Unit 4 - Osteology and Muscles of the Proximal TL

What is another name for the shoulder joint?

- Scapulohumeral joint

What makes up the point of the shoulder?

- Cranial part of the greater tubercle of the humerus

What makes up the point of the elbow?

- Olecranon tuberosity

What part of the scapula are horses missing?

- Acromion

What are the medial, middle, and lateral grooves in the distal part of the radius for?

- Medial: Extensor carpi obliquus tendon

- Middle: Extensor carpir radialis tendon

- Lateral: Common digital extensor tendon

In the horse, what does the cranial superficial epigastric vein drain into?

- Drains into the superficical thoracic v. (spur vein) which either drains directly into the axillary vein or into the thoracodorsal v. and then the axillary vein

What are the extrinsic muscles of the thoracic limb?

- Brachiocephalicus m.

- Omotransversarius m.

- Trapezius m.

- Serratus ventralis m.

- Superficial pectoral n.

- Deep pectoral m.

- Subclavius m.

- Rhomboideus m.

- Latissimus dorsi m.

What is the origin and insertion of the cervical part of the trapezius muscle?

- O: Funicular part of the nuchal ligament

- I: Spine of scapula and fascia of shoulder and brachium

What is the origin and insertion of the thoracic part of the trapezius muscle?

- O: Supraspinous ligament

- I: Tuber of spine of scapula in the horse; scapular spine in ruminants

What is the innervation of the trapezius muscle? The action?

- Inn: Accessory n. and dorsal branches of thoracic spinal nerves

- A: Elevate the scapula; cervical part draws the scapula craniodorsally, thoracic part draws the scapula caudodorsally

What is the origin, insertion, innervation, and action of the latissimus dorsi muscle?

- O: Thoracolumbar fascia, also ribs 9-12 in ruminants

- I: Teres major tuberosity

- Inn: Thoracodorsal n.

- A: Draw the humerus dorsally and caudally thus flexing the shoulder joint; if limb is advanced and fixed, draws the trunk cranially

What is the origin and insertion of rhomboideus thoracis?

- O: Spinous processes of T2-T7 in the horse via the dorsoscapular ligament; Diff vertebrae in ruminants

- I: Caudomedial surface of scapular cartilage

What is the origin and insertion of rhomboideus cervicis?

- O: Funicular part of nuchal ligament

- I: Craniomedial surface of scapular cartilage

What is the innervation and action of rhomboideus?

- Inn: Cervical and thoracic spinal nerves

- A: Draw the scapula dorsally and cranially; when limb is fixed, elevate the neck

What is the origin and insertion of serratus ventralis?

- O: Cervicis = Transverse processes of C3/C4-C7; Thoracis = Lateral surface of first 8-9 ribs

- I: Serrated face of scapula and scapular cartilage

What is the innervation and action of serratus ventralis?

- Inn: C5-C8 spinal nerves and long thoracic nerve

- A: Suspends the trunk between the two scapula; raises the thorax, cervical part draws the dorsal part of the scapula cranially; thoracic part aids in drawing the limb cranially by pulling the dorsal part of the scapula caudally

Describe the gross appearance differences between the serratus ventralis cervicis and thoracis.

- Cervical part is fleshy, thoracic part has tendinous sheets

What are the two parts of the superficial pectoral muscles?

- Descending part

- Transverse part

What is the origin, insertion, innervation, and action of the descending part of the superficial pectoral muscle?

- O: Cartilage of the manubrium

- I: Deltoid tuberosity (in the horse) and crest of humerus and brachial fascia

- Inn: Pectoral nn.

- A: Adduct and advance the thoracic limb

What is the origin, insertion, innervation, and action of the transverse part of the superficial pectoral muscle?

- O: Costal cartilages 1-6 and adjacent sternum in the horse; sternebrae 2-4 or 6 in ruminants; fibrous raphe between right and left muscles

- I: Fascia on the proximal third of the forearm; and on the humerus with descending pectoral in the horse

- Inn: Pectoral n.

- A: Adduct the thoracic limb and tense the fascia of the forearm

Describe the transverse part of the superficial pectoral m. in the ruminant.

- Poorly developed

What is the origin, insertion, innervation, and action of the deep (ascending) pectoral muscle?

- Origin: Xiphoid cartilage and ventral aspect of the sternum, cartilages of ribs 4-9, abdominal tunic

- I: Greater and lesser tubercles of the humerus, cranial parts, also tendon of origin of coracobrahcialis in the horse and several attachment sites on the humerus in small ruminants

- Inn: Pectoral nn.

- A: Adduct and retract the thoracic limb; if the limb is advanced and fixed, draw the trunk cranially

What is the origin, insertion, innervation, and action of the subclavius m.?

- O: Cranial part of the lateral surface of the sternum in the horse; cartilage of the first rib in ruminants

- I: Aponeurosis which covers the dorsal part of the supraspinatus m., and the scapular fascia in the horse; medial surface of the brachiocephalicus near the clavicular intersection in ruminants

- Inn: Pectoral nn.

- A: In the horse - adduct and retract the thoracic limb, when limb is advanced and fixed, draw the trunk cranially

What is the origin, insertion, innervation and action of the supraspinatus m.?

- O: Supraspinous fossa, spine of scapula and distal part of scapular cartilage

- I: Cranial parts of greater and lesser tubercles of humerus

- Inn: Suprascapular n.

- A: Extend the shoulder joint

What is the origin, insertion, innervation and action of the infraspinatus m.?

- O: Infraspinous fossa and scapular cartilage; spine of scapula in ruminants

- I: Superficial tendon - on the greater tubercle of humerus distal to the lateral insertion of supraspinatus; Deep tendon - On the caudal part of the greater tubercle

- Inn: Suprascapular n.

- A: Abduct the brachium and rotate it laterally; lateral stabilizer of the shoulder joint

Where is the infraspinous bursa located?

- Located between the superficial tendon of the infraspinatus and the caudal part of the greater tubercle of the humerus

What is the origin, insertion, innervation and action of the deltoideus m.?

- O: Proximal part of the caudal border of the scapula, spine of scapula by way of an aponeurosis which covers infraspinatus, and the acromion in ruminants

- I: Deltoid tuberosity of humerus and brachial fascia

- Inn: Axillary n.

- A: Flex the shoulder joint, and abduct the brachium

What is the origin, insertion, innervation and action of the teres minor m.?

- O: Distal and caudal part of the infraspinous fossa and distal half of the caudal border of the scapula

- I: Deltoid tuberosity and teres minor tuberosity

- Inn: Axillary n.

- A: Flex the shoulder joint, and abduct the brachium

What is the origin, insertion, innervation and action of the subscapularis m.?

- O: Subscapular fossa; and scapular cartilage in ruminants

- I: Caudal part of the lesser tubercle of humerus

- Inn: Subscapular and axillary nn.; also cranial pectoral nn. in horse

- A: Adduct the humerus

What is the origin, insertion, innervation and action of the teres major m.?

- O: Caudal angle of the scapula and adjacent caudal border of the scapula

- I: Teres major tuberosity of humerus

- Inn: Axillary n.

- A: Flex the shoulder joint and adduct the brachium

What are the stabilizers of the shoulder joint? How?

- Supraspinatus m.: Stabilizes the shoulder joint

- Infraspinatus m.: Lateral stabilizer

- Subscapularis m.: Medial stabilizer

What is the origin, insertion, innervation and action of the tensor fasciae antebrachii m.?

- O: Tendon of insertion of the latissimus dorsi and the caudal border of the scapula

- I: Deep antebrachial fascia and the olecranon

- Inn: Radial n.

- A: Tense the fascia of the antebrachium and extend the elbow joint

What are the four heads of the triceps brachii m? What is their origins?

- Long Head: Caudal border of the scapula

- Lateral Head: Deltoid tuberosity proximolateral humerus, fascia along the lateral aspect of the antebrachium

- Medial head: Middle third of medial aspect of humerus, caudal and distal to teres major tuberosity

- Accessory head (Ruminants): Caudal border of the humerus at middle third

What is the insertion, innervation, and action of the triceps brachii m.?

- I: Olecranon

- Inn: Radial n. l

- A: Extend the elbow joint, flex the shoulder joint

What are the triceps brachii bursae and their locations?

- Subtendinous: Located between the long head of the triceps brachii and the olecranon

- Subcutaneous: Located between the triceps brachii tendon and the skin

What is a "capped elbow"?

- Inflammation of the subcutaneous bursa of the triceps brachii m.

What is the origin, insertion, innervation and action of the anconeus m.?

- O: Distal third of the caudal surface of the humerus

- I: Lateral surface of the olecranon

- Inn: Radial n.

- A: Extend the elbow joint; raise the capsule of the joint and prevent it from being pinched during extension

What is the origin, insertion, innervation and action of the biceps brachii m.?

- O: Supraglenoid tubercle

- I: Radial tuberosity of the radius, medial collateral ligament of the elbow joint, antebrachial fascia, tendon of extensor carpi radialis via lacertus fibrosus

- Inn: Musculocutaneous n.

- A: Extend the shoulder joint; flex the elbow joint; fix the shoulder and elbow while standing; assist the extensor carpi radialis m.; tense the antebrachial fascia

What is the lacertus fibrosus? Describe it in ruminants.

- Tendinous insertion of biceps brachii on extensor carpi radialis m.; Part of the stay apparatus

- Poorly developed in ruminants

House does the bicipital (intertubercular) bursa differ between the horse/ox and the sheep/goat?

- In the horse and ox, the bursa is separate from the shoulder joint

- In the sheep and goat, the bursa is a pouch of shoulder joint capsule that extends into the intertubercular groove

Explain how to perform an injection into the bicipital (intertubercular) bursa.

- Insert needle between biceps and humerus, slightly above the level of the deltoid tuberosity; Direct needle dorsomedially toward the opposite point of the shoulder

What is the origin, insertion, innervation and action of the brachialis m.?

- O: Proximal third of caudal humerus

- I: Proximomedial surface of radius; also on the medial surface of the coronoid process of the ulna in the goat

- Inn: Musculocutaneous n.

- A: Flex the elbow joint

What is the origin, insertion, innervation and action of the coracobrachialis m.?

- O: Coracoid process of scapula

- I: Proximal to teres major tuberosity and middle third of cranial surface of the humerus in the horse; teres major tuberosity and cranial medial portion of the humerus in ruminants

- Inn: Musculocutaneous n.

- A: Adduct the brachium and flex the shoulder joint

What is the bursa of the coracobrachialis m.?

- Located between the tendon of origin of coracobrachialis and the terminal part of subscapularis m.