Bones and how to side them

Vertebra:

Types of vertebra:

Atlas (C1) – no body, no spinous process, dens foramen, transverse foramen, anterior and posterior arch and tubercle

Axis (C2) – dens, bifid spine, transverse foramen

Cervical vertebra – bifid spine (C7 is long and not bifid), transverse foramen and horizontal articular facets

Thoracic vertebra – vertical articular facets, heart shaped body, spine long and downwards

Lumbar vertebra – sagittal articular facets, kidney shaped body

Vertebral ligaments:

• Anterior longitudinal – prevent hyper extension
• Posterior longitudinal – prevent hyper flexion
• Ligamentum flavum – prevent abrupt flexion (between laminas)
• Interspinous
• Supraspinous
• Intertransverse ligament

• Static stability of vertebral column – ligaments
• Dynamic – back muscles ie. iliocostalis, longissimus, spinalis (from lateral to medial)

NB: Vertebral column divided into 3 vertical parallel columns:

Anterior column:

• Anterior longitudinal ligament
• Anterior 2/3 of vertebral body
• Anterior 2/3 of intervertebral disc (annulus fibrosus)

Middle column:

• Posterior 1/3 of vertebral body
• Posterior 1/3 on intervertebral disc
• Posterior longitudinal ligament

Posterior column:

• Ligament flavum
• Pedicles
• Facet joints and articular processes

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Scapula:

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Clavicle:

• Acromial/lateral end is flat
• Sternal/medial end is thick and round
• Superior surface is smooth, inferior surface is rough
• Medial curve protrudes outward

Unique features of clavicle:

• Ossifies during week 5 (fetal) and completed at 25 years, others ossify at week 8 and complete at 18-21 years
• Runs a sigmoid, horizontal course
• No marrow cavity, core occupied by spongy bone
• Medial 2/3 ossify endochondrally, lateral 1/3 intramembranously

Functions of clavicle:

• Hold upper limb away from trunk and increase range of movement such as abduction
• Transmit weight from upper limbs to axial skeleton
• Provide attachment for muscles

Clinicals:

• Fracture between medial 2/3 and lateral 1/3
• Lateral fragment pulled medial and forward by pectoralis major
• Injury to brachial plexus and axillary vessels
• Injury to subclavian artery

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Sternum:

Sternal angle – angle formed by the junction of manubrium and body of sternum.

Importance: landmark to indicate level at which the 2nd rib joint with the sternum

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Humerus:

• Medial epicondyle more outwards than lateral
• Lateral side – capitulum and deltoid tuberosity

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Radius:

• Anterior surface smooth and concave at lower end
• Laterally – convex, lateral styloid process
• Medially – ulnar notch and medial tuberosity
• Lower end is large

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Ulna:

• Medial styloid process
• Convex medially

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Bones of hand:

From thumb to little finger:

• Trapezius, trapezoid, capitate, hamate
• Scaphoid, lunate, triquetral, pisiform

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Muscle attachment on bones

Clinicals:

• Dropped shoulder – trapezius paralyzed
• Winged shoulder – serratus anterior paralyzed

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Arteries

NB: Same for deep veins of the arm, all deep veins are venae commitantes with the arteries.

(I) Axillary artery – chest, axilla, breast and shoulder joint

• Continuation of subclavian artery from lateral border of first rib
• Divided into 3 parts by passing posterior to pectoralis minor:

1. 1st part – Superior thoracic
2. 2nd part – Thoracoacromial and lateral thoracic
3. 3rd part – Anterior circumflex humeral, posterior circumflex humeral, subscapular

• Continues as brachial artery from inferior border of teres major

(II) Brachial artery – all arm muscles and elbow joint

• Descends on ventral surface
• Medial to humerus
• Median nerve crosses over it from lateral to medial
• At apex of cubital fossa, divides into radial and ulnar arteries
• Other branches: profunda brachii (which gives middle and radial collateral), superior and inferior ulnar collateral and humeral nutrient artery

(III) Ulnar artery – anterior forearm muscles

• Descends obliquely on ulnar side and runs along ulnar border to wrist
• Deep to pronator teres
• Deep to superficial and intermediate muscles
• Lateral to ulnar nerve
• Superficial to flexor retinaculum
• Through Hook of Hamate and Guyon’s canal
• Divides into superficial and deep palmar arch
• Branches: anterior and posterior ulnar recurrent, common interosseous

(IV) Radial artery – posterior forearm muscles

• Descends obliquely on radial side and runs along radial border
• Anterior to pronator teres
• Winds around head of radius to go posterior
• Medial to radial nerve
• Through anatomical snuff box
• Divides into superficial and deep palmar arch

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Veins

Superficial veins of arm:

NB: Cephalic V. used for:

• Drawing of blood
• Intravenous injection
• Venous cutdown

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Nerves

Cutaneous innervation of upper limbs:

Dermatomes of upper limbs:

(I) Musculocutaneous nerve – anterior arm muscles, lateral forearm skin

• Roots – C5, C6, and C7
• At inferior border of pectoralis minor
• Pierce coracobrachialis muscle
• Runs between brachialis and biceps brachii
• Becomes lateral cutaneous nerve of forearm
• Runs in cubital fossa with cephalic vein

(II) Median nerve – anterior forearm muscles except flexor carpi ulnaris, elbow and wrist joint

• Roots – C5-T1
• The 2 cords join in axilla to form median nerve
• Crosses over brachial artery from lateral to medial
• Through cubital fossa
• Between 2 heads of pronator teres
• Through carpal tunnel
• Divides into recurrent and palmer digital nerves

Clinical: Carpal tunnel syndrome, hand of Benediction/ monkey hand

Entrapments: Carpal tunnel, cubital fossa, pronator teres heads

(III) Ulnar nerve – elbow joint, flexor carpi ulnaris and flexor digitorum profundus muscles

• Roots – C8-T1
• Runs in medial arm
• Passes posterior to medial epicondyle at elbow
• Between 2 heads of flexor carpi ulnaris
• Travels on the ulna side
• Superficial to flexor retinaculum
• Through hook of Hamate and Guyon’s canal
• Divides into superficial and deep branches

Clinical: Ulnar claw, fracture at medial epicondyl

Entrapments: Cubital tunnel, Guyon’s canal, flexor carpi ulnaris 2 heads

(IV) Radial nerve – Posterior arm and forearm muscles and skin

• Roots – C5-T1
• Posterior to axillary artery in axilla
• Posterior to brachial artery
• Between long and medial head triceps
• Exists via lower triangular space with profunda artery
• Runs in radial groove of humerus
• Pierce lateral intermuscular septum
• Anterior to lateral epicondyle of humerus
• Through cubital fossa
• Winds around neck of radius
• Penetrates supinator
• Descends between superficial and deep muscles of the posterior forearm
• Lateral to radial artery in anatomical snuff box

Clinicals:

• Injury in axilla/ humerus fracture – elbow, wrist and finger drop
• Injury in radial groove – wrist and finger drop
• Injury in radial head fracture – finger drop
• All have loss of sensation

Entrapments: Axilla, lower triangular space, radial groove, cubital fossa, anatomical snuff box

NB:

• Brachialis muscle supplied by both radial and musculocutaneous nerves
• Flexor digitorum profundus supplied by both ulnar and median nerves

(V) Axillary nerve – Glenohumeral joint, teres minor and deltoid muscle, skin of superolateral arm

• Roots – C5-C6
• Exists axilla via quadrangular space (with posterior circumflex humeral)
• Posterior division supplies teres minor
• Anterior division winds around neck of humerus – supplies anterior part of deltoid

Clinicals:

• Fracture of surgical neck
• Entrapment in quadrangular space
• Glenohumeral joint dislocation
• All this leads to paralysis of deltoid and teres minor and loss of skin sensation

Entrapments: Shoulder dislocations, axilla, quadrangular space

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Joints

(I) Glenohumeral/shoulder joint

Classification: Ball and socket synovial

Articular surfaces: Head of humerus and glenoid fossa

Stability factors:

1. Static: Coracoacromial arch (prevent superior displacement), coracoacromial ligament, glenohumeral ligament
2. Dynamic: Rotator cuff muscles, deltoid, trapezius

Movements: Flexion, extention, abduction, adduction, medial and lateral rotation

NB: For abduction:

• 0 – 15 degrees – supraspinatus
• 15 -90 degrees – deltoid middle part
• 90 – 120 degrees – infraspinatus, teres minor
• 120 – 180 degrees – trapezius and serratus anterior

Blood supply: Anterior and posterior circumflex humeral

Nerve supply: Axillary, suprascapular

Clinicals: Due to shallow fossa, pulled anterior and inferior, damages axillary nerve

NB: Glenohumeral joint capsule has opening for biceps tendon

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(II) Elbow joint

Classification: Synovial uniaxial hinge

Articular surfaces:

• Trochlea – trochlea notch on ulna
• Capitulum – head of radius

Stability factors:

1. Static: Annular ligament, radial and ulnar collateral ligaments

2. Dynamic: Triceps, biceps, brachialis and radiobrachialis

Movements: Flexion and extension

Blood supply: Elbow anastomosis (written in arteries)

Nerve supply: Musculocutaneous, radial and ulna

Clinicals: Bursitis, dislocation, golfers elbow (medial epicondylitis), tennis elbow (lateral epicondylitis)

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(III) Radioulnar joint

Proximal:

Classification: Synovial pivot uniaxial

Articular surfaces: Head of radius, radial notch on ulna

Stability factors: Annular ligament

Movements: Supination and pronation

Nerve supply: Musculocutaneous, median, radial and ulna

Distal:

Classification: Synovial pivot uniaxial

Articular surfaces: Ulna head and ulnar notch on radius

Movements: Supination and pronation

Blood supply: Anterior and posterior interosseous

Nerve supply: Anterior and posterior interosseous

Clinicals: Subluxation of radial head

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(IV) Wrist joint

Classification: Ellipsoid synovial

Articular surfaces: Scaphoid, lunate, articular disc and distal end of radius

Stability factors:

1. Static: Joint capsule and ligaments:

• Palmer radiocarpal
• Dorsal radiocarpal
• Ulnar collateral – styloid process to trapezoid and pisiform
• Radial collateral – styloid process to scaphoid and trapezius

2. Dynamic: Carpal tunnel contents

Movements: Flexion, extension, abduction and adduction

Blood supply: Dorsal and palmer carpal arches

Nerve supply: Median nerve

Clinicals: Anterior lunate dislocation, carpal tunnel syndrome

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(V) Sternoclavicular joint

Classification: Synovial saddle

Articular surfaces: Clavicle sternal end, manubrium of sternum, 1st costal cartilage

NB: Covered in fibrocartilage, separated into 2 compartments by articular disc

Stability factors: Anterior and posterior sternoclavicular ligament, interclavicular ligament, costoclavicular ligament

Clinicals: Anterior and posterior dislocations

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(VI) Acromioclavicular joint

Classification: Plane synovial

Articular surfaces: Lateral end clavicle and acromion

NB: Covered in fibrocartilage, separated into 2 compartments by articular disc

Stability factors: Acromioclavicular ligament

Movements: Anterior and posterior

Clinicals: Suspend weight from upper limb from clavicle, dislocation

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Others

1. Intervertebral disc – hyalin cartilage, shock absorber, hold adjacent vertebra together, distributes weight transmission

Clinicals: prolapsed IVD, herniation of IVD

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2. Primary curvature – Kyphosis – thoracic and sacral

Secondary curvature – Lordosis – Cervical and lumbar

Clinical: Scoliosis

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3. Mammary glands:

Extent:

Medially                  Laterally

               2nd rib

Sternum ———-Mid axillary line

                6th rib

• Axillary tail extends into axilla laterally
• Nipple at 4th intercostal space

Relations: overlies pectoral fascia covering 4 muscles

1. Pectoralis major
2. Serratus anterior
3. External abdominis aponeurosis
4. Rectus abdominis

Separated from fascia by retromammary space with loose connective tissue. This is the basis for free mobility of the breast chest wall

Base of breast ⇒ Retromammary space ⇒ Pectoral fascia

Blood supply:

• Perforationg branches of lateral thoracic
• Perforating branches of posterior intercostal arteries
• Superior thoracic
• Thoracoacromial

Nerve supply: 4th to 6th intercostal nerves

Lymphatic drainage:

• Internal mammary/ Internal thoracic
• Axillary (anterior, posterior, lateral and central)
• Supraclavicular nodes

Clinicals:

• Breast cancer – spread via lymphatics/venous channels. Due to axillary tail, axillary lymph nodes in breast cancer examined – swollen axillary nodes
• Mammography – radiography of breasts
• Masectomy – breast removal
• Mastities – infection through nipple during lactation
• Peau d’orange – ridges due to edema, inverted nipple

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4. Triangle of auscultation – hear respiratory sounds

• Trapezius
• Scapular border
• Latissimus dorsi

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5. Deltopectoral triangle:

Contents: Cephalic vein and thoracoacromial branch

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6. Clavipectoral fascia – fills gap between pectoralis minor and clavicle

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7. Rotator cuff:

• Supraspinatus
• Infraspinatus
• Subscapularis
• Teres minor

Clinicals:

• Rotator cuff tendinitis (inflamed tendons)
• Rotator cuff tear (supraspinatus)

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8. Spaces of the arm:

1. Quadrangular space – Axillary nerve and posterior humeral circumflex vessels
2. Upper triangular space – Circumflex scapular vessels
3. Lower triangular space – Radial nerve and profunda brachii vessels

Clinicals: Entrapment syndrome

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9. Axilla:

Boundaries:

1. Anterior wall: Pec minor, pec major and clavipectoral fascia
2. Medial wall: Serratus anterior, intercostal muscles, 1-4 ribs
3. Lateral wall: Coracobrachialis, short head biceps brachii
4. Posterior wall: Subscapularis, teres major, latissimus dorsi
5. Base: Skin and fascia
6. Apex:

• Anterior – clavicle
• Posterior – superior border scapula
• Medial – 1st rib

Contents:

• Axillary artery and vein
• Brachial plexus cords
• Axillary lymph nodes
• Axillary tail of breasts

Clinicals: Aneurysms, lymphomas

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10. Cubital fossa:

Boundaries:

Contents: Medial to lateral

• Median nerve
• Brachial artery
• Biceps brachii tendon
• Radial nerve

Mnemonic: My Bottoms Turned Red

Clinicals: 

• Brachial pulse
• Venepuncture – median cubital vein
• Cubital fossa syndrome

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11. Carpal tunnel:

Anterior relations – Ulnar nerve and artery, palmaris longus tendon

Clinicals: Carpal tunnel syndrome – compressed median nerve, swollen tendons, thickened ligaments. Feelings of numbness and tingling

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12. Anatomical snuff box:

Boundaries:

Floor – Scaphoid and trapezium

Contents:

• Radial artery
• Branch of radial nerve
• Cephalic vein

Clinical: Scaphoid fracture (arthritis, avascular, necrosis)

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These are summarized notes from various sources, mainly TeachMeAnatomy and Wikipedia