Anatomy of the musculoskeletal system
Function of the MSK
- Image shows a cross-section through a basic joint. Is a synovial joint
- Function of MSK is to give:
1) Form – the shape of the human body
2) Support – for the internal viscera, which are hanging or
supported by parts of the msk
3) Stability – enables to move and have stable form of
function
4) Movement – ability to perform tasks and move from A
to B
5) Store – links to the support aspect. Is a mineral store e.g.
magnesium, phosphate and calcium. In pregnancy
maternal calcium stores deplete to allow growth and
foetal ossification
6) Protection - thoracic cage protects lungs and the heart,
and the cranium protects the brain etc
Musculoskeletal system
- Are 7 main tissues which form part of a joint:
- Bone: at their articulate (from the joint) surfaces
you have hyaline cartilage/articular cartilage.
o Can be worn away from overuse or
trauma.
- In-between the joint space there are discs which
are fibrocartilage, are triangular in shape.
- The synovium lines the joint cavity. Is mostly
cellular in structure in contrast to other tissues
which have ECM
- Produces synovial fluid - lubricating fluid that
looks after the articular cartilage.
- Ligaments – attach bone to bone. Prevent
movement in unwanted directions.
- Tendons – attach bone to muscle and holds them together. Facilitate movement. Some
tendons in wrist are enveloped in synovial sheaths, which are filled with fluid to allow swift
and frictionless movement of the tendons but also to dissipate heat from friction.
o Bursa are fluid filled sacs that protect the tendon/ligament from the bone to prevent
wear and tear
- LAX (laxation) ligaments = when ligaments become loose. Can be because of genetic
predisposition such as a connective tissue disorder.
, Joint Tissues
- Ligaments and tendons
resist tension – type 1
collagen allows this
- Hyaline cartilage resists
compression – type 2
collagen allows this
- Cartilage isn’t as good at
resisting tension as
tendons or ligaments.
- Are taller in the morning
as cartilage, particularly
in the intervertebral
discs, loose water. The
more upright you are the more compressed they become.
- Type I and II collagen are known as fibrillar collagens – means they look like a piece of
string/fibre like.
o They have 3 amino acids that make up their protein – a repeat motif = there is a
simple sequence of amino acids. The repeat motif is Gly-X-Y. Glycine, Proline,
Hydroxy proline
o Glycine is important in this collagen structure as it is the smallest amino acid and
only has a hydrogen sidechain. This enables the collagen molecule to wind up
extremely tightly. [Just like how a piece of string frays out when cut into smaller
pieces, so does collagen, this is due to glycine only having the hydrogen side chain
which winds into the middle and enables the collagen to pack together incredibly
tightly.]
- Type II has GAGs bound to it, type I doesn’t.
o Glycosaminoglycans – these are sugar side chains. GAGs are proteoglycans (proteins
and sugars). These are hydrophilic and promote water to go into cartilage.
o Therefore, hyaline cartilage resist compression as it is full of water
- Fibrocartilage is fibrous. It is tougher and resists compression and tension. To do this it has a
mixture of type I and II collagen.
- Bone is the most rigid of the structures. Very good at resisting compression to an extent and
then snaps. It can to some extent resist tension. And can resist a bit of torsion (twisting) as
well – but not great.
o It is able to do this as it has the rope like collagen I and II molecules and then
wrapped around them they have hydroxyapatite which is a complex calcium salt and
is the mineral component of bone.
- Synovium is mainly cellular and is producing lubricant in the form of synovial fluid. Synovial
fluid is important as it brings nourishment to the articular cartilage - important as cartilage is
hypoxic (doesn’t have a blood supply).
Types vs Categories of bone
- Types of bones: long, short, flat, irregular or sesamoid:
- Long bones are longer than they are wide e.g. femur, ulna, radius, humerus
- Short bones are the same length as they are wide e.g. carpals in hand.
- Flat bones are typically found in the skull e.g. parietal, frontal, occipital.
Function of the MSK
- Image shows a cross-section through a basic joint. Is a synovial joint
- Function of MSK is to give:
1) Form – the shape of the human body
2) Support – for the internal viscera, which are hanging or
supported by parts of the msk
3) Stability – enables to move and have stable form of
function
4) Movement – ability to perform tasks and move from A
to B
5) Store – links to the support aspect. Is a mineral store e.g.
magnesium, phosphate and calcium. In pregnancy
maternal calcium stores deplete to allow growth and
foetal ossification
6) Protection - thoracic cage protects lungs and the heart,
and the cranium protects the brain etc
Musculoskeletal system
- Are 7 main tissues which form part of a joint:
- Bone: at their articulate (from the joint) surfaces
you have hyaline cartilage/articular cartilage.
o Can be worn away from overuse or
trauma.
- In-between the joint space there are discs which
are fibrocartilage, are triangular in shape.
- The synovium lines the joint cavity. Is mostly
cellular in structure in contrast to other tissues
which have ECM
- Produces synovial fluid - lubricating fluid that
looks after the articular cartilage.
- Ligaments – attach bone to bone. Prevent
movement in unwanted directions.
- Tendons – attach bone to muscle and holds them together. Facilitate movement. Some
tendons in wrist are enveloped in synovial sheaths, which are filled with fluid to allow swift
and frictionless movement of the tendons but also to dissipate heat from friction.
o Bursa are fluid filled sacs that protect the tendon/ligament from the bone to prevent
wear and tear
- LAX (laxation) ligaments = when ligaments become loose. Can be because of genetic
predisposition such as a connective tissue disorder.
, Joint Tissues
- Ligaments and tendons
resist tension – type 1
collagen allows this
- Hyaline cartilage resists
compression – type 2
collagen allows this
- Cartilage isn’t as good at
resisting tension as
tendons or ligaments.
- Are taller in the morning
as cartilage, particularly
in the intervertebral
discs, loose water. The
more upright you are the more compressed they become.
- Type I and II collagen are known as fibrillar collagens – means they look like a piece of
string/fibre like.
o They have 3 amino acids that make up their protein – a repeat motif = there is a
simple sequence of amino acids. The repeat motif is Gly-X-Y. Glycine, Proline,
Hydroxy proline
o Glycine is important in this collagen structure as it is the smallest amino acid and
only has a hydrogen sidechain. This enables the collagen molecule to wind up
extremely tightly. [Just like how a piece of string frays out when cut into smaller
pieces, so does collagen, this is due to glycine only having the hydrogen side chain
which winds into the middle and enables the collagen to pack together incredibly
tightly.]
- Type II has GAGs bound to it, type I doesn’t.
o Glycosaminoglycans – these are sugar side chains. GAGs are proteoglycans (proteins
and sugars). These are hydrophilic and promote water to go into cartilage.
o Therefore, hyaline cartilage resist compression as it is full of water
- Fibrocartilage is fibrous. It is tougher and resists compression and tension. To do this it has a
mixture of type I and II collagen.
- Bone is the most rigid of the structures. Very good at resisting compression to an extent and
then snaps. It can to some extent resist tension. And can resist a bit of torsion (twisting) as
well – but not great.
o It is able to do this as it has the rope like collagen I and II molecules and then
wrapped around them they have hydroxyapatite which is a complex calcium salt and
is the mineral component of bone.
- Synovium is mainly cellular and is producing lubricant in the form of synovial fluid. Synovial
fluid is important as it brings nourishment to the articular cartilage - important as cartilage is
hypoxic (doesn’t have a blood supply).
Types vs Categories of bone
- Types of bones: long, short, flat, irregular or sesamoid:
- Long bones are longer than they are wide e.g. femur, ulna, radius, humerus
- Short bones are the same length as they are wide e.g. carpals in hand.
- Flat bones are typically found in the skull e.g. parietal, frontal, occipital.
