Deep fascia in general
Definition:
a fibrous membrane of variable thickness, devoid
of fat, which invests
- the muscles,
- the several groups and the individual
muscles,
- the nerves and vessels,
- various organs and glands
- becomes specialized
around the joints to form or strengthen ligaments,
•
and binds all the
structures together into a firm compact mass
Modification
of deep fascia :
- Aponeurosis
- Retinaculum
- Bursa
- Capsules of joint
- Sheath around the neurovascular bundle Ex: carotid sheath
- Septa – intermuscular septum
- Ligaments
- Connective tissue around the muscle fibre(endomysium) , muscle
bundle(perimysium ) and muscle (epimysium)
Deep fascia is well define in
- Limb
- Neck
SN: very well define deep fascia is iliotibial tract
of fascia lata of thigh
Deep fascia is absent in
- Most of the face
- Anterior Abdominal Wall
to allow extension of abdominal organs.
3. Ischioanal fossa
General features of deep fascia
- It acts as a base for superficial fascia
- It is inelastic and tough
- It is devoid of fat
- Histologically it is dense irregular connective tissue
- It contains variable amount of fibroblasts with the ability to
contract known as myofibroblasts
- It is rich in hyaluronic acid
- It surrounds the muscles, bones, nerves and blood vessels of body
- It encloses different muscle groups
and also individual muscle
- It is rich in Ruffini’s and
pacini’s corpuscles which carry proprioception
- Lacerations of the deep fascia are easily recognized and should be
closed
Importance & functions of the deep fascia
1.
It covers the underlying muscles so it assists them in their action by the tension and pressure it exerts on their surfaces.
2.
From its deep surface, septa pass between muscles. These
septa may extend to be attached to the bones and form definite intermuscular
septa which divide up the interior of the limbs into compartments.
3.
It is thickened in the palm & sole to form palmer & planter aponeuroses which provide protective function to deeper
structures.
4.
It is thickened around distal joints (e.g. wrist & ankle)
to form strong bands (retinacula) which hold the
underlying tendons in position.
5.
It is thickened opposite the flexor surfaces of the fingers
and toes to form tendon sheathes (fibrous flexor sheath) which hold the tendon and prevent their
bending.
Nerve supply of deep fascia Deep fascia
1.
Deep fascia is very sensitive
2.
Its nerve supply and that of subcutaneous periosteum is that
of the overlying skin
3.
The nerves to muscles supply the intermuscular septa and deep
periosteum
4.
Ruffini, Pacini and rare Golgi Mazzoni corpuscles are also
present within the deep fascia
Histology of deep fascia
Histologically it is dense
irregular connective tissue
Mean thickness of fascia
100-200 µm
It is formed by multiple
layers of collagen fibre bundle
Each layer is separated by a
thin layer of adipocytes.
Description of single layer
:
Each layer is formed by
collagen fibres and elastic fibres and ground substance is rich in hyaluronic
acid . the size of collagen fibre are variable , wavy coarse and parallel with each
other . The alignment of collagen fibre bundle differ from layer to layer . all
fascial layers contain a variable amount of fibroblasts with the ability to
contract known as myofibroblasts . the star shaped cytoplasm of elongated
fibroblast are arranged between collagen fibre bundle. Elastic fibre are
arranged between collagen bundles. They are short, branch, not arrange in
bundle, less orderly manner to form a irregular mesh.
Numerous vessels and small
nerve are present in deep fascia. The arrangement of nerves are more around the
vessels.
Interesting facts about deep fascia :
1.
All fascia is connective tissue but not all connective tissue
is fascia
2.
Fascia mostly made up by non-living material known as extra
cellular matrix . it is like the inner ocean of our bodies.
3.
Deep fascia is made up mostly by collagen fibre, one of the
most common protein in body
4.
The density and direction of collagen fibre of deep fascia is depend on
the function of the individual
Collagen fibres are
curve structure why ?
Nature hates straight lines curve structures not only allow for tension to
be absorbed but also distributed and transmitted
The arrangement of collagen fibres are multi directional that allow
movement in lots of different directions
Interesting point is collagen fibre is also very adaptable and well lay
down more fibres in new direction of strain , if the movement and loading is
repeated after enough
Continued movement leads to continued
ability to move and stillness leads to stiffness.
The enemy
of deep fascia is extended bouts of stillness. Daily regular movement through a
wide range without extensive stretching is likely to maintain the health and
flexibility of fascia .
• An extreme example is that
of Amar Bharati a sadhu, who over 40 years ago decided to raise his arm above
his head as a tribute to Shiva.
• Over the years the pain that
he first experienced, subsided to numbness. The collagen fibres
surrounding the muscle tissue and the joint will, most probably, have become
fibrous and hard. The effort of holding the arm up will have ceased to be
an effort, with the fibres taking over the task of holding the arm in that position.
• The rest of him keeps doing
a good job. We can see him squatting on the ground demonstrating great
flexion ability through his knees, hips and ankles. It’s a perfect
demonstration of how continued movement leads to continued ability to move and
how stillness leads to stiffness.
