ANAT2511 Muscle Tissue

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ANAT2511 Fundamentals of Anatomy This histology practical support page content is not part of the histology practical class and provides only background information for student self-directed learning purposes. Histology lecturer notice.

General Objective

To know the histological structure and ultrastructure of the three main types of muscle and how their structure relates to function.

Reading: Human Anatomy, Marieb et al., 6th ed., pages 240‐260
Virtual Slides: Histology of Muscle

Skeletal Muscle

There are 3 types of muscle, 2 striated (skeletal, cardiac) and 1 non-striated (smooth).

Skeletal muscle connects with bones, cartilages, ligaments, and skin. The connection can be either directly, or through fibrous structures (tendons or aponeuroses). Where muscle is attached to bone or cartilage, the fibers end in blunt extremities upon the periosteum or perichondrium, and do not come into direct relation with the osseous or cartilaginous tissue.

Skeletal muscle structure cartoon.jpg Skeletal muscle histology 016.jpg
Skeletal muscle anatomy structure, this is a typical skeletal muscle.

The muscle is attached to the skeleton that it moves by a tough connective tissue (tendon).

The muscle is formed by muscle cells (myofibres), each of which has highly organised cell machinery that allows the muscle cell to shorten in length.

Skeletal muscle histology showing the cell machinery forming contractile units (sarcomeres).

The contractile units (sarcomeres) are organised in series within the muscle fibre, giving the muscle a "striated" appearance. In series each shorten a small distance (microns) that add together to shorten the whole muscle fibre (centimetres).

Sarcomere animation.gif

Cardiac Muscle

Electron micrograph of heart (cardiac) muscle. Cardiac muscle is also striated muscle.

Cardiac muscle EM02.jpg

Image Top - A cardiac muscle cell (cardiomyocyte) with 2 contractile units (sarcomere) shown by white arrows.

The A and I bands, shown by black arrows, are the regions visible by light microscope as cross-striations. Notice also the mitochondria, packed between the sarcomeres, that provide the energy needed for continuous contraction.

Image Middle - Two cardiac muscle cells (cardiomyocytes) are coloured (labeled cell 1 and cell 2) and are joined by a specialized cell junction (intercalated disc).

These junctions join all cardiac muscle cells allowing them to contract together as a syncitium.

Image Bottom Right - A capillary (red) enclosed by an endothelial cell and its basement membrane contains a red blood cell. There are many capillaries throughout the muscle to provide nutrition and remove waste.

Smooth Muscle

The gastrointestinal tract and uterus have muscular walls formed by smooth muscle, called smooth because it does not have a striated appearance. There is also varying amounts of smooth muscle in many other tissues and organs, for example around the walls of blood vessels.

Smooth muscle histology 001.jpg Smooth muscle histology 002.jpg
The gastrointestinal tract has smooth muscle forming two layers: an outer longitudinal layer and an inner circular.

These 2 layers contract to mix or move food along the tract.

Higher magnification view of the 2 muscle layers.

Smooth muscle is not striated, though the muscle contracts by using similar machinery not organised in the same way as skeletal and cardiac muscle.

Smooth muscle is involuntary muscle that you do not knowingly control (like cardiac muscle) and between the 2 layers are the nerve cells (ganglia) that control the smooth muscle contraction.

Course Links

Histology Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | ANAT2241 Support | Histology | Histology Stains | Embryology Glossary

Virtual slides

Pages require student zpass to access.

ANAT2511 | Virtual Microscopy, Cells and Types of Tissue | Selected Basic Tissues | Histology of Bone and Joints | Histology of Muscle | Histology of Nervous Tissue | Integumentary System | Circulatory System Histology | Respiratory System Histology | GIT Histology | Urinary System Histology

Practical support

Pages can be accessed from any internet connected computer.

ANAT2511: Practical 1 Introduction to Histology | Practical 3 Basic Tissues | Practical 5 Bones and Joints | Practical 7 Muscle Tissue | Practical 9 Nervous Tissue | Practical 11 Integumentary (Skin) System | Practical 13 Circulatory System | Practical 15 Respiratory System | Practical 17 Gastro‐intestinal Tract, Liver and Gallbladder | Practical 19 Urinary System | Histology Drawings