Power Point Lecture Slides prepared by Barbara Heard

The Muscular System • Muscle tissue – all contractile tissues – Skeletal, cardiac, smooth muscle • Focus on skeletal muscle – How muscles interact to movement – Criteria for naming muscles – Principles of leverage © 2013 Pearson Education, Inc.

Actions and Interactions of Skeletal Muscles • Muscles can only pull; never push •

Actions and Interactions of Skeletal Muscles • Functional Groups – Prime mover (agonist) • Major responsibility for producing specific movement – Antagonist • Opposes or reverses particular movement – Prime mover and antagonist on opposite sides of joint across which they act © 2013 Pearson Education, Inc.

Figure 10. 1 The action of a muscle can be inferred by the position of the muscle relative to the joint it crosses. (Examples given relate to the shoulder joint. ) A muscle that crosses on the anterior side of a joint produces flexion* Example: Pectoralis major (anterior view) A muscle that crosses on the posterior side of a joint produces extension* Example: Latissimus dorsi (posterior view) The latissimus dorsi is the antagonist of the pectoralis major. A muscle that crosses on the lateral side of a joint produces abduction Example: Deltoid middle fibers (anterolateral view). A muscle that crosses on the medial side of a joint produces adduction Example: Teres major (posterolateral view) The teres major is the antagonist of the deltoid. *These generalities do not apply to the knee and ankle because the lower limb is rotated during development. The muscles that cross these joints posteriorly produce flexion, and those that cross anteriorly produce extension. © 2013 Pearson Education, Inc.

Skeletal Muscles: Functional Groups • Same muscle may be – Prime mover of one

Naming Skeletal Muscles • Muscle location—bone or body region with which muscle associated • Muscle shape—e. g. , deltoid muscle (deltoid = triangle) • Muscle size—e. g. , maximus (largest), minimus (smallest), longus (long) • Direction of muscle fibers or fascicles—e. g. , rectus (fibers run straight), transversus (fibers run at right angles), and oblique (fibers run at angles to imaginary defined axis) © 2013 Pearson Education, Inc.

Naming Skeletal Muscles • Number of origins—e. g. , biceps (2 origins) and triceps (3 origins) • Location of attachments—named according to point of origin and insertion (origin named first) • Muscle action—named for action they produce, e. g. , flexor or extensor • Several criteria can be combined, e. g. , extensor carpi radialis longus © 2013 Pearson Education, Inc.

Figure 10. 5 Superficial muscles of the body: Anterior view. Facial Epicranius, frontal belly Head Temporalis Masseter Shoulder Trapezius Deltoid Arm Triceps brachii Brachialis Forearm Pronator teres Brachioradialis Flexor carpi radialis Palmaris longus Pelvis/thigh Iliopsoas Pectineus Thigh Rectus femoris Vastus lateralis Vastus medialis Leg Fibularis longus Extensor digitorum longus Tibialis anterior © 2013 Pearson Education, Inc. Orbicularis oculi Zygomaticus Orbicularis oris Neck Platysma Sternohyoid Sternocleidomastoid Thorax Pectoralis minor Pectoralis major Serratus anterior Intercostals Abdomen Rectus abdominis External oblique Internal oblique Transversus abdominis Thigh Tensor fasciae latae Sartorius Adductor longus Gracilis Leg Gastrocnemius Soleus

Figure 10. 6 Superficial muscles of the body: Posterior view. Arm Triceps brachii Brachialis Forearm Brachioradialis Extensor carpi radialis longus Flexor carpi ulnaris Extensor digitorum Extensor carpi ulnaris Iliotibial tract Leg Gastrocnemius Soleus Fibularis longus Calcaneal (Achilles) tendon © 2013 Pearson Education, Inc. Neck Epicranius, occipital belly Sternocleidomastoid Trapezius Shoulder Deltoid Infraspinatus Teres major Rhomboid major Latissimus dorsi Hip Gluteus medius Gluteus maximus Thigh Adductor magnus Hamstrings: Biceps femoris Semitendinosus Semimembranosus

Muscles of the Head • Two groups – Muscles of facial expression – Muscles

Muscles of Mastication • Four pairs involved in mastication; all innervated by cranial nerve V (trigeminal nerve) – Prime movers of jaw closure • Temporalis and masseter – Grinding movements • Medial and lateral pterygoids – Chewing role - holds food between teeth • Buccinator © 2013 Pearson Education, Inc.

Figure 10. 8 a Muscles promoting mastication and tongue movements. Temporalis Orbicularis oris Buccinator

Figure 10. 8 b Muscles promoting mastication and tongue movements. Lateral pterygoid Medial pterygoid

Muscles of the Anterior Neck and Throat • Two groups – Suprahyoid muscles –

Muscles of the Neck and Vertebral Column • Two functional groups – Muscles that

Muscles of the Neck and Vertebral Column: Head Movement • Sternocleidomastoid—major head flexor – Suprahyoid and infrahyoid—synergists to head flexion • Sternocleidomastoid and scalenes— lateral head movements • Splenius capitis and cervicis portions head extension, rotation, and lateral bending • Semispinalis capitis—synergist with sternocleidomastoid © 2013 Pearson Education, Inc.

Figure 10. 10 a Muscles of the neck and vertebral column that move the head and trunk. 1 st cervical vertebra Sternocleidomastoid Base of occipital bone Mastoid process Middle scalene Anterior scalene Posterior scalene Anterior © 2013 Pearson Education, Inc.

Figure 10. 10 c Muscles of the neck and vertebral column that move the head and trunk. Platysma (cut) Sternocleidomastoid (cut) Internal jugular vein Omohyoid Sternothyroid Sternocleidomastoid Pectoralis major © 2013 Pearson Education, Inc.

Muscles of the Neck and Vertebral Column: Trunk Extension • Deep (intrinsic) back muscles – Erector spinae (sacrospinalis) group—prime movers of back extension and lateral bending • Iliocostalis • Longissimus • Spinalis – Semispinalis and quadratus lumborum— synergists in extension and rotation © 2013 Pearson Education, Inc.

Figure 10. 10 d Muscles of the neck and vertebral column that move the head and trunk. Mastoid process of temporal bone Longissimus capitis Iliocostalis cervicis Longissimus cervicis Iliocostalis thoracis Ligamentum nuchae Semispinalis capitis Semispinalis cervicis Semispinalis thoracis Longissimus thoracis Spinalis thoracis Iliocostalis Erector Longissimus spinae Spinalis Iliocostalis lumborum External oblique © 2013 Pearson Education, Inc. Multifidus Quadratus lumborum

Deep Muscles of the Thorax: Breathing • Muscles of respiration • External intercostals—more superficial muscles; elevate ribs for inspiration • Internal intercostals—deeper muscles; aid forced expiration • Diaphragm – Partition between thoracic and abdominal cavities – Most important muscle in inspiration – Innervated by phrenic nerves © 2013 Pearson Education, Inc.

Figure 10. 11 a Muscles of respiration. External intercostal Internal intercostal © 2013 Pearson

Figure 10. 11 b Muscles of respiration. Xiphoid process of sternum Foramen for inferior vena cava Foramen for esophagus Costal cartilage Central tendon of diaphragm Foramen for aorta 12 th rib Diaphragm Lumbar vertebra Quadratus lumborum Psoas major © 2013 Pearson Education, Inc.

Figure 10. 11 c Muscles of respiration. Central tendon of diaphragm Body of thoracic vertebra Aorta Diaphragm (muscular part) Inferior vena cava Esophagus Pericardial sac © 2013 Pearson Education, Inc. Pericardium (cut)

Muscles of the Abdominal Wall • Four paired muscles, their fasciae and aponeuroses form lateral and anterior abdominal wall – Rectus abdominis – External obliques – Internal obliques – Transversus abdominis © 2013 Pearson Education, Inc.

Figure 10. 12 a Muscles of the abdominal wall. Pectoralis major Serratus anterior Linea alba Tendinous intersection Transversus abdominis Rectus abdominis Internal oblique External oblique Aponeurosis of the external oblique © 2013 Pearson Education, Inc. Inguinal ligament (formed by free inferior border of the external oblique aponeurosis)

Muscles of the Abdominal Wall • run at angles to one another, provide added strength • All innervated by intercostal nerves • Actions of these muscles – Lateral flexion and rotation of trunk – Help promote urination, defecation, childbirth, vomiting, coughing, and screaming © 2013 Pearson Education, Inc.

Figure 10. 12 b Muscles of the abdominal wall. External oblique Iliac crest Rectus abdominis Internal oblique Pubic tubercle © 2013 Pearson Education, Inc. Lumbar fascia Transversus abdominis Inguinal ligament Lumbar fascia

Figure 10. 12 c Muscles of the abdominal wall. Transversus abdominis External oblique Aponeuroses

Superficial Muscles of the Thorax • Most - extrinsic shoulder muscles – Act in combination to fix shoulder girdle (mostly scapula); move it to increase range of arm movements – Actions - elevation, depression, rotation, lateral and medial movements, protraction, and retraction • Two groups of muscles: anterior and posterior PLAY A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (a) PLAY A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (b) © 2013 Pearson Education, Inc.

Superficial Muscles of the Thorax • Muscles of anterior thorax – Pectoralis minor – Serratus anterior – Subclavius PLAY A&P Flix™: Muscles of the pectoral girdle (a) PLAY A&P Flix™: Muscles of the pectoral girdle (b) © 2013 Pearson Education, Inc.

Figure 10. 14 a Superficial muscles of the thorax and shoulder acting on the scapula and arm. Sternocleidomastoid Subclavius Clavicle Subscapularis Deltoid Pectoralis minor Pectoralis major Sternum Serratus anterior Biceps brachii PLAY Coracobrachialis Humerus A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (b) © 2013 Pearson Education, Inc.

Superficial Muscles of the Posterior Thorax • Posterior extrinsic shoulder muscles – Trapezius – Levator scapulae – Rhomboids (major and minor) PLAY A&P Flix™: Muscles of the pectoral girdle (c) PLAY A&P Flix™: Movement of the pectoral girdle © 2013 Pearson Education, Inc.

Figure 10. 14 c Superficial muscles of the thorax and shoulder acting on the scapula and arm. Levator scapulae Trapezius Supraspinatus Clavicle Deltoid Rhomboid minor Rhomboid major Spine of scapula Infraspinatus Teres minor Teres major Humerus Latissimus dorsi © 2013 Pearson Education, Inc.