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.