Difference between revisions of "Thoracic Limb Extrinsic Muscles - Horse Anatomy"
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(Created page with "==Introduction== These muscles are responsible for joining the forelimb to the trunk, forming a '''synsarcosis''' rather than a conventional joint. Collectively, they act to t...") |
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==Introduction== | ==Introduction== | ||
| − | 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. | + | 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 [[Limb Bones and Cartilages - Horse Anatomy#Scapula|scapula]]. |
====Superficial Musculature==== | ====Superficial Musculature==== | ||
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:'''Innervatation''': Accessory n. | :'''Innervatation''': Accessory n. | ||
:'''Origin''': Mid-dorsal raphe and supraspinous ligament | :'''Origin''': Mid-dorsal raphe and supraspinous ligament | ||
| − | :'''Insertion''': Spine of the scapula | + | :'''Insertion''': Spine of the [[Limb Bones and Cartilages - Horse Anatomy#Scapula|scapula]] |
:'''Body''': Two parts, cervical and thoracic, separated by aponeurosis | :'''Body''': Two parts, cervical and thoracic, separated by aponeurosis | ||
| − | :'''Action''': Raises the scapula against the trunk and swings cranially to advance the limb | + | :'''Action''': Raises the [[Limb Bones and Cartilages - Horse Anatomy#Scapula|scapula]] against the trunk and swings cranially to advance the limb |
'''''Brachiocephalic''''' | '''''Brachiocephalic''''' | ||
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:Two parts ('''cleidobrachial''' and '''cleidocephalic''' muscle) separated by the clavicle, where it exists | :Two parts ('''cleidobrachial''' and '''cleidocephalic''' muscle) separated by the clavicle, where it exists | ||
:'''Origin''': Mastoid process of temporal bone, nuchal crest, wing of atlas and the transverse processes of the 2nd-4th cervical vertebrae | :'''Origin''': Mastoid process of temporal bone, nuchal crest, wing of atlas and the transverse processes of the 2nd-4th cervical vertebrae | ||
| − | :'''Insertion''': Deltoid tuberosity and crest of the humerus | + | :'''Insertion''': Deltoid tuberosity and crest of the [[Limb Bones and Cartilages - Horse Anatomy#Humerus|humerus]] |
| − | :'''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 | + | :'''Action''': Advances the limb and extends the [[Joints and Ligaments - Horse Anatomy#Shoulder Joint|shoulder]] joint when limb is in motion. Draws the head and neck ventrally when the limb is fixed |
'''''Cleidomastoid''''' | '''''Cleidomastoid''''' | ||
:'''Innervatation''': Accessory n. and Axillary n. | :'''Innervatation''': Accessory n. and Axillary n. | ||
:'''Origin''': Mastoid process of the temporal bone and nuchal crest | :'''Origin''': Mastoid process of the temporal bone and nuchal crest | ||
| − | :'''Insertion''': Deltoid tuberosity, crest of the humerus and fascia of the shoulder as the '''cleidobrachialis''' muscle | + | :'''Insertion''': Deltoid tuberosity, crest of the [[Limb Bones and Cartilages - Horse Anatomy#Humerus|humerus]] and fascia of the [[Joints and Ligaments - Horse Anatomy#Shoulder Joint|shoulder]] as the '''cleidobrachialis''' muscle |
| − | :'''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. | + | :'''Action''': If acting bilaterally, it draws the head and neck down and backwards. If the acting with one [[Joints and Ligaments - Horse Anatomy#Shoulder Joint|shoulder]] fixed, it draws the head, upper arm fascia and neck to one side. |
'''''Latissimus dorsi''''' | '''''Latissimus dorsi''''' | ||
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:The broadest muscle of the back | :The broadest muscle of the back | ||
:'''Origin''': Thoracolumbar fascia | :'''Origin''': Thoracolumbar fascia | ||
| − | :'''Insertion''': Teres tuberosity of the humerus | + | :'''Insertion''': Teres tuberosity of the [[Limb Bones and Cartilages - Horse Anatomy#Humerus|humerus]] |
| − | :'''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. | + | :'''Action''': Antagonist to the brachiocephalic m. It retracts the free limb and flexes [[Joints and Ligaments - Horse Anatomy#Shoulder Joint|shoulder]] joint. It also draws the trunk forward over the fixed limb. |
'''''Superficial Pectorals''''' | '''''Superficial Pectorals''''' | ||
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::Caudal ('''transverse''') - First six costal cartilages and ventral sternum | ::Caudal ('''transverse''') - First six costal cartilages and ventral sternum | ||
:'''Insertion''': | :'''Insertion''': | ||
| − | ::Cranial ('''descending''') - The crest of the humerus, distal to the deltoid tuberosity | + | ::Cranial ('''descending''') - The crest of the [[Limb Bones and Cartilages - Horse Anatomy#Humerus|humerus]], distal to the deltoid tuberosity |
::Caudal ('''transverse''') - Covers the elbow joint to insert on the medial fascia of the forearm | ::Caudal ('''transverse''') - Covers the elbow joint to insert on the medial fascia of the forearm | ||
:'''Action''': Adducts the forelimb, assist in protraction and retraction | :'''Action''': Adducts the forelimb, assist in protraction and retraction | ||
| − | :The cranial ('''descending''') pectoral muscle forms a visible prominence cranial to the sternum; extending between the manubrium and the humeral crest. | + | :The cranial ('''descending''') pectoral muscle forms a visible prominence cranial to the sternum; extending between the manubrium and the [[Limb Bones and Cartilages - Horse Anatomy#Humerus|humeral crest]]. |
====Deep Musculature==== | ====Deep Musculature==== | ||
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:'''Innervation''': Cranial and caudal thoracic n. | :'''Innervation''': Cranial and caudal thoracic n. | ||
:'''Origin''': Xiphoid and 4th costal cartilages of the sternum | :'''Origin''': Xiphoid and 4th costal cartilages of the sternum | ||
| − | :'''Insertion''': Two branches on the lesser and greater tubercles of the humerus, supraglenoid tubercle of scapula | + | :'''Insertion''': Two branches on the lesser and greater tubercles of the [[Limb Bones and Cartilages - Horse Anatomy#Humerus|humerus]], supraglenoid tubercle of [[Limb Bones and Cartilages - Horse Anatomy#Scapula|scapula]] |
| − | :'''Action''':Draws the limb back, supports the trunk, moves the trunk cranially over an advanced limb and extends the shoulder. | + | :'''Action''':Draws the limb back, supports the trunk, moves the trunk cranially over an advanced limb and extends the [[Joints and Ligaments - Horse Anatomy#Shoulder Joint|shoulder]]. |
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:'''Innervation''': Dorsal and ventral Cervical n., long thoracic n. | :'''Innervation''': Dorsal and ventral Cervical n., long thoracic n. | ||
:'''Origin''': 1st-7th rib, transverse process of cervical vertebrae | :'''Origin''': 1st-7th rib, transverse process of cervical vertebrae | ||
| − | :'''Insertion''': Medial scapula and scapular cartilage | + | :'''Insertion''': Medial [[Limb Bones and Cartilages - Horse Anatomy#Scapula|scapula and scapular cartilage]] |
:'''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. | :'''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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::Thoracic - Spinous processes of 2nd-6th cervical and 7th thoracic vertebrae | ::Thoracic - Spinous processes of 2nd-6th cervical and 7th thoracic vertebrae | ||
:'''Insertion''': | :'''Insertion''': | ||
| − | ::Cervical - Unites with trapezius to insert on scapular cartilage | + | ::Cervical - Unites with trapezius to insert on [[Limb Bones and Cartilages - Horse Anatomy#Scapula|scapular cartilage]] |
| − | ::Thoracic - Scapula | + | ::Thoracic - [[Limb Bones and Cartilages - Horse Anatomy#Scapula|scapula]] |
| − | :'''Action''': Draws the limb forward and elevates the limb and neck. Fixes the scapula against the trunk. | + | :'''Action''': Draws the limb forward and elevates the limb and neck. Fixes the [[Limb Bones and Cartilages - Horse Anatomy#Scapula|scapula]] against the trunk. |
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| + | [[Category:Muscles - Horse Anatomy]] | ||
Latest revision as of 16:36, 3 January 2023
Introduction
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.
Superficial Musculature
Trapezius
- Innervatation: Accessory n.
- Origin: Mid-dorsal raphe and supraspinous ligament
- Insertion: Spine of the scapula
- Body: Two parts, cervical and thoracic, separated by aponeurosis
- Action: Raises the scapula against the trunk and swings cranially to advance the limb
Brachiocephalic
- Innervation: Accessory n.
- Two parts (cleidobrachial and cleidocephalic muscle) separated by the clavicle, where it exists
- Origin: Mastoid process of temporal bone, nuchal crest, wing of atlas and the transverse processes of the 2nd-4th cervical vertebrae
- Insertion: Deltoid tuberosity and crest of the humerus
- 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
Cleidomastoid
- Innervatation: Accessory n. and Axillary n.
- Origin: Mastoid process of the temporal bone and nuchal crest
- Insertion: Deltoid tuberosity, crest of the humerus and fascia of the shoulder as the cleidobrachialis muscle
- 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.
Latissimus dorsi
- Innervation:Local branch of brachial plexus
- The broadest muscle of the back
- Origin: Thoracolumbar fascia
- Insertion: Teres tuberosity of the humerus
- 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.
Superficial Pectorals
- Innervation: Brachial plexus
- Two muscles, cranial (descending) and caudal (transverse)
- Origin:
- Cranial (descending) - Manubrium of the sternum
- Caudal (transverse) - First six costal cartilages and ventral sternum
- Insertion:
- Cranial (descending) - The crest of the humerus, distal to the deltoid tuberosity
- Caudal (transverse) - Covers the elbow joint to insert on the medial fascia of the forearm
- Action: Adducts the forelimb, assist in protraction and retraction
- The cranial (descending) pectoral muscle forms a visible prominence cranial to the sternum; extending between the manubrium and the humeral crest.
Deep Musculature
Deep Pectorals
- Innervation: Cranial and caudal thoracic n.
- Origin: Xiphoid and 4th costal cartilages of the sternum
- Insertion: Two branches on the lesser and greater tubercles of the humerus, supraglenoid tubercle of scapula
- Action:Draws the limb back, supports the trunk, moves the trunk cranially over an advanced limb and extends the shoulder.
Serratis ventralis
- Divided into cranial (cervical) and caudal (thoracic) parts.
- Innervation: Dorsal and ventral Cervical n., long thoracic n.
- Origin: 1st-7th rib, transverse process of cervical vertebrae
- Insertion: Medial scapula and scapular cartilage
- 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.
Rhomboids
- Deep to the trapezius, forms the withers region. Divided into cervical and thoracic parts.
- Innervation: Dorsal and ventral branches of Cervical n., Long thoracic n.
- Origin:
- Cervical - Nuchal ligament at the axis
- Thoracic - Spinous processes of 2nd-6th cervical and 7th thoracic vertebrae
- Insertion:
- Cervical - Unites with trapezius to insert on scapular cartilage
- Thoracic - scapula
- Action: Draws the limb forward and elevates the limb and neck. Fixes the scapula against the trunk.
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