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Shoulder Muscles - Horse Anatomy (view source)
Revision as of 17:29, 15 October 2012
, 17:29, 15 October 2012Created page with "The muscles of the shoulder are grouped: ====='''Lateral'''===== '''''Supraspinatus ''''' :'''Innervation''':Suprascapular n. of the brachial plexus :'''Origin''': Supraspin..."
The muscles of the shoulder are grouped:
====='''Lateral'''=====
'''''Supraspinatus '''''
:'''Innervation''':Suprascapular n. of the brachial plexus
:'''Origin''': Supraspinous fossa of the scapula
:'''Insertion''': Lesser and greater tubercles of the humerus
:'''Action''': Extends and braces the shoulder
'''''Infraspinatus'''''
:'''Innervation''':Suprascapular n. of the brachial plexus
:'''Origin''': Supraspinatous fossa and spine of the scapula
:'''Insertion''': Tendon of insertion bifurcates into a deep part and a superficial part.
:: Deep - Greater tubercle of the humerus
:: Superficial - Lateral humerus, distal to the greater tubercle
:'''Action''': Brace the shoulder, supporting flexion or extension.
:'''Clinical significance''': The bursa between the superficial tendon of the infraspinatus, and the lateral tubercle of the humerus can be the site of inflammation (bursitis).
====='''Medial'''=====
'''''Supscapularis'''''
:'''Innervation''': Subscapular n. from the brachial plexus
:'''Origin''': Deep surface of the scapula
:'''Insertion''': Lesser tubercle of the humerus
:'''Action''': Braces medial shoulder joint. Primarily acts as an extensor of the shoulder, but can contribute to maintaining flecion.
'''''Coracobrachialis'''''
:'''Innervation''': Musculocutaneous n. of the brachial plexus
:'''Origin''': Coracoid process of scapula
:'''Insertion''': Proximal shaft of the humerus
:'''Action''': Fixator
====='''Caudal (Flexors)'''=====
'''''Deltoid'''''
:'''Innervation''': Axillary n. of the brachial plexus
:'''Origin''': Caudal border and spine of the scapula. One head in the horse, compared with two in species with an acromion (site of second origin.
:'''Insertion''': Deltoid tuberosity of humerus
:'''Action''': Flexes shoulder
:In the horse, the aponeurosis of the deltoid is partially fused to the ''infraspinatus''.
'''''Teres Major'''''
:'''Innervation''': Axillary n. of the brachial plexus
:'''Origin''': Dorsal part of the caudal scapula
:'''Insertion''': Teres major tuberosity midway down the humerus
:'''Action''': Flexes the shoulder, supports adduction.
'''''Teres Minor'''''
:'''Innervation''': Axillary n. of the brachial plexus
:'''Origin''': Distal third of scapula, deep to the deltoid
:'''Insertion''': Teres minor tuberosity midway down the humerus
:'''Action''': Flexes the shoulder
NB// There are no defined extensors of the shoulder. Those involved (brachiocephalic m., biceps brachii, supraspinatus, and ascending pectorals) have other, more primary roles.
====='''Lateral'''=====
'''''Supraspinatus '''''
:'''Innervation''':Suprascapular n. of the brachial plexus
:'''Origin''': Supraspinous fossa of the scapula
:'''Insertion''': Lesser and greater tubercles of the humerus
:'''Action''': Extends and braces the shoulder
'''''Infraspinatus'''''
:'''Innervation''':Suprascapular n. of the brachial plexus
:'''Origin''': Supraspinatous fossa and spine of the scapula
:'''Insertion''': Tendon of insertion bifurcates into a deep part and a superficial part.
:: Deep - Greater tubercle of the humerus
:: Superficial - Lateral humerus, distal to the greater tubercle
:'''Action''': Brace the shoulder, supporting flexion or extension.
:'''Clinical significance''': The bursa between the superficial tendon of the infraspinatus, and the lateral tubercle of the humerus can be the site of inflammation (bursitis).
====='''Medial'''=====
'''''Supscapularis'''''
:'''Innervation''': Subscapular n. from the brachial plexus
:'''Origin''': Deep surface of the scapula
:'''Insertion''': Lesser tubercle of the humerus
:'''Action''': Braces medial shoulder joint. Primarily acts as an extensor of the shoulder, but can contribute to maintaining flecion.
'''''Coracobrachialis'''''
:'''Innervation''': Musculocutaneous n. of the brachial plexus
:'''Origin''': Coracoid process of scapula
:'''Insertion''': Proximal shaft of the humerus
:'''Action''': Fixator
====='''Caudal (Flexors)'''=====
'''''Deltoid'''''
:'''Innervation''': Axillary n. of the brachial plexus
:'''Origin''': Caudal border and spine of the scapula. One head in the horse, compared with two in species with an acromion (site of second origin.
:'''Insertion''': Deltoid tuberosity of humerus
:'''Action''': Flexes shoulder
:In the horse, the aponeurosis of the deltoid is partially fused to the ''infraspinatus''.
'''''Teres Major'''''
:'''Innervation''': Axillary n. of the brachial plexus
:'''Origin''': Dorsal part of the caudal scapula
:'''Insertion''': Teres major tuberosity midway down the humerus
:'''Action''': Flexes the shoulder, supports adduction.
'''''Teres Minor'''''
:'''Innervation''': Axillary n. of the brachial plexus
:'''Origin''': Distal third of scapula, deep to the deltoid
:'''Insertion''': Teres minor tuberosity midway down the humerus
:'''Action''': Flexes the shoulder
NB// There are no defined extensors of the shoulder. Those involved (brachiocephalic m., biceps brachii, supraspinatus, and ascending pectorals) have other, more primary roles.