1 - Introduction to MSK Flashcards by Abby McCabe

What are the functions of skeletal muscle?

Continence
Locomotion
Metabolic
Venous return
Posture
Heat production

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What are fascia?

Sheets of tough connective tissue for protection and compartmentalisation

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What are the two main types of cartilage in the body at joints?

- Articular: decrease friction

- Fibrocartilage: shock absorptin and increase bone congruity

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What are bursa?

Snyovial fluid-filled sacs to protect tendons and ligaments from friction, hard to see.

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What is collagen in the bone for?

To reenforce it and give it tensile strength, like metal rods in concrete

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How does bone act as a store?

Matrix is made up of calcium phosphate. Amount of storage depends on how good the blood supply is

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What gives bone its mechanical properties?

Calcium phosphate gives it great compresssive strength and collagen gives it great tensile strength
All components of the bone are the same as other conenctive tissues but different proportions

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What are the two divisions of the skeleton?

Appendicular - Bones of upper and lower limbs

Axial - Longitudinal axis of the body

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What is the function of all the different shapes of bones?

- Long: Act as lever in appendicular skeleton

- Short: Great range of movement and stability

- Flat: Protect and attachment of muscles

- Irregular: Protection (have no growth plates or epiphysis)

- Sesamoid: Embedded in tendons to protect from stress and wear

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Where do muscles attach to bones?

Bony prominences, larger the prominence the more powerful the muscle is

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What are the articulating processes of bone?

- Head: rounded articular projection supported by neck

- Condyle: Large knuckle like projection (medial condyle of femur)

- Facet: Smooth flat surface (inferior and superior vertebrae)

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What are non-articulating processes?

- Trochanter: Blunt projection only on femur

- Epicondyle: Smaller projection above condyle. Attachement for muscles and ligaments

- Tubercle: Small knob-like rounded process

- Tuberosity: Large, rounded, usually rough process

- Crest: Prominent border on ridge

- Line: Less prominent ridge

- Spine: Sharp slender process

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What is the difference between a tubercle and a tuberosity?

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Why do non-articulating processes form?

Result of traction on developing bone by muscles and ligaments. Stronger force exerted on the bone, larger the prominence that develops

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What are some depressions on the surface of the bone?

- Fovea: Pit-like landmark

- Sulcus/Groove: Furrow that accomodates soft tissue such as blood vessels and nerves

- Fossa: Basin-like depression

- Cavity: spacious open area

- Notch: c or u shaped depression

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Why do depressions occur on the bone?

Provide the passage of blood vessels and other soft tissues

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What are some bone openings and why do they occur?

Occur to allow blood vesels and nerves to pass into or through the bone

Foramen: Hole or window in the bone

- Fissure: Narrow slit like opening between bones

- Canal: Tube-like passageway

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What is the blood supply to the bone?

Top half is child, metaphysis artery separate. Bottom half is adult and anastomosis occurs between metaphyseal and epiphyseal arteries

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What is avascular necrosis?

- When the bone dies due to lack of blood suppy. Can be due to fractures, alcoholism, steroid use, decompression sickness.

- MOST COMMONLY DUE TO INTRACAPSULAR FRACTURE OF FEMUR.

More likely to happen to children as if their epiphyseal artery is cut off then no blood supply to epiphysis

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What happens to the size of a cricketer’s arm bones?

Their dominant arm will become thicker due to remodelling. Osteocytes will detect dominant hand is being used and signal osteoblasts to deposit more bone

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What is a joint and the three classifications of joints?

An articulation between two surfaces. More mobile the joint, less stable it is

What are fibrous joints?

United by collagen fibres
Virtually no movement so very stable
e. g sutures of the skull

What is a cartilaginous joint?

Bones held together by cartilage, found in midline of body and epiphyseal growth plates

- Primary: Completely immobile and united by hyaline cartilage, e.g first sternocostsal joint

- Secondary: Symphyses. Articular surfaces covered by hyaline cartilage and a pad of fibrocartilage between them

What are synovial joints?

Separate bones capped with articular hyaline cartilage and a thin film of synovial fluid separating them
Highly mobile

- Fibrous capsule surrounds the joint and is composed of interlacing and longitudinal collagen.

What is the function of the fibrous capsule?

Stabilises the joint, permitting movement but preventing dislocation. Continous with the periosteum of the bones

What are the different types of synovial joints?

**- Plane:** Smooth movement in all directions, e.g carpals **- Condyloid:** Two bowls nestled together **- Saddle:** Motion in two different plates at same time with degree of slidding **- Hinge:** stable flexion and extension in one plane **- Pivot:** Peg with ring hole. Allow rotation with no gliding **- Ball and Socket:** Stable movement in several directions without slippage. Most mobile

What are tendon sheaths?

Elongated bursae that wrap around tendons to reduce friction associated with movement of the tendon

What is the structure and function of the synovial fluid?

- Yellow, viscous, slightly alkaline fluid - Less than half a ml in healthy people - Contains collagenases, lubricin, hyaluronic acid **- Shock absorber, reduce friction and nourish the articular cartilage with plexus of arteries**

What factors affect the movement of joints?

- Structure/shape of articulating bone - Strength and tension of ligaments - Tone and arrangment of surrounding muscles - Apposition of neighbouring soft tissues (restricting) - Effect of hormones (e.g pregnancy) - Disuse of a joint

How do synovial joints develop embryonically?

- During week 6 synovial joints will for at **joint interzone** **-** Cells at centre of the interzone undergo **apoptosis** - Surrounding MSC/chondrocytes in perichondrium will form periosteum - Some remaining chondrocytes in knee will also form **intra-articular ligaments**

What is the relationship between length of lever and force generation?

Longer the lever means larger amount of power generated but limited range of displacement of the load

What is the origin and insertion points of a muscle?

What are important points to know when looking at muscles and movement?

- Muscles can only pull - Muscles can only act on joints they cross - Action of muscle is a function of starting anatomical position of joint - Muscles work together and almost never in isolation

What are the three types of contraction of a muscle?

What is a synergist and a neutraliser?

**Synergist:** Assists movement of an agonist with the angle of pull **Neutraliser:** Holds one body part immobile whilst the other is moving

How can you tell what nerve supplies a muscle?

- All muscles in one compartment have similar action and are innervated by the same nerve - Also same blood supply in the compartment

What are the different muscle shapes?

What is a fascia compartment?

Region of the limb that contains muscles, nerves and blood, surrounded by a deep fascia

What are examples of superficial and deep fascia?

**Superficial:** Subcut fat/Hypodermis **Deep:** Epimysium (regular dense CT)

What is the fascia of the thigh called?

Fascia Lata. Adhesion of skin to underlying fascia causes the creases

Why do tendons heal slowly after injury?

Poor blood supply and low water content so poor diffusion of nutrients

What is the role of ligaments?

To stabilise joints and limit their range of movement. Can store energy to assist with propulsion

What do aponeurosis do?

Flattened tendons that connect muscle to muscle. Some have lost contact with their original muscle

What does Hilton's Law state?

How does segmentation occur?

Hox Genes. Confer segmental identity but do not form actual segments themselves

What is a homeotic mutant?

Someone who has a mutation in their hox genes so can lead to different numbers of digits and ribs. Can present clinically, e.g extra rib, as they compress nerves and arteries

What is serial homology?

- Hip joint serially homologous with shoulder, femur with humerus, great toe and thumb, radial nerve and femoral nerce etc

What explains the spiral dermatome map?

How do the limbs form in utero?

1. **Limb buds** form on lateral body wall during **4th week** 2**. Mass of mesenchyme** surrounded by ectoderm, with the tip of limb bud dividing to form **apical ectoderm ridge** 3. Ridge encourages **mesenchyme to proliferate** 4. Upper limb precedes lower limb growth by a few days 5. Skeleton formed by **cell aggregation** in mesenchyme that then ossifies 6. As this is occurring **myoblasts aggregate and develop muscle mass** in each bud that separates into **dorsal (extensor) and ventral (flexor)** 7. Inwards and outward rotation of the limbs

What are the three componenets of a synovial joint?