Musculoskeletal System - Muscle Development

Introduction

There are 3 different types of muscle: skeletal, cardiac and smooth. This page describes skeletal muscle development, descriptions of cardiac muscle and smooth muscle development can be found in other notes. (More? Cardiac or GIT Development)

Skeletal muscle forms by fusion of mononucleated myoblasts to form mutinucleated myotubes.

Differentiation/determination of mesoderm into muscle cells is thought to involve a family of basic Helix-Loop-Helix transcription factors, the first of which discovered was MyoD1. (see OMIM entry). It needs to form a dimer to be active and is maintained in an inactive state by binding of Id (see OMIM entry).

Historic Embryology - Musculoskeletal
1853 Bone \| 1885 Sphenoid \| 1902 - Pubo-femoral Region \| Spinal Column and Back \| Body Segmentation \| Cranium \| Body Wall, Ribs, and Sternum \| Limbs \| 1901 - Limbs \| 1902 - Arm Development \| 1906 Human Embryo Ossification \| 1906 Lower limb Nerves and Muscle \| 1907 - Muscular System \| Skeleton and Limbs \| 1908 Vertebra \| 1908 Cervical Vertebra \| 1909 Mandible \| 1910 - Skeleton and Connective Tissues \| Muscular System \| Coelom and Diaphragm \| 1913 Clavicle \| 1920 Clavicle \| 1921 - External body form \| Connective tissues and skeletal \| Muscular \| Diaphragm \| 1929 Rat Somite \| 1932 Pelvis \| 1940 Synovial Joints \| 1943 Human Embryonic, Fetal and Circumnatal Skeleton \| 1947 Joints \| 1949 Cartilage and Bone \| 1957 Chondrification Hands and Feet \| 1968 Knee

--Mark Hill 09:25, 14 April 2010 (EST) Page Template only - content from original UNSW Embryology site currently being edited and updated.

Myotome

In both development and the adult, the group of skeletal muscles supplied by a specific segmental spinal nerve is referred to as a myotome. The muscle arises from a specific somite and the spinal nerve arises from a specific level of the spinal cord (identified by veretebral column).

In humans this corresponds to the following spinal nerves (from top to bottom) and muscular functions:

C3,4 and 5 supply the diaphragm for breathing.
C5 supply shoulder muscles and muscles to bend our elbow.
C6 for bending the wrist back.
C7 for straightening the elbow.
C8 bends the fingers.
T1 spreads the fingers.
T1 –T12 supplies the chest wall and abdominal muscles.
L2 bends the hip.
L3 straightens the knee.
L4 pulls the foot up.
L5 wiggles the toes.
S1 pulls the foot down.
S3,4 and 5 supply the bladder, bowel, sex organs, anal and other pelvic muscles.

Additional Images

Endochondral bone

Terms

Glossary Links

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Cite this page: Hill, M.A. (2024, April 23) Embryology Musculoskeletal System - Muscle Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Musculoskeletal_System_-_Muscle_Development

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