Histology of Muscle

1. Skeletal, Striated, Voluntary Muscle:

Nucleus pushed to one side of cells

2. Smooth, Unstriated, Involuntary Muscle:

Nucleus in center of cell

3. Cardiac, Striated, Involuntary; Nucleus in

center of branching & anastomosing cells

and cells connected by intercalated

discs(desmosomes and gaps) specialized

cells conduct messages to contract (Purkinje

cells)

Skeletal (Voluntary, Striated)

MuscleSkeletal, Striated, Voluntary Muscle:

Nucleus pushed to one side of cells

Nucleus

Nucleus

~2,000X

1.5um

plastic

section

c

o

n

t

r

a

c

t

i

o

n

Z

I

A

H (& M)

A

I

Z

one sarcomere

Z

I

A

H (& M)

A

I

Z

N

u

c

l

e

u

s

C

o

n

t

r

a

c

t

i

o

n

H

Sarcomere shortened =

contraction

ACTIN

MYOSIN

MYOSIN

Motor end plates terminating on muscle fibers

Nerve fibers

External alligator

musculature (Skeletal)

Massive

Pterygoideus m.

Cardiac (Involuntary) Muscle:

only in HEART

Cardiac, Striated, Involuntary; Nucleus in

center of branching & anastomosing cells

and cells connected by intercalated

discs(desmosomes and gaps) specialized

cells conduct messages to contract

(Purkinje cells)

L RInterventricular

Septum

(Posterior)

Bicuspid

Valve

Left Atrium

Thick

myocardium

Thin

myocardium

Tricuspid

Valve

Apex

Papillary

Muscle

Chordae Tendineae

Right Atrium w/

Pectinate Musc.

Pumps

blood to

Body

Pumps blood to

Lungs through

Pulmonary Arteries

Cardiac Muscle (Involuntary):

yellow arrows = intercalated Discs

Nucleus

Nuclei

Cardiac Muscle (Involuntary):

yellow arrows = intercalated Discs

Cardiac Muscle (Involuntary):

yellow arrows = intercalated Discs

SA node to AV node to

interventricular septum

Smooth (Involuntary) Muscle –

Digestive Tube, Urinary and

Reproductive system and

Arteries, etc..

Smooth, Unstriated, Involuntary Muscle:

Nucleus in center of cell

mesentery

serosa

Outer Longitudinal smooth muscle

Ganglion cells

of ANS

Lamina

propria Muscularis

mucosa

Lymphoid

tissue

Submucosa

Submucosal

Gland

saMucosa

Inner Circular smooth muscle

External gland e.g.

Pancreas

Stratified Squamous to

Columnar Epithelium true

ectoderm

Smooth muscle

in uterine tube

cilia

Smooth muscle

in uterine tube

Note elongate, spindle-shape cells & elongate, centrally located nuclei

Circular & Longitudinal Muscle of GUT

tube (Stomach)

Muscularis Mucosa

is also Smooth M.

Smooth muscle (outer longitudinal, middle circular and

inner longitudinal) in URETER wall

Connective

Tissue of

Mucosa=

L.P.