and away from each other.

    • Interior: Pull down and away.

  • Purpose: Maintain distance between ribs.

  • Obliques:

    • Exterior: Pull belly button up and away.

    • Interior: Pull belly button down and out.

  • Transverse Abdominis: Flattens abdomen.

  • Rectus Abdominis: Flexes the trunk.

Page 14: Anterior Body Wall Layers

  • Muscle Layers:

    • Most superficial: External obliques

    • Next layer: Internal obliques

    • Deeper: Transverse abdominis

    • Most internal: Rectus abdominis.

  • Other important structures: Aponeurosis, rectus sheath, linea alba.

Page 15: The Diaphragm

  • Functionality:

    • Separates thoracic and abdominal cavities.

    • Primary muscle of respiration.

    • Inspiration: Involves contraction of diaphragm.

    • Expiration: Forceful expiration utilizes abdominal muscles.

Page 16: Pelvic Floor

  • Key Areas:

    1. Urethral Sphincter: Controls urination.

    2. Anal Sphincter: Controls defecation.

  • Note: Individual muscles are not required to be memorized.

Page 17: Appendicular Muscles (Limb Muscles)

  • Important Muscles:

    • Brachial muscles

    • Flexor carpi

    • Palmars longue

    • Flexor digitorum.

    • Various adaptations and branches are specified in the notes.

Page 18: Shoulder Muscles

  • Main Muscles:

    • Deltoid: Covers shoulder joint and serves as arm abductor.

    • Rotator Cuff Muscles:

      1. Supraspinatus: Arm abduction.

      2. Infraspinatus: External rotation of the arm.

      3. Teres Minor: External rotation and assists in adduction.

      4. Subscapularis: Internal rotation.

    • Teres Major: Arm adductor; assists with internal rotation.

Page 19: Anterior Arm Muscles

  • Key Muscles:

    • Biceps Brachii: Main elbow flexor.

    • Brachialis: Assists in elbow flexion.

    • Coracobrachialis: Assists in shoulder adduction and flexion.

Page 20: Posterior Arm Muscles

  • Key Muscle:

    • Triceps Brachii: Role in extending elbow; consists of lateral, long, and medial head origins.

Page 21: Anterior Forearm Muscles

  • Key Muscles:

    • Pronator Teres: Arm pronation.

    • Palmaris Longus: Longest muscle, aids wrist flexion.

    • Flexor Carpi Muscles: Flex wrist.

    • Flexor Pollicis: Flexes the thumb.

    • Flexor Digitorum: Flexes digits 2-5.

Page 22: Posterior Forearm Muscles

  • Key Muscles:

    • Supinator: Arm supination.

    • Brachioradialis: Assists in elbow flexion and pronation/supination.

    • Extensor Carpi Muscles: Extends wrist.

    • Extensor Digitorum: Extends digits 2-5.

    • Extensor Pollicis: Extends thumb.

Page 23: Lower Extremity Muscles

  • Muscle Overview: Listed key muscles associated with lower extremities; includes gluteal and hamstring muscles among others.

  • Notable Functions: Highlighted for various actions such as hip extension, abduction, and flexion.

Page 24: Gluteal Muscles Functions

  • Main Functions:

    • Hip extension, abduction, and lateral rotation.

  • Key Muscles:

    • Gluteus Maximus - Major hip extensor and abductor.

    • Gluteus Medius - Assists in hip extension and abduction.

    • Gluteus Minimus - Same function as Gluteus Medius.

    • Piriformis - Lateral rotator.

Page 25: Muscles of Pelvic Floor and Medial Thigh

  • Key Muscles:

    • Hip Flexors: Iliacus and Psoas Major.

    • Hip Adductors: Adductor Magnus, Longus, Brevis, and Gracilis.

Page 26: Muscles of the Posterior Thigh (Hamstrings)

  • Key Muscles:

    • Semimembranosus

    • Semitendinosus

    • Biceps Femoris Long Head

    • Biceps Femoris Short Head

  • Functions: Hip extensors and knee flexors.

Page 27: Muscle of Anterior Thigh (Quadriceps)

  • Functions:

    • Extends knee: Rectus Femoris, Vastus Lateralis, Vastus Intermedius, Vastus Medialis.

    • FLEXES knee: Sartorius, with insertion at the medial surface of proximal tibia; origin is superior iliac spine.

Page 28: Muscles of Anterior Leg

  • Functions:

    • Toe and foot extensors/Dorsi flexors include: Extensor Digitorum Longus, Extensor Hallucis Longus, and Tibialis Anterior.

Page 29: Muscles of Lateral Leg

  • Main Muscles:

    • Foot flexors/plantar flexors: Fibularis Longus, Fibularis Brevis.

    • Other associated muscles include Vastus Medialis, Lateral head of Gastrocnemius, Soleus.

Page 30: Muscles of Posterior Leg

  • Functions:

    • Foot flexors/plantar flexors: Gastrocnemius and Soleus.

    • Toe flexors: Tendons of Flexor Digitorum Longus and Flexor Hallucis Longus.

Page 31: Dorsal Foot Muscles

  • Function:

    • Toe extensors; focus on relevant functions rather than specific muscle names.

Page 32: Plantar Foot Muscles

  • Function:

    • Toe flexors; focus on relevant functions rather than specific muscle names.

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