Lab 9: Gross Anatomy of Muscular System & Histology of Muscles – Part 1

  • Overview of muscle tissue types: Skeletal, Cardiac, and Smooth

  • Key functions of the muscular system:

    • Movement of the skeleton

    • Maintenance of posture

    • Production of heat during muscle contraction

  • Histological characteristics:

    • Skeletal muscle: Striated and voluntary

    • Cardiac muscle: Striated and involuntary, with intercalated discs

    • Smooth muscle: Non-striated and involuntary, found in walls of hollow organs

  • Importance of muscle fiber types in exercise physiology:

    • Type I fibers (slow-twitch) vs Type II fibers (fast-twitch)

Major Muscles of the Human Body

Anterior View

  • Head Muscles:

    • Temporalis

    • Masseter

  • Shoulder Muscles:

    • Deltoid

  • Arm Muscles:

    • Triceps brachii

    • Biceps brachii

    • Brachialis

  • Facial Muscles:

    • Frontalis

    • Orbicularis oculi

    • Zygomaticus

    • Orbicularis oris

  • Neck Muscles:

    • Sternohyoid

    • Sternocleidomastoid

    • Platysma

  • Thorax Muscles:

    • Pectoralis minor

    • Pectoralis major

    • Serratus anterior

    • Intercostals

  • Forearm Muscles:

    • Pronator teres

    • Brachioradialis

    • Flexor carpi radialis

    • Palmaris longus

    • Flexor carpi ulnaris

  • Pelvis/Thigh Muscles:

    • Tensor fascia lata

    • Iliopsoas

    • Pectineus

  • Thigh Muscles:

    • Sartorius

    • Adductor longus

    • Gracilis

    • Rectus femoris

    • Vastus lateralis

    • Vastus medialis

  • Leg Muscles:

    • Fibularis longus

    • Tibialis anterior

    • Extensor digitorum longus

    • Gastrocnemius

    • Soleus

  • Abdominal Muscles:

    • Rectus abdominis

    • Internal oblique

    • Transversus abdominis

    • External oblique

Muscles of the Vertebral Column

Cadaver Photo Insights

Spinalis - On vertebral column

Longissium - next to the spinalis, supports it

  • Erector Spinae Group:

    • Spinalis capitis

    • Longissimus capitis

    • Longissimus cervicis

    • Spinalis cervicis

    • Iliocostalis cervicis (where thorax begins)

    • Spinalis thoracis

    • Longissimus thoracis

    • Iliocostalis thoracis

    • Iliocostalis lumborum- connects to pelvic girdle

  • Deep Back Muscles:

    • Semispinalis capitis

    • Ligamentum nuchae

    • Semispinalis cervicis

    • Semispinalis thoracis

    • Multifidus

    • Quadratus lumborum- opposite of iliocostalis lumborus, connects to pelvic girdle

Muscles of the Abdomen

Anterior View Features

  • Muscle Structure:

    • Rectus sheath

    • Rectus abdominis

      • Linea alba

    • Internal oblique

    • Transversus abdominis

    • External oblique

    • Aponeurosis of external oblique

    • Inguinal ligament (formed by free inferior border of aponeurosis of external oblique)

Muscle Labeling Activities

Major Muscles Illustrated

  1. External oblique

  2. Internal intercostals

  3. External intercostals

  4. Internal oblique

  5. Rectus abdominis

  6. Splenius capitis

  7. Sternocleidomastoid

  8. Iliocostalis

  9. External intercostals

  10. Internal oblique

  11. Spinalis

  12. Longissimus

  13. External oblique

Practical Applications

1. Botox Usage

  • Definition: Botox is an injection of botulinum toxin, often used to reduce the appearance of wrinkles and frown lines.

  • Application: Typically injected into muscles such as those causing forehead, eye, and mouth lines to prevent muscle contraction.

  • Candidate Muscles for Botox:

    • Orbicularis oris

    • (Mention others in class)

2. Impingement Syndrome in Athletes

  • Condition: Occurs in individuals frequently lifting their arms above shoulder height (e.g., throwers).

  • Shoulder Muscles Involved in Abduction:

    • Primarily responsible: Supraspinatus (most affected in impingement due to bony anatomy of shoulder joint).

3. Breathing Issues in Asthma

  • Context: Emma is struggling to breathe during an asthma attack, affecting inhalation.

  • Muscles Enabling Increased Thoracic Cavity Volume:

    • External intercostals

    • (Include other accessory muscles involved)

Structure and Function of Skeletal Muscle Fibers

Pre-Lab Assignment 10

Key Definitions

  1. Actin: Contractile protein that makes up the thin filaments.

  2. Myofibril: Cylindrical organelle composed of myofilaments, found within the sarcoplasm of muscle cells.

  3. Myosin: Contractile protein constituting thick filaments.

  4. Sarcomere: Functional unit of muscle contraction.

  5. Sarcolemma: Plasma membrane encompassing a muscle cell.

  6. Sarcoplasm: Cytoplasm of a muscle cell.

  7. Sarcoplasmic Reticulum (SR): A modified smooth endoplasmic reticulum surrounding each myofibril, storing Ca2.

  8. Terminal Cisternae: Enlargements of the SR adjacent to the transverse tubules.

  9. Transverse (T) Tubule: Formed by the invagination of the sarcolemma.

  10. Triad: The structure consisting of one T-tubule and two terminal cisternae.

Types of Muscle Tissue

Muscle Tissue Comparison Table

Type of Muscle Tissue

Structure

Location

Voluntary/Involuntary

Function

Skeletal

Long, cylindrical striated muscle fibers; multiple nuclei

Mostly attached to skeleton

Voluntary

Produces movement of body

Cardiac

Short, wide, branching striated muscle cells with intercalated discs; single nucleus or two nuclei

Heart

Involuntary

Produces beating of the heart

Smooth

Thin, spindle-shaped muscle cells with gap junctions; single nucleus

Walls of hollow organs, skin, eyes

Involuntary

Changes diameter of hollow organs; causes hair to stand erect; adjusts the lens and pupil size of the eye

Additional Muscle Labeling Activities

Muscle Labeling Tasks

  • 1. Frontalis (epicranius, frontal belly)

  • 2. Zygomaticus

  • 3. Depressor anguli oris

  • 4. Mentalis

  • 5. Omohyoid

  • 6. Orbicularis oculi

  • 7. Orbicularis oris

  • 8. Depressor labii inferioris

  • 9. Sternohyoid

  • 1. Iliopsoas (psoas major)

  • 2. Tensor fasciae latae

  • 3. Sartorius

  • 4. Adductor magnus

  • 5. Rectus femoris

  • 6. Vastus lateralis

  • 7. Vastus medialis

  • 8. Tibialis anterior

  • 9. Extensor digitorum longus

  • 10. Gluteus maximus

  • 11. Biceps femoris

  • 12. Semitendinosus

  • 13. Gracilis

  • 14. Gastrocnemius

  • 15. Calcaneal tendon (covering soleus)

Group Activity Instructions

  • Split into teams of 4.

  • Add labels to the models using the reference image shown in the slides.

  • Take a picture of the completed labels.

  • Email the picture with the following details:

    • Subject: Lab 9Muscular systemIn class activity

    • Student names: (List names)

    • Email to: hanandhi@kean.edu