Skeletal Muscles

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Skeletal Muscles
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Muscles are named according to function

• Flexion
• Flexor carpi radialis
• Flexor digiti minimi brevis

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Muscles are named according to function

• Extension
• Extensor indicis

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Muscles are named according to function

• Adduction Adductor pollicis

• Abduction Abductor digiti
  minimi

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Muscles are named according to function

• Levator levator scapulae

Tensor Tensor fascia lata
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Muscles are named according to Origin/Insertion

• 10. Sternocleidomastoid

• 5. sternohyoid

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Muscles are named according to the number of
bellies

• Biceps brachii

Triceps brachii
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Skeletal Muscles Lever Systems
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Lever Systems and Leverage Parts of the Lever

• 1. Fulcrum or Axis the fixed point on which a
  lever moves
• 2. Resistance the load to be overcome, the
  weight
• 3. Effort the force exerted to overcome the
  resistance

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First class leverE--- F---R
Effort semispinalis and other posterior neck
muscles Fulcrum atlanto-occipital joint
Resistance weight of the head

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Second Class Lever F R E

• Fulcrum distal heads of the
  metatarsals
• Resistance weight of body
• Effort contraction of gastrocnemius

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Third Class Lever F E-- R

• Fulcrum elbow/olecranon process of the ulna
• Effort contraction of the biceps brachii
• Resistance weight of forearm and ball

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And now for some specific musclesMuscles of
Facial Expression

• Get Body Smart.com

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Fig. 11.04a,b
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Extrinsic Muscles of the Eye

• All innervated by III cranial nerve, Oculomotor
• Superior rectus
• Inferior rectus
• Medial Rectus
• Inferior Oblique
• Lateral Rectus 6th cranial nerve, Abducens
• Superior Oblique 4th cranial nerve, Trochlear

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Fig. 11.05a,b
Most 3 Others SO4LR6
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And now for some specific musclesMuscles of
Mastication (Chewing)

• Muscles of Mastication

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Extrinsic Muscles of the Tongue

• Genioglossus
• Styloglossus
• Palatoglossus
• Hyoglossus
• Innervation Mostly 12th cranial nerve
  Hypoglossal

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More Specific Muscle Groups Strap muscles of
the neck

• Digastric
• Stylohyoid
• Mylohyoid
• Geniohyoid
• Omohyoid
• Sternohyoid
• Sternothyroid
• Thyrohyoid

Action depends on the relationship of the muscle
to the hyoid bone Suprahyoid muscles elevate
the hyoid bone Infrahyoid muscles depress the
hyoid bone
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Fig. 11.08a
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Fig. 11.08b
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Muscles of the Neck that Move the Head

• Sternocleidomastoid
• O sternum and clavicle
• I mastoid process
• A together flex the neck
• individually laterally rotate and
  flex the head to the side
  opposite the contraction.
• N Cranial nerve XI, spinal accessory

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Fig. 11.09
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More Neck Muscles that Move the Head

• Semispinalis capitis
• Splenius capitis
• Longissimus capitis

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Muscles that act on the abdomen

• Muscles of the Abdomen

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Muscles of the thorax breathing
DIAPHRAGM EXTERNAL INTERCOSTALS INTERNAL
INTERCOSTALS
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Diaphragm

• O xiphoid process costal cartilages of
  lowest 6 ribs lumbar vertebrae
• I central tendon of the diaphragm
• A contraction, flattens the diaphragm,
  increasing the volume of the thorax so that air
  flows in relaxation allows diaphragm to assume
  its relaxed domed state, decreasing the volume of
  the thorax, and pushing air out
• N phrenic nerve (C3-C5)

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Muscles of the Pelvic Floor

• Pelvic Diaphragm supports and maintains pelvic
  viscera resists increased intra-abdominal
  pressure constricts anus, urethra, and vagina.
  Mostly innervated by the pudendal nerve (sacral
  spinal nerves)
• Levator ani (elevates the anus)
• Pubococcygeus
• Iliococcygeus
• Ischiococcygeus

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Borders of the perineum

• Anterior pubic symphysis
• Lateral ischial tuberosities
• Posterior Coccyx
• Anterior(urogenital) Triangle vs. Posterior
  (anal) triangle
• (as differentiated from the Bermuda triangle)

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Muscles of the Perineum

• Superficial group stabilizes perineum helps
  expel urine, assists in erection in both sexes
• Superficial transverse perineal
• Bulbospongiosus
• ishiocavernosus

All innervated by the pudendal nerve
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Muscles of the Perineum

• Deep group helps expel last drops of urine and
  semen keeps urethra/anus
• Deep transverse perineus
• External urethral sphincter
• External anal sphincter

All innervated by the pudendal nerve
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Fig. 11.12
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Fig. 11.13
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Muscles of the chest and shoulder that move the
humerus

• Shoulder Muscles

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Muscles that move the pectoral girdleAnterior

• Pectoralis minor
• O 3-5 ribs
• I coracoid process
• N pectoral nerves
• A abducts scapula elevates ribs when scapula is
  fixed

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Muscles that move the pectoral girdle-Anterior

• Serratus anterior
• O 1-8 ribs
• I vertebral border and inferior angle of
  scapula
• N long thoracic
• A abducts scapula and rotates it superiorly
• the boxers muscle -- important in horizontal
  arm movements like punching and pushing

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Muscles that move the pectoral girdle- Posterior

• Trapezius
• O occipital one ligamentum nuchae C7-C12
  spines
• I clavicle, acromion, scapular spine
• N XI and C3/C4 spinal nerves
• A elevates clavicle, adducts scapula,
  elevates/depresses/extends the head

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Muscles that move the pectoral girdle- Posterior

• Levator scapulae deep to sternomastoid and
  trapezius
• Rhomboid major and minor used when forcibly
  lowering the raised upper limbs
• (using a sledgehammer)

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• Muscles of the Shoulder and Humerus

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Fig. 11.10a,b
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2
3
4
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6
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Fig. 11.14a,b
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Muscles that move the humerus

• Pectoralis major
• O clavicle, sternum, 2-6 ribs
• I greater tubercle of the humerus
• N pectoral nerves
• A adducts and medially rotates arm flexes arm

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Muscles that move the humerus

• Latissimus dorsi
• O spines of lower 6 thoracic vertebrae, lumbar
  vertebrae, sacrum, ilium, lower 4 ribs.
• I intertubercular sulcus/groove of humerus
• N thoracodorsal nerve
• A extends, adducts, and medially rotates arm
  at shoulder draws arm inferiorly and posteriorly
• swimmers muscle think crawl

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Muscles that move the humerus

• Deltoid O clavicle, acromion, scapular spine
• I lateral surface of humerus
• N axillary nerve
• A abducts arm
• -- Teres major O inferior angle of scapula
• I intertubercular groove of humerus
• N subscapular nerves
• A extends, adducts, medially rotates
  arm

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Rotator Cuff

• Subscapularis
• Supraspinatus
• Infraspinatus
• Teres minor

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• Subscapularis
• O subscapular fossa
• I lesser tubercle of humerus
• N subscapular nerves
• A medially rotates arm

• Supraspinatus
• O supraspinous fossa
• I greater tubercle of humerus
• N suprascapular nerve
• A assists deltoid in abduction

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Teres minor O inferior lateral border of
scapulaI greater tubercle of humerusN
axillary nerve A lateral rotation, adduction
of arm

• Infraspinatus
• O infraspinous fossa
• I greater tubercle of humerus
• N suprascapular nerve
• A laterally rotates arm

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Muscles that move the forearm

• FLEXORS EXTENSORS
• Biceps Brachii Triceps Brachii
• Brachialis
• Brachioradialis

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Pronators and Supinators

• Pronator teres
• Action pronation
• Nerve median
• Supinator
• Action Supination
• Nerve deep radial

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Muscles that move the wrist, hand, thumb, and
fingers

• Anterior group
• flexors originate on medial epicondyle
• Median and ulnar nerves
• Posterior group
• extensors originate on lateral epicondyle
• radial nerve

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Anterior compartment

• Flexor carpi radialis (radial nerve)
• Flexor carpi ulnaris (ulnar nerve)
• Palmaris longus
• Flexor digitorum superficialis
• Flexor digitorum profundus
• Flexor pollicis longer

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Posterior compartment of the forearm all
innervated by part of the radial nerve

• Extensor carpi radialis longus
• Extensor carpi radialis brevis
• Extensor digitorum
• Extensor carpi ulnaris
• Abductor pollicis longus
• Extensor pollicis brevis
• Extensor indicis

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Intrinsic muscles of the hand

• Thenar eminence
• Abductor pollicis brevis (M)
• Opponens pollicis (M)
• Flexor pollicis brevis (MU)
• Adductor pollicis (U)
• Hypothenar eminence all U
• Abductor digiti minimi
• Flexor digiti minimi
• Opponens digiti minimi

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And the interosseous muscles of the hand- all
ulnar nerve

• 4 dorsal interossei
• abductors of fingers II, III, IV
• 3 palmar interossei
• adductors of fingers II, IV, V
• Lumbricals for really precise/fine movement
• connect flexor digitorum profundus tendons with
  the extensor expansions of dorsal interossei

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More on the Hand

• Movements adduction, abduction, opposition
• Axial line of hand 3rd finger/metatarsal
• Palmar aponeurosis
• Fibrous sheaths around the tendons..with synovial
  fluid bursae
• Hand infections can be very serious
• Flexor retinaculum

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Muscles that move the vertebral column

• Erector spinae complex
• Extend the vertebral column
• Maintenance of posture
• Innervation dorsal rami of spinal nerves
• There are a multitude of small muscles that
  connect individual vertebrae. Just know that they
  exist.

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More Muscles that Move the vertebral column

• Scalenes
• O Cervical vertebrae to lst 2 ribs
• I anterior spine
• N cervical spinal nerves
• A assist in inspiration, rotation, flexion of
  neck

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Muscles that produce movement at the hip

• Strengthen and stabilize hip joint
• Transmit weight to from trunk, upper extremity,
  and head and neck
• Help preserve erect posture
• Move the body through space
• Provide stable platform for trunk flexion

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Muscles to know in detail

• Iliopsoas (anterior to the spine)
• O lumbar vertebrae, iliac fossa
• I lesser trochanter of femur
• N L2/L3, femoral nerve
• A flexes thigh and vertebral column laterally
  rotates thigh

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Muscles to know in detail

• Gluteus maximus
• O-iliac crest, sacrum, coccyx, aponeurosis of
  erector spinae
• I-gluteal tuberosity of femur iliotibial tract
• N inferior gluteal nerve
• A- extends thigh laterally rotates thigh

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Muscles to know in detail

• Gluteus medius and minimus
• O ilium
• I greater trochanter
• N superior gluteal nerve
• A abducts and medially rotates the femur.
• When R leg is swinging, it holds up the L
  pelvis by pulling against the fixed thigh on the
  L side.

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iliopsoassartoriusfemoral triangleadductors
tensor fascia lata
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Gluteus maximus
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Tensor fascia lata

• O iliac crest
• I tibia via iliotibial tract
• N superior gluteal nerve
• A flexion and abduction of thigh

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More thigh muscles

• Piriformis
• Obturator internus and externus
• Superior and inferior gemellus
• Quadratus femoris

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• Forearm muscles

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Muscles of the Posterior Thigh Hamstrings

• These muscles cross the hip AND the knee.
• Action of all 3 flexion of the knee and
  extension of the thigh
• Innervation of all tibial nerve (subdivision of
  the sciatic)

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Hamstrings, continued.

• Biceps femoris the lateral hamstring
• O ischial tuberosity, femur
• I fibular head, lateral condyle of tibia
• Semitendinosus, Semimembranosus the medial
  hamstrings
• O ischial tuberosity
• I medial condyle and surface of the tibia

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Hamstrings.
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Muscles of the anterior thigh
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Fig. 11.15a
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The end . . . . .for today
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