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Chapter 11 Muscles Exam 1 will cover sections 11.1-11.4.

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Presentation on theme: "Chapter 11 Muscles Exam 1 will cover sections 11.1-11.4."— Presentation transcript:

1 Chapter 11 Muscles Exam 1 will cover sections 11.1-11.4

2 Section 1 Fascicle Arrangement Fascicles: bundles of muscle fibers in skeletal muscle fibers in each fascicle are parallel, but fascicle arrangement can vary – parallel muscles- fascicles are parallel to long axis of muscle (biceps brachii), when muscle fibers contract, muscle shortens by 30 % – convergent muscles- fascicles extend over a broad area & meet (converge) at the attachment site, (pectoralis muscles)

3 – Pennate muscles- (feather) fascicles form a shared angle w/ tendon contracted muscle doesn’t move tendon as far as parallel muscles-fibers pull @ angle contain more muscle fibers than parallel muscle, so they produce more tension – Circular muscles- (sphincter) arranged around openings when contracted, diameter decreases


5 11.2 Classes of Levers Nature and site of muscle connection determine force, speed, and range of motion – lever (bone) moves when the applied force (AF) is great enough to overcome the load (L) or resistance (R) that would prevent the movement – in the body, each joint acts as a fulcrum, and muscles provide the applied force – the load can vary (weight of limb, object held, or entire body)

6 – levers can change direction of applied force distance & speed of movement effective strength of applied force Classes of levers – first class: fulcrum in the middle (teeter totter) – second class: load in the middle (wheel barrow), small force can move a larger weight, at the expense of speed and distance

7 – third class: most common in body, force is between the load and the fulcrum, speed and distance traveled are increased at the expense of effective force (muscles must generate 6X the tension to support the load)

8 11.3 Muscle Origins & Insertions Ends of skeletal muscle are attached to structures that limit their motion (bone, cartilage, connective tissue) – origin-the place where fixed end of muscle attaches – insertion-the site where the moveable end attaches to another structure – action- movement produced when muscle contracts

9 Actions Actions are described – by bone or region affected (flexion of forearm) – by joint involved (flexion of elbow) – based on functions agonist (prime mover)- contraction responsible for producing specific movement, ex: biceps brachii muscle produces flexion of elbow antagonist- muscle whose action opposes the action of an agonist, ex: triceps brachii extends the elbow, going against the biceps brachii

10 synergist- helps a larger agonist work efficiently, may provide pull near insertion or may stabilize near origin; useful in start of motion fixator- a synergist that stabilizes origin of agonist by preventing movement at another joint

11 11.4 Descriptive terms Locational terms – regional terms are common; abdominis- abdomen, capitis- head, femoris- femur, etc (PG 342) Origin and Insertion – first part of name indicates the origin, second part, the insertion ex: sternocleidomastoid originates at sternum, inserts at the clavicle (cleido)

12 Fascicle organization – Rectus: straight, parallel muscles that run along long axis of body (rectus abdominis) – transverse/oblique: muscles have fibers that run at an angle to long axis of body (external obliques) Position – externus/superficialis: visible at the body surface – internus/profundus:deeper muscles – Intrinsic: located within an organ

13 Structural Characteristics number of tendons (biceps brachii, triceps brachii) shape- muscles named after their shape: trapezius, deltoid(triangle), rhomboid length and size: – longus (long), longissimus (longest) – teres (long & round), brevis (short) – magnus (large), major (bigger), or maximus (biggest) – minor (small), or minimus (smallest)

14 Stop! Test 1 will cover 11.1-11.4

15 11.5 Muscles of facial expression Orbicularis oculi – Sphincter muscle of eyelid – O: frontal & maxillary bones – I: tissue of eyelid – Action: closes eye – Nerve: facial / CN VII (11.6)

16 Muscles of facial expression Zygomaticus – O: zygomatic bone – I: corners of mouth – Action: smiling – Nerve: facial / CN VII (11.6) Major and Minor

17 Muscles of mastication Masseter – O: zygomatic arch – I: angle & ramus of mandible – Action: elevate mandible – Nerve: trigeminal nerve / CN V (foramen ovale) (11.7a) Masseter

18 Muscles of mastication Temporalis – O: temporal fossa – I: coronoid process of mandible – Action: elevate and retract mandible – Nerve: trigeminal n. / CN V (11.7a)

19 Extrinsic tongue muscles Styloglossus – O: styloid process of temporal bone – I: tongue – Action: retract & elevate tongue – Nerve: hypoglossal n. / CN XII (11.7c) Styloglossus

20 Extrinsic tongue muscles Hyoglossus – O: hyoid bone – I: tongue – Action: depresses tongue – Nerve: hypoglossal n. / CN XII (11.7c) Hyoid bone

21 Muscles of neck & throat Digastric – two muscle bellies with an intermediate tendon attached to the hyoid bone – O: inferior margin of mandible (anterior belly); mastoid process of temporal bone (posterior belly) – I: hyoid bone – Action: elevate hyoid, stabilize hyoid, depress mandible – Nerve: trigeminal n. / CN V (anterior belly), facial n. / CN VII (posterior belly) (11.8a) Anterior belly Posterior belly

22 Muscles of neck & throat Stylohyoid – O: styloid process of temporal bone – I: hyoid bone – Action: elevate & retract hyoid, swallow – Nerve: facial n. / CN VII (11.7c) Stylohyoid

23 Muscles of neck & throat Sternohyoid – O: manubrium & medial end of clavicle – I: hyoid bone – Action: depress hyoid (11.8a) Sternohyoid

24 Muscles of neck & throat Pharyngeal constrictors – O: mandible, pterygoid process, hyoid, laryngeal cartilages – I: posterior medial raphe of pharynx – Action: peristaltic contraction / swallow (11.8b) Superior Middle Inferior

25 Muscles of neck & throat Sternocleidomastoid – O: manubrium & medial clavicle – I: mastoid process of temporal bone – Action: head & neck flexion, rotate head contralaterally – Nerve: accessory n. / CN XI (11.8a)

26 Muscles of neck & throat Sternocleidomastoid

27 Back muscles Spinalis – O: spines of upper lumbar and lower thoracic vertebrae – I: spines of upper thoracic and cervical vertebrae – Action: extends vertebral column (11.9d)


29 Deep thorax muscles External & internal intercostals – O&I: inferior & superior border of ribs – Action: inspiration and expiration (11.10a) Internal

30 Deep thorax muscles Diaphragm – O: inferior internal surface of rib cage & sternum, inferior costal cartilages, lumbar vertebrae – I: central tendon – Action: flattens on contraction (inspiration) – Nerve: phrenic nerves (11.10b) Xiphoid process


32 Abdominal wall muscles Rectus abdominis – O: pubic crest & symphysis – I: xiphoid process and costal cartilages of ribs 5-7 – Action: flex & rotate lumbar vertebrae, fix & depress ribs, stabilize pelvis during walking, increase intraabdominal pressure – Note: 3 tendinous insertions, aponeurosis & linea alba (11.11ab)


34 Superficial thorax muscles Pectoralis minor – O: anterior surface of ribs 3-5 – I: coracoid process of scapula – Action: with ribs fixed, pulls scapula anterior & inferior; with scapula fixed, pulls ribs superiorly – Nerve: Medial and lateral pectoral nerves (C6-C8) (11.13a)

35 Superficial thorax muscles

36 Superificial thorax muscles Serratus anterior – O: ribs 1-8 – I: vertebral border of scapula – Action: hold scapula against chest wall, moves inferior angle of scapula lateral & superior (abduction, pushing, punching) – Nerve: long thoracic nerve (11.13a,8.1a reversed)

37 Superificial thorax muscles Trapezius – O: occipital bone, ligamentum nuchae, C7- T12 spinous processes – I: acromion, spine of scapula, lateral third of clavicle – Action: stabilize, elevate, adduct, depress scapula, extend head – Nerve: Accessory (CNXI), C3 and C4 (11.13b)


39 Shoulder muscles Pectoralis major – O: medial clavicle, sternum, cartilage of ribs 1-6, aponeurosis of external oblique – I: greater tubercle of humerus – Action: arm-flexion, medial rotation, adduction, elevation of rib cage (11.13a) -Nerve: Medial and lateral pectoral nerves (C6-C8)

40 Shoulder muscles Deltoid – O: lateral clavicle, acromion & spine of scapula (compare to insertion of trapezius) – I: deltoid tuberosity of humerus – Action: arm-abduction, flexion, extension, medial & lateral rotation – Nerve: Axillary nerve(C5- C-6) (11.13ab)

41 Shoulder muscles Subscapularis – O: subscapular fossa – I: lesser tubercle of humerus – Action: medial rotate arm, stabilize shoulder joint – Nerve: Subscapular nerves (C5-C7) (11.14d)

42 Shoulder muscles Infraspinatus – O: infraspinous fossa – I: greater tubercle of humerus – Action: lateral rotate humerus, stabilized shoulder joint – Nerve: Suprascapular nerve (11.14b)

43 Rotator cuff muscles Act to stabilize head of humerus in glenoid cavity and prevent dislocation Supraspinatous(Suprascapular nerve) Infraspinatus (Suprascapular nerve)  Subscapularis(Subscapular nerve) Teres minor(Axillary nerve)

44 Elbow muscles Triceps brachii – O: long head- infraglenoid tubercle, lat. & med. heads-posterior shaft of humerus – I: olecranon process of ulna – Action: extend forearm, assist adduction of arm – Nerve: Radial nerve (11.14b)

45 Elbow muscles Biceps brachii – O: short head-coracoid process, long head-tubercle above glenoid cavity and lip of glenoid cavity (intertubercular groove) – I: radial tuberosity – Action: flex elbow, supinate forearm, weak arm flexor – Nerve: Musculocutaneous nerve (C5 & C6) (11.14c)


47 Forearm muscles Flexor carpi (radialis & ulnaris) – O: medial epicondyle of humerus, ulna – I: metacarpals and carpals – Action: wrist flexion, abduct & adduct hand – Carpal tunnel (Median nerve) syndrome p. 184 (11.15a) Anterior view radialis ulnaris


49 Forearm muscles Extensor carpi – O: lateral epicondyle of humerus – I: base of metacarpals – Action: extend, abduct, and adducts wrist – Palpate forearm muscles


51 Hip & knee muscles Quadriceps femoris – O: anterior inferior iliac spine, superior margin of acetabulum, greater trochanter, shaft of femur – I: patella and tibial tuberosity via patellar tendon – Action: extend knee, flex thigh

52 Hip & knee muscles Gluteus muscles – O: ilium, sacrum, coccyx – I: shaft & greater trochanter of femur – Action: extend thigh (climb stairs, running), lateral & medial rotate thigh, abduct thigh, steadies pelvis

53 Hip & knee muscles Hamstrings – O: ischial tuberosity, shaft of femur – I: lateral & medial condyles and shaft of tibia, head of fibula, lateral condyle femur – Action: extend thigh, flex knee – Makes touching toes hard

54 Leg muscles Tibialis anterior – O: lateral condyle and shaft of tibia – I: tarsal and first metatarsal bones – Action: dorsiflexion

55 Leg muscles Gastrocnemius – O: medial & lateral condyles of femur – I: calcaneus via Achilles tendon – Action: plantar flexion, flex knee

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