Muscles of the Equine Neck and Shoulders
Muscle Origin Insertion Innervation Action
Cutaneous omobrachialis m. Superficial Fascia of the Shoulder Over Elbow Joint Intercostobrachial n. Moves skin over the shoulder
Cutaneous colli m. Manubrium of the Sternum Medial aspect of Shoulder Lateral Thoracic n.
&
Intercostobrachial n.
Moves skin over the cranial aspect of trunk
Omotransversarius m. Fascia of Shoulder Scapular Cartilage
&
Transverse Processes of C2-4
Ventral Branches of Local Cervical Spinal nn. Advances limb

Adducts limb

Moves neck laterally

Brachiocephalicus m.  
Cleidobrachialis m.
(merges with omotransversarius m.)
Inscription of Clavicle Crest of the Humerus Axillary n. Advances limb

Adducts limb

Cleidomastoideus m. Clavicular Intersection Mastoid Process of Temporal Bone Ventral Branch of Accessory n.
(cranial nerve XI)
Forms dorsal border of jugular groove

Advances limb

Flexes neck

Turns head

Sternocephalicus m.
(Sternomandibularis)
Manubrium of the Sternum Caudal Border of Mandible Ventral Branch of Accessory n.
(cranial nerve XI)
Forms ventral border of jugular groove

Flexes neck

Turns head

Opens mouth

Omohyoideus m. Subscapular Fascia Lingual Process of Basihyoid Bone Spinal Nerve C1 Forms medial border of jugular groove

Retracts basihyoid bone & tongue

Trapezius m.
cervical & thoracic parts
Nuchal Ligament & Supraspinous Ligaments of C2-10 Cervical Part:
Entire Scapular Spine

Thoracic Part:
Dorsal Third of Scapular Spine

Dorsal Branch of Accessory n.
(cranial nerve XI)
Advances thoracic limb

Abducts thoracic limb

Elevates shoulder

Rhomboideus m.
cervicis and thoracis
Nuchal Ligament
&
Dorsoscapular Ligaments of C2-T8
Scapular Cartilage Local Thoracic nn.
&
Local Cervical nn.
Elevates neck

Draws scapula cranially and dorsally

Latissimus dorsi m. Supraspinous Ligaments from T3
&
Thoracolumbar Fascia
Teres Major Tuberosity of Humerus Thoracodorsal n. Flexes shoulder and draws limb caudally

Draws trunk cranially when limb is fixed

Superficial pectoral m.  
Descending pectoral m. Manubrium of the Sternum Deltoid Tuberosity
&
Crest of Humerus
Cranial Pectoral n.
&
Caudal Pectoral n.
Adducts limb

Stabilizes shoulder joint

Transverse pectoral m. Sternum
&
Costal Cartilages 1-6
Fascia of the Forearm Cranial Pectoral n.
&
Caudal Pectoral n.
Adducts limb

Stabilizes shoulder joint

Deep pectoral m.
(Ascending pectoral m.)
Sternum Major and Minor Humeral Tubercles
&
Tendon of Coracobrachialis
Cranial Pectoral n.
&
Caudal Pectoral n.
Adducts limb

Stabilizes shoulder joint

Subclavius m. Sternum
&
Costal Cartilages 1-4
Fascia of Shoulder
&
Supraspinatus m.
Cranial Pectoral   nn. Stabilizes shoulder joint

Suspends trunk

Serratus ventralis m.  
cervicis Transverse Processes of C4-7 Scapular Cartilage
&
Medial Scapula
Ventral Branches of Local Cervical nn. Supports trunk between forelimbs

Raises neck when limb is fixed

thoracis Ribs 1-8/9 Scapular Cartilage
&
Medial Scapula
Long Thoracic n. Supports trunk between forelimbs

Raises neck when limb is fixed

Splenius m.
capitis & cervicis
Nuchal Ligament
&
Spinous Processes of T3-5 (via thoracolumbar fascia)
Nuchal Crest
&
Mastoid Process of Temporal Bone
Dorsal Branch of Accessory n.
(cranial nerve XI)
&
Dorsal Branches of Local Spinal nn.
Extends neck

Elevates neck

Bends neck laterally

Longissimus mm.
cervicis
capitis
atlantis

Note:  continuous with -thoracis et lumborum
Transverse Processes of Cervical and Thoracic Vertebrae Wing of Atlas
&
Mastoid Process of Temporal Bone
Dorsal Branches of Local Spinal nn. Elevates head and neck

Bends head and neck laterally

Stabilizes and extends vertebral column

Semispinalis capitis m. Articular Processes of C2/3-7
&
Transverse Processes of T1-6/7
Occipital Bone Dorsal Branches of Local Spinal nn. Elevates head and neck

Bends head and neck laterally

Longus capitis m. Transverse Processes of C3-5 Base of Skull Ventral Branches of Local Spinal nn.  
Longus colli m.  
cervical part Transverse Processes of C3-7 Ventral Tubercle of Atlas
&
Bodies of Cervical Vertebrae
Ventral Branches of Local Spinal nn. Flexes head
thoracic part Bodies of T1-6 Transverse Processes of C6-7 Ventral Branches of Local Spinal nn. Flexes head

Bends head laterally

Obliquus capitis caudalis m. Spinous Process of the Axis Wing of the Atlas Dorsal Branch of C2 Rotates atlas and Head
Rectus capitis dorsalis m.  
major Spinous Process of the Axis Nuchal Crest Dorsal Branch of C1 Elevates head

minor

Dorsal Arch of the Atlas Occipital Bone Dorsal Branch of C1 Elevates head

Muscle Origin Insertion Innervation Action
Cutaneous omobrachialis m. Superficial Fascia of the Shoulder Over Elbow Joint Intercostobrachial n. Moves skin over the shoulder
Cutaneous colli m. Manubrium of the Sternum Medial aspect of Shoulder Lateral Thoracic n.
&
Intercostobrachial n.
Moves skin over the cranial aspect of trunk
Omotransversarius m. Fascia of Shoulder Scapular Cartilage
&
Transverse Processes of C2-4
Ventral Branches of Local Cervical Spinal nn. Advances limb

Adducts limb

Moves neck laterally

Brachiocephalicus m.  
Cleidobrachialis m.
(merges with omotransversarius m.)
Inscription of Clavicle Crest of the Humerus Axillary n. Advances limb

Adducts limb

Cleidomastoideus m. Clavicular Intersection Mastoid Process of Temporal Bone Ventral Branch of Accessory n.
(cranial nerve XI)
Forms dorsal border of jugular groove

Advances limb

Flexes neck

Turns head

Sternocephalicus m.
(Sternomandibularis)
Manubrium of the Sternum Caudal Border of Mandible Ventral Branch of Accessory n.
(cranial nerve XI)
Forms ventral border of jugular groove

Flexes neck

Turns head

Opens mouth

Omohyoideus m. Subscapular Fascia Lingual Process of Basihyoid Bone Spinal Nerve C1 Forms medial border of jugular groove

Retracts basihyoid bone & tongue

Trapezius m.
cervical & thoracic parts
Nuchal Ligament & Supraspinous Ligaments of C2-10 Cervical Part:
Entire Scapular Spine

Thoracic Part:
Dorsal Third of Scapular Spine

Dorsal Branch of Accessory n.
(cranial nerve XI)
Advances thoracic limb

Abducts thoracic limb

Elevates shoulder

Rhomboideus m.
cervicis and thoracis
Nuchal Ligament
&
Dorsoscapular Ligaments of C2-T8
Scapular Cartilage Local Thoracic nn.
&
Local Cervical nn.
Elevates neck

Draws scapula cranially and dorsally

Latissimus dorsi m. Supraspinous Ligaments from T3
&
Thoracolumbar Fascia
Teres Major Tuberosity of Humerus Thoracodorsal n. Flexes shoulder and draws limb caudally

Draws trunk cranially when limb is fixed

Superficial pectoral m.  
Descending pectoral m. Manubrium of the Sternum Deltoid Tuberosity
&
Crest of Humerus
Cranial Pectoral n.
&
Caudal Pectoral n.
Adducts limb

Stabilizes shoulder joint

Transverse pectoral m. Sternum
&
Costal Cartilages 1-6
Fascia of the Forearm Cranial Pectoral n.
&
Caudal Pectoral n.
Adducts limb

Stabilizes shoulder joint

Deep pectoral m.
(Ascending pectoral m.)
Sternum Major and Minor Humeral Tubercles
&
Tendon of Coracobrachialis
Cranial Pectoral n.
&
Caudal Pectoral n.
Adducts limb

Stabilizes shoulder joint

Subclavius m. Sternum
&
Costal Cartilages 1-4
Fascia of Shoulder
&
Supraspinatus m.
Cranial Pectoral   nn. Stabilizes shoulder joint

Suspends trunk

Serratus ventralis m.  
cervicis Transverse Processes of C4-7 Scapular Cartilage
&
Medial Scapula
Ventral Branches of Local Cervical nn. Supports trunk between forelimbs

Raises neck when limb is fixed

thoracis Ribs 1-8/9 Scapular Cartilage
&
Medial Scapula
Long Thoracic n. Supports trunk between forelimbs

Raises neck when limb is fixed

Splenius m.
capitis & cervicis
Nuchal Ligament
&
Spinous Processes of T3-5 (via thoracolumbar fascia)
Nuchal Crest
&
Mastoid Process of Temporal Bone
Dorsal Branch of Accessory n.
(cranial nerve XI)
&
Dorsal Branches of Local Spinal nn.
Extends neck

Elevates neck

Bends neck laterally

Longissimus mm.
cervicis
capitis
atlantis

Note:  continuous with -thoracis et lumborum
Transverse Processes of Cervical and Thoracic Vertebrae Wing of Atlas
&
Mastoid Process of Temporal Bone
Dorsal Branches of Local Spinal nn. Elevates head and neck

Bends head and neck laterally

Stabilizes and extends vertebral column

Semispinalis capitis m. Articular Processes of C2/3-7
&
Transverse Processes of T1-6/7
Occipital Bone Dorsal Branches of Local Spinal nn. Elevates head and neck

Bends head and neck laterally

Longus capitis m. Transverse Processes of C3-5 Base of Skull Ventral Branches of Local Spinal nn.  
Longus colli m.  
cervical part Transverse Processes of C3-7 Ventral Tubercle of Atlas
&
Bodies of Cervical Vertebrae
Ventral Branches of Local Spinal nn. Flexes head
thoracic part Bodies of T1-6 Transverse Processes of C6-7 Ventral Branches of Local Spinal nn. Flexes head

Bends head laterally

Obliquus capitis caudalis m. Spinous Process of the Axis Wing of the Atlas Dorsal Branch of C2 Rotates atlas and Head
Rectus capitis dorsalis m.  
major Spinous Process of the Axis Nuchal Crest Dorsal Branch of C1 Elevates head

minor

Dorsal Arch of the Atlas Occipital Bone Dorsal Branch of C1 Elevates head