Download Chapter 10B - FacultyWeb

Chapter 10
The Muscular
System
Part B
Shilla Chakrabarty, Ph.D.
Copyright © 2010 Pearson Education, Inc.
Muscles of the Thorax
• Muscles of respiration
• External intercostals—more superficial muscles that
elevate ribs for inspiration
• Internal intercostals—deeper muscles that aid forced
expiration
• Diaphragm
• Partition between thoracic and abdominal cavities
• Most important muscle in inspiration
• Innervated by phrenic nerves
Copyright © 2010 Pearson Education, Inc.
External
intercostal
(a)
Copyright © 2010 Pearson Education, Inc.
Internal
intercostal
Figure 10.10a
Xiphoid process of sternum
Foramen for inferior
vena cava
Central
tendon of
diaphragm
Foramen
for aorta
12th rib
(b)
Copyright © 2010 Pearson Education, Inc.
Foramen for
esophagus
Costal cartilage
Diaphragm
Lumbar
vertebra
Quadratus
lumborum
Psoas major
Figure 10.10b
Muscles of the Abdominal Wall
• Four paired muscles; their fasciae and aponeuroses form
the lateral and anterior abdominal wall
• Muscles that flex vertebral column and compress
abdominal wall are:
• Internal obliques
• External obliques
• Transversus abdominis
• Rectus abdominis
• Origin Pubic crest and symphysis
• Insertion Xiphoid process and costal cartilage of ribs 5-7
• Function Flex and rotate lumbar region of vertebral column
Copyright © 2010 Pearson Education, Inc.
Pectoralis major
Serratus anterior
Linea alba
Transversus abdominis
Internal oblique
External oblique
Aponeurosis of the
external oblique
(a)
Copyright © 2010 Pearson Education, Inc.
Tendinous
intersection
Rectus
abdominis
Inguinal ligament
(formed by free
inferior border of
the external oblique
aponeurosis)
Figure 10.11a
Muscles of the Abdominal Wall
• Fascicles of these muscles run at angles to
one another, providing added strength
• All are innervated by intercostal nerves
• Actions of these muscles
• Lateral flexion and rotation of the trunk
• Help promote urination, defecation, childbirth,
vomiting, coughing, and screaming
Copyright © 2010 Pearson Education, Inc.
Rectus
abdominis
Internal
oblique
External
oblique
IIiac crest
Pubic
tubercle
Transversus
abdominis
Inguinal
ligament
Lumbar
fascia
Lumbar
fascia
(b)
Copyright © 2010 Pearson Education, Inc.
Figure 10.11b
Muscles of the Pelvic Floor
• Pelvic floor (pelvic diaphragm) is composed of two paired muscles
•
Levator ani
•
Coccygeus
• Both are innervated by sacral nerves
• Functions of the pelvic diaphragm
 Seals the inferior outlet of the pelvis
 Supports pelvic organs
 Lifts pelvic floor to help release feces
 Resists increased intra-abdominal pressure
Anterior
Levator
ani
Symphysis pubis
Urogenital diaphragm
Urethra
Vagina
Anal canal
Pubococcygeus
IIiococcygeus
Obturator
internus
Coccyx
Levator ani
Coccygeus
Piriformis
(a)
Copyright © 2010 Pearson Education, Inc.
Posterior
Pelvic
diaphragm
Superficial Muscles of the Thorax
• Most are extrinsic shoulder muscles
 Act in combination to fix the shoulder girdle (mostly the
scapula) and move it to increase range of arm
movements
 Actions include elevation, depression, rotation, lateral
and medial movements, protraction, and retraction
• Two groups of muscles: anterior and posterior
Copyright © 2010 Pearson Education, Inc.
Superficial Muscles of the Thorax
• Anterior extrinsic shoulder muscles
• Pectoralis minor
• Serratus anterior
• Subclavius
Sternocleidomastoid
Deltoid
Pectoralis
major
Sternum
Biceps brachii
(a)
Copyright © 2010 Pearson Education, Inc.
Subclavius
Clavicle
Subscapularis
Pectoralis minor
Coracobrachialis
Serratus anterior
Humerus
Superficial Muscles of the Posterior Thorax
• Posterior extrinsic
shoulder muscles
 Trapezius
 Levator scapulae
 Rhomboids (major
and minor)
Trapezius
Levator
scapulae
Supraspinatus
Clavicle
Deltoid
Rhomboid
minor
Rhomboid
major
Spine of
scapula
Infraspinatus
Teres minor
Teres major
Humerus
Latissimus
dorsi
(c)
Copyright © 2010 Pearson Education, Inc.
Muscles Crossing the Shoulder Joint
• Nine muscles cross the shoulder joint to insert on and
move the humerus
• Some originate off the scapula; others originate off the
axial skeleton
• Three are prime movers of the arm
• Pectoralis major
• Latissimus dorsi
• Deltoid
• Actions include flexion, extension, adduction,
abduction, and rotation of humerus
Copyright © 2010 Pearson Education, Inc.
Muscles Crossing the Shoulder Joint
• Four muscles are rotator cuff muscles
• Supraspinatus
• Infraspinatus
• Teres minor
• Subscapularis
• Reinforce the capsule of the shoulder
• Act as synergists and fixators
• Two additional muscles are synergists: coracobrachialis and teres major
Muscles Crossing the Elbow Joint
• Posterior extensor muscles
• Triceps brachii—prime mover of forearm extension
• Anconeus—weak synergist
Copyright © 2010 Pearson Education, Inc.
Muscles Crossing the Shoulder Joint
Clavicle
Supraspinatus*
Spine of scapula
Deltoid (cut)
Greater tubercle
of humerus
Infraspinatus*
Deltoid
Sternum
Teres minor*
Pectoralis major
Coracobrachialis
Teres major
Triceps brachii:
Lateral head
Long head
Triceps brachii:
Lateral head
Long head
Medial head
Latissimus dorsi
Biceps brachii
Brachialis
Brachioradialis
(a) Anterior view
Copyright © 2010 Pearson Education, Inc.
Humerus
Olecranon process
of ulna
Anconeus
(b) Posterior view
* Rotator cuff muscles
Muscles of the Forearm
• Actions: movements of the
wrist, hand, and fingers
• Most anterior muscles are
flexors
• Some forearm muscles act
to produce pronation and
supination of the forearm
Superficial transverse
ligament of palm
Palmar aponeurosis
Flexor retinaculum
Flexor digitorum
superficialis
Flexor carpi ulnaris
Palmaris longus
Flexor carpi radialis
Copyright © 2010 Pearson Education, Inc.
Flexor pollicis longus
Extensor carpi radialis longus
Brachioradialis
Pronator teres
Medial epicondyle
of humerus
Medial head of
triceps brachii
Pronator quadratus
Tendon of biceps brachii
Biceps brachii
(a)
Muscles of the Forearm
Extensor
expansion
• Most posterior muscles
are extensors
Tendons of
extensor
digitorum
Extensor pollicis
longus
Extensor pollicis
brevis
Abductor
pollicis longus
Extensor digitorum
Extensor carpi
radialis brevis
Extensor carpi
radialis longus
(a)
Copyright © 2010 Pearson Education, Inc.
Tendons of extensor carpi
radialis brevis and longus
Extensor indicis
Extensor digiti
minimi
Extensor carpi
ulnaris
Flexor carpi
ulnaris
Anconeus
Insertion of
triceps brachii
Brachioradialis
Antero-medial
Postero-lateral
Intrinsic Muscles of the Hand
• Small weak muscles
• Lie entirely within the palm of the hand
• Control precise movements of metacarpals and fingers
(e.g., threading a needle)
• Abductors and adductors of the fingers
• Produce opposition—move the thumb toward the little
finger
Copyright © 2010 Pearson Education, Inc.
Muscles Crossing Hip and Knee Joints
• Most anterior muscles flex the femur at the hip and extend the leg at
the knee (fore swing of walking)
• Most posterior muscles extend the thigh and flex the leg (backswing
of walking)
• Medial muscles all adduct the thigh
• All three groups are enclosed by the fascia lata
Copyright © 2010 Pearson Education, Inc.
Movements of the Thigh
• Include flexion, extension,
abduction, adduction,
circumduction, and rotation
• Thigh flexors pass in front of
the hip joint
• Iliopsoas (iliacus and
psoas major): prime
mover of flexion
12th rib
Quadratus lumborum
Psoas minor
Iliac crest
Psoas major
Iliopsoas
Iliacus
Tensor fasciae latae
Pectineus
Sartorius
Quadriceps femoris
• Rectus femoris
• Vastus lateralis
• Rectus femoris
Adductor longus
Gracilis
Adductor magnus
• Vastus medialis
Tendon of quadriceps femoris
Patella
Patellar ligament
(a)
Copyright © 2010 Pearson Education, Inc.
5th lumbar vertebra
Anterior superior iliac spine
• Tensor fasciae latae
• Assisted by medial
adductors and sartorius
12th thoracic vertebra
Movements of the Thigh
• Thigh extensors
• Hamstring muscles
(prime movers of
extension)
• Biceps femoris
• Semitendinosus
• Semimembranosus
• Gluteus maximus
(prime mover during
forceful extension)
Copyright © 2010 Pearson Education, Inc.
Muscles of the Thigh that Move the Knee Joint
12th rib
• Quadriceps femoris—
sole extensor of the knee
• Hamstring muscles—
flex the knee, and are
antagonists to the
quadriceps femoris
12th thoracic vertebra
Quadratus lumborum
Psoas minor
Iliac crest
Psoas major
Iliopsoas
Iliacus
5th lumbar vertebra
Anterior superior iliac spine
Tensor fasciae latae
Pectineus
Sartorius
Quadriceps femoris
• Rectus femoris
Adductor longus
Gracilis
Adductor magnus
• Vastus lateralis
• Vastus medialis
Tendon of quadriceps femoris
Patella
Patellar ligament
(a)
Copyright © 2010 Pearson Education, Inc.
Muscles of the Anterior Compartment of the Leg
• Primary toe extensors and
ankle dorsiflexors
• Tibialis anterior
Fibularis longus
• Extensor digitorum longus
Gastrocnemius
• Extensor hallucis longus
Tibia
• Fibularis tertius (not always
present)
Tibialis anterior
Extensor digitorum longus
Soleus
Extensor hallucis longus
Fibularis tertius
Superior and inferior
extensor retinacula
Extensor hallucis brevis
Extensor digitorum brevis
Copyright © 2010 Pearson Education, Inc.
(a)
Muscles of the Posterior Compartment of
the Leg
• Flexors of the foot and the toes
• Gastrocnemius
• Soleus
• Plantaris
Plantaris
Gastrocnemius Medial head
Lateral head
• Popliteus
• Tibialis posterior
Tendon of
gastrocnemius
• Flexor digitorum longus
Calcaneal tendon
• Flexor hallucis longus
Medial malleolus
Lateral malleolus
Calcaneus
(a) Superficial view of the posterior leg.
Copyright © 2010 Pearson Education, Inc.
Anterior
Posterior
Muscles
Origin
Insertion
Function
Ilipsoas
Transverse processes
ofT12-L5; iliac fossa
Lesser trochanter of
femur
Major flexion of thigh
Sartorius
Anterior superior iliac spine
Proximal tibia
Flexes and laterally rotates
thigh
Copyright © 2010 Pearson Education, Inc.
Lateral
Copyright © 2010 Pearson Education, Inc.
Medial