Lecture 2 -- Scapula + Humerus

Name all the structure in scapular. What aspect is this picture taken at?

Name all the structure in scapular. What aspect is this picture taken at?

Medial aspect of the scapular

What are the centers of ossification in the scapula?

Body, Supraglenoid tubercle.

What are the different between cats’ scapular and dogs’ scapular?

Cat’s scapular has a more rounded cranial angel than dogs’ and there is a supeurhamate process (proximal to acromion process) present in cats that is absent in dogs.

Identify the key structure of scapular in horses

1. Narrow suparspinous fossa
2. Prominent tuber spine
3. Absence of acromion process
4. Supraglenoid tubercle separate from glenoid cavity

Identify the key structure of scapular in cattle

1. Wider dorsal boarder

2. Narrow supraspinous fossa = Larger infraspinous fossa

3. Tuber spine is less prominent/ even absent

4. Acromion process does not reach to level of glenoid cavity

   

Identify the key structure of scapular in pig

1. Supraspinous fossa is equal to the size of infraspinous fossa

2. Very prominent tuber spine

3. Acromion process do not extend to the glenoid cavity

4. Poorly defined acromion

What are the bony structure of scapular can we palpate in live animals?

Cranial border, dorsal border, cranial angle, spine and acromion

Which bony structures of scapular are difficult to palpate?

Caudal border because it sits beneath muscles

What is the significance of the supraglenoid tubercle?

It serves as the attachment point for the biceps brachii muscle.

Where does the brachiocephalic muscle originate from and insert to? What is the function of the brachiocephalic muscle?

Originate: Crevice-thoracic fasia

Insertion: Humerus

Function: Protractor

How many part are there in brachiocephalic muscle? Which nerves innervate each part of brachiocephalic muscle?

3
→ Cleidocephalicus + cleidomastoideus innervated by cervical ad accessory nerves

→ cleidobrachialis innervated by axillary nerve

Unlike cats, dogs lack a clavicle. What do they have instead?

They have a clavicular insertion between clediomastodieus and clediobrachalis, which is a fibrous band

Where does the omotransversarius muscle originate from and insert to? What nerve innervate omotransversarius muscle? What is the function of the omotransversarius muscle?

Originate: Wing of atlas (C1)

Insertion: Acromion process

Nerve: Accessory nerve

Function Protractor

Where does the latissimus dorsi muscle originate from and insert to? Which nerve innervate latissimus dorsi? What is the function of the latissimus dorsi muscle?

Originate: Thoraco-lumbar fascia

Insertion: Humerus

Nerve: Thoracodorsal nerve (C7, C8, T1)

Function: Retraction

Where do the serrates ventralis muscle originate from and insert to? What is the main function of serrates ventralis muscle?

Originates: Cervical vertebra + Thoracic wall

Insertion: Medial aspect of scapular

Function: Cranial portion: Retraction; Caudal portion: Protraction

Where do the trapezius originate from and insert to? What is the main function of trapezius muscles?

Originate: Cervicothoracic fasia

Insertion: Spine of scapular

Function: No function on shoulder BUT help abduction of limbs

How many parts are there in the trapezius muscle?

2 (Cervical part + thoracic part)

What the muscle runs beneath trapezius muscle? What do it originate from and insert to? What is the main function of it?

Rhomboideus muscle

Originates: Deep cervicothoracic fascia

Insertion: Dorsal border of scapular

Function: No effect on shoulder BUT Abductor of limb

Where do the pectoral muscles originate from and insert to? Which nerves innervate pectoral muscle? What is the main function of pectoral muscles?

→ Origination: Sternum

→ Insertion: Humerus

→ Nerve: Pectoral nerve

→ Function: Adduction of the limb

Identify the key structure of humerus

Identify the ket structure of humerus at the distal end?

Which aspect is the trochlea located — medial or lateral?

Medial

Which aspect is the capitulum located — medial or lateral?

Lateral

Which aspect is the olecranon fossa located?

Caudal aspect

Which aspect is the radial fossa located?

Cranial aspect

What is the medial epicondyle's significance compared to lateral epicondyle?

It is larger than the lateral epicondyle and an important site for muscle attachment.

What is the difference between olecranon fossa and radial fossa?

Olecranon fossa is more deeper than radial fossa

How many centres of ossification does the humerus have?

5

Proximal epiphyses, Body, and Medial half of condyle; Lateral half of condyle and medial epicondyle

What features distinguish the distal end of the humerus in cats vs dogs?

Cats lack a supratrochlear foramen but have supracondylar foramen instead

What passes through the supracondylar foramen?

Median nerve and brachial artery

Identify the key structure of humerus in horses

1. Greater tubercles are divided into cranial and caudal part, with similar level to humeral head → Two inter tubercular groove

2. Lesser tubercle is similar size with greater tubercle

3. Absence of supratrochlear foramen

4. Very prominent deltoid tuberosity

Identify the key structure of humerus in cattle

1. Greater tubercles are divided into cranial and caudal part, with higher level of humerus

2. Greater tubercle has pointed shape

3. Cranial part of greater tubercle is massive → Single intertubercular groove

4. Circular area of greater tubercle = Thumb print→ Allow the insertion of infraspinatus muscle

5. No supratrochlear foramen

Which muscle is attached to the thrumb print?

Infraspinatus muscle

Identify the key structure of humerus in pigs

Similar to cow

BUT 1. No flattened thumb print 2. Greater tubercle is rounded shape not pointed shape