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| | ===[[Extrinsic Musculature of the Thoracic Limb- Horse Anatomy|Extrinsic Musculature]]=== | | ===[[Extrinsic Musculature of the Thoracic Limb- Horse Anatomy|Extrinsic Musculature]]=== |
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| − | These muscles are responsible for joining the forelimb to the trunk, forming a '''synsarcosis''' rather than a conventional joint. Collectively, they act to transfer the weight of the body to the forelimbs, as well as to stabilize the scapula.
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| − | ====Superficial Musculature==== | + | ===[[Intrinsic Musculature of the Thoracic Limb- Horse Anatomy|Intrinsic Musculature]]=== |
| − | '''''Trapezius'''''
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| − | :'''Innervatation''': Accessory n.
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| − | :'''Origin''': Mid-dorsal raphe and supraspinous ligament
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| − | :'''Insertion''': Spine of the scapula
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| − | :'''Body''': Two parts, cervical and thoracic, separated by aponeurosis
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| − | :'''Action''': Raises the scapula against the trunk and swings cranially to advance the limb
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| − | '''''Brachiocephalic'''''
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| − | :'''Innervation''': Accessory n.
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| − | :Two parts ('''cleidobrachial''' and '''cleidocephalic''' muscle) separated by the clavicle, where it exists
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| − | :'''Origin''': Mastoid process of temporal bone, nuchal crest, wing of atlas and the transverse processes of the 2nd-4th cervical vertebrae
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| − | :'''Insertion''': Deltoid tuberosity and crest of the humerus
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| − | :'''Action''': Advances the limb and extends the shoulder joint when limb is in motion. Draws the head and neck ventrally when the limb is fixed
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| − | '''''Cleidomastoid'''''
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| − | :'''Innervatation''': Accessory n. and Axillary n.
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| − | :'''Origin''': Mastoid process of the temporal bone and nuchal crest
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| − | :'''Insertion''': Deltoid tuberosity, crest of the humerus and fascia of the shoulder as the '''cleidobrachialis''' muscle
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| − | :'''Action''': If acting bilaterally, it draws the head and neck down and backwards. If the acting with one shoulder fixed, it draws the head, upper arm fascia and neck to one side.
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| − | '''''Latissimus dorsi'''''
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| − | :'''Innervation''':Local branch of brachial plexus
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| − | :The broadest muscle of the back
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| − | :'''Origin''': Thoracolumbar fascia
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| − | :'''Insertion''': Teres tuberosity of the humerus
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| − | :'''Action''': Antagonist to the brachiocephalic m. It retracts the free limb and flexes shoulder joint. It also draws the trunk forward over the fixed limb.
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| − | '''''Superficial Pectorals'''''
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| − | :'''Innervation''': Brachial plexus
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| − | :Two muscles, cranial ('''descending''') and caudal ('''transverse''')
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| − | :'''Origin''':
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| − | ::Cranial ('''descending''') - Manubrium of the sternum
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| − | ::Caudal ('''transverse''') - First six costal cartilages and ventral sternum
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| − | :'''Insertion''':
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| − | ::Cranial ('''descending''') - The crest of the humerus, distal to the deltoid tuberosity
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| − | ::Caudal ('''transverse''') - Covers the elbow joint to insert on the medial fascia of the forearm
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| − | :'''Action''': Adducts the forelimb, assist in protraction and retraction
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| − | :The cranial ('''descending''') pectoral muscle forms a visible prominence cranial to the sternum; extending between the manubrium and the humeral crest.
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| − | ====Deep Musculature====
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| − | '''''Deep Pectorals'''''
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| − | :'''Innervation''': Cranial and caudal thoracic n.
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| − | :'''Origin''': Xiphoid and 4th costal cartilages of the sternum
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| − | :'''Insertion''': Two branches on the lesser and greater tubercles of the humerus, supraglenoid tubercle of scapula
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| − | :'''Action''':Draws the limb back, supports the trunk, moves the trunk cranially over an advanced limb and extends the shoulder.
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| − | '''''Serratis ventralis'''''
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| − | :Divided into cranial ('''cervical''') and caudal ('''thoracic''') parts.
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| − | :'''Innervation''': Dorsal and ventral Cervical n., long thoracic n.
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| − | :'''Origin''': 1st-7th rib, transverse process of cervical vertebrae
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| − | :'''Insertion''': Medial scapula and scapular cartilage
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| − | :'''Action''': Supports the weight of the trunk. It is reinforced by strong fascia. The cervical portion can retract the limb and the caudal portion can advance the limb.
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| − | '''''Rhomboids'''''
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| − | :Deep to the trapezius, forms the withers region. Divided into cervical and thoracic parts.
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| − | :'''Innervation''': Dorsal and ventral branches of Cervical n., Long thoracic n.
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| − | :'''Origin''':
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| − | ::Cervical - Nuchal ligament at the axis
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| − | ::Thoracic - Spinous processes of 2nd-6th cervical and 7th thoracic vertebrae
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| − | :'''Insertion''':
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| − | ::Cervical - Unites with trapezius to insert on scapular cartilage
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| − | ::Thoracic - Scapula
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| − | :'''Action''': Draws the limb forward and elevates the limb and neck. Fixes the scapula against the trunk.
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| − | ===Intrinsic Musculature===
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| | ====Muscles of the Shoulder==== | | ====Muscles of the Shoulder==== |