Skeletal Muscle Anatomy PDF

Skeletal Muscle BIOL 201 – Human Anatomy Danny M. Pincivero, Ph.D. Department of Biology University of Waterloo 1  Muscle Structure and Function Skeletal muscle Approximately 50% of body weight. Function of muscle Physical movement, stabilit...

Skeletal Muscle BIOL 201 – Human Anatomy Danny M. Pincivero, Ph.D. Department of Biology University of Waterloo 1  Muscle Structure and Function Skeletal muscle Approximately 50% of body weight. Function of muscle Physical movement, stability, control of openings, heat production, and glycemic control. Speech Writing Stability…. Approximately…. 3 types…… 2  Muscle types Skeletal muscle Smooth muscle Cardiac muscle 3  Muscle properties 1) Contractility Ability to shorten and develop force. Measured mechanically. 2) Excitability Ability to respond to a stimulus. 3) Conductivity Ability to transmit 4) Elasticity Ability to elongate (stretch) 5) Adaptability Ability to change characteristics Stimuli: Training, de-training, immobilization 4 Muscle structure 5  Skeletal Muscle Attachment Muscle attachment is the location on the bone where the muscle connects. Origin…. Tends to be…... Insertion…. Connection is with the fibrous periosteum of the bone. Tubercles, trochanters & crests.Fig. 10.1 6  Naming Skeletal Muscles Several criteria are used in naming muscles. Location…..e.g.. Shape…..e.g.. Relative size…..e.g.. Direction of fascicles & fibres…..e.g.. Location of attachments…..e.g.. Number of origins…..e.g.. Actions……e.g.. 7  Muscular system Prime movers….. Antagonists…... Synergists Muscles with same effect…... Example: Elbow flexion…... Fixators – synergists that immobilize a bone or muscle’s origin. Naming skeletal muscles Number of origins – e.g., Location of attachments – named according to point of origin or insertion Action – e.g., flexor or extensor, as in the names of muscles that flex or extend, respectively. Typically muscles contract……. 8 Synergists and antagonists 9  Muscle mechanics (shapes) (a) (b) (g) (a) Circular (f) (b) Convergent (c) (e) (c) Parallel (d) (d) Unipennate (f) Fusiform (g) Multipennate (e) Bipennate 10  Muscles and movement Sagittal plane motions Flexion……. Elbow Wrist Shoulder Hip Ankle Trunk flexion 11  Muscles and movement Frontal plane motions Shoulder Shoulder Shoulder Hip Hip Abduction….. Adduction….. Shoulder elevation…. Shoulder depression….. 12  Muscles and movement Frontal plane motions Ankle Trunk Inversion…. Eversion…. 13  Muscles and movement Transverse plane motions Shoulder Hip Trunk rotation (right) 14  Muscles of the head Epicranius Galea aponeurotica Frontal belly Orbicularis oculi Occipital belly Temporalis Buccinator Masseter Sternocleidomastoid Orbicularis oris Trapezius Splenius capitis Platysma 15  Muscles of mastication Prime movers of jaw closure Masseter muscle Mandible elevation. Temporalis muscle Temporalis Orbicularis oris Masseter Buccinator 16 Muscles of mastication Lateral pterygoid Medial pterygoid Lateral pterygoid Medial pterygoid Masseter pulled away 17  Neck and vertebral column Sternocleidomastoid Middle scalene Anterior scalene Posterior scalene 18  Neck and vertebral column Splenius capitis Splenius cervicis 19  Neck and vertebral column Deep (intrinsic) back muscles Capitis….. Cervicis…... Thoracis….. Semispinalis Lumborum…. Longissimus capitis capitis Iliocostalis cervicis Semispinalis cervicis Longissimus cervicis Iliocostalis Semispinalis thoracis thoracis Longissimus thoracis Prime movers Spinalis thoracis Iliocostalis Erector Longissimus spinae Spinalis Multifidus Iliocostalis lumborum Quadratus lumborum 20 Anterior abdominal wall muscles Superficial 21  Anterior abdominal wall muscles Rectus abdominis Trunk flexion……. Extends from……. Enclosed by rectus sheath. Three transverse tendinous intersections…….. External abdominal oblique External layer of lateral abdominal muscle Supports viscera, unilateral contraction causes contralateral rotation of waist 22  Anterior abdominal wall muscles Internal abdominal oblique Intermediate layer. Unilateral contraction…... Aponeuroses Tendons of oblique and transverse muscles. Broad, fibrous sheets. Transverse abdominal Deepest of lateral with horizontal fibers. Compresses Contributes to movements of vertebral column. 23  Anterior abdominal wall muscles Deep 24 Muscles of the shoulder girdle Subscapularis 25  Thorax/shoulder muscles Trapezius Supraspinatus Infraspinatus Teres minor Teres major 26  Thorax/shoulder muscles Deltoid Clavicle Pectoralis major Biceps brachii Brachialis Triceps brachii: Lateral head Long head Brachioradialis Medial head 27 Thorax/shoulder muscles Rotator cuff muscles S…. Spine of scapula I….. T….. S….. Teres major Triceps brachii Anconeus Latissimus dorsi Olecranon process of ulna 28  Muscles of the forearm (anterior) Flexor-pronator muscle group (lateral to medial) Deep muscles Extensor carpi radialis longus Brachioradialis Biceps brachii 29  Muscles crossing hip and knee joints Iliopsoas Iliac crest TFL…... Hip adductors Anterior superior iliac spine Tendon of quadriceps femoris Knee extensors Patella Patellar ligament 31  Muscles crossing hip and knee joints Iliopsoas Iliac crest TFL…... Hip adductors Anterior superior iliac spine Tendon of quadriceps femoris Knee extensors Patella Patellar ligament 31 Muscles crossing hip and knee joints Gluteus medius Gluteus maximus Hamstring group Origin…... Adductor magnus Insertion……. Gracilis Bi-articulate group…... Iliotibial tract Long head Hip extension/knee flexion. Short head 32  Lower leg muscles Anterior compartment Fibularis longus Gastrocnemius Tibia Superior and inferior extensor retinacula Soleus Superior and inferior extensor retinacula 33  Lower leg muscles Lateral compartment Head of fibula Gastrocnemius Soleus Extensor digitorum longus Tibialis anterior Extensor hallucis longus Lateral malleolus 34  Lower leg muscles Posterior compartment Superficial Deep Medial malleolus Lateral malleolus Calcaneus 35  Lower leg muscles Posterior compartment Plantar flexion and toe flexion. Superficial Gastrocnemius Deep Soleus Plantaris Popliteus Tibialis posterior Flexor digitorum longus Flexor hallucis longus Tendon of tibialis posterior Medial malleolus Calcaneus 36 Intrinsic foot muscles Four ventral muscle layers: 37