Difference between revisions of "Muscles of the Crus - Horse Anatomy"

Revision as of 16:10, 31 October 2012

Introduction

These muscles can be divided into two groups. On the craniolateral aspect of the limb are the flexors of the tarsus and extensors of the digit. On the caudal aspect are the extensors of the tarsus and flexors of the digit.

Craniolateral Muscles of the Crus

These muscles arise from the distal femur or proximal tibia tibia or fibula. Their tendinous insertions are often multiarticular and insert on the metatarsals or phalanges. They are innervated by the peroneal nerve.

Flexors of the tarsus

Cranial Tibial (Tibialis Cranialis)

Origin: Lateral condyle and tuberosity of the tibia

Insertion: Bifurcates into a medial and lateral branch. The lateral branch inserts on the metatarsal tuberosity. The medial branch inserts on the combined first and second tarsal bones. The medial branch is also known as the cunean tendon.

Action: Flexes the tarsus (hock)

Its tendinous insertion has a synovial sheath, and a bursa is present between its medial branch and the medial ligament of the tarsus (hock).

In the horse, its fibres join with the third fibular muscle proximal to the tarsus.

Peroneus tertius

Origin: Extensor fossa of the femur

Insertion: Proximal extremity of the third metatarsal and third tarsal bone. Also the calcaneus and fourth tarsal bones.

Action: An almost exclusively tendinous muscle that plays an important part in the Stay Apparatus

Extensors of the Digits

Long digital extensor

Origin: Extensor fossa of the femur, shared tendon of origin with the third fibular muscle

Insertion: Extensor process of the distal phalanx, and the dorsal surfaces of the proximal extremities of the proximal and middle phalanges

Action: Extends the digits, assists in flexing the tarsus (hock)

Its tendon of insertion passes over the front of the hock , and is held in place by three annular ligaments (proximal, middle and distal) and a synovial sheath. The tendon of the lateral digital extensor joins the tendon in the approximately the middle of thethird metatarsal (cannon) bone. It is also joined by two branches of the suspensory ligament before its insertion.

Lateral digital extensor

Origin: Lateral patella ligament, proximal fibula, lateral border of the tibia and the interosseous ligament. It lies between the long digital extensor muscle and the long flexor muscle of the first digit.

Insertion: Long digital extensor tendon

Action: It appears to have no function, apart from maybe to support the long digital extensor.

Caudal Muscles of the Crus

These are innervated by the tibial nerve.

Extensors of the Tarsus

Gastrocnemius

Origin: Lateral head from the lateral supracondyloid crest of the femur. The medial head from the medial supracondyloid crest.

Insertion: calcaneus as part of the common calcaneal tendon

Action: Extends the tarsus, assists in flexing the stifle

The two bellies combine in the middle of the crus, which twists around to the dorsal aspect of the superficial digital flexor. A large bursa lies between these two tendons and a small bursa lies between the gastrocnemius and the its point of insertion on the calcaneus.

Soleus

Origin: Head of the fibula

Insertion: Joins the lateral head of the gastrocnemius to become part of the gastrocnemius tendon

Action: Mainly to assist the gastrocnemius

Flexors of the Digits

Superficial digital flexor

Origin: Supracondylar fossa on the caudal femur, attached to the lateral head of the gastrocnemius

Insertion: Calcaneus, the eminences on the sides of the proximal extremity of the middle phalanx, and the distal extremity of the proximal phalanx behind the collateral ligament of the proximal interphalangeal (pastern) joint .

Action: Extends the digit, assists in extending the tarsus and flexing the stifle.

Almost entirely tendinous, major component of the common cunean tendon which forms the caudal part of the reciprocal apparatus.

Widens at the point of the hock to form a cap over the calcaneal tuberosity. The calcaneal bursa lies between the calcaneal tuberosity and the superficial digital flexor tendon.

Deep digital flexor

Origin: The deep digital flexor muscle has three heads, originating from the lateral condyle of the fibula, the caudal and medial aspect of the tibia.

Insertion: Semilunar crest and adjacent surface of the cartilage of the distal phalanx, continues as the deep digital flexor tendon to insert on the distal phalanx

Action: Flexes the digit

The tendon has a synovial sheath from the distal fourth of the tibia, to a third of the way down the metatarsus.

Muscles of the Crus - Horse Anatomy Learning Resources
Drag and Drop (Dragster) Test your knowledge using drag and drop boxes	Equine Crus and Pes Surface Anatomy Resources (I, II & III)

@@ Line 17: / Line 17: @@
 :'''Action''': Flexes the [[Joints and Ligaments - Horse Anatomy#Tarsal Joint|tarsus]] (hock)
 :Its tendinous insertion has a synovial sheath, and a bursa is present between its medial branch and the medial ligament of the [[Joints and Ligaments - Horse Anatomy#Tarsal Joint|tarsus]] (hock).
-:In the horse, its fibres join with the third fibular muscle proximal to the [[Joints and Ligaments - Horse Anatomy#Tarsal Joint|tarsus]].
+:In the horse, its fibres join with the ''third fibular muscle'' proximal to the [[Joints and Ligaments - Horse Anatomy#Tarsal Joint|tarsus]].
 '''''Peroneus tertius'''''
@@ Line 33: / Line 33: @@
 '''''Lateral digital extensor'''''
-:'''Origin''': Lateral patella ligament,  proximal [[Bones and Cartilages - Horse Anatomy#Tibia and Fibula|fibula]], lateral border of the [[Bones and Cartilages - Horse Anatomy#Tibia and Fibula|tibia]] and the interosseous ligament. It lies between the long digital extensor muscle and the long flexor muscle of the first digit.
+:'''Origin''': Lateral patella ligament,  proximal [[Bones and Cartilages - Horse Anatomy#Tibia and Fibula|fibula]], lateral border of the [[Bones and Cartilages - Horse Anatomy#Tibia and Fibula|tibia]] and the interosseous ligament. It lies between the ''long digital extensor'' muscle and the ''long flexor muscle of the first digit''.
 :'''Insertion''': [[Tendons - Horse Anatomy#Extensors|Long digital extensor tendon]]
-:'''Action''': It appears to have no function, apart from maybe to support the long digital extensor.
+:'''Action''': It appears to have no function, apart from maybe to support the ''long digital extensor''.
 =='''Caudal Muscles of the Crus'''==
@@ Line 44: / Line 44: @@
 '''''Gastrocnemius'''''
-:'''Origin''': Lateral head from the lateral supracondyloid crest of the femur. The medial head from the medial supracondyloid crest.
+:'''Origin''': Lateral head from the lateral supracondyloid crest of the [[Bones and Cartilages - Horse Anatomy#Femur|femur]]. The medial head from the medial supracondyloid crest.
-:'''Insertion''': Calcaneus as part of the '''common calcaneal tendon'''
+:'''Insertion''': [[Bones and Cartilages - Horse Anatomy#Tarsal Bones|calcaneus]] as part of the '''common calcaneal tendon'''
-:'''Action''': Extends the tarsus, assists in flexing the stifle
+:'''Action''': Extends the [[Joints and Ligaments - Horse Anatomy#Tarsal Joint|tarsus]], assists in flexing the [[Joints and Ligaments - Horse Anatomy#Stifle Joint|stifle]]
-:The two bellies combine in the middle of the crus, which twists around to the dorsal aspect of the superficial digital flexor. A large bursa lies between these two tendons and a small bursa lies between the gastrocnemius and the its point of insertion on the calcaneus.
+:The two bellies combine in the middle of the crus, which twists around to the dorsal aspect of the ''superficial digital flexor''. A large bursa lies between these two tendons and a small bursa lies between the gastrocnemius and the its point of insertion on the [[Bones and Cartilages - Horse Anatomy#Tarsal Bones|calcaneus]].
 '''''Soleus'''''
-:'''Origin''': Head of the fibula
+:'''Origin''': Head of the [[Bones and Cartilages - Horse Anatomy#Tibia and Fibula|fibula]]
-:'''Insertion''': Joins the lateral head of the gastrocnemius to become part of the gastrocnemius tendon
+:'''Insertion''': Joins the lateral head of the ''gastrocnemius'' to become part of the gastrocnemius tendon
-:'''Action''': Mainly to assist the gastrocnemius
+:'''Action''': Mainly to assist the ''gastrocnemius''
 ==='''Flexors of the Digits'''===
 '''''Superficial digital flexor'''''
-:'''Origin''': Supracondylar fossa on the caudal femur, attached to the lateral head of the ''gastrocnemius''
+:'''Origin''': Supracondylar fossa on the caudal [[Bones and Cartilages - Horse Anatomy#Femur|femur]], attached to the lateral head of the ''gastrocnemius''
-:'''Insertion''': Calcaneus, the eminences on the sides of the proximal extremity of the second phalanx, and the distal extremity of the first phalanx behind the collateral ligament of the pastern joint.
+:'''Insertion''': [[Bones and Cartilages - Horse Anatomy#Tarsal Bones|Calcaneus]], the eminences on the sides of the proximal extremity of the [[Phalanges - Horse Anatomy#Middle Phlanax|middle phalanx]], and the distal extremity of the [[Phalanges - Horse Anatomy#Proximal Phalanx|proximal phalanx]]  behind the collateral ligament of the [[Joints and Ligaments- Horse Anatomy#Proximal Interphalangeal (Pastern) Joint|proximal interphalangeal]] (pastern) joint .
-:'''Action''': Extends the digit, assists in extending the hock and flexing the stifle.
+:'''Action''': Extends the digit, assists in extending the [[Joints and Ligaments - Horse Anatomy#Tarsal Joint|tarsus]] and flexing the [[Joints and Ligaments - Horse Anatomy#Stifle Joint|stifle]].
-:Almost entirely tendinous, major component of the common cunean tendon which forms the caudal part of the reciprocal apparatus.
+:Almost entirely tendinous, major component of the '''common cunean tendon''' which forms the caudal part of the [[Stay Apparatus - Horse Anatomy#Reciprocal Mechanism|reciprocal apparatus]].
-:Widens at the point of the hock to form a cap over the calcanean tuberosity. The calcaneal bursa lies between the calcaneal tuberosity and the superficial digital flexor tendon.
+:Widens at the point of the [[Joints and Ligaments - Horse Anatomy#Tarsal Joint|hock]] to form a cap over the [[Bones and Cartilages - Horse Anatomy#Tarsal Bones|calcaneal tuberosity]]. The calcaneal bursa lies between the [[Bones and Cartilages - Horse Anatomy#Tarsal Bones|calcaneal tuberosity]] and the [[Tendons - Horse Anatomy#Flexors|superficial digital flexor tendon]].
 '''''Deep digital flexor'''''
-:'''Origin''': The deep digital flexor muscle has three heads, originating from the lateral condyle of the tibia, the caudal and medial aspect of the tibia.
+:'''Origin''': The deep digital flexor muscle has three heads, originating from the lateral condyle of the [[Bones and Cartilages - Horse Anatomy#Tibia and Fibula|fibula]], the caudal and medial aspect of the [[Bones and Cartilages - Horse Anatomy#Tibia and Fibula|tibia]].
-:'''Insertion''': Semilunar crest and adjacent surface of the cartilage of the third phalanx, continues as the deep digital flexor tendon to insert on the distal phalanx
+:'''Insertion''': Semilunar crest and adjacent surface of the cartilage of the [[Phalanges - Horse Anatomy#Distal Phalanx|distal phalanx]], continues as the [[Tendons - Horse Anatomy#Flexors|deep digital flexor tendon]] to insert on the [[Phalanges - Horse Anatomy#Distal Phalanx|distal phalanx]]
 :'''Action''': Flexes the digit
-:The tendon has a synovial sheath from the distal fourth of the tibia, to a third of the way down the metatarsus.
+:The tendon has a synovial sheath from the distal fourth of the [[Bones and Cartilages - Horse Anatomy#Tibia and Fibula|tibia]], to a third of the way down the [[Bones and Cartilages - Horse Anatomy#Metacarpals and Metatarsals|metatarsus]].
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