Osteology - Forelimbs

Osteology

The study of bones

Mid-dorsal line/raphe

Fibrous CT running down the middle of the animal; muscles are symmetrical on either side

Umbilicus

Navel or belly button

Carpal pad

The small pad that protrudes palmar to the carpus.

Metacarpal pad

The largest pad in the paw; it is triangular and located on the palmar side of the metacarpophalangeal joints.

Digital pads

Ovoid and flattened pads located palmar to the distal interphalangeal joint.

Linea Alba

Single layer fibrous CT; similar to Mid-dorsal raphe

Entry point of abdominal Sx

Gross Anatomy

The study of structures visible with the naked eye; no use of microscopes or other magnification

Anatomy

Greek: cutting apart

Medical: study of form, structure and dispositions of tissues and organs that form the body.

Why study anatomy?

Knowing the normal to correct the abnormal

What is an anatomical landmark?

Point of orientation to locate structures deep/non-visible within the body

Skeleton Function

Support (posture/gait)

Locomotion (lever)

Protection

Mineral homeostasis

Hemopoiesis

Mineral homeostasis

Ca++ & P stored in bone marrow, released as needed

Hemopoiesis

Formation of RBC & WBC; occurs in bone marrow

Why are different breeds prone to different clinical conditions?

The "breed standard" body condition causes stress on the body

How are bones classified?

Topography

Development

Shape

3 Topographical categories

Axial

Appendicular

Splanchnic

Axial bones Structure

Head, vertebral column, sternum, ribs, hyoid apparatus

Axial bone Function

Protect the central nervous system, heart, brain, and other organs.

Axial bone Location

The series of central bones including the cranium, spine, sternum, and ribs.

Appendicular bone Structure

Thoracic: Humerus, Radius, Ulna, Carpals, Digits

Pelvic: Femur, Fibula, Tibia, Tarsals, Digits

Appendicular bone Function

Locomotion

Appendicular bone Location

Forelimbs & hindlimbs

Splanchnic bone Structure

Formed from calcified cartilage;

Os penis - canine, Ossa cordis - cattle

Splanchnic bone Function

Support and protection of surrounding tissues

Splanchnic bone Location

Can be found throughout the body

2 Developmental categories

Endochondral & Intramembranous

Endochondral

Bones that begin as cartilage and are later replaced with bone. Ex: Femoral growth plates

Intramembranous

Bones that differentiated directly into fibrous CT. Ex: skull & face

5 Shape categories

Long

Short

Flat

Irregular

Sesamoid

Long bone Structure

Diaphysis, epiphysis, epiphyseal plate and periosteum

Length > Width

3 centers of ossification

Long bone Function

Levers for locomotion

Long bone Location

Arms and legs

Long bone Clinical significance

Many fractures occur here

Metaphysical fracture

A fracture occurring within the metaphysis

Epiphyseal fractue

A fracture occurring within the epiphyses of the bone (growth plate)

Epiphysis

Proximal and distal ends of a long bone

Metaphysis

Growth zone between the epiphysis and the diaphysis during development of a long bone

Sesamoid bone Structure

Small and round; embedded in tendons of insertion

Sesamoid bone Function

Move tendon away from moving bone edges

Increase leverage

Sesamoid bone Location

Patella

Thoracic Bone Structure

Scapula

Humerus

Ulna & Radius

Carpals/forepaw

Pectoral girdle Structure

Scapula & clavicle

Antebrachium Structure

Ulna & Radius

Brachium (Humerus) Structure - ventral

Head

Neck, deltoid tuberosity

Body

Condyle, lateral epicondyle

Forepaw Structure

Carpus

Metacarpus

Phalanges - proximal, middle, distal

Digit structure

Proximal + middle + distal bones

Scapula Structure

Flat bone

2 surfaces, 3 borders, spine, acromion, supraspinous & intraspinous fossa

Scapula Location

Appendicular skeleton; lateral to ribcage; oriented diagonally on chest

Palpable structures: borders, spine, acromion, supragenoid tubercle

Medial scapula Structure

Serrated face & sub-scapular fossa

Medial scapula Function

Serratus ventralis & subscapularis muscle attachment

Glenoid cavity Structure

Shallow cavity

Glenoid cavity Function

Receives head of humerus

Glenoid cavity Location

Distral end of shoulder joint; medial to supraglenoid cavity

Supraglenoid tubercle Location

Distal end of scapula, lateral to Glenoid cavity

Coracoid process Location

Distal end of scapula, lateral to Supraglenoid cavity

Coracoid process Function

Coracoid muscle attachment

Clavicle structure

Cartilagenous oval plate

Poorly developed in animals, slightly larger in cats

Clavicle location

Cranial to the shoulder, w/i clavicular tendon & brachiocephalis muscle

Clavicle Clinical Significance

Visible in radiographs & can be misinterpreted

Rarely fractured in animals due to small size

Feline scapula

Broaded via suprahamate & hamate processes @ distal end of scapula

Tubercle

Smooth, boney projection

Tuberosity

Rough, boney projection

Foramen

Hole/opening in bone

Intertubercle groove Function

Passageway for tendon of the biceps

Deltoid Tuberosity Function

Deltoid insertion

Feline Brachium Structure

Supracondylar foramen & olecranon fossa

Supracondylar foreman & Olecranon Fossa Function

Passageway for brachial artery & medial nerve

Supracondylar foreman & Olecranon Fossa Clinical Significance

Avoid brachial artery & medial nerve when repairing fractures

Brachium Function

Articulate with the scapula forming the shoulder joint

Articulate with the radius & ulna to form the elbow

Brachium location

Distal to humerus, proximal to radius and ulna

Brachium Clinical significance

Casting the bone won't work due to curvature of the bone, must be set with intramedullary pins @ intertubercle groove

Olecranon fossa Functon

Fossa - receives ancoeal process of ulna

Brachium (Humerus) Structure - Dorsal

Greater, lesser tubercle

Intertubercle groove

Deltoid tuberosity

Supratrochlear process

Medial epidondule, Trochlea, Capitulum

Antebrachium Location

Below the brachium (humerus)

Ulna Location

Caudo-medial to Radius in the upper forearm

Lateral to Radius in lower forearm

Radius Structure

Head

Radial tuberosity

Ulnar notch

Styloid process, Artiuclar face

Radius Function

Articulate with Humerus proximally, and carpus distally

Radius Location

Proximal to Ulna on caudal surface

Distal to Ulna on lateral border

Ulna structure

Olecranon tuber

Anconeal process

trochlear notch

Medial & lateral coronoid processes

Radial notch

Ulna Function

Articulate with Humerus proximally, by trochlear notch

Ulna Clinical Significane

Processes have their own ossification centers; can fail to fuse to ulnar bone. Common in large breeds

Olecranon tuber Function

Point of the elbow

Olecranon tuber location

5th intercostal space

Olecranon tuber Clinical Significance

landmark for heart & lung ausculation

Manus (forepaw) Structure

Carpal bones ( 2 rows)

Metaparpal bones ( 1 row)

Phalanges/Digits ( 3 rows)

Carpal bone structure

7 total bones

Proximal: intermedioradial, ulna, & accessory

Distal: I-IV

Number carpal bones

From lateral to medial

Metacarpal Structure

5 total bones

Proximal, middle, distal ends

Digit-I forms the dewclaw

Phalanges Structure

3 rows

Proximal, middle, distal - for digits II-IV; digit-I only has 2 phalanges

Conditions that affect the forelimbs

Factures

Tumors

Panosteistis

Degenerative Joint Disease

Hypertrophic Osteodystrophy

Osteosarcoma

Malignant tumor in dogs

Common in large breeds

Starts deep

Panosteitis

Idiopathic inflammation of the bone

Primarily affecting young, large breed

Self-limiting

Hypertrophic Osteodystrophy (HOD)

An inflammatory condition of long bones (metaphysis region) which affects rapidly growing puppies.

What is another name for HOD?

Skeletal scurvy, Moller-Barlow's Disease, Osteodystrophy II