Anatomy of muscle and fascia

Question 1

What is a fascia?

Answer 1

It is a connective tissue that binds tissues and organs together

Question 2

What are the types of fascia?

Answer 2

1) External: Immediately deep into the skin covering the whole body

2) Internal: Lines of body cavities from inside extending between organs (helps in binding the organs together

Question 3

What are the subdivisions of the external fascia?

Answer 3

1) Superficial fascia “subcutaneous tissue”: soft fibro-fatty layer, present all over the body with varying thickness

2) Deep fascia: though fibrous sheet, under the superficial fascia, it is not stretchable, and requires stitches after surgery

Question 4

Describe the composition of the superficial fascia

Answer 4

• Fibrous network filled with fat
• Under the skin covers the entire body
  1) Very thin “no fat” in the eyelid, under the skin nipple, areolar of the breast, & the external genitalia as some needs lower temperatures

2) Slightly thickened in the dorsum of the hands and feet

3) Very thick in the back of the neck, trunk, buttocks, palm of hands and sole of the foot

Question 5

What are the functions of the superficial fascia?

Answer 5

1) Binds the skin to the deep fascia

2) Contains subcutaneous blood vessels and nerves

3) Contains mammary glands in females

4) Due to its high-fat content it serves as a (1) Heat insulator and regulator, storage of natural food, energy & hormones, gives the body its rounded contour, provides the insertion to some muscles

Question 6

Describe the structure of the deep fascia

Answer 6

• Dense, tough, inelastic fibrous membrane
• Separates the superficial fascia from deeper structures
• Forms tight sheath around limb muscles and preserves the rounded contour

Question 7

The deep fascia is absent in which sites in the body?

Answer 7

1) Scalp & face (as it will restrict the movement of the face “no facial expression would be possible”)

2) The front of the body (anterior abdominal wall), will restrict breathing, digestion, and uterus stretching during pregnancy

Question 8

What are the functions of the deep fascia?

Answer 8

1) Provides accessory attachment to the muscles

2) Forms vascular sheaths around vessels from one region to another (axillary sheath, femoral sheath, etc)

3) Forms capsules covering glands (like thyroid, & parathyroid, which will cause pain in the cause of the swelling of any of the glands as they will swell against an inelastic sheath

4) Fibrous flexor sheaths: Thickening of the deep facia in front of the fingers, in the flexor side of the fingers, binds tendon to bones
-If the flexor is absent, when the tendon contracts it will move away from the bone and lose its shape.
- if there is an infection it will lead to intra-compartment pressure and necrosis so we can treat it by antibiotics in the early stages and in the late stages we can treat it by surgery.

Question 9

What is meant by compartment syndrome?

Answer 9

When blood fills up the inner area of a deep fascia building up pressure, you can release it by cutting through the fascia

Question 10

What are the derivatives of the deep fascia?

Answer 10

1) Inter-muscular septa: Fibrous extension from the deep fascia into the surface of the bones inside, dividing the limb into compartments, it also separates between the extensor and flexor muscles

2) Retinacula: Thickening of the deep fascia around the joint, keeping the underlying tendons in place

3) Aponeurosis (palmar & plantar): Thickening of the deep fascia in the palms and soles

Question 11

What should you do if the compartments get swollen or there is a fracture in them?

Answer 11

This will cause intra-compartment pressure blocking the blood supply leading to necrosis “gas gangrene” which will cause amputation of the limb, to treat it surgical intervention must be done by opening the fascia, decreasing the inner pressure

Question 12

What are the different types of muscles?

Answer 12

1) Smooth: involuntary, in the walls of BV, Digestive, respiratory & urinary tract

2) Cardiac: involuntary, in the wall of the heart

3) Skeletal: voluntary, forms the bulk of our body 1/2 of BW, attached mainly to the skeleton

Question 13

What are the attachments of muscles?

Answer 13

1) Origin: less mobile, and more proximal

2) Insertion: More mobile and distal, mostly attached to the movable bone

• During contraction the insertion moves towards the origin

Question 14

What are the different types of tissues that form muscle attachments?

Answer 14

1) Tendon: cord-like end of the muscle

2) Aponeurosis: a flat sheet of the muscle (contractile in the abdomen, fibrous and inelastic in the palmar and plantar)

3) Raphe: Flat elastic insertion in the midline forming the floor of mouth and pelvis

Question 15

What is the percentage of motor neuron innervation to the muscles?

Answer 15

60%

Question 16

How does Connective Tissue organize muscle fibers?

Answer 16

1) Endomysium: inner loose connective tissue surrounding the single muscle fiber

2) Perimysium: a sheath of C.T. surrounding a group of fibers within the muscle

3) Epimysium: a C.T. sheath surrounding the whole muscle

Question 17

How are skeletal muscles classified into different groups?

Answer 17

1) Shape of the muscle: (Strap-like, quadrate, rhomboid, triangular, & spiral)

2) Arrangement of its fibers: (Parallel “fusiform type”, Triangular type, pennate type “Unipennate, bipennate, multipennate, circumpennate”)

3) The number of heads in the muscle:(biceps, triceps, quadriceps) origin depends on the number of heads but they all have 1 insertion

4) Number of joints in action: Uni-articulate, Bi-articulate, multi-articulate (like the muscles that move the fingers)

5) According to the action of the muscles:

• Prime mover The muscle that initiates the main action of the bone
• Synergistic (muscles that work together)
  a) Helps the prime mover in the
  b) synergistic antagonistic: prevents unwanted movement by mixing an intermediate joint so that another muscle can cross that joint and act primarily on a distal joint
• Fixator: Stabilizes the origin of another muscle & fixates the bone by isometric contraction helping it to work efficiently
• Antagonistic: Have actions opposite to those of the prime movers. They relax when the prime movers
  contract