Muscle, joint, movements

Bone, skeletal muscle, tendons, cartilage

Support, movement (breathing and communication), posture, protection (any three)

Cartilage lacks blood supply

Tendon have weak blood supply

Bone has good supply

Axial skeleton and appendicular skeleton

• Axial - scalp, ribs, vertebral column

• Appendicular - upper and lower limbs, attach at the pectoral and pelvic girdles

• Long bones - Long length and narrow width. It has a shaft (middle) and 2 ends. It also has a medullary cavity in the centre containing bone marrow

• Short bones - Length and width are similar, found in hands and feet

• Flat bones - e.g. bones of skull cap, ribs, sternum

• Irregular bones - a bone that has a complex shape that doesn’t fit any of the above categories such as vertebrae

• Sesamoid bones - develops and is found inside a tendon e.g. patella

• Middle - Diaphysis (shaft)

• 2 ends - Epiphysis

• junction that connects ends with middle - Metaphysis

The region between the diaphysis (shaft / middle) and epiphysis (the ends)

Epiphyseal (growth) plate

• these are layers of cartilage that undergo endochondral ossifiction to give rise to bone.

• Appears dark on Xray in children, not visible in adult

Process by which hyaline cartilage is replaced by bone at the epiphyseal growth plate, as one get older

Once the bone matures its named - head, neck, shaft and base

• Cortical bone is the compact bone, in long bones it is found on the outside of the bone. It is found more in the shaft of the bone and is denser and stronger.

• Trabecular bone, also known as spongy or cancellous bone is the more porous bone found within (middle) long bones.

Some bones have hollows in the middle containing bone marrow

Cortical bone

Provide attachment sites for tendons and ligaments

• larger attachment = more prominant

Foramen, canal, groove, meatus, fossa (any two)

Hyaline cartilage, fibrocartilage, elastic cartilage

Fibrocartilage

• Found in secondary cartilaginous joints

• Forms articular discs in some joints, and is also found in the pubic symphysis and intervertebral discs

• It resists compression and is used for shock absorption

Hyaline cartilage

• Forms growth plates of growing long bones (primary cartilaginous joints)

• Reduces friction at synovial joints

• Found in various structures such as the external ear

• Provides support and is flexible

It is avascular and has no blood supply

Fibrous, cartilaginous, synovial joint

Skull sutures or interosseous membrane (between ulna and radius)

• Bones bound together by fibrous connective tissue

• Permits very little movement

• Examples are sutures between bones, intraosseous membrane between radius and ulna.

Hyaline cartilage

• Bones are lined by hyaline cartilage

• They form the epiphyseal plate in growing long bones.

• When the growth of the long bone completes, these cartilaginous joints becomes bone by ossification

Fibrocartilage

• Bones are lined by fibrocartilage which provides strength, shock absorption and flexibility.

• They function to withstand compression forces. E.g. intervertebral discs

• Permits some movement

Synovial fluid

• produced by synovial membrane

Synovial joints

• Articulating ends of bones are lined with hyaline cartilage and separated by synovial cavity

• The synovial cavity is lined by innter synovial membrane and outer joint capsule

• The outer joint capsule is composed of fibrous tissue

Hinge joints - Hinge and move in one plane

Pivot joint - Circular hollow, allows bone to rotate around another e.g cervical vertebra

Saddle joint - saddle shaped hollow, moves in 1 plane e.g 1st MCP (thumb)

Condyloid - oval shaped hollow, provides movement in 1 direction

Ball and socket joint - allows large range of movement in all planes

Plane synovial joint - Don’t allow much movement – 2 flat bons comes together

Hinge joint

Ball and socket joint

Atlanto-axial joint (C1–C2)

• Uniaxial movement is one plane, e.g. hinge joints (elbow)

• Biaxial movement is in 2 planes e.g. condyloid joints

• Multiaxial movement is in more than 2 planes, e.g. ball and socket joints

Muscle belly

• it is the red fleshy part of the muscle

Attach muscle to bone and transmit force

• it is the white, non-contractile portion of the muscle

• Tendons are organised collagen bundles

Isometric (dont change in length), concentric (shortens) and eccentric (lengthens) contration

• Maximum force of contraction depends on the muscle’s effective mass. Larger mass = stronger force

• Maximum range os contration depends on the length of muscle fibre.

Concentric contraction

Eccentric contraction

Unipennate - Fascicles insert into only one side of the tendon, at an angle, diagonally

Bipennate - Fibres are aligned at an angle, on two sides of tendon in the middle

Multipennate - multiple fibres attach like feathers to a tendon.

Circular - Concentrically arranged bundles of muscle fibres (no tendon)

Fusiform - muscle tissue bulges along the midline and tapers off at the ends > tendon

Strap/Flat - All strands are parallel, attach to tendons at both ends

Spiral muscle - twists and spirals to get to the tendon it articulates with.

A muscle with two heads of origin

• Some muscles can be classified as:

  • Two-bellie = two muscular bellies unite at an intermediate tendon

  • two / muti-headed = two / multiple heads of orgin

Retraction

Upward movement of the foot at the ankle

Skeleton with bones and cartilage, muscles and tendons, ligaments

• skeletal muscles are well supplied with nerves + blood

• Fascia around muscles

• muscle belly wrapped in epimysium

• Fasicles wrapped in perimysium

• musle fibre (single cell) wrapped in endomysium

• myofibrils and myofilaments

Perimysium

Endomysium

Myofibrils and myofilaments

Via the deep surface of the muscle (main artery, along with vein and nerve)

• Accessory arteries enter elsewhere.

Because muscle movement may stretch or tear the vessels

By compressing intramuscular veins during contraction

• Certain muscles can act as pumps, helping pump venous blood to travel to the heart, often against gravity from the lower limbs.

• This occurs in intramuscular veins such as in the calf muscles. They compress the veins when they contract, pushing blood towards the heart. Veins have valves that prevent backflow

Veins contain valves that prevent backflow

A single nerve

• in contrast, the abdominal wall muscles are supplied by multiple nerves

Motor neurones (supplies a group of muscle fibres) and

sensory neurones (supplying neuromuscular spindles, Golgi tendon organs, free pain endings)

Muscle spindles and Golgi tendon organs

Myotome of the somites from paraxial mesoderm

Increase in number of muscle fibres

Increase in size of muscle fibres (hypertrophy)

Increase in muscle fibre size due to muscle stem cells (satellite cell) merge into muscle fibres.

Resistance training, muscle overloading, protein ingestion, various horomes ( IGF-1, GH, testosterone)

Disuse, ageing, chronic inflammation, neuropathy

Appearance, location, attachments, function (any two)

The proximal attachment that remains fixed during contraction

The distal attachment that moves during contraction

Along the line of the tendon

Strap (parallel) muscles - long and thin, develop low forces but long ranges of contraction

Pennate muscles - have a large number of fibres, they produce larger forces but have shorter ranges of contraction

Spiral muscles

• Tendons: collagen-rich cords or straps

• Aponeuroses: sheet-like tendons

• Fascia: dense connective tissue

• Fleshy/direct (epimysium directly attaches to periosteum)

A synovial fluid-filled sac between moving structures

• are pockets of synovial fluid between/under muscles or tendons, under  ligaments or under skin. Reduce friction at joints or moving parts

A synovial membrane wrapped around a tendon

It allows tendons to move freely without adhering to surrounding tissue

The Structural functions:

• Giving the body its shape

• Supporting the weight of the body

• Providing site for muscle attachment and allowing movement

• Protecting delicate tissues and organs

other functions:

• Making blood (haemopoiesis)

• Storing calcium and phosphorous

• Composed of specialised connective tissue, bones and cartilages.

• Originally develops as cartilage then it ossifys later

• Not all cartilages ossified, some cartilages persists at some site - ends of the bone, front of the sternum where ribs joins, voice box and trachea.

Cartilage is a strong, flexible connective tissue. It serves as a shock absorber for joints and bones. In the skeleton,

• supports soft tissue

• Provides smooth surfaces at joints (hyaline cartilage)

• Enables long bone growth (cartilage can grow faster than bone)

• stiff and load-bearing e.g in meniscus at the knee

• Cells (chondrocytes and chondroblasts (makes cartilage)) are embedded in a matrix of proteoglycans and collagen

• It is avascular and has no nerves

  • Repairs poorly and is replaced by fibrous tissues

• Able to resist compression, tension and shearing forces

• Hyaline e.g articular cartilage, most synovial joints

  • Present on the end of bones in a joint, have moderate amount of collagen and makes up growth plates

• Elastic e.g. External ear

  • Provides support, its flexible, contains collagen and elastin fibres

• Fibrocartilage e.g Intervertebral disc, TMJ, sternoclavical joint, pubic symphysis

  • very dense CT, lots of collagen in the matrix

It develops from embryonic mesenchyme (loose connective tissue). Grow via 2 methods:

Appositional growth (outside)

• Secretion of new matrix onto existing cartilage surface.

• This causes the cartilage to expand and widen

• The secretion is done by chondroblasts

Interstitial growth (middle)

• Secretion of new matrix within cartilage tissue.

• This causes the cartilage to elongate

• This is done by chondrocytes

• This is the mode of growth of growth plates in long bones

• Bone is a specialised connective tissue

• It is extremely hard and resilient

• Cells (osteoblasts, osteocytes, osteoclasts) are embedded in a mineralised EC matrix

  • Osteocytes are ‘trapped’ in the lacunae of the bone

• It is highly vascular

• It is extremely strong

1. Compact (cortical) - 80% bone mass

   • Dense, hard outer layer (forms most of bone mass)

   • Histologically it appears cylindrical units - ‘osteons’

   • Centre of the osteons is vascular bundle

   • In the long bone it makes up most of diaphysis

   • Within cortical bone, there are microscopic pores for vascular and nerve supply

1. Trabecular (cancellous / spongy) - 20% bone mass

   • Porous, spongy, highly vascularised inner layer, presen in epiphysis of long bones

   • Separated from cortical layer by endosteum tissue which contains osteoblasts

   • Contains red marrow - produces blood cells

2. Woven bone = immature bone, collagen fibres are randomly arranged

Compact bone

• the round features are osteons

• The black dots on the bottom Pic are the ‘trapped’ osteocytes.

Trabecular bone

• Bones are covered by collagenous connective tissue called periosteum

  • Outer layer - dense fibrous CT

  • Inner layer - contains osteoprogenitor cells which differentiate into osteoblasts for bone formation

  • Not present in articular surface, tendon / ligaments

  • Important for healing post bone #

  • Has rich innervation by sensory nerves, allows attachment of muscles, tendons and ligaments to the bone by sharpey fibres

• Most bones are pre-formed as cartilage - develop by endochondral ossifcation

• Some develop from embryonic mesenchyme by intramembranous ossification - skull

• ONLY appositional growth (as oppose to cartilate which can grow by apposition and interstitial)

Process of bone formation is called Ossification. Occursin 2 ways:

1. Intramembembranous ossification

   • Fetal connective tissue (messencyme) is invaded by osteoblast directly forming bone

   • This process forms clavicles and skull

2. Endochondral ossification

   • The messenchyme is 1st converted to cartilage by chondroblasts.

   • The cartilage is then invaded by oestoblasts, which calcifies it forming bone tissue. This takes years

• Long bones - composed of a long diaphysis (shaft), and the two ends known as epiphysis (secondary ossification centres), which are separated from the diaphysis by a layer of metaphysis. E.g. femur and humerus.

• Short bones- similar width and length e.g. ankles

• Flat bones - Two layers of cortical bone with a thin layer of spongy bone in between, e.g. bones of the skull and the sternum

• Irregular bone - do not fit any of the above classifications, e.g. vertebrae and facial bones

• Sesamoid - Bones that develop within tendons such as the patella.

• Osteocytes

  • Regulates mineral deposition, produces FGF23 (controls phosphate excretion), responds to mechanical stimuli and regulates action of osteoclast and osteoblasts.

  • Cells that maintains bone

• Osteoblasts

  • Produces ECM and deposits hydroxyapatite

  • Mostly found along bone surfaces

• Osteoclast

  • Bone resorption by breaking it (Howship’s lacunae), releases Ca2+ and PO4 into blood.

• The diaphysis (central shaft of a long bone)

• Epiphyses (ends of the bones)

• Metaphyses (area where diaphysis and epiphyses join)

> The diaphysis ossifies 1st then the epiphyses (ends) ossify later in adult stage

> Epiphyses (ends) separated from metaphysis by layer of hyaline cartilage known as growth plate (physis)

> Growth plates are the site of secondary ossification to elongate the bones by interstitial growth

> Later, the elongated growth plate is ossified by osteoblasts

> finally, epiphyses and metaphyses fuse and growth plate disappears. (15yr in female, 21yr in male) - after this bone no longer grow in length, only grow by appositional growth causing it to widen.

• in an Xray of a child, bones may appear to have gaps - these are cartilaginous growth plates at the end of growing bones

• As they age to adult, growth plates decrease in size / close

• After a #, haematoma forms around the broken ends

• the area get inflammed

• Proliferation of osteoblast and chondroblast from periosteum and endosteum > lay down cartilaginous and osteoid (non-mineralised) components between 2 broken ends forming soft callus

• Soft callus is eventually replaced by mineralised, hard (lamellar) bone to form hard callus

• The bone undergoes further remodelling to return to original structure.

Cartilage and bone are specialised connective tissue

1. Cells - fixed or transient

2. Protein fibres (ECM)

3. Ground substances (ECM)

Formation of cartilage by chondroblasts

• Cells of cartilage - Chondroblasts (immature) secrete ECM

• These get ‘trapped’ by the matrix as they secerete more matrix > Chondrocytes (mature) which maintains cartilage

• The chondrocytes sits in small spaces called lacunae (see pic below)

Cartilage lacks blood and nerve supply.

Has high water content (80%) and the nutrients diffuse through the cartilage.

Perichondrium (top of the image ‘P’))

• A dense irregular connective tissue, found surrounding hyaline and elastic cartilage (NOT found in fibrocartilage).

• Vascularised and has 2 layers:

  • Outer fibrous - fibroblasts produce collagen fibres

  • Inner chondrogenic (Cg) - gives rise to chondroblast (Cb)

  • ‘C’ - chondrocytes

Hyaline Cartilage

• Found in synovial joints, foetal skeleton, larynx, trachea, costal cartilage.

• It is approx. 5% cells and 95% matrix (translucent and clear)

• Consists of mainly type II collagen fibres

• The chondrocytes can exist individually or in isogenous groups (they divide to form groups) - see pic

• Surrounded by perichondrium (not found on articular surfaces)

Elastic Cartilage

• Found in auricle of ear, auditory tube, epiglottis

• Mainly type II collagen fibres

• Singular and isogenous groups of chondrocytes are also present (see circle in pic)

• Matrix features elastic fibres (differes from hyaline) which allow cartilage to be flexible - see arrow on pic, black lines

• Surrounded by perichondrium

Fibrocartilage

• Located in intervertebral discs, pubic symphysis, menisci. Acts as a shock absorber

• Mix of hyaline cartilage and dense regular connective tissue

• Mainly type I collagen fibres

• Chondrocytes often exist as columns (see pic)

• There is no perichondrium

Osteoarthritis - This is a degenerative joint disease

• Features the erosion of hyaline cartilage in synovial joints

• Can be due to aging, wear and tear, injuries and genetics

• There is an inability of repair

• Complete loss of cartilage leads to the bones rubbing against one another (eburnation)

Note: the wavy line at the bottom of the pic seperates the bone at the bottom from cartilage at home.

Endosteum - thin single inner osteogenic layer

• Periosteum covers outer bone surfaces. Not present in articular surfaces / tendon / ligament. Its a dense fibrous CT

They are osteoblast precursors (Op) - Narrow spindle shape (inactive)

• Osteoblasts (ob) are broad spindle shaped / cuboidal - active

  • cells secreting unmineralised matrix - osteoid

  • Predominantly found along bone surfaces

• Osteocytes (oc) are inactive ‘trapped’ osteoblasts in lacunae - maintains bone

  • Dendric processes within canaliculi allows communication between osteocytes e.g nutrient exchange

Using Dedric processes within canaliculi allows communication between osteocyes. E.g. exchange of nutrients

Osteoclasts (O)

• Bone resorbing cells - seceretes acid that dissolves the mineral component

• Big nucleated cells

• Resides in Howship lacunae (H) / resorption bays

• Bone remodelling = balanced activity of osteoblast and osteoclast.

Osteogenesis = bone development

Most bones are developed by Endochondral ossification (other type is intramembranous ossification)

• forms long bones, vertebrae, pelvis and base of skull

• Hyaline cartilage is the precuror of bone (blue on the pic) - replaced by bone

  • Primary ossification centre - begins at diaphysis (shaft), presence of blood vessel

  • Secondary ossification centre - mineralisation of epiphysis (ends)

Most Bone development occurs via Endochondral ossification.

Starts with hyaline cartilage which later get replaced by bone.

• Primary ossification centre = Replacement of bone begins at the diaphysis (shaft)

• Secondary ossification centre = next the mineralisation begins at the epiphyses (ends)

• Appositional growth is growth in width, matrix is added at the periosteal surface

• Interstitial growth is growth in length, this occurs at the epiphyseal growth plate

• Also known as ‘physis’ - its a hyaline cartilage plate located at the ends of long bones

• plays crucial role in longitudinal growth of bones during childhood and adolescence

• Consits of chrondrocytes in a collagen mix, blood supply from epiphyseal arteries.

• Amount of cartilage being produced equals amount of ossification → consistent thickness of epiphyseal growth plate

• Addition of new cartilage “pushes” epiphyses away from diaphysis = increase in length

• Growth plate zone (reserve zone), consists of chondrocytes, ready to start dividing

• Proliferative zone - chondrocytes divide and multiply

• Hypertrophic zone - chondrocytes enlarge and prepare to calcify cartilage

• Calcified cartilage zone - chondrocytes undergo apoptosis, the ECM undergoes calcification

• Zone of ossification - tissue is calcified, bone tissue is formed, the blood vessels form

This type of ossification forms the flat bones of skull, mandible, clavicle

• Mesenchymal cells aggregate to form ossification centres (pointy bits on the skull of a child)

• These cells differentiate into osteoblasts (ob).

Initially forms woven bone (B) before becoming lamellar

• Collagen fibres are randomly distributed in Woven (immature) bone, while in a matured bone its organised neatly.

Osteons (Haversian system) - responsible for strength and mineralisation of the bone tissue.

• Contains central canal (Haversian canal) surrounded by concentric layers of bone tissue called Lamellae

  • Haversian = longitudinal canal contains nerves and vessels

  • Volkmann = transverse canals connects one Harvesian canal to other

• Circumferential lamellae > at the peri (outer)/endosteal (inner) surfaces

• Interstitial lamellae > between osteons

• Within the lamellaes are lacunae that house osteocytes - they communicate via dendric processes of osteocytes in canaliculi

• Haversian Canal (logitudinal) - at centre of osteons, contains nerves and vessels - (2 arrows)

• Volkmann canal (transverse) - connects Haversian canals

The circle on the pic shows circumferential lamellae

Trabecular bone

• Has a sponge/meshwork like appearance of trabeculae.

• Spaces filled with bone marrow and adipose tissues

• Doesn’t have osteons but still has lamellar organisation in mature tissue

• There are few or no Haversian systems.

• It is strong but lighter than compact bone

• Balanced activity of osteoclasts and osteoblasts

  • Osteoclast removes, osteoblast forms new osteoid into cavity > new osteon

• Maintains bone by replacing old tissues - cyclic process that occurs throughout life.

• Response to biomechanical stress

• Primary osteons - formed during appositional growth

• This get replaced by secondary osteon - bones becomes more packed

• Fragmentary osteons are the remnants of osteons being replaced.

• Throughout life, more and more osteons are packed into compact bone

Metabolic bone disease where bone resorption (osteoclastic activity) exceeds bone formation (osteoblastic activity) causing a loss in bone mass.

• Starts with thinning of trabecular bone > progresses to cortical bone (trabecularisation)

• Huge gaps (resorption bays) seen in cortical bone = increased intracoritcal porosity due to widening of Haversian canals within osteon.

• Bones becomes more fragile > prone to #. Common sites are where high compression forces e.g. vetebrae or neck of femur

• Primary osteoporosis exists as 2 types:

  • postmenopausal (Type I) - occurs due to decreased oestrogen levels

  • senile (Type II) e.g elderly

• Secondary osteoporosis is due to disease/ medication/ lifestyle (sedentary)

High vascularity

1. Haematoma - due to bleeding > vasoconstriction + clotting

2. Soft callus - formed of fibrous tissue

3. Primary bony calus - osteoblast invade, lay down bone (1st type is Woven = immature bone)

4. Secondary bony callus - Woven bone replaved by lamellar bone

5. remodelled to restore shape and medullary cavities

Pectoral girdle, shoulder joint, arm, elbow joint, forearm, wrist joint, hand

Scapula and clavicle

• The pectoral girdle is the collection of appendicular bony structures by which the upper limb is attached to the axial skeleton

• Also known as shoulder girdle, supports the upper limb.

Attaches the upper limb to the axial skeleton

Sternoclavicular joint - Between sternum and clavicle

Acromioclavicular joint - Between clavicle and scapula

Glenohumeral joints - Between humerus and glenoid cavity of scapula.

Glenohumeral joint

Ball-and-socket synovial joint

• The shoulder (glenohumeral) joint is a ball and socket synovial joint between the head of the humerus and the glenoid cavity of the scapula

The rotator cuff is a group of muscles and their tendons which support the shoulder joint and facilitate movement

Clavicle

• the ‘collar-bone’

• S-shaped, articulates with sternum and scapula

• Attachment site for ligaments and muscles

• Only bony attachment between the upper limb and axial skeleton - the pectoral girdle is joined to the axial skeletal to the sternum via clavicle

• Palpable for its whole extent

• Develops by process of intermembranous ossifications

Note - the superior (top) view of the clavicle is smooth, the inferior (bottom) is rough as it attaches ligaments

• The clavicle transmits force from the upper limb to the trunk and is therefore prone to fracture.

  • Fracture most frequently occurs at the junction between the middle one third and lateral one third of the bone.

  Dislocation can also occur, more likely at the acromioclavicular joint - the clavile moves superiorly which can be felt as a raised bump on the skin on the shoulder

Sternoclavicular joint

Saddle synovial joint

• clavicle forms the sternoclavicular joint between sternal end of clavicle and claviclular notch of manubrim (upper part of the sternum)

• A saddle synovial joint - articular ends lined with fibrocartilage (most synovial joints are usually lined by hyaline cartilage)

• Articular disc present in joint cavity and several ligaments blend witth joint capsule

Fibrocartilage

Plane synovial joint

• Acromial end of clavicle + acromion of the scapula

• It has uniaxial mobility - limited movement

• It is strengthened by a acromioclavicular ligament and a large coracoclavicular ligament made of the Trapezoid and Conoid ligaments

Trapezoid ligament and conoid ligament

• These helps to stablise the joint and to keep it in place

Elevation, depression, protraction, retraction, and rotation

• The clavicle permits movement in the superior-inferior and antero-posterior planes.

• It permits a small amount of rotation.

• The majority of the movement occurs at the sternoclavicular joint rather than the acromioclavicular joint

Flat triangular bone on the posterolateral thoracic wall

• Known as ‘shoulder blade’

• ‘Floats’ in a musclular suspension with only a small articulation to axial skeleton, the clavicle.

• Has many prominence due to muscle attachment sites

• 3 angles - lateral, superior and inferior angles

• 3 borders - lateral, superior and medial borders

• 2 surfaces - costal (anterior) and dorsal (posterior)

• 3 processes - acromion, spine, and coracoid process

• 3 fossae - supraspinous, infraspinous, subscapular fossa

Acromion

• Lateral projection of the spine, articulates with the clavicle in the acromioclavicular joint

Supraspinous and infraspinous fossae and the spine process

It also possesses the acromion

• The costal (anterior) surface features subscapular fossa

Glenohumeral joint

• From lateral view of scapula, the coracoid process provide attachment site for muscles such as pectoralis minor and short head of biceps brachii.

• Glenoid cavity articulates with head of humerus to form glenohumeral joint

Superior and inferio to the glenoid cavity are 2 tubercles:

• Supraglenoid Tubercle –attach long head of biceps brachi

• infraglenoid turbercle – attach long head of triceps brachi

The scapula is capable of

• Protraction and retraction

• Rotation, through shoulder abduction and adduction

• Elevation and depression

• This is achieved through the muscles of the scapula

• Trapezius - rotates, elevate, retract, depress

• Levator - elevate

• Rhomboid minor and major - elevate and retract

Accessory nerve (CN XI)

• It is a powerful rotator of the scapula

• Upper fibres elevate the scapula

• Middle fibres retract the scapula

• Lower fibres depress the scapula

Rhomboid major and rhomboid minor

• Attach from the medial border of the scapula to the adjacent vertebrae

• Elevate and retract the scapula

• Innervated by dorsal scapular nerve

Levator scapulae

• Elevates the scapula

• Innervated by branches from anterior rami of C3 and C4 spinal nerves and branches of the dorsal scapular nerve

Serratus anterior

• Fan-shaped muslce located on lateral wall of the thorax

  • Attaches from the medial border of the scapula to the ribs

• Contributes to protraction (pulls scapula anteriorly), rotation and stabilisation of the scapula

• Innervated by long thoracic nerve - condition winged scapula is caused by paralysis if the long thoracic nerve

• The serratus and trapezius muscles maintains scapula in position during shoulder movement

Long thoracic nerve

• it is very superficial to the muscle, prone to damage > unable to contract the serratus muslce > pulls away from the rib > winged scapula

• The condition winged scapula, is caused by paralysis of the long thoracic nerve.

• This causes the inferior angle and medial border of the scapula to pull away from the thoracic wall.

• Full abduction of the arm is no longer possible (difficulty to raise arm above the head)

• serratus anterior and trapezius muscle maintain scapula in position during shoulder movement

• GH joint only contributes to the 1st 120 degree

• For full 180 degree abduction of the arm, serratus anterior and trapezius permit rotation of the scapula to achieve this movement.

  • So damage to long throacic nerve which supplies serratus muscle can impair the ablity to fully abduct.

• The scapula muscles fix it in place. The trapezius and serratus anterior muscles rotate the scapula

Head of humerus (ball) and glenoid cavity of scapula (socket)

• Its a ball and socket synovial joint

• Glenoid cavity is deepened by glenoid labrum (fibrocartilaginous structure that serves as rim for glenoid cavity)

• Multiaxial (wide range of) movements in 3 planes

• Low stability > prone dislocation

• Hyaline cartilage lines articular ends of bone and synovial membrane attaches the margins of articular surfaces to make up the synovial cavity.

Shallow socket and high mobility

Abduction, adduction, flexion, extension, medial rotation, lateral rotation, circumduction

Supraglenoid tubercle and blends with glenoid labrum (deepens joint cavity)

• Tendon passes within the joint cavity > intertubercular sulcus > deep to the transverse humeral ligament > attaches to the tubercle of the scapula.

Intertubercular sulcus

To allow abduction

• Synovial membrane is redundant (loose) inferiorly to allow abduction.

• Bursae (small sacs filled with synovial fluid) and synovial sheath reduces friction at the joint

Fibrous outer joint capsule has 3 locations where it is thickened:

• Coracohumeral ligament

• glenohumeral ligaments (superior, middle and inferior)

• transverse humeral ligament

Anterior circumflex humeral artery

posterior circumflex humeral artery

Suprascapular & circumflex scapular arteries

Suprascapular nerve, axillary nerve

• Proximal humerus is the part that forms the ball of the glenohumeral joint. Distinct features:

• Greater tubercle and lesser tubercle (or tuberiosity) - attachment site for muscle tendon that moves the GH joint

• Intertubercular sulcus (bicipital groove) - occupied by the tendon of long head of biceps brachii muscle

• Anatomical neck - between head of humerus and tubercle

• Surgical neck - between tubercle and shaft of humerus. Common site of #

Tendon of long head of biceps brachii

Surgical neck

A = fracture of the surgical neck of humerus

B = dislocation of the head of humerus

A group of four muscles that aids stabilisation and movement of the glenohumeral joint

SITS = Supraspinatus, infraspinatus, teres minor, subscapularis

• Forms a musculotendinous collar that stabilises and holds head of humerus in glenoid cavity

Supraspinatus

• Sits in the supraspinous fossa

• It inserts into the greater tubercle of humerus

• It is innervated by the suprascapular nerve

• Initiates abduction, the first 15 degrees (15-90 degree by deltoid and >90 degree by trapezius)

Infraspinatus

• Sits in the infraspinous fossa

• Inserts into the greater tubercle of the humerus

• Innervated by the suprascapular nerve

Teres minor

• Origin: posterior surface of the lateral border of the scapula

• Insertion: greater tubercle of the humerus

• Innervated by the axillary nerve

Subscapularis

• Sits in the subscapular fossa

• Inserts into the lesser tubercle of the humerus

• Innervated by the upper and lower subscapular nerves

• 5 main bursae (small sacs filled with synovial fluid) in the shoulder which reduce friction:

Subacromial-subdeltoid

subscapular

subcoracoid

coracoclavicular

Supra-acrominal

Impingement or tendinopathy of rotator cuff muscle tendons

• Tendinopathy = degenerative change in the tendon, due to to poor vasculator of the tendon. Heals very slowly.

  • Damage > calcium deposition > extreme pain > susceptible to partial or full thickness tears

Supraspinatus

• Because it passes beneath the acromion and acromioclavicular ligament through tight space.

• Impinged by swelling of the muscle or subacromial bursa, fluid build up or bony spurs

Anterior dislocation (and inferiorly) of head of humerus

• Shoulder has highest range of motion of any joint in the body

• Prone to dislocation

• complications —> Anterior glenoid labrum may tear (increase chance of recurrence), can cause axillary nerve compression > deltoid paralysis

Axillary nerve > deltoid muscle paralysis and loss of sensation of the skin over the deltoid. = regimental badge sign

Deltoid muscle

• Major abductor of the shoulder, between 15 and 90 degrees

• The anterior fibres assist in flexion, Posterior fibres assist in extension

• The tendon inserts onto the lateral surface of the humerus on the deltoid tuberosity

• It is innervated by the axillary nerve

Pectoralis major

• Large powerful muscle that produces adduction and medial rotation of the glenohumeral joint.

• Clavicular fibres flex the arm from an extended position

• Sternocostal fibres extend the arm from a flexed position

• It is innervated by medial and lateral pectoral nerves

Latissimus dorsi

• Powerful extensor of the glenohumeral joint from a flexed position

• It is responsible for medial rotation and adduction of the glenohumeral joint

• It is innervated by the thoracodorsal nerve

• Responsible for medial rotation and extension at GH joint

• Innervated by lower subscapular nerve

Pectoralis minor

• Assists in protraction of the scapula

• Innervated by medial and lateral pectoral nerves

Subclavius

• Responsible for stabilisation of shoulder joint

Coracobrachialis

• Flexion, adduction of the shoulder

• Innervated by the musculocutaneous nerve

Rotation of the scapula by trapezius and serratus anterior

Head, anatomical neck, surgical neck, greater and lesser tubercles and proximal shaft

• Arm = region between shoulder and elbow. Humerus is the bone in the arm

• Head of humerus articulates with glenoid fossa of the scapula to form shoulder joint.

• Distal humerus articulates with ulna and radius to form elbow joint

Deltoid tuburosity is where deltoid muscle attaches

Greater and lesser tubercles are seperated by intertubercular sulcus (bicipital groove)

• Tendon of the long head of biceps brachii runs through here

Surgical neck

• 3 terminal branches of brachial plexus runs very close to hunerus. Axillary, radial and ulnar nerve

• fracture in these locations may affect the nerve / blood vessels.

Circumflex humeral arteries - these supplies the tissues of the head of humerus

Radial nerve - This innervates the posterior arm and forearm muscles

• Damaged during mid-humeral fracture

Wrist drop

• radial nerve is responsible for wrist extension so # leads to wrist drop —> inability to extend the wrist

Capitulum and trochlea

• It also had lateral and medial epicondyles - common sites of origin of common extensor and flexor muscles respectively

• Trochlea of the humerus articulates with trochlear notch of the ulna

• Capitulum of the humerus articulates with radial head of the radius

Medial epicondyle

Lateral epicondyle

Ulnar nerve

They accommodate the forearm bones during flexion

• 2 fossas of distal humerus - coronoid fossa (anteriorly) and olecranon fossa (posteriorly)

3 Bones - humerus, ulna and radius

2 articulations:

• Humero-ulnar joint= between trochlea of humerus and trochlear notch of the ulna

• Humero-radial joint = between capitulum and radial head

Pivot joint between head of radius and ulna

• allows supination and pronation

Hinge synovial joint. Features includes:

• Articular surfaces are lined by hyaline cartilage

• Joint is enclosed by fibrous capsule

• Capsule is reinforced by extracapsular ligaments

• Internal surfaces are lined with synovial membranes

• fossas where the bones move into has fat pads to protect the bone

• Has one set of opposing movement - Flexion / extension

Usually, the carrying angle of the women is slightly wider than men.

• Medial (ulnar) collateral ligament - located medially connects ulna to humerus

• Lateral (radial) collateral ligament - located laterally, connects radius to humerus

• Annular ligament - forms ring around head of radius, holding it tight against ulna

• Quadrate ligament - connects radius to ulna

Radial head subluxation (nursemaid’s elbow), occurs in children

• occurs due to incomplete formation of ligaments

• Radial head moves away (subluxes) from annular ligament (which is loose in children)

• Mechanism of injury - upward force on abducted arm (lifting a child holding their hand)

Ulnar nerve

• A muscle can only move a joint if it (or its tendon) crosses that joint

  • Muscles in the arm crosses the elbow so moves the elbow

• 2 muscle compartments in the arm: flexor / extensor

  • Muscles in the anterior flex the elbow

  • Muscles in the posterior extends the elbow

Deep facia surrounds the entire compartment then extends into becomes intermuscular septa.

Anterior (flexor) has 3 mucles:

• Biceps brachii - has 2 heads (short head attached to coracoid process, long head to supraglenoid tubercle)

  • Crosses shoulder and elbow joint (at radial tuberosity)

  • Elbow flexion, shoulder flexion, supination

• Brachialis - deep to biceps brachii, proximal attachment is humeral shaft, distally to ulna.

  • Elbow flexion (only crosses elbow)

• Coracobrachialis - small, attach to coracoid process, inserts on humeral shaft.

  • Weak shoulder flexion (only crosses shoulder)

• Anterior muscles are innervated by Musculocutaneous n.

Intermuscular septa - continuous with deep facia. Deep investing facia attaches to humerus.

Neuro-vascular structures are usually medially to the arm.

BB = Biceps Brachii (long head laterally, short head medialy)

B = Brachialis

CB = coracobrachialis

arrow = musculocutanous nerve that supplies these muscles

Other structures on the pic:

D = deltoid

SA = serratus anterior

LD = satissimus dorsi

Pm = pectoralis minor

Posterior (extensor) has 2 muscles: supplied by radial nerve (C5-T1)

Triceps brachii - has 3 heads, all insert via common tendon on to olecranon of ulna. Extends the elbow

• Long head - attaches to scapula > shoulder extension

• Lateral head - attaches to posterior humeral shaft

• Medial head - deep to lateral + medial, attach to humeral shaft

Anconeus - elbow extension, joint stability

Arterial:

• Brachial artery (main) > radial and ulnar arteries (forearm)

• Profunda (deep) brachii artery supplies posteriorly

Venous:

• Cephalic + basilic veins (superficial)

• Brachial + axillary veins (deep)

Note: Subclavian > axillary > brachial artery

Blood test is taken usually from median cubital vein

#bicen brachii tendon, Axillary artery and median nerve pass through the cubital fossa.

• ulna and radial nerve runs lateral to the fossa

Musculocutaneous nerve (C5-7)

• Motor: all muscles in the anterior compartment of the arm

• Sensory: Lateral cutaneous nerve of forearm

Radial nerve (C5-T1)

• Motor: All muscles in the posterior compartments of the arm and forearm

• Sensory: Inferior lateral cutaneous nerve of arm

3 of the terminal branches of the brachial plexus run very close to the humerus:

Axillary nerve = surgical neck

Radial nerve = radial groove

Ulnar nerve = medial epicondyle

Cubital tunnel, lateral epicondyle, medial epicondyle, olecranon

Medial epicondylitis = inflammation at the medial epicondyle tendon = ‘golfer’s elbow (common flexor muscles are injured)

Lateral epicondylitis = inflammation at the lateral epicondyle tendon = ‘tennis elbow’ (common extensor muscles are injured)

• pain radiates into forarm along the muscles

• Rx - rest, corticosteroids injections

• Bursa = fluid filled sac located around joint, areas of potential friction.

• When inflammed > bursitis

• Cause - excessive, repeated pressure and friction over the olecranon

• Sx - bursa swells and painful

• Rx - analgesia, compression

Above the epicondyles

• may injure the median nerve > impaired forearm muscle function > sensory disturbances in the skin supplied by median nerve

• Can also injure brachial artery > ischaemia of forearm muscles

Note: dislocation of the elbow posteriorly can affect / stretch ulna nerve

• Dx - # surgical neck of humerus

• Nerve - axillary nerve (innervates deltoid, teres minor and the skin over upper lateral arm.

• Ax - deltoid abducts the shoulder beyond 15 degree, teres minor rotates shoulder laterally.

  • so ask patient to abduct arm

  • Test sensation over upper lateral arms B/L and compare

Dx - humeral shaft fracture (spiral)

Nerve affected - Radial nerve (supplies posterior arm = extension)

Artery - profunda brachii artery

Ax - test extension of the arm and sensation of posterior arm.

Dx: Subluxation - head of the radius is pulled away from ulna.

Confusion: growth plate of the radius and ulna noted as it is normally found in children

Neurovascular - radius dislocates laterally and could stretch the radial nerve but its likley to be

Brachial artery

Basilic vein

Median nerve

Bicep brachi tendon

Brachioradialis

Radial nerve

Radial nerve

Musculocutaneous nerve

Intermuscular septum

Biceps brachii, brachialis, coracobrachialis

Biceps brachii

Brachialis

Coracobrachialis

Triceps brachii

Extension

Musculocutaneous nerve

Biceps brachii

Identify cause, identify structures involved, determine time course, assess systemic involvement, assess precipitant, assess impact (any three)

History of presenting complaint, systems review, past medical history, family history, social history, treatment history (any five)

Pain or stiffness in muscles/joints/back; difficulty dressing (assesing upper limb); difficulty climbing stairs (assessing lower limb)

Lower limb dysfunction

Pain, stiffness/swelling, loss of function

Site, distribution, onset/timing, nature

SOCRATES

Monoarticular = 1 joint; e.g Gout

oligoarticular = 2–4 joints e.g Psoriasis

polyarticular = more than 4 joints e.g. rheumatoid arthritis

Trauma - ACL rupture

Infection - septic arthritis

Inflammation - RA

Degeneration - OA

E.g of inflammatory - RA

E.g. of degenerative - OA

Severe, localised, may disturb sleep e.g bone cancer

Diffuse and poorly localised around a joint e.g tendonitis

Pain travelling along the path of a nerve

e.g sciatica, pain radiates down the leg. Neck pain radiates to fingers and hip pain radiates to knee

Tendinitis

Shooting, burning, electric shock like pain, tingling (parasthesia), numbness

When and how it occurred; mechanism; force involved; previous injury (any three)

Peripheral circulation, peripheral nervous system, central nervous system, fitness for anaesthetic

Psoriasis, oral ulcers, scleritis, alopecia (any two)

• Cardiovascular system - Raynaud's phenomenon

• Kidneys - Blood in urine

• GI tract - Change in bowels

• Respiratory - Chest pain

• Nervous system - Tingling/numbness

Previous infections; bowel symptoms; skin disease; childhood MSK problems; travel (any two)

Risk of infection-related arthritis

• Food poisioning with E.coli can cause RA

Identifies repetitive strain or occupational risk factors

Many MSK diseases are polygenic and familial

• Monogenic - rare inflammatory syndromes (arthritis).

Autoimmune diseases cluster within families but may present differently

Limitation of activities; time off work; personal hygiene difficulty; need for aids; psychological impact (any two)

Osteoarthritis, gout, tendonitis, bursitis, bone tumours (any four)

Rheumatoid arthritis

Systemic conditions that affect the whole body but also have prominent features at joints

Sickle cell disease (bone pain); cancer metastasis; vitamin D deficiency (rickets in children) (any two)

Supraspinatus tendon impingement in subacromial space

• supraspinatous tendon passes through the subacromial space. Inflammation of this tendon reduces the space > painful arc during shoulder abduction between 60-120 degrees

Scaphoid fracture (in younger adults)

• Forces transmitted through thenar eminence of lateral bones of carpus (trapezoid, trapezium and scaphoid)

• In older aduts, this will result in Colle’s fracture (# lower end of radius)

• Scaphoid is most commonly # carpal bone —> pain on dorsiflexion, tenderness in anatomical snuff box and pain on grip.

Colles’ fracture

Median nerve > numbness and loss of power

LOFA

Lateral 2 lumbricals

Opponens pollicis

Flexor pollicis brevis

Abductor pollicis brevis

Digital cutaneous branch

Sprain or rupture

Joint instability > Feeling of giving way or instability

Clavicle, scapula, humerus, radius, ulna, carpals, metacarpals, Proximal, middle and distal phalanges

Elbow is a hinge joint - these joint usually has collateral ligaments.

• Proximal radioulnar joint - at elbow, between head of radius, and radial notch of ulna

• Distal radioulnar joint - at wrist, between head of ulna, and ulnar notch on radius. It is separated from the wrist joint by a fibrous articular disc

Annular ligament is the collateral ligament at the elbow that wraps around the radial head.

Pivot synovial joints

• Enable rotation in one plane

• Size of Radius and ulna changes as they continue distally - Radius is narrow proximally and wider near the wrist, ulna is wide proximally and narrows towards wrist

A fibrous sheet (syndesmosis) connecting medial border of radius to the lateral border of ulna.

• Seperates the anterior and posterior comparments of the forarm

• Vessels pass between anterior and posterior comparments.

• Keep the ulna and radius in place and enables supernation and pronation. (during pronation the distal radius crosses over the ulna)

Radius

• Motility of the proximal and distal radio-ulnar joint as well as humero-radial joint allows radius to rotate medially or laterally > pronation and supination.

• Movement of the hand is due to radius because this is the major bone attached to had not the ulna

• wrist joint also able to adduct and abduct

Antero-Medial rotation of the radius crossing over the ulna > X shape.

From pronated position, Lateral rotation of the radius returning to parallel with the ulna

There are 3 muscles of pronation - 2 in anterior, 1 in posterior compartment

• Pronator teres (main) - from medial epicondyle of humerus to lateral surface of radius

• Pronator quadratus (main) - from distal end of ulna to distal end of radius

• Anconeus (accessory) - it abducts the distal end of ulna to maintain the central position of the palm of the hands during pronation. Located in posterior compartment of the forearm.

  • from lateral epicondyle of humeral to proximal end of ulna

Biceps brachii - powerful supinator, located in anterior comparment

Supinator - located in posterior comparment

Eight flexor muscles > movement at the wrist, flexion of fingers or pronation. They all originate from medial epicondyl of humerus (common felxor origin) and are innervated by median nerve (C6-T1) - except flexor carpi ulnaris (innervated by ulnar nerve (C8-T1)

• 5 superficial = flexor carpi ulnaris, palmaris longus, flexor carpi radialis, Pronator teres and flexor digitorum superficialis

• 3 deep = flexor digitorum profundus, flexor pollicis longus (unipennete) and pronator quadratus

Median nerve (C6-T1)

• Flexor carpi ulnaris and medial half of flexor digitorum profundus are innervated by ulnar nerve (C8-T1)

Flexor carpi ulnaris

The medial half of flexor digitorum profundus is also supplied by ulna nerve (C8-T1)

Flexor carpi radialis (pulse papated lateral to it) - a poweful flexor and abductor of wrist

Flexor digitorum superficialis (to II, III, IV and V)

• Responsible for flexion of each finger’s MCP and proximal interphalangeal joint + wrist joint

• Innervated by median nerve

And Flexor digitorum profundus

Flexor digitorum profundus

• has 4 tendons which pass through carpal tunnel > phalanx of fingers II, III, IV, V.

• Responsible for felxion of MCP, proximal and distal interphalangeal joints and wrist

Lateral half by anterior interosseous nerve (median nerve); medial half by ulnar nerve

Flexor pollicis longus

• extends one large tendon through carpal tunnel > thumb

Anterior interosseous nerve (branch of median nerve)

• flat, square shaped muscle

• Responsible for pronation by rotating the distal end of the radius over ulna

Twelve muscles > move wrist, extend fingers or supinate the hand. All are innervated by radial nerve (C5-T1). Common origin is lateral epicondyle

• 7 superficial muscles - Brachioradialis (flexes is semi ronation), extensor carpi (=wrist) radialis longus (=long), extensor carpi radialis brevis (=short), extensor digitorum, extensor digiti minimi, extensor carpi ulnaris and anconeus

• 5 deep muscles - supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus and extensor indicis

Radial nerve (C5-T1)

The cubital fossa is bound:

• superiorly by an imaginary line between lateral and medial epicondyles

• laterally by the brachioradialis

• medially by the pronator teres

Wrist is a condyloid synovial joint

• Carpals (8 bones)

• Metacarpals (5)

• Proximal phalanges (5)

• Middle phalanges (4, because thumb only has 2 phalanges)

• Distal phalanges (5)

Eight carpals arranged in two rows of four bones (articulate with neighbouring carpals.

• Proximal row - Scaphoid, lunate, triquetrum, pisiform

  • scaphoid and lunate articulate with radius while lunate and triquetrum articulate with ulna.

• Distal row - Trapezium, trapezoid, capitate, hamate.

  • Articulate with metacarpals

They are arranged to form arch shape (carpal arc) which forms the base and side of carpal tunnel

Scaphoid and lunate

Condyloid synovial joint - formed by 4 joints > abduction, adduction, extension and flexion

• carpometacarpal joint (distal carpal + Metacarpals)

• Radiocarpal joint (Scaphoid + lunate)

• Ulnocarpal joint ( lunate + triquetrum)

• Distal radioulnar joint

First carpometacarpal joint (thumb)

• there are 5 metacarpals (1-5), these are long bones, have base, shaft and head.

• 2-5 are very rigid with limited movement, 1st MCP joint is very mobile.

Two (proximal and distal)

• other 4 fingers have 3 phalanges (proximal, middle and distal)

2nd - 5th metacarpophalangeal joints are mobile > adduction, abduction, flexion and extension.

Hinge joints

Connect MCP joints of digits II–V and restrict relative movement

Lateral border: abductor pollicis longus and extensor pollicis brevis

medial border: extensor pollicis longus

Scaphoid bone can be felt here and # > tenderness.

Scaphoid bone get blood supply from the edge and # can cause avascular necrosis.

Scaphoid and trapezium

Site for palpating scaphoid fractures and radial pulse

A triangular thickening of deep fascia covering the palm.

It extends longitudinal fibres to cover anterior bases of the digits

Allows coordinated extension and fine finger movements

• These are complex, triangular connective tissue structures covering the dorsal surface of the digits

• Formed by the tendons of the extensor digitorum and extensor pollicis longus muscles.

• Palmaris brevis

• Interossei

• Adductor pollicis

• Thennar (3) - opponens pollicis, flexor pollicis brevis, abductor pollicis brevis

• hypothenar muscles (3) - opponens digiti minimi, abductor digiti minimi and flexor digiti minimi brevis

• Lumbricals (4) - 2 medial and 2 lateral

Interossei (dorsal abduct, palmar adduct)

Deep branch of the ulnar nerve

Median nerve

Flex MCP joints and extend IP joints

• Lumbricals are main muscles of this action assisted by interosseous musles. Both attached to extensor hoods of the finger

• Enables precision grip and writing