Today and Wednesday – muscles!

• how muscles work – in general• muscles that move the mandible• abdominal wall muscles

• anterior and posterior• inferior and superior• inguinal hernia’s

• muscles that move the humerus and scapula• rotator cuff tears, impingement syndrome

• muscles that move the femur• sprains, strains and “Charley horse”

• muscles that move the foot• shin splints, anterior compartment syndrome• Achilles tendon injuries

skeletal cardiac smooth

Tendon

Deep fascia

EpimysiumEpi = upon, above

PerimysiumPeri = around

EndomysiumEndo = within

Connective tissue wrappings of skeletal muscle

Myo, mys = muscle

1 muscle fiber = 1 muscle cellMuscle cells are multinucleated

Working outAtrophy & agingSteroids

Bellies

Insertion

Insertion

Origins Origins

Muscle attachments

Ligaments: bone to boneTendons: muscle to bone

Direct vs Indirect attachment

Aponeurosis

Muscle to skinMuscle to muscle via tendon sheet

Synaptic vesiclescontaining Ach (acetylcholine)

Motor endplate

Calcium + ATP = muscle contractionLow blood Ca and muscle

Neurotoxins• botulism• curare• tetanus toxin

Neuromuscular junction

Attachments:• Proximal• Distal

• Direct• Indirect

Muscle actions:• agonist• antagonist• synergist• fixator

Biceps brachiiBrachialisTriceps brachii

Extending your knee

• Extend your knee a few times• Where are the agonist muscles that extend

your knee?• Which joint do they cross?• When you extend you knee, where are the

antagonist muscles located?

Quadriceps = agonists Hamstrings = antagonists

Mandibular fossa

1. Depress & elevate2. Medial & lateral excursion3. Protraction & retraction

Moving the mandible

Temporalis

Masseter

• attachments• actions

Muscles that move the mandible

Medial pterygoid Lateral pterygoid

• attachments• actions

Depress mandible• gravity• digastric muscle• geniohyoid & mylohyoid• when hyoid is fixed

Temporalismassater

Medial pterygoidLateral pterygoid

MylohyoidDigastric

Rectus abdominus

External oblique

Those flashy “core” muscles

OverdevelopedPectoralis major

Rectus abdominis

External oblique

Internal oblique

Transversus abdominis

• Attachments• Actions

Muscles that move (and protect) the abdomen/trunk

ABC

D Rectus sheath(aponeurosis)

Linea alba

Abdominal wall• abdominal muscles• back muscles

• quadratus lumborum• Psoas (iliopsoas)

• diaphragm• pelvic diaphragm• “holes” in the wall

• hernia (hiatal) • congenital or acquired

Spermatic cord

Inguinal canal – men & womenintestines

Parietal peritoneum

scrotum

Inguinal hernia

1. Name the 4 layers of connective tissue that wrap around skeletal muscles.

2. Which ones are continuous with a tendon?

3. Botox (botulinum toxin) works by blocking the release of ACh at the neuromuscular junction. How does this help with:

• crossed eyes• uncontrolled blinking • those pesky forehead wrinkles

1. Location of shoulder muscles2. Which joints do these muscles cross?

Muscle that move the humerus and scapula

3. What movements do these muscle perform?

• attachments• actions (on humerus)

• abduct (lateral fibers)• flex, medially rotate (anterior fibers)• extend, laterally rotate (posterior fibers)

Deltoid

• attachments• actions

• flexion (agonist)• adduction• medial rotation• elevate ribs

Subscapularis• medially rotate

Supraspinatus• abduct

Infraspinatus•Extend•Laterally rotate

Teres minor• adduct• laterally rotate

4 Rotator cuff muscles

Scapula movers & stabilizers

Levator scapulae• elevate scapula• flex neck

Rhomboids• retract• elevate• fix scapula• rotate downward

Trapezius• elevate, rotate upward (S)• retract (M)• depress (I)• extend neck• flex laterally (one trap)

TrapeziusRhomboidsDeltoidTeres majorTricepsLatissimus dorsi

SupraspinatusInfraspinatusSubscapularis Levator scapulae

Impingement syndrome

Rotator cuff tears

1. Location of hip and thigh muscles2. Which joints do these muscles cross?

Muscles that move the femur

3. What kind of movements do these muscle perform?

Iliopsoas• flex hip

Adductors• adduct femur• flex hip• flex knee• (lateral rotation)

Lateral rotators• piriformis• obturator externus

Groin pull

TensorFasciaeLatae (TFL)• flex• abduct• med. rot

Rectus Femoris• flex hip• extend knee Vastus lateralis

vastus intermediusVastus medialis• extend knee

• Charley horse• patella tracking

Patellar tendon

Iliotibial Band (IT band)

G. MaximusTensor Fasciae Latae• flex femur• abducts femur• medially rotates femur• stabilizes knee

G. minimus

piriformis

G. Medius

G. Maximus

Gluts: extend, abduct, laterally rotates femurPiriformis: abduct, laterally rotates femur

Hamstring group: flex knee, extend hip

Muscle strains from quick extensions

Anterior

Posterior

Muscle compartments of the thigh

medial

anterior

posterior

Compartments:• each wrapped with deep fasciae• each has own nerve & blood supply• compartment syndrome

IliopsoasTFLSartorius

Adductorsquads Glut max & medius

hamstringsPiriformisSciatic nerve

Achilles tendon

calcaneus

gastrocnemiusAttachments of the gastrocnemiusAttachments of the soleus

Actions of the gastrocnemius1. Flex the knee2. Plantarflex the foot

Actions of the soleus1. Plantarflex the foot

Ruptured Achilles tendonPulled calf muscle

Tibialis Anterior

Tibialis anterior

AttachmentsActions

1. Dorsiflex ankle2. Invert foot3. Support arch

Shin splintsCompartment syndrome

1. Agonist of elbow extension?

2. A strained biceps brachii would result in pain when ____.

3. When viscera protrude through a weak point in the diaphragm, what is that condition called (be specific).

4. In a male, what passes through the inguinal canal?

5. Name one muscle that moves the mandible laterally.