Difference between revisions of "Shoulder Muscles - Horse Anatomy"
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The muscles of the shoulder are grouped: | The muscles of the shoulder are grouped: | ||
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'''''Supraspinatus ''''' | '''''Supraspinatus ''''' | ||
:'''Innervation''':Suprascapular n. of the brachial plexus | :'''Innervation''':Suprascapular n. of the brachial plexus | ||
| − | :'''Origin''': Supraspinous fossa of the [[ | + | :'''Origin''': Supraspinous fossa of the [[Bones and Cartilages - Horse Anatomy#Scapula|scapula]] |
| − | :'''Insertion''': Lesser and greater tubercles of the [[ | + | :'''Insertion''': Lesser and greater tubercles of the [[Bones and Cartilages - Horse Anatomy#Humerus|humerus]] |
:'''Action''': Extends and braces the shoulder | :'''Action''': Extends and braces the shoulder | ||
'''''Infraspinatus''''' | '''''Infraspinatus''''' | ||
:'''Innervation''':Suprascapular n. of the brachial plexus | :'''Innervation''':Suprascapular n. of the brachial plexus | ||
| − | :'''Origin''': Supraspinatous fossa and spine of the [[ | + | :'''Origin''': Supraspinatous fossa and spine of the [[Bones and Cartilages - Horse Anatomy#Scapula|scapula]] |
:'''Insertion''': Tendon of insertion bifurcates into a deep part and a superficial part. | :'''Insertion''': Tendon of insertion bifurcates into a deep part and a superficial part. | ||
| − | :: Deep - Greater tubercle of the [[ | + | :: Deep - Greater tubercle of the [[Bones and Cartilages - Horse Anatomy#Humerus|humerus]] |
| − | :: Superficial - Lateral [[ | + | :: Superficial - Lateral [[Bones and Cartilages - Horse Anatomy#Humerus|humerus]], distal to the greater tubercle |
:'''Action''': Brace the shoulder, supporting flexion or extension. | :'''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 [[ | + | :'''Clinical significance''': The bursa between the superficial tendon of the infraspinatus, and the lateral tubercle of the [[Bones and Cartilages - Horse Anatomy#Humerus|humerus]] can be the site of inflammation (bursitis). |
=='''Medial'''== | =='''Medial'''== | ||
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'''''Supscapularis''''' | '''''Supscapularis''''' | ||
:'''Innervation''': Subscapular n. from the brachial plexus | :'''Innervation''': Subscapular n. from the brachial plexus | ||
| − | :'''Origin''': Deep surface of the [[ | + | :'''Origin''': Deep surface of the [[Bones and Cartilages - Horse Anatomy#Scapula|scapula]] |
| − | :'''Insertion''': Lesser tubercle of the [[ | + | :'''Insertion''': Lesser tubercle of the [[Bones and Cartilages - Horse Anatomy#Humerus|humerus]] |
:'''Action''': Braces medial shoulder joint. Primarily acts as an extensor of the shoulder, but can contribute to maintaining flecion. | :'''Action''': Braces medial shoulder joint. Primarily acts as an extensor of the shoulder, but can contribute to maintaining flecion. | ||
'''''Coracobrachialis''''' | '''''Coracobrachialis''''' | ||
:'''Innervation''': Musculocutaneous n. of the brachial plexus | :'''Innervation''': Musculocutaneous n. of the brachial plexus | ||
| − | :'''Origin''': Coracoid process of [[ | + | :'''Origin''': Coracoid process of [[Bones and Cartilages - Horse Anatomy#Scapula|scapula]] |
| − | :'''Insertion''': Proximal shaft of the [[ | + | :'''Insertion''': Proximal shaft of the [[Bones and Cartilages - Horse Anatomy#Humerus|humerus]] |
:'''Action''': Fixator | :'''Action''': Fixator | ||
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'''''Deltoid''''' | '''''Deltoid''''' | ||
:'''Innervation''': Axillary n. of the brachial plexus | :'''Innervation''': Axillary n. of the brachial plexus | ||
| − | :'''Origin''': Caudal border and spine of the [[ | + | :'''Origin''': Caudal border and spine of the [[Bones and Cartilages - Horse Anatomy#Scapula|scapula]]. One head in the horse, compared with two in species with an acromion (site of second origin. |
| − | :'''Insertion''': Deltoid tuberosity of [[ | + | :'''Insertion''': Deltoid tuberosity of [[Bones and Cartilages - Horse Anatomy#Humerus|humerus]] |
:'''Action''': Flexes shoulder | :'''Action''': Flexes shoulder | ||
:In the horse, the aponeurosis of the deltoid is partially fused to the ''infraspinatus''. | :In the horse, the aponeurosis of the deltoid is partially fused to the ''infraspinatus''. | ||
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'''''Teres Major''''' | '''''Teres Major''''' | ||
:'''Innervation''': Axillary n. of the brachial plexus | :'''Innervation''': Axillary n. of the brachial plexus | ||
| − | :'''Origin''': Dorsal part of the caudal [[ | + | :'''Origin''': Dorsal part of the caudal [[Bones and Cartilages - Horse Anatomy#Scapula|scapula]] |
| − | :'''Insertion''': Teres major tuberosity midway down the [[ | + | :'''Insertion''': Teres major tuberosity midway down the [[Bones and Cartilages - Horse Anatomy#Humerus|humerus]] |
:'''Action''': Flexes the shoulder, supports adduction. | :'''Action''': Flexes the shoulder, supports adduction. | ||
'''''Teres Minor''''' | '''''Teres Minor''''' | ||
:'''Innervation''': Axillary n. of the brachial plexus | :'''Innervation''': Axillary n. of the brachial plexus | ||
| − | :'''Origin''': Distal third of [[ | + | :'''Origin''': Distal third of [[Bones and Cartilages - Horse Anatomy#Scapula|scapula]], deep to the deltoid |
| − | :'''Insertion''': Teres minor tuberosity midway down the [[ | + | :'''Insertion''': Teres minor tuberosity midway down the [[Bones and Cartilages - Horse Anatomy#Humerus|humerus]] |
:'''Action''': Flexes the shoulder | :'''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. | NB// There are no defined extensors of the shoulder. Those involved (''brachiocephalic'' m., ''biceps brachii'', ''supraspinatus'', and ''ascending pectorals'') have other, more primary roles. | ||
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Revision as of 10:28, 31 October 2012
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.
- 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.