An aponeurosis (; plural: ''aponeuroses'') is a type or a variant of the deep fascia, in the form of a sheet of pearly-white fibrous tissue that attaches sheet-like muscles needing a wide area of attachment. Their primary function is to join muscles and the body parts they act upon, whether bone or other muscles. They have a shiny, whitish-silvery color, are

histologically Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...

similar to

tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

s, and are very sparingly supplied with blood vessels and

nerves A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the e ...

. When dissected, aponeuroses are papery and peel off by sections. The primary regions with thick aponeuroses are in the

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

abdominal The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso ...

region, the dorsal lumbar region, the ventriculus in birds, and the palmar (palms) and

plantar Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

(soles) regions.

Anatomy

Anterior abdominal aponeuroses

The anterior abdominal aponeuroses are located just superficial to the

rectus abdominis muscle The rectus abdominis muscle, ( la, straight abdominal) also known as the "abdominal muscle" or simply the "abs", is a paired straight muscle. It is a paired muscle, separated by a midline band of connective tissue called the linea alba. It ex ...

. It has for its borders the

external oblique The abdominal external oblique muscle (also external oblique muscle, or exterior oblique) is the largest and outermost of the three flat abdominal muscles of the lateral anterior abdomen. Structure The external oblique is situated on the lateral ...

, pectoralis muscles, and the latissimus dorsi.

Posterior lumbar aponeuroses

The posterior lumbar aponeuroses are situated just on top of the epaxial muscles of the thorax, which are

multifidus spinae The multifidus (multifidus spinae : ''pl. multifidi'' ) muscle consists of a number of fleshy and tendinous fasciculi, which fill up the groove on either side of the spinous processes of the vertebrae, from the sacrum to the axis. While very thin ...

and

sacrospinalis The erector spinae ( ) or spinal erectors is a set of muscles that straighten and rotate the back. The spinal erectors work together with the glutes (gluteus maximus, gluteus medius and gluteus minimus) to maintain stable posture standing or sitt ...

Palmar and plantar aponeuroses and extensor hood

The palmar aponeuroses occur on the palms of the hands. The

extensor hood An extensor expansion (extensor hood, dorsal expansion, dorsal hood, dorsal aponeurosis) is the special connective attachments by which the extensor tendons insert into the phalanges. These flattened tendons ( aponeurosis) of extensor muscles s ...

s are aponeuroses at the back of the fingers.
The plantar aponeuroses occur on the plantar aspect of the foot. They extend from the calcaneal tuberosity then diverge to connect to the bones, ligaments and the dermis of the skin around the distal part of the metatarsal bones.

Anterior and posterior intercostal membranes

The anterior and posterior intercostal membranes are aponeuroses located between the ribs and are continuations of the external and internal intercostal muscles, respectively.

Scalp aponeuroses

The

epicranial aponeurosis The epicranial aponeurosis (aponeurosis epicranialis, galea aponeurotica) is an aponeurosis (a tough layer of dense fibrous tissue). It covers the upper part of the skull in humans and many other animals. Structure In humans, the epicranial ...

, or galea aponeurotica, is a tough layer of dense fibrous tissue which runs from the

frontalis muscle The frontalis muscle () is a muscle which covers parts of the forehead of the skull. Some sources consider the frontalis muscle to be a distinct muscle. However, Terminologia Anatomica currently classifies it as part of the occipitofrontalis muscle ...

anteriorly to the

occipitalis The occipitalis muscle (occipital belly) is a muscle which covers parts of the skull. Some sources consider the occipital muscle to be a distinct muscle. However, Terminologia Anatomica currently classifies it as part of the occipitofrontalis mu ...

posteriorly.

Pennate muscles and aponeuroses

Pennate muscle A pennate or pinnate muscle (also called a penniform muscle) is a type of skeletal muscle with fascicles that attach obliquely (in a slanting position) to its tendon. This type of muscle generally allows higher force production but a smaller ra ...

s, in which the muscle fibers are oriented at an angle to the line of action, typically have two aponeuroses. Muscle fibers connect one to the other, and each aponeurosis thins into a

which attaches to bone at the origin or insertion site.

Function

s, aponeuroses attached to pennate muscles can be stretched by the forces of muscular contraction, absorbing energy like a spring and returning it when they recoil to unloaded conditions. Also serving as an origin or insertion site for certain muscles e.g latissimus dorsi.

References

{{Authority control Tissues (biology)