Exploring the Anatomy and Function of Skeletal Muscles

Lab Activity #9 © Cory Lindsay 2022 1 The muscular system consists of an estimated 650 skeletal muscles. These skeletal muscles connect with bones and joints to enable movement of body parts—both basic movements and more complex ones. In this lab, you will first focus on the organization of the muscular system and the microanatomy of skeletal muscle. Attention towards the structure of the muscle sarcomere is provided. Although you aren’t responsible for learning all 650 muscles, you will locate and identify numerous superficial muscles and muscle groups on models and specimens in lab. This lab also emphasizes the attachment sites of muscles, explaining how larger muscles with many muscle fiber groups insert into bones from different angles to enable different actions. The importance of fascia and how it relates to muscle origins and insertions is also explored. This lab employs various muscle models, dissected cat specimens and full use of Complete Anatomy. Skeletal muscle organization 1. Identify four (4) distinct ways that skeletal muscles can be classified in the human body and explain the basis of each classification scheme. 2. Define the following terms as they relate to skeletal system anatomy and function: a. Origin — b. Insertion — c. Action — 3. Compare and contrast the relationship between an agonist , antagonist and synergist . Lab objectives: 1. Explain the classifications of skeletal muscles in the body 2. Describe the microanatomy of skeletal muscle 3. Locate/identify and understand the function of major groups of skeletal muscles 4. Locate/identify major skeletal muscle groups on dissected cat specimens and compare to human muscle anatomy

Lab Activity #9 © Cory Lindsay 2022 2 Complete the table below and (1) describe the arrangement of muscles fascicles for each type, and (2) provide specific skeletal muscle examples. Description Examples Fusiform Parallel Triangular Unipennate Bipennate Multipennate Circular Myofibril and sarcomere anatomy After watching the video, answer the following questions/statements below regarding the structure of skeletal muscle. 4. What is the region that lacks thin filaments called? 5. What defines the boundaries of one sarcomere? 6. What is the smallest unit of skeletal muscle organization? 7. The region of the sarcomere where thick and thin filaments overlap is called the _______________. 8. What is the region that surrounds the M-line of a sarcomere? 9. Thin filaments are comprised of ______________. Sarcomere

Lab Activity #9 © Cory Lindsay 2022 3 Muscles of facial expression Answer the following questions/statements below regarding facial muscle anatomy and function. 10. What is special about the insertion of some facial muscles that makes them unique compared to other skeletal muscles? 11. Describe the location of the buccinator on the face in context with other facial muscles. 12. Identify five (5) distinct actions that are produced by facial muscles using the mouth/lips. 13. What muscle serves as the agonist to for elevation of the eyebrow? 14. Describe the importance of the galea aponeurotica . 15. Describe the location of the corrugator supercilii on the face in context with other facial muscles. 16. The FDA approved Botox cosmetic only for the treatment of frown lines between the eyebrows. Identify some of the muscles into which a physician would likely inject Botox treatment. Muscles of mastication 17. Identify and describe the two (2) basic actions that constitute mastication . 18. Describe the action of mandible excursion in your own words. 19. Identify the landmarks on the mandible that serve as insertion points for muscles that enable mastication movements.

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Lab Activity #9 © Cory Lindsay 2022 4 Muscles that move the head 20. Describe the location on the body where muscles that flex the head are found and provide an explanation for why they are located there. 21. Describe the location on the body where muscles that flex the head are found and provide an explanation for why they are located there. 22. Besides flexion, what other movement of the head does the sternocleidomastoid accommodate? 23. Describe the location of the splenius capitis in context with other major neck muscles. Muscles that move the scapula Answer the following statements below using the word bank to the right. Each answer can only be used once. 24. A muscle whose primary action is to adduct the scapula. 25. A muscle that inserts on the coracoid process. 26. A muscle that moves the clavicle as well as the scapula. 27. A muscle found superior to the rhomboid minor. 28. A muscle with an origin only on the thoracic vertebra. 29. A muscle that protracts the scapula. Word Bank Trapezius Serratus anterior Pectoralis minor Rhomboid major Rhomboid minor Levator scapulae

Lab Activity #9 © Cory Lindsay 2022 5 30. Watch the video and then describe the contrasting actions of the superior (descending), transverse and inferior (ascending) muscle fibers of the trapezius . Muscles that move the humerus 31. Watch the video and then describe the contrasting actions of the anterior, middle and posterior muscle fibers of the deltoid . 32. What muscle action does the deltoid not produce on the humerus? 33. What muscles form the rotator cuff ? Why is the teres major not a part of the rotator cuff? 34. What is the only rotator cuff muscle found on the anterior aspect of the scapula? 35. What common insertion(s) do rotator cuff muscles share versus other muscles that move the humerus? 36. Besides enabling movement, what other function do rotator cuff muscles provide for the shoulder joint? Trapezius Deltoid

Lab Activity #9 © Cory Lindsay 2022 6 37. Radial mastectomy, once a common treatment for breast cancer, involved removal of the pectoralis major along with the breast. What functional impairments would result from this? What synergists could a physical therapist train a patient to use to replace the function of the pectoralis major? Muscles that move the forearm, wrist and hand 38. Describe the features (including common muscle origin/insertion or action) of the following muscle groups located in the forearm and provide specific examples of individual muscles found in each compartment: a. Anterior compartment — b. Posterior compartment — c. Medial compartment — d. Lateral compartment — 39. Describe the importance of the flexor retinaculum and extensor retinaculum in the forearm. 40. Which forearm muscle is absent in approximately 20% of the human population? Why? Muscles that move the thigh, lower leg and feet 41. Describe the features (including common muscle origin/insertion or action) of the following muscle groups located in the thigh and provide specific examples of individual muscles found in each compartment: a. Anterior compartment — b. Posterior compartment —

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Lab Activity #9 © Cory Lindsay 2022 7 c. Medial compartment — d. Lateral compartment — 42. Which thigh muscle is necessary for enabling “crossing of the leg” while sitting? 43. Identify the muscles that comprise the anterior lower leg compartment . Describe the actions these muscles permit with the foot. 44. Identify the muscles that comprise the posterior lower leg compartment . Describe the actions these muscles permit with the foot. Skeletal muscle fiber/sarcomere model (Complete Anatomy) Sarcoplasmic reticulum Transverse tubule (T- tubule) Terminal cisterna Triad Endomysium Nucleus Sarcomere Mitochondria H-zone Thin filaments Thick filaments I-band A-band Appendix I: Skeletal muscle & associated structures lab practical checklist

Lab Activity #9 © Cory Lindsay 2022 8 Muscles of facial expression (and associated structures) Corrugator supercilii Orbicularis oculi Depressor anguli oris Orbicularis oris Frontalis Galea aponeurotica Buccinator Risorius Mentalis Zygomaticus major Levator palpebra superioris Platysma Muscles of mastication Masseter Medial pterygoid Temporalis Lateral pterygoid Digastric Omohyoid Mylohyoid Sternohyoid Muscles that move the head Sternocleidomastoid Splenius capitis Muscles that move the shoulder (scapula) Levator scapulae Rhomboid major Pectoralis minor Rhomboid minor Pectoralis minor Trapezius Serratus anterior Muscles that move the arm (humerus) Teres minor Subscapularis Supraspinatus Infraspinatus Deltoid Latissimus dorsi Pectoralis major Teres major Muscles that move the forearm (radius and/or ulna) Brachialis Coracobrachialis Biceps brachii Brachioradialis Triceps brachii Muscles moving the wrist, hand and fingers (and associated structures) Extensor carpi radialis longus Extensor digitorum Flexor carpi ulnaris Palmaris longus Flexor digitorum superficialis Extensor carpi ulnaris Extensor retinaculum Flexor carpi radialis Flexor retinaculum

Lab Activity #9 © Cory Lindsay 2022 9 Palmar aponeurosis Pronator teres Supinator Abductor pollicis brevis Flexor pollicis brevis Adductor pollicis brevis Muscles acting on the abdominal wall (and associated structures) Rectus abdominis Internal oblique External oblique Transversus abdominis Tendinous inscriptions Abdominal aponeurosis Thoracolumbar fascia Muscles that move the thigh (femur) and/or leg (tibia/fibula) Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius Semimembranosus Semitendinosus Biceps femoris Psoas major Illiacus Gluteus maximus Gluteus medius Adductor longus Adductor magnus Gracilis Sartorius Tensor fascia latae Illiotibial tract Illiopsoas Piriformis Muscles that move the foot and toes (and associated structures) Tibialis anterior Extensor digitorum longus Gastrocnemius Flexor hallicus longus Soleus Extensor hallicus longus Fibularis longus Achilles/Calcaneal tendon Extensor retinaculum Plantar aponeurosis Flexor retinaculum Flexor digitorum longus Muscles of the anterior neck and face Sternocleidomastoid Masseter Mylohyoid Digastric Sternohyoid Muscles/structures of the anterior thorax Pectoantebrachialis Linea alba Pectoralis minor Xiphihumeralis Pectoralis major Appendix II: Cat skeletal muscle & associated structures lab practical checklist

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Lab Activity #9 © Cory Lindsay 2022 10 Muscles of the anterior abdomen Rectus abdominus External oblique Internal oblique Transversus abdominus Superficial muscles of the back and shoulders Clavotrapezius Acromiotrapezius Spinotrapezius Latissimus dorsi Serratus anterior Levator scapulae ventralis Clavodeltoid (clavobrachialis) Acromiodeltoid Spinodeltoid Forelimb muscles (anterior compartment) Flexor carpi ulnaris Flexor carpi radialis Biceps brachii Palmaris longus Brachioradialis Brachialis Forelimb muscles (posterior compartment) Triceps brachii Extensor digitorum lateralis Extensor carpi radialis longus Extensor carpi ulnaris Extensor digitorum communis Hindlimb muscles (anterior compartment) Gracilis (superficial) Vastus medialis (deep) Vastus lateralis (deep) Sartorius (superficial) Hindlimb muscles (posterior compartment) Biceps femoris Semimembranosus Semitendinosus Gastrocnemius (superficial) Soleus (deep)

Lab Activity #9 © Cory Lindsay 2022 11 Appendix III: Cat skeletal muscle atlas Face and neck. (A) masseter, (B) sternomastoid, (C) digastric, (D) mylohyoid, (E) sternohyoid. Anterior thorax and abdomen. (A) xiphihumeralis, (B) pectoralis minor, (C) pectoralis major, (D) pectoantebrachialis, (E) latissimus dorsi, (F) external oblique, (G) serratus anterior.

Lab Activity #9 © Cory Lindsay 2022 12 Back and shoulders. (A) clavo - trapezius, (B) acromiotrapezius, (C) spinotrapezius, (D) latissimus dorsi, (E) clavodeltoid, (F) acromio- deltoid, (G) spinodeltoid, (H) levator scapulae ventralis, (I) triceps brachii long head, (J) triceps brachii lateral head Anterior forelimb (top) and posterior forelimb (bottom). (A) palmaris longus, (B) flexor carpi radilias, (C) extensor carpi ulnaris, (D) extensor digitorum lateralis, (E) extensor digitorum communis, (F) extensor carpi radialis longus, (G) brachioradialis, (H) triceps brachii lateral head, (I) brachialis.

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Lab Activity #9 © Cory Lindsay 2022 13 Abdomen. (A) xiphihumeralis, (B) external oblique, (C) internal oblique, (D) transversus abdominus, (E) linea alba, (F) abdominal aponeurosis, (G) rectus abdominus. Posterior hindlimb (left) and anterior hindlimb (right). (A) biceps femoris, (B) semitendinosus, (C) semimembranosus, (D) gastrocnemius, (E) soleus, (F) calcaneal tendon, (G) sartorius, (H) gracilis.

Lab Activity #9

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