ANP1111 Lecture 9 Muscles Part 1 PDF

Chapter 10: The Muscular System http://en.wikibooks.org/wiki/Human_Physiology/The_Muscular_System  Fig. 9.1a MUSCLE ATTACHMENTS most muscles span joints most muscles are attached to bones in at least 2 places origin: …………………….. insertion: …………………….. Most...

Chapter 10: The Muscular System http://en.wikibooks.org/wiki/Human_Physiology/The_Muscular_System  Fig. 9.1a MUSCLE ATTACHMENTS most muscles span joints most muscles are attached to bones in at least 2 places origin: …………………….. insertion: …………………….. Most attachments are indirect attachments involving either a tendon or an aponeurosis  ARRANGEMENT OF FASCICLES all skeletal muscles have fascicles 4 basic patterns: Parallel: can be straplike (sartorius) or fusiform (biceps brachii) Pennate: unipennate (eg: extensor digitorum longus) bipennate (eg: rectus femoris) multipennate (eg: deltoid) Convergent: muscle is triangular or fan- shaped (eg: pectoralis major) Circular: concentric rings surround ext openings & contract to close opening (eg: obicularis oris) Fig. 10.1  5.2 INTERACTIONS OF SKELETAL MUSCLES muscles can work together or in opposition 3 functional groups: prime movers, antagonists & synergists and muscles can change their roles depending on the movement 1) Prime Mover: …………………………………………………………………………………….. eg: biceps brachii & elbow flexion 2) Antagonist: …………………………………………………………………………………….. can provide resistance to prevent overshoot or control rate of movement a single muscle can be a prime mover for one action & an antagonist for another action - eg: biceps brachii & triceps brachii 3) Synergists: muscles that help the prime mover by: a) promoting the same movement b) reducing undesirable movements (eg: finger flexor muscles cross both wrist & phalangeal joints) c) some are fixators- eg: muscles involved in posture Naming Skeletal Muscles 1. Location of muscle: bone or body region – eg: temporalis, intercostal 2. Shape of muscle: eg: deltoid (triangular), right & left trapezius muscles form a trapezoid 3. Relative size of muscle: maximus, minimus, longus, brevis – eg: gluteus maximus & gluteus minimus 4. Direction of muscle fibers: eg: rectus = straight, parallel to midline (rectus femoris); also transversus abdominis, oblique 5. Number of origins: biceps, triceps, quadriceps – eg: biceps brachii 6. Location of muscle’s origin and/or insertion: if both are indicated, origin always indicated first – eg: sternocleidomastoid (neck region – dual origin on sternum and clavicle & insertion on mastoid process of temporal bone) 7. Action of the muscle: flexor, extensor, adductor – eg: adductor longus for thigh adduction & supinator muscle in forearm What can we say about the extensor carpi radialis longus??? Fig. 10.3. Lever Systems 5.3 Muscles of the Head – Facial Expression insert into skin or other muscles, not bones; innervated by the facial nerve epicranius = main muscle of scalp – consists of: (i) frontal belly: raises eyebrows, wrinkles forehead (ii) occipital belly: fixes aponeurosis and pulls scalp posteriorly orbicularis oculi: surrounds rim of orbit; protects eyes from light by producing blinking, squinting, also draws eyebrows down zygomaticus (zygomatic bone to mouth): smiling muscle; major & minor orbicularis oris: lips; multi-layered; closes, purses, protrudes lips mentalis (mandible to chin): V-shaped pair – protrudes lower lip (pout); wrinkles chin ʘ buccinator (mandible/maxilla to orb.oris): deep to masseter – whistling, sucking; hold food in place when chewing; especially in nursing infants platysma (fascia of chest to mandible): helps depress mandible; tenses skin of neck Fig. 10.6 Fig. 10.7 A&P Flix: Go into the Study Area of Mastering A&P; Choose Animations & Videos, then choose A&P Flix Buccinator 5.4 Muscles that move the tongue genioglossus (mandible to inferior tongue & hyoid bone): prime mover of tongue protrusion; anchors tongue to prevent obstruction of respiration hyoglossus (hyoid bone to inferolateral tongue): depresses tongue, especially lateral margins styloglossus (styloid process of temporal bone to inferolateral tongue): retracts & elevates tongue Fig. 10.8c 2. Muscles of the Head: Mastication, etc 4 pairs involved in chewing; all innervated by mandibular division of cranial nerve V ʘ masseter (zygomatic bone to mandible): prime mover of jaw closure ʘ temporalis (temporal bone to mandible): elevates and retracts mandible (closes jaw); maintains closed jaw at rest medial and lateral pterygoid (sphenoid [for medial, also palatine bone & maxilla] to mandible;): both two-headed; additional jaw movements (eg: side-to-side grinding movements) buccinator (mandible/maxilla to orbicularis oris): compresses cheek to help keep food between grinding surfaces of teeth during chewing Fig. 10.8 Masseter Temporalis 5.5 Muscles of the Neck & Vertebral Column: Head & Trunk Movements the head is moved by muscles originating from the axial skeleton sternocleidomastoid (manubrium/clavicle to mastoid process of temporal): 2- headed; deep to platysma; prime mover (both sides) of head flexion; muscle action on one side for head rotation to opposite side, head tilts to same side scalenes (cervical vertebrae to 1st two pairs of ribs): more lateral and deep to platysma & sternocleidomastoid – elevate first two pairs of ribs, role in coughing, flex & rotate neck ʘ splenius (vertebrae to mastoid process of temporal): superficial; “bandage muscle”; head extension (both sides) or if one side, rotation, tilts to same side Fig. 10.10a,b Splenius capitis 5.6 Muscles of the Neck & Vertebral Column: Head & Trunk Movements erector spinae: prime mover of back extension; consists of 3 columns of muscles (iliocostalis, longissimus, spinalis); resistance to bending forward & extensors for return to erect position ʘ semispinalis: deeper, composite muscle from thoracic region to head; extends vertebral column & head, rotation of head, synergistic with sternocleidomastoid muscles quadratus lumborum (iliac crest to lumbar vertebrae): individual muscles flex vertebral column laterally; jointly to extend lumbar spine & fix 12th rib; maintain upright posture Fig. 10.10d Semispinalis capitis  Fig. 10.11 External Internal 5.7a Muscles of Respiration ʘ external intercostals: 11 pairs, originate on rib above; oblique; pull ribs up & out to elevate rib cage during inspiration;1st ribs fixed by scalene muscles) internal intercostals: 11 pairs, originate on rib below;  to external intercostals; pull ribs down & in to depress rib cage during expiration; 12 th ribs fixed by quadratus lumborum) diaphragm: dome-shaped when relaxed; prime mover of inspiration External intercostals  5.7b Muscles of Abdominal Wall ʘ rectus abdominis – medial superficial; pubis to rib cage; lumbar rotation, fix & depress ribs, stabilize pelvis during walking external oblique – largest & most superficial lateral muscle; together they increase abdominal pressure & flex vertebral column; individually → rotation internal oblique – deeper, but same actions as ext obliques transversus abdominis – deepest; compresses abdominal contents Fig. 10.12 Rectus abdominis 5.8 Muscles of the pelvic floor and perineum levator ani (pubis to inner coccyx): supports visceral organs of pelvis & forms supportive sling at anorectal junction & vagina; resists downward increases in intra-abdominal pressure (e.g. during coughing, vomiting) coccygeus (spine of ischium to sacrum & coccyx): supports pelvic viscera & coccyx (e.g. pulls it forward after childbirth) urogenital diaphragm: supports pelvic organs and constricts urethra levator ani & coccygeus = pelvic diaphragm 5.10 Superficial Muscles of Thorax:arm movements pectoralis major (sternum/rib cartilages to humerus): prime mover of arm adduction (with LD); rotates arm medially; assists in arm flexion ʘ latissimus dorsi (vertebrae to humerus): broad, flat back muscle; prime mover of arm extension, arm adductor, rotates arm at shoulder, rowing, swimming ʘ deltoid (clavicle/scapula to humerus): thick, rounded, site of IM injection, prime mover of arm abduction (all fibers); also lateral & medial rotations, flexion or extensions if only some fibers used; swinging arm when walking Fig. 10.14 trapezius (occipital bone & vertebrae to scapula): superficial, stabilizes, raises, retracts, rotates scapula rhomboids (vertebrae to scapula): deep to trapezius; aid in scapula movements (eg: squaring shoulders, rotation when lowering arm) + subscapularis = rotator cuff muscles Fig. 10.14c Latissimus dorsi Deltoid