Difference between revisions of "Carpal and Digital Muscles - Horse Anatomy"

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==Introduction==
 
==Introduction==
 
The horse, as well as other domestic mammals, have a limited range of motion in the carpal joints compared with humans; therefore these muscles act as either extensors or flexors.
 
The horse, as well as other domestic mammals, have a limited range of motion in the carpal joints compared with humans; therefore these muscles act as either extensors or flexors.
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=='''Extensors'''==
 
=='''Extensors'''==
  
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The extensors are located at the craniolateral position on the forearm, almost all originate from the lateral '''epicondyle of the [[Limb Bones and Cartilages - Horse Anatomy#Humerus|humerus]]'''. All of these muscles are innervated by the '''radial n'''. from the brachial plexus.
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The craniolateral position on the forearm, almost all originate from the lateral epicondyle of the [[Bones and Cartilages - Horse Anatomy#Humerus|humerus]]. All innervated by the radial n. from the brachial plexus.
  
 
'''''Extensor carpi radialis'''''
 
'''''Extensor carpi radialis'''''
 
:The most medial
 
:The most medial
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::'''Insertion''': Metacarpal tuberosity of the proximal [[Limb Bones and Cartilages - Horse Anatomy#Metacarpals and Metatarsals|third metacarpal]] (cannon) bone. Uniquely in the horse, the lacertus fibrosus (detachment of the ''biceps brachii'') joins this muscle prior to its insertion.  
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::'''Insertion''': Metacarpal tuberosity of the proximal [[Bones and Cartilages - Horse Anatomy#Metacarpals and Metatarsals|third metacarpal]] (cannon) bone. Uniquely in the horse, the lacertus fibrosus (detachment of the ''biceps brachii'') joins this muscle prior to its insertion.  
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::'''Action''': Extends and fixes the [[Joints and Ligaments - Horse Anatomy#Carpal Joint|carpus]], flexes the [[Joints and Ligaments - Horse Anatomy#Elbow Joint|elbow]]
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::'''Action''': Extends and fixes the carpus, flexes the elbow
  
 
'''''Extensor carpi obliquus''''' (aka '''''abductor pollicis longus''''')
 
'''''Extensor carpi obliquus''''' (aka '''''abductor pollicis longus''''')
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:'''Origin''': Cranial [[Limb Bones and Cartilages - Horse Anatomy#Radius and Ulna|radius]]
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:'''Origin''': Cranial [[Bones and Cartilages - Horse Anatomy#Radius and Ulna|radius]]
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:'''Insertion''': Head of [[Limb Bones and Cartilages - Horse Anatomy#Metacarpals and Metatarsals|second metacarpal]] (medial splint) bone
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:'''Insertion''': Head of [[Bones and Cartilages - Horse Anatomy#Metacarpals and Metatarsals|second metacarpal]] (medial splint) bone
 
   
 
   
 
'''''Common Digital Extensor'''''
 
'''''Common Digital Extensor'''''
 
: Deep to the ''extensor carpi radialis''
 
: Deep to the ''extensor carpi radialis''
 
:'''Insertion''': Extensor process of the [[Phalanges - Horse Anatomy#Distal Phalanx|distal phalanx]] via the [[Tendons - Horse Anatomy#Extensors|common digital extensor tendon]].
 
:'''Insertion''': Extensor process of the [[Phalanges - Horse Anatomy#Distal Phalanx|distal phalanx]] via the [[Tendons - Horse Anatomy#Extensors|common digital extensor tendon]].
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:'''Action''': Extends [[Joints and Ligaments - Horse Anatomy#Carpal Joint|carpus]] and digit
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:'''Action''': Extends carpus and digit
  
 
'''''Lateral Digital Extensor'''''
 
'''''Lateral Digital Extensor'''''
 
: Caudal to the ''common digital extensor'' muscle on the lateral antebrachium
 
: Caudal to the ''common digital extensor'' muscle on the lateral antebrachium
 
:'''Insertion''': Dorsal [[Phalanges - Horse Anatomy#Proximal Phalanx|proximal phalanx]] via the [[Tendons - Horse Anatomy#Extensors|lateral digital extensor tendon]].
 
:'''Insertion''': Dorsal [[Phalanges - Horse Anatomy#Proximal Phalanx|proximal phalanx]] via the [[Tendons - Horse Anatomy#Extensors|lateral digital extensor tendon]].
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:'''Action''': Extends the [[Joints and Ligaments - Horse Anatomy#Carpal Joint|carpus]] and [[Joints and Ligaments - Horse Anatomy#Metacarpophalangeal (Fetlock) Joint|metacarpophalangeal]] (fetlock) joint
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:'''Action''': Extends the carpus and metacarpophalangeal (fetlock) joint
  
 
=='''Flexors'''==
 
=='''Flexors'''==
  
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These muscles are at the caudal position on the forearm. They originate from the '''caudal medial epicondyle of the [[Limb Bones and Cartilages - Horse Anatomy#Humerus|humerus]]''' and are innervated by the '''median or ulnar n.''' of the brachial plexus.
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Caudal position on the forearm, originate from the caudal medial epicondyle of the humerus. All innervated by the median or ulnar n. of the brachial plexus.
  
 
'''''Flexor carpi radialis'''''
 
'''''Flexor carpi radialis'''''
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:The most medial, inserts on the proximal part of the [[Limb Bones and Cartilages - Horse Anatomy#Metacarpals and Metatarsals|second metacarpal]] (medial splint)bone
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:The most medial, inserts on the proximal part of the second metacarpal(medial splint)bone
  
 
'''''Flexor carpi ulnaris'''''  
 
'''''Flexor carpi ulnaris'''''  
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:The most lateral, inserts on the [[Limb Bones and Cartilages - Horse Anatomy#Carpal Bones|accessory carpal bone]].
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:The most lateral, inserts on the accessory carpal bone.
  
 
'''''Ulnaris lateralis'''''
 
'''''Ulnaris lateralis'''''
 
:The most caudolateral
 
:The most caudolateral
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:'''Insertion''': [[Limb Bones and Cartilages - Horse Anatomy#Carpal Bones|accessory carpal bone]] and the [[Limb Bones and Cartilages - Horse Anatomy#Metacarpals and Metatarsals|fourth metacarpal]] (lateral splint) bone.
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:'''Insertion''': Accessory carpal bone and the fourth metacarpal (lateral splint) bone.
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:'''Action''': Flexes the [[Joints and Ligaments - Horse Anatomy#Carpal Joint|carpus]] rather than extends it, due to its insertion caudal to the [[Joints and Ligaments - Horse Anatomy#Carpal Joint|carpal joint]]  axis.  
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:'''Action''': Flexes the carpus rather than extends it, due to its insertion caudal to the carpal joint axis.  
  
 
'''''Superficial Digital Flexor'''''
 
'''''Superficial Digital Flexor'''''
 
: Overlies, and is partially fused with, the ''deep digital flexor'' muscle.
 
: Overlies, and is partially fused with, the ''deep digital flexor'' muscle.
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:'''Insertion''': Proximal extremity of [[Phalanges - Horse Anatomy#Middle Phalanx|middle phalanx]] and the distal extremity of [[Phalanges - Horse Anatomy#Proximal Phalanx|proximal phalanx]] via the [[Tendons - Horse Anatomy#Flexors|superficial digital flexor tendon]].
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:'''Insertion''': Proximal extremity of middle phalanx and the distal extremity of proximal phalanx via the [[Tendons - Horse Anatomy|superficial digital flexor tendon]].
  
 
'''''Deep Digital Flexor'''''
 
'''''Deep Digital Flexor'''''
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:Deep to the ''superficial digital flexor'' muscle and flexor muscles of the [[Joints and Ligaments - Horse Anatomy#Carpal Joint|carpus]]. Passes through the carpal canal before branching and continues to insert on the palmar [[Phalanges - Horse Anatomy#Distal Phalanx|distal phalanx]] via the [[Tendons - Horse Anatomy#Flexors|deep digital flexor tendon]].
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:Deep to the ''superficial digital flexor'' muscle and flexor muscles of the carpus. Passes through the carpal canal before branching and continues to insert on the palmar distal phalanx via the [[Tendons - Horse Anatomy|deep digital flexor tendon]].
  
 
'''''Interosseus muscle/Suspensory ligament'''''
 
'''''Interosseus muscle/Suspensory ligament'''''
 
:This is covered in more detail in the [[Tendons - Horse Anatomy|Equine Tendons]] section.
 
:This is covered in more detail in the [[Tendons - Horse Anatomy|Equine Tendons]] section.
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[[Category:Muscles - Horse Anatomy]]
 

Revision as of 10:39, 31 October 2012

Introduction

The horse, as well as other domestic mammals, have a limited range of motion in the carpal joints compared with humans; therefore these muscles act as either extensors or flexors.

Extensors

The craniolateral position on the forearm, almost all originate from the lateral epicondyle of the humerus. All innervated by the radial n. from the brachial plexus.

Extensor carpi radialis

The most medial
Insertion: Metacarpal tuberosity of the proximal third metacarpal (cannon) bone. Uniquely in the horse, the lacertus fibrosus (detachment of the biceps brachii) joins this muscle prior to its insertion.
Action: Extends and fixes the carpus, flexes the elbow

Extensor carpi obliquus (aka abductor pollicis longus)

Origin: Cranial radius
Insertion: Head of second metacarpal (medial splint) bone

Common Digital Extensor

Deep to the extensor carpi radialis
Insertion: Extensor process of the distal phalanx via the common digital extensor tendon.
Action: Extends carpus and digit

Lateral Digital Extensor

Caudal to the common digital extensor muscle on the lateral antebrachium
Insertion: Dorsal proximal phalanx via the lateral digital extensor tendon.
Action: Extends the carpus and metacarpophalangeal (fetlock) joint

Flexors

Caudal position on the forearm, originate from the caudal medial epicondyle of the humerus. All innervated by the median or ulnar n. of the brachial plexus.

Flexor carpi radialis

The most medial, inserts on the proximal part of the second metacarpal(medial splint)bone

Flexor carpi ulnaris

The most lateral, inserts on the accessory carpal bone.

Ulnaris lateralis

The most caudolateral
Insertion: Accessory carpal bone and the fourth metacarpal (lateral splint) bone.
Action: Flexes the carpus rather than extends it, due to its insertion caudal to the carpal joint axis.

Superficial Digital Flexor

Overlies, and is partially fused with, the deep digital flexor muscle.
Insertion: Proximal extremity of middle phalanx and the distal extremity of proximal phalanx via the superficial digital flexor tendon.

Deep Digital Flexor

Deep to the superficial digital flexor muscle and flexor muscles of the carpus. Passes through the carpal canal before branching and continues to insert on the palmar distal phalanx via the deep digital flexor tendon.

Interosseus muscle/Suspensory ligament

This is covered in more detail in the Equine Tendons section.
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