Chapter 10—The Muscular System

Ch. 10 Muscular system-- Study Guide Critically read Chapter 10 pp. 320-327. Also read Tables 10.4 and 10.5 (pp. 339-343) Comprehend Terminology (those in bold in the textbook) within the reading scope above Study-- Figure questions, Think About It questions, and Before You Go On (section-ending) questions (within the reading scope above) . Before You Go On Questions 1-6 (on p. 325) and Questions 11-12 (on p. 349). Do end-of-chapter questions— Testing Your Recall— 2, 11-13, 17-20 True or False– 1 10-2 2 2

I. Introduction & connective tissues of a muscle

§ Introduction of Muscles 600 Human skeletal muscles The study of muscles– M___________

§ The Functions of Muscles Movement of body parts and body contents– Examples Maintain posture and prevent unwanted movement— resist the gravity etc. Communication – Control of openings and passageways– Examples-- eyelids, __________________ Heat production– 85% of our body heat is from skeletal muscle contraction

§ Connective Tissues of a Muscle 5. Tendon 4. Deep fascia 3. Epimysium 2. Perimysium Muscle fascicle 1. Endomysium Muscle fiber

Connective Tissues of a Muscle Endomysium thin areolar tissue around each muscle fiber allows room for ____________________ Perimysium slightly thicker layer of connective tissue surrounds bundle of cells called a fascicle Epimysium covers whole muscle belly blends into CT sheets called fascia (next slide)

Location of Fascia Deep Fascia Femur Skin Deep fascia found between adjacent muscles; no fat Superficial fascia (adipose tissue; hypodermis) between skin and muscles Superficial Fascia Deep Fascia Femur Skin

§ Ways of Muscle Attachments To bone directly-- epimysium is continuous with periosteum of a bone Ex.– intercostal muscles To bone indirectly-- epimysium continues as tendon that merges into periosteum Ex.-- many including biceps brachii to scapula To fascia or tendon of another muscle-- To collagen fibers (dermis)-- Ex.--muscles for facial expression To a broad sheetlike tendon, aponeurosis-- Ex.--certain abdominal muscles (Fig. 10.15)

II. General anatomy of skeletal muscles and classification of muscles

§ Anatomy of Skeletal Muscles Origin— stationary end of a muscle when contracts Belly-- thicker, middle region of muscle Insertion— mobile end of muscle Detail fig. next slide Biceps brachii

§ Muscle types based on fascicle direction-1

Skeletal Muscle types —based on fascicle direction-2 Fusiform muscles Features: biceps brachii m., gastrocnemius of the calf Parallel muscles; long, uniform width, having parallel fascicles rectus abdominis m., sartorius of the thigh, zygomaticus major Convergent muscle; fan-shaped, broad at origin and tapering to a narrower insertion pectoralis major of the chest Fig. 10.15

Skeletal Muscle type—based on fascicle direction-3 Pennate muscles (feather-shaped) fascicles insert obliquely on a tendon, like the shaft of the feather Unipennate—fascicles approach the tendon from one side; palmar interosseus (hand) (Fig.) Bipennate—fascicles approach the tendon from both sides; rectus femoris (thigh) (Fig.) Multipennate--like feathers with their quills on a single point; deltoid (shoulder) (Fig.) Circular muscles (sphincters) Features: orbicularis oculi (eyelids), orbicularis oris, urethral and anal sphincters 10-17

Figure 10.29c

Fig. 10.35a

Fig. 10.22a

III. Action of muscle groups and muscle innervation

§ 4 categories of muscles based on actions Action— movement produced by a muscle Prime mover or agonist produces . . . Example: in flexing the elbow, the prime mover is the brachialis Synergist aids the prime mover May stabilize the nearby joint Or modify the direction of movement Example: works with brachialis, biceps brachii as a synergist to flex the elbow * In some textbooks 1 and 2 are opposite.

§ 4 categories of muscles based on actions Antagonist is a muscle that . . . opposes the _____________ Moderates the speed or range of the agonist; preventing excessive movement and injury Example: Triceps brachii Fixator is a muscle that . . . prevents _______________ Elbow flexion– the rhomboids holds the scapula in place (Fig. 10.17) 10-23

In-class activity Question--Muscle Actions during Elbow Flexion ID which specific muscle of the upper arm is responsible for the above action. (based on the text) Prime mover (agonist) = ? Synergist = ? Antagonist = ? Fixator = ?

§ Skeletal Muscle Innervation Cranial nerves arising from the brain exit the skull through foramina numbered I to XII (Fig. 14.27) Innervate muscles of the ______________ Spinal nerves arising from the spinal cord Muscles elsewhere are supplied by these nerves From spinal cord and exit the vertebral column through intervertebral foramina (Fig. 13.1, 8.23b)

Oh Olfactory (I) Once Optic (II) One Oculomotor (III) Takes Trochlear (IV) The Trigeminal (V) Anatomy Abducens (VI) Final Facial (VII) Very Vestibulocochlear (VIII) Good Glossopharyngeal (IX) Vacations Vagus (X) Are Accessory (XI) Heavenly Hypoglossal (XII)

Figure 13.1b; posterior view

Figure 8.23b

§ How Muscles are Named Terminologia Anatomica system of Latin names developed in 1895 updated since then English names for muscles are slight modifications of the Latin names. Table 10.1 = terms used to name muscles; Examples: Major = large (Criteria: ____); pectoralis major Deltoid = triangular (Criteria: _____); Deltoid Quadriceps = having 4 heads; quadriceps femoris etc.

§ Learning Strategy (start with Fig. 10.4a and b) Explore the location, origin, insertion and innervation of 160 skeletal muscles use tabular information in this chapter. Increase your retention examining models and atlases palpating yourself (atlas B) observe an articulated skeleton say the names aloud and check your pronunciation

Quadriceps femoris

IV. Muscles involved in respiration

§ Muscles of Respiration Breathing requires the use of muscles Diaphragm (prime mover of inspiration) external intercostal muscles internal intercostal muscles Contraction of first 2 produces inspiration Expiration-- ?? Contraction of last produces-- forced expiration Normal expiration requires little muscular activity

1. Muscles of Respiration- Diaphragm Muscular dome between thoracic and abdominal cavities Muscle fascicles converge from the margins (Origin) toward a fibrous central tendon (Insertion) Contraction flattens it Increases/decreases the vertical dimension of the thorax Central tendon

2. External/internal Intercostals External intercostals O- inferior margin of rib above; I- superior border of next lower rib extend downward and anteriorly from rib to rib pull ribcage up/down (when contract) Internal intercostals O- and I- opposite of that in external intercostals extend upward and anteriorly from rib to rib pull ribcage downward/upward (during forced expiration)

3. Breathing-a mechanical step Mechanism of normal quiet inspiration (expiration are opposite)— Diaphragm contracts and move downward External intercostals muscles contract  the ribs elevated  Chest volume:  intra-alveolar pressure:  Air flows inward; why? Deeper inspiration, 2 neck muscles are involved

Inspiration Contraction of external intercostal muscles Contraction Elevation of ribs & sternum Increase side-to-side and front-to-back dimensions of thoracic cavity (X & Y axes) External intercostal muscles (relaxed) Contraction of external intercostal muscles Elevated rib cage Sternum Contraction of diaphragm Diaphragm (relaxed) vertical (Z axis) dimension increases in thoracic cavity Before inspiration Inspiration Contractions of external intercostal muscles causes elevation of ribs, which increases side-to-side dimension of thoracic cavity

Size of thorax  on contraction of inspiratory muscles 760 Size of thorax  on contraction of inspiratory muscles Size of lungs  as they are stretched to fill the expanded thorax 759 mm Hg During inspiration

4. Muscles in breathing Muscles of active expiration Accessory inspiration Internal intercostal muscles 1. Sternocleidomastoid 2. Scalenus Muscles of active expiration 1. External intercostal muscles 2. Diaphragm Abdominal muscles Major muscles of inspiration

Active expiration Contraction of abdominal muscles Passive expiration Relaxation of external intercostal muscles Contraction of internal intercostal muscles Contraction of internal intercostal muscles flattens ribs and sternum, further reducing side-to-side and front-to-back dimensions of thoracic cavity Contraction of abdominal muscles Position of relaxed abdominal muscles Relaxation of diaphragm Contractions of abdominal muscles cause diaphragm to be pushed upward, further reducing vertical dimension of thoracic cavity Passive expiration Return of diaphragm, ribs, and sternum to resting position on relaxation of inspiratory muscles restores thoracic cavity to preinspiratory size Active expiration

§ Muscles of the Abdomen 4 Pairs of sheetlike muscles external oblique (most superficial) internal oblique transverse abdominal (the first three: from superficial to deep) rectus abdominal Functions support the viscera stabilize the vertebral column help in respiration, urination, defecation and childbirth

Aponeuroses (broad fibrous sheet-like tendons)– tendons of the oblique and transverse muscles Rectus abdominis-- wrapped by rectus sheath Linea alba (“white line”)– at the median line where aponeuroses meet

External Oblique & Rectus Abdominal vertical, straplike from pubis (O) to xiphoid process (I) 3 tendinous intersections rectus sheath encloses rectus abdominal They meet at the median line called linea alba External abdoominal oblique Superficial (O-Ribs 5-12; to I-pelvis and linea alba) Fibers downward and anteriorly The aponeurosis of external oblique forms inguinal ligament External oblique Rectus abdominis

Internal oblique & transverse abdominis Fibers pass upward and anteriorly Perpendicular to those of external oblique Transverse abdominal Horizontal fiber orientation Deepest layer Transverse abdominis Internal oblique