Lectures 12-14 Muscular System 10-1
Properties of Muscle Ability of a muscle to shorten with force Capacity of muscle to respond to a stimulus Muscle can be stretched to its normal resting length and beyond to a limited degree Ability of muscle to recoil to original resting length after stretched 9-2
General Principles of Muscles Tendons: Attach muscles to bones : A very broad tendon Muscles Attachment sites: Belly: Largest portion of the muscle between origin and insertion Agonist (prime mover): Muscle causing an action when it contracts Antagonist: A muscle working in opposition to agonist Synergists: Muscles that work together to cause a movement : Stabilize joint/s crossed by the prime mover 9-3
Muscle Shapes Table 10.5 9-4
Muscle Shapes Table 10.5 9-5
Example - extensor carpi radialis longus Fig. 10.14 9-6
Points to Remember Skeletal muscles have many shapes and in each instance contraction of the muscle tissue causes body movements through their attachments to the skeleton or beneath the skin. Understanding the meaning of the parts of a muscle name helps one to learn the muscle. 9-7
Axial Muscles 10-8
Muscles of the Neck Superficial Deep Deep Deeper Mylohyoid Digastric Anterior belly Semispinalis capitis Sternocleidomastoid Geniohyoid Posterior belly Hyoid bone Semispinalis capitis (cut) Splenius capitis Splenius capitis (cut) Sternocleidomastoid Levator scapulae Trapezius Fig. 11.10 Clavicle Fig. 11.8 Anterolateral Neck Muscles One or both may contract Posterior Neck Muscles Semispinalis capitis, Splenius capitis, 10-9
Muscles of Facial Expression Superficial Deep Frontal belly of occipitofrontalis Orbicularis oculi Levator labii superioris Zygomaticus Depressor labii inferioris Platysma Elevators, Occipitofrontalis, Zygomaticus Depressors Depressor labii inferioris, Masseter Buccinator Orbicularis oris Temporalis Depressor labii inferioris Platysma Orbicularis oculi Levator labii superioris Zygomaticus Orbicularis oris Fig. 11.2 Other actions, Orbicularis oculi, 10-10
Muscles of Facial Expression 10-11
Muscles of Facial Expression Fig. 11.3 10-12
Muscles of Mastication Fig. 11.5 Major Muscles Temporalis and Masseter Temporalis: Superior- temporal lines of parietal Inferior- Masseter: Superior- Inferior- lateral side of mandible 10-13
Hyoid Muscles Superficial Deep Digastric Mylohyoid Anterior belly Posterior belly Mylohyoid Digastric Anterior belly Posterior belly Geniohyoid Hyoid bone Clavicle Fig. 11.8 Actions of hyoid muscles move mandible and hyoid 10-14
Trunk Muscles - Muscles of Vertebral Column Deep Deeper Semispinalis Erector spinae Iliocostalis Longissimus Spinalis Multifidus Fig. 11.11 Erector spinae: (Iliocostalis, Longissimus, Spinalis) Semispinalis ( ) Multifidus Interspinalis Actions: Extension, rotation, and of the back 10-15
Muscles of Respiration Inhalation: is primary muscle of inspiration (depresses floor of thoracic cavity) elevate ribs Fig. 11.13 Exhalation: depress ribs 10-16
Appendicular Muscles 10-17
Muscles That Move the Pectoral Girdle Fig. 12.4 Attachment sites - Elevation - levator scapulae, trapezius ( ), rhomboids Depression - trapezius ( ), pectoralis minor 10-18
Muscles That Move the Glenohumeral Joint/Arm Pectoralis major ( shoulder) and Latissimus dorsi ( shoulder) Fig. 12.4 10-19
Muscles of The Arm Fig. 12.5 Rotator cuff Supraspinatus, Infraspinatus, Teres minor, Subscapularis Deltoid of shoulder antagonist of Pectoralis major and Latissimus dorsi 10-20
Arm and Forearm Muscles Fig. 12.7 Flexors on anterior side of humerus Biceps brachii, Brachialis is a synergist in elbow flexion Fig. 12.8 Extensors on posterior side of humerus 10-21
Forearm Muscles Acting on Wrist and Hand Fig. 12.11 Pronation - Pronator teres Supination - Supinator & Flexors of wrist - Flexor carpi radialis & Flexor carpi ulnaris, 10-22
Forearm Muscles Acting on Wrist and Hand Fig. 12.13 Extensors of wrist - extensor carpi radialis & extensor carpi ulnaris, 10-23
Muscles of the Pelvic Girdle Gluteus maximus of the thigh Fig. 12.15 backswing of leg during walking lift of leg when climbing stairs generates most force when thigh is flexed to trunk at 10-24
Muscles of the Knee Joint/Leg Fig. 12.17 Iliopsoas of thigh Quadriceps femoris prime of knee attaches to tibial tuberosity Fig. 12.18 Adductors adductor of thigh thigh Hamstrings flex knee extends thigh with Gluteus maximus 10-25
Muscles of the Leg Fig. 12.21 Fig. 12.22 Gastrocnemius & Soleus attach to by calcaneal tendon foot 10-26
Points to Remember Muscles of the face move the skin rather than a joint allowing a vast range of facial expressions Muscles that move the mandible are also known as muscles of mastication because they provide the chewing action Complexity of muscles of the vertebral column required for flexibility and maintaining posture 10-27
Points to Remember Muscles that move the pectoral girdle also stabilize it Muscles that move the humerus originate from the scapula and axial skeleton Muscles of the forearm that act as flexors and extensors are organized into flexor (anterior) and extensor (posterior) groups Most muscles that move the femur originate from the pelvic girdle Muscles that move the femur and tibia and fibula are organized into extensor (anterior), flexor (posterior) and adductor (medial) groups 10-28
Questions? 10-29