Chapter 9 B The Muscular System Muscle Organization

Chapter 9 B: The Muscular System Muscle Organization & Function (Not Interactive)

Muscle Organization and Function • Muscle organization affects power, range, and speed of muscle movement • Muscle cells (fibers) are organized in bundles (fascicles)

Organization of Skeletal Muscle Fibers • 4 patterns of fascicle organization: – – parallel convergent pennate circular

Parallel Muscles • Fibers parallel to the long axis of muscle • e. g. , biceps brachii

Parallel Muscle Body • The center or body of the muscle thickens when parallel muscle contracts • Parallel muscles contract about 30%

Convergent Muscles Figure 11– 1 b

Convergent Muscles • A broad area converges on attachment site (tendon, aponeurosis, or raphe) • Muscle fibers pull in different directions, depending on stimulation • e. g. , pectoralis muscles

Pennate Muscles Figure 11– 1 c, d, e

Pennate Muscles • Unipennate: – fibers on 1 side of tendon – e. g. , extensor digitorum • Bipennate: – fibers on both sides of tendon – e. g. , rectus femoris • Multipennate: – tendon branches within muscle – e. g. , deltoid

Pennate Muscles • Form an angle with the tendon • Do not move as far as parallel muscles • Contain more myofibrils than parallel muscles • Develop more tension than parallel muscles

Circular Muscles Figure 11– 1 f

Circular Muscles • Also called sphincters • Open and close to guard entrances of body • e. g. , obicularis oris

Levers • Mechanically, each bone is a lever (a rigid, moving structure): – and each joint a fulcrum (a fixed point) • Muscles provide applied force (AF): – required to overcome resistance (R)

Functions of a Lever • To change: – direction of an AF – distance and speed of movement produced by an AF – effective strength of an AF

3 Classes of Levers • Depend on the relationship between applied force, fulcrum, and resistance: – first class – second class – third class

First-Class Levers • Seesaw is an example • Center fulcrum between applied force and resistance • Force and resistance are balanced

Second-Class Levers • Wheelbarrow is an example • Center resistance between applied force and fulcrum • A small force moves a large weight

Third-Class Levers • Most common levers in the body • Center applied force between resistance and fulcrum • Greater force moves smaller resistance • Maximizes speed and distance traveled

Origins and Insertions • Muscles have 1 fixed point of attachment (origin) and 1 moving point of attachment (insertion) • Most muscles originate or insert on the skeleton • Origin is usually proximal to insertion

Actions • Movements produced by muscle contraction • Body movements – e. g. , flexion, extension, adduction, etc. • Described in terms of bone, joint, or region

Muscle Interactions • Muscles work in groups to maximize efficiency • Smaller muscles reach maximum tension first, followed by larger, primary muscles

Muscle Terminology Based on Function • Agonist (prime mover): – produces a particular movement • Antagonist: – opposes movement of a particular agonist • Synergist: – a smaller muscle that assists a larger agonist – helps start motion or stabilize origin of agonist (fixator)

Muscle Opposition • Agonists and antagonists work in pairs: – when 1 contracts, the other stretches – i. e. , flexors–extensors, abductors– adductors, etc.

Names of Skeletal Muscles • Correct names of muscles include the term muscle • Exceptions: – platysma – Diaphragm ****STUDY THE DIAGRAMS ON THE NEXT 2 SLIDES FOR THE QUIZ***

Naming Skeletal Muscles Table 11– 1 (1 of 2)

Naming Skeletal Muscles Table 11– 1 (2 of 2)

Descriptive Names for Skeletal Muscles 1. 2. 3. 4. 5. 6. Location in the body Origin and insertion Fascicle organization Relative position Structural characteristics Action

Location in the Body • Identifies body regions: – e. g. , temporalis muscle

Origin and Insertion • First part of name indicates origin • Second part of name indicates insertion: – e. g. , genioglossus muscle

Fascicle Organization • Describes fascicle orientation within muscle: – i. e. , rectus (straight), transversus, oblique

Relative Position • Externus (superficialis): – visible at body surface • Internus (profundus): – deep muscles • Extrinsic: – muscles outside an organ • Intrinsic: – muscles inside an organ

Structural Characteristics • Number of tendons: – bi = 2, tri = 3 • Shape: – trapezius, deltoid, rhomboid • Size

Names for Muscle Size (1 of 2) • • • Longus = long Longissimus = longest Teres = long and round Brevis = short Magnus = large

Names For Muscle Size (2 of 2) • • Major = larger Maximus = largest Minor = small Minimus = smallest

Action • Movements: – e. g. , flexor, extensor, retractor • Occupations or habits: – e. g. , risor = laughter

Ch. 11 Notes Axial and Appendicular Muscles Part I: Face and Neck Figure 11– 3 a

Axial and Appendicular Muscles Figure 11– 3 b

Divisions of the Muscular System 1. Axial muscles: – – – position head and spinal column move rib cage 60% of skeletal muscles 2. Appendicular muscles: – – – support pectoral and pelvic girdles support limbs 40% of skeletal muscles

The Axial Muscles • Divisions based on location and function: – – muscles of head and neck muscles of vertebral column oblique and rectus muscles of pelvic floor

6 Muscle Groups of the Head and Neck • Muscles of facial expression: – originate on skull • Extrinsic eye muscles: – originate on surface of orbit – control position of eye

6 Muscle Groups of the Head and Neck • Muscles of mastication: – move the mandible • Muscles of the tongue: – names end in glossus • Muscles of the pharynx: – begin swallowing process

6 Muscle Groups of the Head and Neck • Anterior muscles of the neck: – control position of larynx – depress the mandible – support tongue and pharynx

Muscles of Facial Expression • Orbicularis oris: – constricts the mouth opening • Buccinator: – moves food around the cheeks • Muscles of the epicranium (scalp)

Muscles of Facial Expression Figure 11– 4 b

Muscles of the Epicranium (Scalp) • Temporoparietalis • Occipitofrontalis: – frontal and occipital bellies – separated by epicranial aponeurosis • Platysma: – covers anterior surface of neck

Muscles of Facial Expression Figure 11– 4 a

Extrinsic Eye Muscles • Also called extra-ocular muscles Figure 11– 5 a, b

6 Extrinsic Eye Muscles • • • Inferior rectus Medial rectus Superior rectus Lateral rectus Inferior oblique Superior oblique

3 Muscles of Mastication • Masseter: – the strongest jaw muscle • Temporalis: – helps lift the mandible • Pterygoid muscles: – position mandible for chewing

Muscles of Mastication Figure 11– 6

4 Muscles of the Tongue • Palatoglossus: – originates at palate • Styloglossus: – originates at styloid process • Genioglossus: – originates at chin • Hypoglossus: – originates at hyoid bone

Muscles of the Tongue Figure 11– 7

3 Muscles of the Pharynx • Pharyngeal constrictor muscles: – move food into esophagus • Laryngeal elevator muscles: – elevate the larynx • Palatal muscles: – lift the soft palate

Muscles of the Pharynx Figure 11– 8

6 Anterior Muscles of the Neck • Digastric: – from chin to hyoid – and hyoid to mastoid • Mylohyoid: – floor of the mouth • Geniohyoid: – between hyoid and chin

6 Anterior Muscles of the Neck • Stylohyoid: – between hyloid and styloid • Sternocleidomastoid: – from clavicle and sternum to mastoid • Omohyoid: – attaches scapula, clavicle, first rib, and hyoid

Anterior Muscles of the Neck Figure 11– 9

Ch. 11 Axial/Appendicular Muscles Part II: Muscles of the Vertebral Column Figure 11– 10 a

Muscles of the Vertebral Column • Spinal extensors or erector spinae muscles (superficial and deep) • Spinal flexors (transversospinalis)

Muscles of the Vertebral Column Figure 11– 10 b, c

Superficial Spinal Extensors • Spinalis group • Longissimus group • Iliocostalis group

Deep Spinal Extensors • • • Semispinalis group Multifidus muscle Interspinalis muscles Intertransversarii muscles Rotatores muscles

Spinal Flexors • Neck: – longus capitis and longus colli – rotate and flex the neck • Lumbar: – quadratus lumborum muscles – flex spine and depress ribs

Oblique and Rectus Muscles • Lie within the body wall Figure 11– 11 a, b

Oblique and Rectus Muscles • Oblique muscles: – compress underlying structures – rotate vertebral column • Rectus muscles: – flex vertebral column – oppose erector spinae

Oblique Muscles • Cervical region: – scalene muscles – flex the neck

Oblique Muscles • Thoracic region: – intercostal muscles (external and internal intercostals): • respiratory movements of ribs – transversus thoracis: • cross inner surface of ribs

Oblique Muscles • Abdominopelvic region (same pattern as thoracic): – external oblique muscles – internal oblique muscles • Transversus abdominis

Oblique and Rectus Muscles Figure 11– 11 a, c

Rectus Group • Rectus abdominis: – between xiphoid process and pubic symphysis – divided longitudinally by linea alba – divided transversely by tendinous inscriptions

Rectus Group • Diaphragmatic muscle or diaphragm: – divides thoracic and abdominal cavities – performs respiration

Functions of Pelvic Floor Muscles 1. Support organs of pelvic cavity 2. Flex sacrum and coccyx 3. Control movement of materials through urethra and anus

Perineum • Muscular sheet forming the pelvic floor, divided into: – anterior urogenital triangle – posterior anal triangle

Muscles of the Pelvic Floor Figure 11– 12 a

Urogenital Diaphragm • Deep muscular layer between pubic bones: – supports the pelvic floor – and muscles of the urethra • Superficial muscles of the urogenital triangle: – support external genitalia

Pelvic Diaphragm • Deep muscular layer extending to pubis: – supports anal triangle

Muscles of the Pelvic Floor Figure 11– 12 b

What are the principal appendicular muscles of the body and their origins, insertions, actions, and innervations?

Ch. 11 Muscle Notes: Part III The Appendicular Muscles Figure 11– 13 a

The Appendicular Muscles Figure 11– 13 b

The Appendicular Muscles • Position and stabilize pectoral and pelvic girdles • Move upper and lower limbs

Muscles of the Shoulders and Upper Limbs • • Position the pectoral girdle Move the arm Move the forearm and hand Move the hand fingers

Muscles that Position the Pectoral Girdle PLAY 3 D Peel-Away of Muscles of the Pectoral Girdle Figure 11– 14 a

Muscles that Position the Pectoral Girdle Figure 11– 14 b

6 Muscles that Position the Pectoral Girdle (1 of 4) • Trapezius: – superficial – covers back and neck to base of skull – inserts on clavicles and scapular spines

6 Muscles that Position the Pectoral Girdle (2 of 4) • Rhomboid and levator scapulae: – deep to trapezius – attach to cervical and thoracic vertebrae – insert on scapular border

6 Muscles that Position the Pectoral Girdle (3 of 4) • Serratus anterior: – on the chest – originates along ribs – inserts on anterior scapular margin

6 Muscles that Position the Pectoral Girdle (4 of 4) • Subclavius: – originates on ribs – inserts on clavicle • Pectoralis minor: – attaches to scapula

Muscles that Move the Arm Figure 11– 15 a

Muscles that Move the Arm Figure 11– 15 b

9 Muscles that Move the Arm (1 of 3) • Deltoid: – the major abductor • Supraspinatus: – assists deltoid • Subscapularis and teres major: – produce medial rotation at shoulder PLAY 3 D Rotation: Muscles of the Arm

9 Muscles that Move the Arm (2 of 3) • Infraspinatus and teres minor: – produce lateral rotation at shoulder • Coracobrachialis: – attaches to scapula – produces flexion and adduction at shoulder

9 Muscles that Move the Arm (3 of 3) • Pectoralis major: – between anterior chest and greater tubercle of humerus – produces flexion at shoulder joint • Latissimus dorsi: – between thoracic vertebrae and humerus – produces extension at shoulder joint

The Rotator Cuff • Muscles involved in shoulder rotation – supraspinatus, subscapularis, infraspinatus, teres minor, and their tendons

Muscles that Move the Forearm and Hand Figure 11– 16 a

Muscles that Move the Forearm and Hand Figure 11– 16 b

Muscles that Move the Forearm and Hand • Originate on humerus and insert on forearm • Exceptions: – the major flexor (biceps brachii) – the major extensor (triceps brachii) PLAY 3 D Rotation: Muscles of the Forearm and Hand

Extensors and Flexors • Extensors: – mainly on posterior and lateral surfaces of arm • Flexors: – mainly on anterior and medial surfaces

13 Muscles that Move the Forearm and Hand (1 of 8) • Biceps brachii: – – flexes elbow stabilizes shoulder joint originates on scapula inserts on radial tuberosity

13 Muscles that Move the Forearm and Hand (2 of 8) • Triceps brachii: – extends elbow – originates on scapula – inserts on olecranon • Brachialis and brachioradialis: – flex elbow

13 Muscles that Move the Forearm and Hand (3 of 8) • Anconeus: – opposes brachialis • Palmaris longus: – superficial – flexes wrist

13 Muscles that Move the Forearm and Hand (4 of 8) • Flexor carpi ulnaris: – superficial – flexes wrist – adducts wrist

13 Muscles that Move the Forearm and Hand (5 of 8) • Flexor carpi radialis: – superficial – flexes wrist – abducts wrist

13 Muscles that Move the Forearm and Hand (6 of 8) • Extensor carpi radialis: – superficial – extends wrist – abducts wrist

13 Muscles that Move the Forearm and Hand (7 of 8) • Extensor carpi ulnaris: – superficial – extends wrist – adducts wrist

13 Muscles that Move the Forearm and Hand (8 of 8) • Pronator teres and supinator: – originate on humerus and ulna – rotate radius • Pronator quadratus: – originates on ulna – assists pronator teres

Muscles that Move the Hand Fingers Figure 11– 17 a, b

Muscles that Move the Hand Fingers Figure 11– 17 c, d

Muscles of the Pelvis and Lower Limbs • Pelvic girdle is tightly bound to axial skeleton: – permits little movement – has few muscles

Muscles that Position the Lower Limbs 1. Muscles that move thigh 2. Muscles that move the leg 3. Muscles that move the foot and toes

Muscles that Move the Thigh Figure 11– 19 a, b

Muscles that Move the Thigh Figure 11– 19 c, d

Muscles that Move the Thigh • • Gluteal muscles Lateral rotators Adductors Iliopsoas PLAY 3 D Peel-Away of Muscles of the Thigh PLAY 3 D Peel-Away of Rectus Muscle

Gluteal Muscles (1 of 2) • Cover lateral surfaces of ilia • Gluteus maximus: – largest, most posterior gluteal muscle – produces extension and lateral rotation at hip

Gluteal Muscles (2 of 2) • Tensor fasciae latae: – works with gluteus maximus – stabilizes iliotibial tract • Gluteus medius and gluteus minimus: – originate anterior to gluteus maximus – insert on trochanter

Lateral Rotators • Group of 6 muscles, including: – piriformis – obturator

Adductors (1 of 2) • Adductor magnus: – produces adduction, extension, and flexion • Adductor brevis: – hip flexion and adduction • Adductor longus: – hip flexion and adduction

Adductors (2 of 2) • Pectineus: – hip flexion and adduction • Gracilis: – hip flexion and adduction

Iliopsoas • 2 hip flexors insert on the same tendon: – psoas major – iliacus

Muscles that Move the Leg Figure 11– 20 a

Muscles that Move the Leg Figure 11– 20 b, c

Muscles that Move the Leg • Flexors of the knee: – originate on the pelvic girdle • Extensors of the knee: – originate on the femoral surface – insert on the patella

Flexors of the Knee • • Biceps femoris Semimembranosus Semitendinosus Sartorius: – originates superior to the acetabulum • Popliteus: – rotates the tibia to unlock the knee

Hamstrings • Made up of: – biceps femoris – semimembranosus – semitendinosus

Extensors of the Knee • 4 muscles of the quadriceps femoris: – 3 vastus muscles – rectus femoris muscle

Muscles that Move the Foot and Toes Figure 11– 21 a, b

Muscles that Move the Foot and Toes Figure 11– 21 c, d

Muscles that Move the Foot and Toes • Extrinsic muscles that move the foot and toes include: – muscles that produce extension at the ankle – muscles that produce flexion at the ankle – muscles that produce extension at the toes – muscles that produce flexion at the toes

4 Muscles that Produce Extension at the Ankle • • Gastrocnemius Soleus Fibularis Tibialis posterior PLAY 3 D Peelaway of Muscles of the Leg and Foot

The Achilles Tendon • The calcaneal tendon (Achilles tendon): – shared by the gastrocnemius and soleus

Muscles that Produce Flexion at the Ankle • Tibialis anterior: – opposes the gastrocnemius