Muscle Lab Practice and studying

Bio 361: Muscle & Joint Anatomy Lab Notes

Introduction

  • Course: Biology 361, Human Anatomy & Physiology I

  • Lab Focus: Muscles, Joints, and Movement (coverage not necessarily in sequential order)

  • Learning Emphasis: Instead of memorization of muscle origin, insertion, and action (OIA), aim to intuitively understand muscle actions based on their points of attachment.

  • Practical Examination Preparation:

    • Identify bolded muscles from handout.

    • Identify actions based on images or descriptions (examples provided).

    • Identify types of joints (e.g., hinge, saddle, ball & socket) shown.

    • Identify components of the knee joint specifically.

    • Answer multiple-choice questions related to muscle OIA.

    • Name the cranial nerve innervations for certain muscles.

I. Attachments & Actions of the Muscles About the Joints

  • Key Vocabulary: Understanding of movement vocabulary is crucial (refer to Section 8.2 of the text for additional explanations).

    • Origin: Attachment of a muscle to the stationary bone.

    • Insertion: Attachment of a muscle to the moving bone.

    • Action: The movement produced when a muscle contracts, moving the insertion toward the origin.

    • Flexion: Decreasing the angle at a joint, typically in the sagittal plane.

    • Extension: Increasing the angle at a joint, typically in the sagittal plane.

    • Hyperextension: Extension beyond 180˚.

    • Abduction: Movement away from the midline, typically in the frontal plane.

    • Adduction: Movement toward the midline, typically in the frontal plane.

    • Circumduction: Circular movement combined from flexion, extension, abduction, and adduction.

    • Rotation: Movement of a bone around its own axis (e.g., head rotating side to side).

    • Pronation: Rotating forearm so palm faces down.

    • Supination: Rotating forearm so palm faces up (like holding a bowl of soup).

    • Lateral Flexion: Decreasing angle laterally (bending laterally at neck or waist).

    • Plantarflexion: Bending ankle towards plantar surface of foot (ankle extension).

    • Dorsiflexion: Raising foot towards dorsal side (ankle flexion).

    • Protraction: Anterior movement (not a limb), e.g., shoulder or jaw movement.

    • Retraction: Posterior movement (not a limb), e.g., shoulder or jaw movement.

    • Depression: Lowering a structure, e.g., lowering shoulder or jaw (opposite of elevation).

    • Elevation: Raising a structure, e.g., raising shoulder or jaw (opposite of depression).

    • Opposition: Movement of the thumb to touch other fingers.

II. On to the Muscles

  • Learning Strategy: Locate muscles on multiple specimens since appearances can vary. Aim to learn only 10% of the body’s muscles, primarily the more superficial ones.

  • General Insight: Visualize actions; if actions such as medial rotation seem unlikely, mentally rotate the bone laterally to assist understanding.

A. Muscles of the Head and Neck

  1. Muscles Moving the Head & Neck (referencing Table 10.2)

    • Sternocleidomastoid: Together flexes head; unilaterally, lowers and laterally rotates head to the opposite side.

    • Trapezius: Extends head and neck (additional actions on scapula noted in Section C).

    • Innervation: Both muscles above are innervated by the same cranial nerve.

  2. Muscles of Facial Expression (referencing Table 10.3)

    • Orbicularis oculi: Closes eyelid.

    • Orbicularis oris: Puckers lips as if to kiss.

    • Zygomaticus major: Contributes to smiling.

    • Zygomaticus minor: Assists in smiling.

    • Platysma: Depresses lower lip; wrinkles neck skin, expressing fear.

    • Innervation: All listed muscles are innervated by the same cranial nerve.

  3. Muscles of Chewing & Swallowing (referencing Tables 10.4 & 10.5)

    • Temporalis: Elevates jaw.

    • Masseter: Elevates jaw.

    • Digastric: Depresses and retracts jaw.

    • Innervation: Identify the cranial nerves innervating the first two muscles.

  4. Extrinsic Eye Muscles

    • Muscles originate from the sphenoid bone and insert on the eyeball. Observations to make using eye models:

      • Superior rectus: Pulls eye upward.

      • Inferior rectus: Pulls eye downward.

      • Medial rectus: Pulls eye medially (adducts).

      • Lateral rectus: Pulls eye laterally (abducts).

      • Inferior oblique: Pulls eye laterally and upward.

      • Superior oblique: Pulls eye laterally and downward (also known for passing through a pulley).

    • Innervation Questions: Which cranial nerve innervates each muscle, particularly noting the superior oblique and lateral rectus?

B. Muscles of the Thorax and Abdomen (referencing Tables 10.10 & 10.11)

  • Diaphragm: Flattens to increase thoracic cavity for inhalation.

  • Rectus abdominis: Flexes trunk and compresses abdomen (forms the “six-pack”).

  • Linea alba: A dense regular connective tissue structure along the midline.

  • External oblique: Facilitates lateral flexion and abdominal compression.

  • Internal oblique: Assists in lateral flexion and compressing abdomen.

  • Transverse abdominis: Focuses on compressing abdomen.

  • Note: Abdominal muscles may present variably across different torso models.

C. Muscles of the Pectoral Girdle, Brachium & Antebrachium

  • This section details muscles that enable shoulder movement and stability, as well as those influencing arm movement:

  1. Muscles Moving the Scapula (referencing Table 10.13)

    • Pectoralis minor: Depresses scapula or elevates ribs.

    • Serratus anterior: Also depresses scapula or elevates ribs.

    • Trapezius: Achieves elevation, depression, rotation, retraction, and fixation of the scapula; involved in neck extension.

  2. Muscles Moving Brachium or Stabilizing Shoulder (referencing Tables 10.14 & 10.15)

    • Deltoid: Abducts and rotates humerus; flexes and extends humerus as well.

    • Latissimus dorsi: Adducts and extends humerus.

    • Pectoralis major: Flexes, adducts, and medially rotates the humerus.

    • Teres major: Adducts, extends, and medially rotates humerus.

    • Infraspinatus: Stabilizes shoulder and laterally rotates humerus.

    • Subscapularis: Adducts and medially rotates humerus.

    • Supraspinatus: Abducts humerus.

    • Teres minor: Laterally rotates humerus.

    • Rotator Cuff Muscles: Includes infraspinatus, subscapularis, supraspinatus, and teres minor to stabilize the shoulder (notably, supraspinatus is often involved in rotator cuff injuries).

  3. Muscles That Move the Antebrachium (from Tables 10.14, 10.16, & 10.17)

    • Biceps brachii: Flexes and supinates forearm, and also extends shoulder.

    • Brachialis: Prime mover for forearm flexion.

    • Triceps brachii: Extends forearm.

    • Brachioradialis: Flexes forearm.

    • Pronator teres: Facilitates forearm pronation; also a supinator exists but is deeper.

    • Rationale Inquiry: Why are there generally more and larger muscles responsible for flexing the antebrachium than extending it?

  4. Muscles That Move the Hand and Fingers (from Table 10.17)

    • Focus on muscle insertions to understand their actions:

    • Flexor carpi radialis: Flexes and abducts hand.

    • Flexor carpi ulnaris: Flexes and adducts hand, clearly visible from both front and back.

    • Flexor digitorum superficialis: Flexes fingers (and subsequently the wrist).

    • Palmaris longus: Assists in flexing the hand.

    • Question Inquiry: Which side of the arm will the flexors and extensors be located?

D. Muscles of the Leg

  • Note in this section that terms 'hip' and 'thigh' are often interchangeable depending on movement context (flexion/extension vs. abduction/adduction).

  1. Muscles of Hip, Thigh, and Knee (from Tables 10.19, 10.20 & 10.21)

    • Gluteus maximus: Extends, laterally rotates, and abducts thigh.

    • Gluteus medius: Abducts and medially rotates thigh (notable function).

    • Tensor fasciae latae & Iliotibial tract: Flexes the tract; aids in flexion, abduction, and medial rotation.

    • Adductor longus: Adducts, flexes, and medially rotates thigh.

    • Gracilis: Adducts thigh, flexes knee.

    • Quadriceps femoris: Recognized as a group:

      • Rectus femoris: Extends at knee and flexes hip.

      • Vastus lateralis: Extends knee.

      • Vastus medialis: Extends knee.

      • Vastus intermedius: Extends knee.

    • Hamstrings Group: Learn individual muscles along with the group name:

      • Biceps femoris (long head): Extends and laterally rotates hip; flexes knee.

      • Semitendinosus: Extends thigh and flexes knee; medially rotates leg.

      • Semimembranosus: Extends hip and flexes knee; medially rotates leg.

    • Sartorius: Longest muscle, complex actions include flexing both hip and knee, abducting hip, aiding rotation.

  2. Muscles Flexing/Extending the Ankle (from Table 10.22)

    • Tibialis anterior: Dorsiflexion and inversion (associated with 'shin splints').

    • Gastrocnemius: Facilitates plantarflexion and knee flexion.

III. Now the Joints

  • For a muscle to act at a joint, the origin and insertion must be on opposite sides of the joint.

    • Example: Tendons inserting anteriorly on digits influence both finger and wrist movement.

A. Types of Synovial Joints

  • Types and Examples: (Refer to Table 8.4 and the accompanying descriptions in the text)

    • Plane (Gliding)

    • Hinge: Example includes the elbow.

    • Pivot: Rotational movement, e.g., between the first two vertebrae.

    • Condylar (Ellipsoid): Biaxial movements (flex/extend and abduct/adduct).

    • Saddle: Example includes the carpometacarpal joints.

    • Ball & Socket: Most flexible joint type, e.g., hip and shoulder.

B. Sample Synarthrosis: The Knee

  • Recognized as one of the most complex and injury-prone joints in the body.

  • Knee Joint Structures (Identify for Lab):

    • Medial meniscus: Medial fibrocartilage disk; stabilizes the joint.

    • Lateral meniscus: Lateral fibrocartilage disk; aids joint stability.

    • Medial collateral ligament (tibial collateral ligament).

    • Lateral collateral ligament (fibular collateral ligament).

    • Anterior cruciate ligament (ACL).

    • Posterior cruciate ligament (PCL).

    • Patellar ligament.

IV. Exercises

A. Action Identification Exercises

  1. Action for Lateral Leg Movement: Abduction.

  2. Action for Medial Leg Movement:

    • a. Adduction

    • b. Type of Joint Involved: Ball & Socket.

  3. Action of Elbow Flexion:

    • a. Direction of palms after flexing: Superiorly.

    • b. Action performed in turning palms over: Pronation.

    • c. Joint Type when bending elbow: Hinge.

  4. Action when Rotating Palms Upward:

    • a. Action: Supination.

    • b. Joint Type: Pivot.

  5. Action When Looking Up: Hyperextension.

  6. Action Sequence for Head Rotation:

    • a. Actions in order: first lateral rotation then medial rotation.

    • b. Joint involved: Pivot.

B. Silhouette Movement Recognition

  1. Right Shoulder Movement: Abduction.

  2. Left Elbow Movement: Flexion.

  3. Left Wrist Movement: Flexion.

  4. Neck Movement: Lateral rotation.

  5. Left Hip Movement: Considerable lateral rotation with potential abduction.

  6. Right Hand Digit Movement: Flexion.

  7. Left Shoulder Movement (beyond abduction): Medial rotation.

C. Muscle Insertion Placement for Actions

  1. Abduct at Shoulder: Lateral aspect of humerus.

  2. Adduct at Shoulder: Medial aspect of humerus.

  3. Flex at Shoulder: Anterior aspect of humerus.

  4. Extend at Shoulder: Posterior aspect of humerus.

  5. Medially Rotate the Humerus: Medial aspect.

  6. Laterally Rotate the Humerus: Lateral aspect.

Answer Key for Part IV Exercises

  • **A.

  1. Abduction**

  • 2.
    a. adduction
    b. Ball & Socket

  • 3.
    a. superiorly
    b. pronation
    c. hinge

  • 4.
    a. supination
    b. pivot

  • 5. Hyperextension

  • 6.
    a. first lateral rotation and then medial rotation
    b. pivot

  • B.

  1. Abduction

  2. Flexion

  3. Flexion

  4. Lateral Rotation

  5. Lateral Rotation and Abduction

  6. Flexion

  7. Medial Rotation

  • C.

  1. Lateral

  2. Medial

  3. Anterior

  4. Posterior

  5. Medial (or anterior if originating from medial side)

  6. Lateral (or anterolateral).

This guide compiles an extensive collection of definitions, actions, and explanations critical for understanding the muscular and joint anatomy covered in your lab sessions. Use it to enhance your comprehension and studies ahead of practical assessments and laboratory work.