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MUSCLES OF THE BODY Ch 11 Human Anatomy Sonya Schuh-Huerta, Ph.D. Leonardo Da Vinci.

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Presentation on theme: "MUSCLES OF THE BODY Ch 11 Human Anatomy Sonya Schuh-Huerta, Ph.D. Leonardo Da Vinci."— Presentation transcript:

1 MUSCLES OF THE BODY Ch 11 Human Anatomy Sonya Schuh-Huerta, Ph.D. Leonardo Da Vinci

2 Muscles of the Body Skeletal muscles –Produce movements General principles of leverage Muscles act with or against each other Criteria used in naming muscles

3 Naming the Skeletal Muscles Location –Example  the brachialis is located on the arm (brachium) Shape –Example  the deltoid is triangular Relative size –Maximus, minimus, & longus indicate size –Example  gluteus maximus is the large one & gluteus minimus is the small one

4 Naming the Skeletal Muscles Direction of fascicles & muscle fibers –Name tells direction in which fibers run –Example  rectus abdominis & transversus abdominis (rectus = straight up; transverse  across or at right angle to midline) Location of attachments  name reveals point of origin & insertion –Example  brachioradialis

5 Naming the Skeletal Muscles Number of origins –2, 3, or 4 origins –Indicated by the words biceps (2), triceps (3), & quadriceps (4) Action –Action can be part of the muscle’s name –Indicates type of muscle movement Flexor, extensor, adductor, or abductor (ie. extensor digitorum)

6 Arrangement of Fascicles in Muscles Skeletal muscles  consist of fascicles –Fascicles  arranged in different patterns –Fascicle arrangement  tells about action of a muscle

7 Arrangement of Fascicles in Muscles Types of fascicle arrangement –Parallel  fascicles run parallel to the long axis of the muscle Strap-like  sternocleidomastoid Fusiform  biceps brachii

8 Arrangement of Fascicles in Muscles Types of fascicle arrangement –Convergent Origin of the muscle is broad Fascicles converge toward the tendon of insertion Example  Pectoralis major

9 Arrangement of Fascicles in Muscles Types of fascicle arrangement –Pennate Unipennate  fascicles insert into one side of the tendon Bipennate  fascicles insert into the tendon from both sides Multipennate  fascicles insert into one large tendon from all sides

10 Arrangement of Fascicles in Muscles Circular –Fascicles are arranged in concentric rings Surround external body openings Sphincter  general name for a circular muscle Examples –Orbicularis oris & orbicularis oculi

11 (f) Bipennate (rectus femoris) (a) (b) (c) (f) (g) (e) (d) (a) Circular (orbicularis oris) (b) Convergent (pectoralis major) (d) Parallel (sartorius) (c) Fusiform (biceps brachii) (g) Unipennate (extensor digitorum longus) (e) Multipennate (deltoid) Arrangement of Fascicles in Muscles

12 Lever Systems: Bone-Muscle Relationships Movement of skeletal muscles involves leverage –Lever  a rigid bar that moves –Fulcrum  a fixed point –Effort  applied force –Load  resistance

13 Lever Systems Load Effort Load Effort 10 kg 1000 kg Fulcrum 10 x 25 = 1000 x = 250 Effort x length of effort arm = load x length of load arm (force x distance) = (resistance x distance) (a) Mechanical advantage with a power lever Fulcrum 25 cm 0.25 cm

14 Lever Systems: Bone-Muscle Relationships Bones  act as levers Joints  act as fulcrums Muscle contraction  provides effort –Applies force where muscle attaches to bone Load  bone, overlying tissue, & anything being lifted

15 Lever Systems: Bone-Muscle Relationships Levers allow a given effort to –Move a heavier load –Move a load farther

16 Lever Systems: Bone-Muscle Relationships First-class lever –Effort applied at one end –Load is at the opposite end –Fulcrum is located between load & effort (a) First-class lever Arrangement of the elements is load-fulcrum-effort. L L Example: scissors Load Fulcrum Load Effort Fulcrum (a) First-class lever Arrangement of the elements is load-fulcrum-effort. In the body: A first-class lever system raises your head off your chest. The posterior neck muscles provide the effort; the atlanto-occipital joint is the fulcrum; and the weight to be lifted is the facial skeleton. Load Fulcrum Effort

17 Lever Systems: Bone-Muscle Relationships Third-class lever –Effort is applied between the load & fulcrum –Work speedily –Always at a mechanical disadvantage (c) Third-class lever Arrangement of the elements is load-effort-fulcrum. L L Example: tweezers or forceps Fulcrum Load Effort Fulcrum (c) Third-class lever Arrangement of the elements is load-effort-fulcrum. In the body: Flexing the forearm by the biceps brachii muscle exemplifies third-class leverage. The effort is exerted on the proximal radius of the forearm; the fulcrum is the elbow joint; and the load is the hand and distal end of the forearm. Load Effort Fulcrum

18 Embryonic Development of the Muscles Muscles organized into 4 groups –Musculature of the visceral organs –Pharyngeal arch muscles –Axial muscles –Limb muscles

19 Musculature of the visceral organs –Includes smooth & cardiac muscle –Develops from splanchnic mesoderm Pharyngeal arch muscles –Includes Skeletal muscles of the pharynx Muscles of the head & neck –Develop from the 4 th to 7 th somitomeres Embryonic Development of the Muscles

20 Development of the Muscles Limb bud Myotomes Limb bud (a) 6-week embryo Pharynx Eye First (occipital) myotomes Somitomeres

21 (c) Pharyngeal arch (branchiomeric) muscles: 4th–7th somitomeres Pharynx Muscles of facial expression e.g., orbicularis oculi Chewing muscles e.g., temporalis, masseter Suprahyoid muscles (most) Pharyngeal constrictors (key swallowing muscles) Trapezius Pharyngeal Arch Muscles

22 Axial Muscles Lie anterior & posterior to the body axis Muscles of the: –Thorax, abdomen, & pelvis And many muscles of the: –Neck & some of the head Function to move the trunk & maintain posture

23 Deep muscles of the back e.g., erector spinae Extrinsic muscles of the eye Tongue muscles (d) Axial muscles: 1st–3rd somitomeres and myotomes Tongue Muscles of the anterior & lateral trunk e.g., 1. infrahyoid muscles (neck) 2. intercostal muscles (thorax) 3. external & internal obliques (abdomen) 4. muscles of the pelvic floor Axial Muscles

24 Limb Muscles Limb muscles arise from lateral parts of nearby myotomes Extensors –Muscle mass dorsal to limb bones Flexors –Muscle mass ventral to limb bones

25 Limb Muscles Extensors e.g., triceps brachii, extensor digitorum Flexors e.g., biceps brachii, flexor carpi radialis Extensors e.g., quadriceps femoris, tibialis anterior Flexors e.g., hamstrings, gastrocnemius (e) Limb muscles: From myotomes Extensors Flexors

26 Muscle Actions & Interactions A muscle cannot reverse the movement it produces Another muscle must undo the action Muscles with opposite actions lie on opposite sides of a joint

27 Muscle Actions & Interactions Prime mover (= agonist) –Has major responsibility for a certain movement Antagonist –Opposes or reverses a movement Synergist  helps the prime mover –By adding extra force –By reducing undesirable movements

28 Muscle Actions & Interactions Example: Pectoralis major (anterior view) (a) A muscle that crosses on the anterior side of a joint produces flexion* *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. Example: Latissimus dorsi (posterior view) (b) A muscle that crosses on the posterior side of a joint produces extension* *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.

29 Muscle Actions & Interactions Example: Teres major (posterolateral view) (d) A muscle that crosses on the medial side of a joint produces adduction Example: Medial deltoid (anterolateral view) (c) A muscle that crosses on the lateral side of a joint produces abduction

30 Muscle Compartments of the Limbs Dense fibrous connective tissue divides limb muscles into compartments Muscles in opposing compartments are –Agonist & antagonist pairs Each compartment is innervated by one single nerve

31 Muscle Compartments of Arm & Forearm The upper limb has anterior & posterior compartments –Anterior arm compartment muscles: Flex the shoulder or arm Innervation is the musculocutaneous nerve (we’ll learn later) –Anterior forearm compartment muscles: Flex the wrist & digits Innervation is the median or ulnar nerve (..later)

32 Triceps brachii Lateral head Humerus Posterior compartment of arm (extends elbow); innervation: radial nerve Anterior compartment of arm (flexes elbow); innervation: musculocutaneous nerve Long head Medial head (a) Brachialis Short head Long head Biceps brachii (a) Muscles of the arm Extensors Flexors Muscle Compartments of the Arm

33 Muscle Compartments of the Thigh Posterior compartment muscles –Extend the hip & flex the knee –Innervation is the tibial branch of the sciatic nerve (later) Anterior compartment muscles –Flex the hip & extend the knee –Innervation is the femoral nerve (later) Medial compartment –Adduct the thigh –Innervation is the obturator nerve (later)

34 Adductors Vastus lateralis Hamstrings Posterior compartment of thigh (flexes leg and extends thigh); innervation: tibial nerve (portion of sciatic nerve) Medial compartment (adducts thigh); innervation: obturator nerve Anterior compartment (extends leg); innervated by femoral nerve Vastus intermedius Rectus femoris Femur Vastus medialis (a) (a) Muscles of the thigh Posterior compartment muscles Anterior compartment muscles Medial compartment muscles of thigh and lateral compartment muscles of leg Muscle Compartments of the Thigh

35 Lab Guide for Learning the Muscles

36 Superficial Muscles of the Body Trapezius Shoulder Deltoid Arm Triceps brachii Biceps 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 Head Facial Temporalis Epicranius, frontal belly Orbicularis oculi Zygomaticus Orbicularis oris Neck Sternohyoid Sternocleidomastoid Thorax Pectoralis major Pectoralis minor Serratus anterior Intercostals Abdomen External oblique Rectus abdominis Internal oblique Transversus abdominis Thigh Sartorius Tensor fasciae latae Adductor longus Gracilis Leg Gastrocnemius Soleus Masseter Platysma

37 Neck Gracilis Deltoid Arm Triceps brachii Brachialis Forearm Brachioradialis Extensor carpi ulnaris Extensor digitorum Iliotibial tract Leg Gastrocnemius Soleus Fibularis longus Epicranius, occipital belly Sternocleidomastoid Shoulder Hip Gluteus medius Gluteus maximus Thigh Biceps femoris Adductor magnus Semitendinosus Semimembranosus Hamstrings: Latissimus dorsi Rhomboid major Triangle of auscultation Infraspinatus Teres major Flexor carpi ulnaris Extensor carpi radialis longus Calcaneal (Achilles) tendon Trapezius Superficial Muscles of the Body

38 Muscles of the Head – Facial Expression Muscles of facial expression –Lie in the face & scalp –Thin & variable in shape –Often insert in the skin  not on bones –(Innervated by cranial nerve VII  the facial nerve)

39 Corrugator supercilii Orbicularis oculi Levator labii superioris Zygomaticus minor and major Buccinator Risorius Orbicularis oris Mentalis Depressor labii inferioris Depressor anguli oris Platysma Galea aponeurotica Frontal belly Occipital belly Temporalis Masseter Sternocleidomastoid Trapezius Splenius capitis Epicranius Muscles of the Face & Head

40 Muscles of Mastication & Tongue Movement 4 main pairs of muscles involved in mastication –Innervated by mandibular division of the trigeminal nerve (cranial nerve V) –Prime movers of jaw closure Masseter & temporalis –Side-to-side movement Pterygoid muscles –Compression of cheeks Buccinator muscles PLAY A&P Flix: Buccinator PLAY A&P Flix: Masseter PLAY A&P Flix: Temporalis

41 Muscles of Mastication & Tongue Movement Orbicularis oris Temporalis Masseter Buccinator (a) Lateral pterygoid Medial pterygoid Masseter pulled away (b)

42 Muscles of the Anterior Neck & Throat – Swallowing The neck is divided into anterior & posterior triangles Anterior triangle –Divided into suprahyoid & infrahyoid muscles –Participate in swallowing Pharyngeal constrictors –Swallowing muscles  squeeze food into esophagus

43 Muscles of the Anterior Neck & Throat Buccinator Tensor veli palatini Levator veli palatini Superior pharyngeal constrictor Middle pharyngeal constrictor Hyoid bone Thyrohyoid membrane Inferior pharyngeal constrictor Esophagus Mandible Mylohyoid (cut) Geniohyoid Hyoglossus Thyroid cartilage of larynx Trachea Styloid process

44 Muscles of the Neck & Vertebral Column Head movement: –Sternocleidomastoid –Splenius muscles –Neck movement – scalenes 1st cervical vertebra Sternocleido- mastoid Base of occipital bone Middle scalene Anterior scalene Posterior scalene (a) Anterior Mastoid process

45 Splenius capitis Mastoid process Spinous processes of the vertebrae Splenius cervicis (b) Posterior Muscles of the Neck & Vertebral Column

46 Trunk extension –Deep muscles of the back Maintain normal curvatures of the spine Form a column from sacrum to the skull –Erector spinae group Largest of the deep back muscles

47 Mastoid process of temporal bone Semispinalis capitis Semispinalis cervicis Multifidus Quadratus lumborum Semispinalis thoracis Longissimus capitis Iliocostalis cervicis Longissimus cervicis Iliocostalis thoracis Longissimus thoracis Spinalis thoracis Iliocostalis lumborum External oblique Iliocostalis Longissimus Erector spinae Spinalis Ligamentum nuchae Muscles of the Neck & Vertebral Column

48 PLAY A&P Flix: Iliocostalis PLAY A&P Flix: Longissimus PLAY A&P Flix: Spinalis

49 Deep Muscles of the Thorax – Breathing Deep muscles provide movements for breathing –External intercostal muscles Lift the rib cage during inhalation –Internal intercostal muscles Aid expiration during heavy breathing

50 Deep Muscles of the Thorax— Breathing External intercostal Internal intercostal PLAY A&P Flix: External intercostal muscles PLAY A&P Flix: Internal intercostal muscles

51 Deep Muscles of the Thorax – Breathing Diaphragm –Most important muscle of respiration! –Flattens as it contracts Increases the volume of the thoracic cavity How does this aid in breathing? Innervated by phrenic nerve (your brain controls)

52 Foramen for esophagus Costal cartilage Lumbar vertebra Diaphragm Quadratus lumborum Psoas major Xiphoid process of sternum Foramen for inferior vena cava Central tendon of diaphragm Foramen for aorta 12th rib Deep Muscles of the Thorax— Breathing

53 Muscles of the Abdominal Wall Lateral & anterior abdominal wall –Formed from 3 flat muscle sheets External oblique Internal oblique Transversus abdominis –Fourth muscle pair Rectus abdominis –Inserts at the linea alba

54 Serratus anterior Pectoralis major Linea alba Tendinous intersection Rectus abdominis Inguinal ligament (formed by free inferior border of the external oblique aponeurosis) Transversus abdominis Internal oblique External oblique Aponeurosis of the external oblique (a) Muscles of the Abdominal Wall PLAY A&P Flix: Internal obliques PLAY A&P Flix: External obliques

55 PLAY A&P Flix: Transverse abdominis PLAY A&P Flix: Rectus abdominis Rectus abdominis Internal oblique External oblique Transversus abdominis Muscles of the Abdominal Wall

56 Muscles of the Pelvic Floor Pelvic floor (pelvic diaphragm) Sheet of 2 muscles –Both support pelvic organs Levator ani –Formed from iliococcygeus, puborectalis, & pubococcygeus Coccygeus

57 Muscles of the Pelvic Floor Pelvic diaphragm Symphysis pubis Levator ani Piriformis Posterior Anterior Coccyx Coccygeus Obturator internus IIiococcygeus Levator ani Pubococcygeus Urogenital diaphragm Urethra Vagina Anal canal

58 Muscles of the Perineum MaleFemale Penis Midline raphe Ischiocavernosus Clitoris Urethral opening Anus Vaginal opening Bulbospongiosus Superficial transverse perineal muscle Levator ani Gluteus maximus

59 Superficial Muscles of the Anterior Thorax Movements of the scapula –Pectoralis major –Pectoralis minor –Serratus anterior –Subclavius PLAY A&P Flix: Pectoralis major PLAY A&P Flix: Pectoralis minor PLAY A&P Flix: Serratus anterior

60 Superficial Muscles of Anterior Thorax Sternocleidomastoid Deltoid Pectoralis major Sternum Biceps brachii Subclavius Clavicle Subscapularis Pectoralis minor Coracobrachialis Serratus anterior Humerus

61 Superficial Muscles of the Posterior Thorax Movements of the scapula –Trapezius –Levator scapulae –Rhomboid major –Rhomboid minor PLAY A&P Flix: Trapezius PLAY A&P Flix: Levator scapulae PLAY A&P Flix: Rhomboid major PLAY A&P Flix: Rhomboid minor

62 Trapezius Levator scapulae Supraspinatus Clavicle Spine of scapula Infraspinatus Teres minor Humerus Deltoid Teres major Latissimus dorsi Rhomboid minor Rhomboid major Superficial Muscles of the Posterior Thorax

63 Muscles Crossing the Shoulder Joint Movements of the arm –Deltoid –Pectoralis major Clavicle Deltoid Sternum Pectoralis major Lateral head Long head Medial head Coracobrachialis Triceps brachii Biceps brachii Brachialis Brachio- radialis (a) Anterior view PLAY A&P Flix: Deltoid

64 Movements of the arm A&P Flix: Latissimus dorsi A&P Flix: Supraspinatus A&P Flix: Infraspinatus Supraspinatus Spine of scapula (b) Posterior view Deltoid (cut) Greater tubercle of humerus Infraspinatus Teres minor Teres major Triceps brachii Latissimus dorsi Humerus Olecranon process of ulna Lateral head Long head Anconeus PLAY Muscles Crossing the Shoulder Joint

65 Movements of arm A&P Flix: Teres minor A&P Flix: Teres major A&P Flix: Subscapularis Supraspinatus Spine of scapula (b) Posterior view Deltoid (cut) Greater tubercle of humerus Infraspinatus Teres minor Teres major Triceps brachii Latissimus dorsi Humerus Olecranon process of ulna Lateral head Long head Anconeus PLAY Muscles Crossing the Shoulder Joint

66 Questions…? What’s Next? Lab: Muscles Next Lecture: Muscles cont… Wed Lab: Finish Muscles & Review


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