MHHS2401- Musculoskeletal System

Clinsci year 1- session 2

costoclavicular ligament

The impression on the medial inferior surface of the clavicle is the site for the attachment of the:

The other name for the intertubercular sulcus is ___

Bicipital groove

what joint is Sternoclavicular classified as

• saddle

1- Coracoclavicular Ligament

2- Trapezoid Ligament

3-conoid ligament

4-acromioclavicular ligament

Shoulder Joint- Glenoid labrum

• deepens Glenoid cavity

• ring of fibrocartilage

Anterior muscle group: Pectoralis Major

• two origins: Clavicle and sternocostal

• Distal attachment: Lateral lip of bicipital groove (Intertubercular sulcus)

• Action: Helps move humerus through adduction and flexion

• Nerve Supply: Lateral and medial pectoral nerves

Pectoralis Minor

• Origin: Ribs 3 → 5

• Distal Attachment: Coracoid process of scapula

• Action: Stabilizes scapula and helps in respiration

• Nerve Supply: Medial pectoral nerve

Serratus Anterior Muscle (Boxer Muscle)

• Origin: Ribs 1 → 8

• Distal Attachment: Anterior (costal) surface of medial scapular border

• Action: protracts scapula and holds it to thoracic wall when punching, rotates scapula

• Nerve Supply: Long Thoracic nerve

Trapezius

• Origin: C7 → T12

• Distal Attachment: Lateral part of clavicle and acromion and spine of scapula

• Action: Elevates scapula (Superior fibers), retracts scapula (Middle fibers), depresses scapula (Inferior Fibers)

• Nerve Supply: Spinal root of CNXI- motor fibers and cervical nerves C3 and C4 (sensory)

Latissimus dorsi

• Origin: T7 → T12

• Distal Attachment: Floor of intertubercular groove (Bicipital groove)

• Action: movement of humerus and helps body with climbing

• Nerve Supply: Thoracodorsal nerve

Levator scapulae

• Origin: C1 → C4

• Distal Attachment: superior part of medial border of scapula

• Action: elevates scapula and tilts glenoid cavity inferiorly

• Nerve Supply: Dorsal scapular nerve

Rhomboid minor and major

• Origin: Major = T2 → T5, minor = C7 and T1

• Distal Attachment: medial border of scapula

• Action: retract and rotate scapula

• Nerve Supply: Dorsal scapular nerve

Deltoid Muscle

• Origin: lateral part of clavicle,, acromion and spine of scapula

• Distal Attachment: deltoid tuberosity

• Action: Anterior fibers = flexes arm, middle fibers = abduction of arm, posterior fibers = extend arm

• Nerve Supply: axillary nerve

Teres major

• Origin: Inferior lateral border of scapula

• Distal Attachment: medial lip of intertubercular groove

• Action: abduction and medial rotation of at at shoulder joint

• Nerve Supply: lower subscapular nerve

Rotator Cuff Muscle: Supraspinatus

• Origin: Supraspinous fossa

• Distal Attachment: Greater tubercle

• Action: Abduction of arm

• Nerve Supply: Supscapular nerve

Rotator Cuff Muscle: Infraspinatus

• Origin: Infraspinous fossa

• Distal Attachment: Greater tubercle

• Action: Lateral rotator of shoulder

• Nerve Supply: subscapular nerve

Rotator Cuff Muscle: subscapularis

• Origin: Superior part of lateral border of scapula

• Distal Attachment: Lesser tubercle

• Action: Medial rotator of humerus

• Nerve Supply: upper and lower subscapular nerve

Rotator Cuff Muscle: Tres minor

• Origin: Lateral border of scapula

• Distal Attachment: Greater tubercle

• Action: Lateral rotator of shoulder

• Nerve Supply: Axillary nerve

Subtendinous Bursa and subacromial bursa (subdeltoid bursa)

• Where tendon rubs against bone

• acts as cushion

Bone structure- Osteoprogenitors

• Stem cells that differentiate into osteoblasts

Bone structure- Osteoblast

• For bone formation

• Release bone matrix

Bone structure- Bone matrix (Osteoid / hydroxyapatite)

• Osteoid: Organic, mainly collagen

• Hydroxyapatite: inorganic, calcium + phosphate

Bone structure- Osteocytes

• get stuck in bone matrix

• former osteoblasts

Bone structure- Osteoclast

• Bone resorption

• Proteases break down osteoid

• HCL break down hydroxyapatite

Bone structure- Lamellae

• layers of bone

Bone structure- Osteons (Haversian system) / central canal (Haversian canal)

• Osteons: lamellae form osteons

• Central canal: empty space where blood supply and nerves come

Bone structure- Spongey bone (Trabecular bone)

• Irregular lamellae forming trabecular

• NOT RANDOM- align along stress lines and develop fro micro fractures caused by weight bearing

• Blood supply comes from Endosteal capillaries

Bone structure- Compact bone

• Fibers not parallel to resist torsional (twisting) forces and gives strength

• collagen and hydroxyapatite

Formation- What happens in week 9 utero when starting ossification in long bone?

Hyaline cartilage model developed bone collar and primary ossification centre

Formation- Structure during 3 months of utero?

• cartilage matric deterioates

• spongey bone formation begins

Formation- Structure during birth?

• medullary cavity

• secondary ossification centres apear in epiphyses

Formation- Growth plate

• between epiphysis and diaphysis

• articular cartilage

Formation- Longitudinal bone growth

• ends at the end of puberty

• happens at growth plate between head and shaft of long bone

Formation- Endochondral ossification

• where chondrocytes lay down cartilage foundation and osteoblast replace it with trabecular bone matrix

Remodelling and Hormones- RANK-ligand (RANKL)

• secreted by osteoblast

• Activated osteoclast

Remodelling and Hormones- OPG (osteoprotegerin)

• Secreted by osteoblast

• Blocks osteoclast activation

• Allows for less resorption

Remodelling and Hormones- squence

1. osteoclast recruitment

2. Rsorption of matrix

3. osteoblast recruitment

4. bone formation and mineralisation

5. resting bone (90% of bone most the time)

Remodelling and Hormones- apoptosis

• Osteoclasts undergo when they die

Remodelling and Hormones- Appositional growth

• Growth in bone diameter

• occurring at periosteum of diaphysis

Remodelling and Hormones- PTH

• increased blood Ca

• Secreted from parathyroid gland

Remodelling and Hormones- Calcitriol

• made in kidney

• Stimulated by PTH

• increases blood Ca

Remodelling and Hormones- Calcitonin

• Secreted by Thyroid gland

• decreases blood Ca

• promotes bone formation

Remodelling and Hormones- PTH continuous and Intermittent exposure

• Continuous exposure: catabolic (↑RANKL ↓OPG → resorption)

• Intermittent exposure: Daily low-dose → Anabolic → ↑osteoblast differentiation, ↓osteoblast apoptosis → formation

Remodelling and Hormones- Vitamin D3 biosynthesis

1. Diet

2. Liver

3. Kindey (PTH induced)

Remodelling and Hormones- HGH

• Allows for formation of bone

• ↑osteoblast proliferation, ↑apposition, ↑longitudinal growth.

Remodelling and Hormones- TH

• Allows for bone resorption

• ↑osteoblast differentiation, ↓osteoblast proliferation, ↑osteoclast activity.

Remodelling and Hormones- Glucocorticoids (eg. cortasol)

• Allows for resorption

• ↑RANKL, ↓OPG.

Remodelling and Hormones- Estrogen

• Allows for bone formation

• ↓RANKL, ↑OPG, ↑osteoclast apoptosis (effect observed in females).

Remodelling and Hormones- Andogens

• Allows for bone formation

• ↓RANKL, ↑OPG, ↑apposition, ↑longitudinal growth.

Disorders- Osteoporosis

• Metabolic

• Osteoclast hyperactivity

• Due to endocrine supression

Disorders- Osteomalacia

• metabolic

• Abnormal bone mineralisation due to vitamin D deficiency

Disorders- Rickets

• same as osteomalacia

• happens in kids

Disorders- Brown tumour

• metabolic

• Caused by hyperparathyroidism

• Vascular growths in bone

Disorders- Osteogenesis Imperfecta

• Genetic

• Defective collagen type 1

Disorders- osteopetrosis

• Genetic

• Defective osteoclast

• Thick but weak bone

• no medullary cavity

Bony features

Elbow- Joint type and movments?

• synovial hinge Joint

• flexion and extension only

Elbow- Articular surfaces (3)

1. Capitulum + trochlea

2. Head of radius

3. Trochlear notch of ulna

Elbow- Fibrous capsule

• weak anteriorly and posteriorly

• Thickened medially and laterally to form collateral ligamnets

Elbow- Collateral ligaments

• Lateral (radial) collateral ligament

• Medial (ulnar) collateral ligament (3 bands; anterior, posterior and oblique)

Elbow- Carrying angle

• angle between acis of arm and forearm in anatomical position

• Greater in females (> 15% degrees)

• Males (10-15 degrees)

• disappears when supinated

Elbow- Students elbow

• Olecranon bursitis get inflamed

Elbow- Proximal radioulnar joint

• synovial pivot joint

• articular surfaces: Head of radius and radial notch of ulna

• anular ligament of radius holds it together and allows pronation and supination

Arm muscle- intramuscular septum

• divided arm muscles into anterior and posterior

Anterior Arm muscle- 3 muscles that make up anterior compartment

• biceps brachii

• brachialis

• coracobrachialis

• nerve supply: musculocutaneous nerve

Anterior Arm muscle- Biceps brachii

• Long head Origin: Supraglenoid tubercle of scapula

• Short head Origin: coracoid process of scapula

• Insertion: Radial tuberosity

• Action: Flexor at elbow and powerful supinator of forearm

• Nerve supply: musculocutaneous

Anterior Arm muscle- Coracobrachialis

• Origin: coracoid process of scapula

• Insertion: Mid shaft of humerus

• Action: Weak flexor and adductor of arm

• Nerve supply: musculocutaneous

Anterior Arm muscle- Brachialis

• Origin: Mid-shaft of humerus (deep to biceps)

• Insertion: Ulnar tuberosity

• Action: Chief flexor of forearm

• Nerve Supply: musculocutaneous

Posterior arm muscle- Triceps brachii

• Nerve supply: Radial Nerve

• Origin: Long head- infraglenoid tubercle of scapula, medial head- posterior humerus (inferior to radial groove), lateral head- posterior humerus superior to radial groove

• Insertion: Olectanon process

• Action: stabilizes humeral head when abducts arm and chief extensor of forearm

Distal radioulnar joint- Interosseous membrane

• structure that connects radius and ulna

• stabilises bone

• provides attachment for deep forearm muscle

• allows for passage of blood vessels

Distal radioulnar joint- Intermuscular septa

• divides forearm into compartments:

-→posterior: extensors / supernators

→ anterior: flexors / pronators

Distal radioulnar joint- what kind of joint / articular surfaces

• synovial pivot joint

• articular surfaces include:

-→Head of ulna

-→ulnar notch of distal radius

Distal radioulnar joint- Fibrocartilaginous articular disc

• unites distal radioulnar joint

• separates wrist joint cavity

Injuries- Posterior dislocation of elbow joint

• caused by fall on outstretched hands with elbow flexed

• distal humerus driven through weak anterior part of fibrous capsule

Injuries- Pulled elbow

• dislocation of radial head from sudden pulling of upper limb

• distal attachment of anular ligament at neck of radius broken

Injuries- golfer’s elbow (medial epicondylitis)

• Overuse of flexor-pronator muscles

• causes microtrauma

Anterior forearm- 3 layers

• Superficial (4 muscles)

→ common attachment is medial epicondyle of humerus

• Intermediate (1 muscle)

• deep (3 muscles)

innervated by median nerve

Anterior forearm- Nerve supply

• innervated by median nerve

• Except flexor carpi ulnaris and medial half of flexor digitorum profundus

-→ both supplied by ulnar nerve

Anterior forearm (superior)- Flexor carpi radialis

• insertion: base of 2nd metacarpal

• action: abducts and flexes hand at wrist

Anterior forearm (superior)- Pronator teres

• insertion: Mid shaft of radius

• action: pronates forearm

Anterior forearm (superior)- Palmaris longus

• absent in 14% of people

• blends in with palmar aponeurosis

• flexes hand at wrist

Anterior forearm (superior)- Flexor carpi ulnaris

• insertion: pisiform, hook of hamate and 5th metacarpal

• action: flexes and adducts hand at wrist

• Nerve supply: ulnar nerve

Anterior forearm (Intermediate)- Flexor digitorum superficialis

• origin: medial epicondyle of humerus

• insertion: middle phalanges of the medial 4 digits

• action: flexes middle phalanges at PIP joints and flexes proximal phalanges at MCP joint

Anterior forearm (Deep)- Flexor pollicis longus

• Action: Flexes phalanges of thumb

• insertion: base of distal phalanx of thumb

• origin: anterior surface of radius + interosseous membrane

Anterior forearm (Deep)- flexor digitorum profundus

• Action: Flexes distal phalanges at DIP joints, MCP joints and assists hand flexion

• insertion: distal phalanges of medial 4 digits

• origin: proximal anterior surface of ulna

Anterior forearm (Deep)- pronator quadratus

• Attachment: distal anterior surfaces of radius and ulna

• origin: Pronates forearm

Posterior Forearm Muscle- Superficial Group

• Origin: Lateral Epicondyle of Humerus

• Nerve Supply: Radial Nerve

• 6 muscles:

→ Brachioradialis

→ Extensor carpi radialis Longus (Longer) (ECRL)

→ Extensor carpi radialis brevis (shorter) (ECRB)

→ Extensor digitorum

→ Extensor digiti minimi

→ Extensor carpi ulnaris

Posterior Forearm Muscle- Brachioradialis

Insertion: Lateral surface of distal radius

Action: Flexor of forearm at elbow

→ only posterior muscle that doesn’t cross wrist joint

Posterior Forearm Muscle- Extensor carpi radialis Longus (ECRL) / Extensor carpi radialis brevis (ECRB)

Action: Wrist extensors, produce abduction at wrist, limited about 15 degrees

Nerve: Deep branch of radial nerve

Posterior Forearm Muscle- Extensor carpi ulnaris (ECU)

Action: Wrist Extensor, adduction at wrist joint

Nerve: Deep branch of radial nerve

Posterior Forearm Muscle- Extensor digitorum

Insertion: Extensor expansion of medial 4 digits

Posterior Forearm Muscle- Extensor digitorum

Action: primary extending at Metacarpal joint

Insertion: extensor expansion of 5th digit

Posterior Forearm Muscle- Extensor Expansion

• Divides into medial band and two lateral bands

• Lumbrical and dorsal interossei muscle attatch to medial band

Posterior Forearm Muscle- Extensor retinaculum

• holds extensor tendons in place at wrist

Posterior Forearm Muscle- Synocial Tendon sheaths

• Helps reduce friction against bone and tendons

Posterior Forearm Muscle- Deep Group

• 5 muscles

→ Supinator

→Abductor pollicis longus

→ Extensor pollicis bevis

→ Extensor pollicis longus

→ Extensor indicis

Posterior Forearm Muscle- Supinator

Location: Cubital fossa

insertion: Proximal radius

Origin: Lateral epicondyle of humerus

Action:

Nerve: Radial nerve