Bones
Distal Limb
Learn More:
WikiVet: Forelimb
WikiVet: Canine Forelimb
WikiVet: Bovine Forelimb
Anatomy Revision Kit
Colorado State University: Virtual Canine Anatomy
Real 3D anatomy: Dog Skeleton
Interactive Drawings for Veterinary Anatomy
Interactive Equine Anatomy
Interactive Canine Anatomy
Veterinary Anatomy Concept Checkers
Knowledge Testing
1. describe the following actions and list a muscle for each: abduction, adduction, protraction, retraction, flexion, extension, pronation, supination.
2. Name the joints and joint types int the forelimb.
Concept Testing
1.Discuss the evolutionary influences that have adapted the extrinsic structures of the forelimb in the animals we see about us today.
2. Relate the presence or absence of a clavicle in the forelimb girdle to its potential life style.
3. The superficial pectoral m is a protractor, a retractor and an adductor of the forelimb. Rationalise this statement.
4. The concepts of “effective centre of pivot” and “cranio-caudal movement of the centre of pivot” are very important in our cursorial animals. Discuss how the adaptations seen in cursorial animals that lead to change of muscular organisation in this region makes these concepts important. Consequently how are these movements controlled and managed during loaded (stance phase) and unloaded (swing phase) motion?
5. The scapular is in constant movement relative to the trunk during locomotion. Discuss the consequences for other structures which traverse the space between the base of the neck & chest wall out onto the forearm. Outline the organisation of these structures which prevents them being damaged by this activity.
6. Why are the retractors so much bigger muscles than the protractors? - relate to function
- - Clavicle: in bipeds, brachiators, manipulators and diggers this bone provides a bony connection between the limb and thorax providing extra stability to the free upper limb while it is absent or reduced in cursorial animals to allow further protraction of the limb.
- - Scapula: the bony features of the scapula reflect its function. For example, the large acromion in humans, articulates with the developed clavicle and forms part of the bony strutthat suspends the limb from the thorax. In quadrupeds, the clavicle is reduced or absent and as a result the acromion has less significance. In life there is often presence of a scapula cartilage on the cranial border which varies in size between species.
- -Humerus: the humerus is well conserved between species however in larger and more robust animals the bone is larger and thicker.
- -Radius and Ulna: the most interesting difference between radii and ulnae in mammals is the differing degree of fusion between species. Those animals that freely more their limbs and have a large range of pronation and supination have a radius which is seperated/supported by an interosseus ligament. In those animals with increasingly limited movement of the antebrachium the radius and ulna fuse.
- -Manus: the manus is composed of two rows of carpal bones, a series of metacarpal bones and phalanges. This region of the skeleton is most variable in terms of deletions and fusions of bones howeer can all be related back to the conformation of the generalised 'human' manus.
- Superficial Pectoral: this muscle has two parts, a descending and transverse pectoral. it originates from the first two sternebrae and usually a prt of the third; the fibrous raphe between adjacent muscle and inserts at the whole crest of the greater tubercle of hte humerus. It adducts the limb when it is not bearing weight or to prevent the limb being abducted when bearing weight and is innervated by cranial pectoral nerves (C7, C8)
- Deep Pectoral: This muscle originates at the ventral part of the sternum and the fibrous raphe between fellow muscles. and insernts on the lesser tubercle of the humerous and an aponeurosis to the greater tubercle and its crest. it pulls the trunk cranially when the limb is protracted and also retracts the limb. Is innervated by caudal pectoral nerves (C8, T1)
- Brachiocephaclicus: this muscle comes in two parts, the cleidobrachialis and cleidocephalicus (which is then broken down into the cleidocephalicus and pars cervicalis and beneath this a pars mastoidea) The cervical part of the clecephalicus attaches to the mid-dorsal fibrous raphe and the cleidbrachialis attaches to the distal end of the cranial border of the humerus. This muscle protracts the limb and draws the neck and head to the side, it is innerveated by the accessory nerve and ventral branches of cervical spinal nerves.
- sternocephalicus: this muscle originates at the mnubrium and inserts at the mastoid part of the temporal bone and the nuchal crest of the occipital bone. It draws the head and neck to the side and is innervated by the accessory nerve and ventral branches of cervical spinal nerves.
- sternohyoideus: Thi muscle originates at the first sternebra and first costal cartilage and inserts at the basihyoid bone. It pulls the tongue and larync caudally and is innervated by ventral branches of cervical spinal nerves
- sernothyroideus: this muscle iringinates at the first costal cartilage and inserts at the caudolaterl surfaces of the thyroid cartilage. It has the same function of the sternohyoideus and is innervated by ventral branches of cervical spinal nerves.
- Omotransversarius: this muscle originates at the transverse wing of the atlas and inserts to the distal end of the spine of the scapula. Itadvances the limb and flexes the neck and is innervated by the accessory nerve.
- trapezius: this muscle is divided into cervical and thoracic parts, separated by an aponeurosis. It originates at the median raphe of the neck and supraspinous ligament from the level of the third cervical vertebra to the level of the ninth thoracic vertebra and inserts at the spin of the scapule. It elevates and apducts the forelimb and is innervated by the accessory nerve.
- Rhomoideus: this muscle has three parts; captial, cervical and thoracic. It originates at the nuchal crest of the occipital bone and teb median firbous raphe of the neck; the spinous processes of the first seven thoracic vertebrae and inserts at th dorsal border and adjacent surfaces fo the scapula. It functions to elevate the forelimb and draw the scapula against the trunk (retraction) is innervated by ventral branches of cervical and htoracic spial nerves (brachial plexus)
- Latissumus dorsi: this muscle originates at the thoracolumbar fascia from the spinous processes of the lumbar and the last seven or eight thoracic vertebrae; a muscular attachment to the last two or three ribs. It inserts at the teres major tuberosityof the humerus and the teres major tendon. It draws the free limb caudally as in digging, to flex the shoulder joint.
- Serratus ventralis: this muscle is probken into two parts cervical and thoracc. It originates from the transverse processes of the last five cervical vertebrae and first seven or eight ribs ventral to their middle. It inserts at the dorsomedial thrd of the scapula (serrated face) and functions to suppirt the trunk and depress the scapula and is innervated by ventral branches of cervical spinal nerves and the long thoracic nerve (C7)
- deltoideus: originates from the spine and acromial process of the scapula and inserts at the deltoid tuberosity funcion to flex th shoulder, innervated by the axillary nerve.
- infraspinatus: originates at the infraspinous fossa and inserts on a small, cricumscribed area on the lateral side of thegreater tubercle fo the humerus. It can extend or flex the joint and can abduct the shoulder and rotate it laerally and is innervated by the suprascapular nerve.
- teres minor: originates from teh infraglenoid tubercle and distal third of the caudal border of the scapula, inserting to the teres minor tuberosity fo the humerus. It flexes the shoulder and rotates it laterally (preventing medial rotation) and is innervated by the axxilary nerve.
- supra spinatus: originates from teh supraspinous fossa and inserts to the greater tubercle of the humerus so to extend and stabilise the shoulder joint, being innervated by the suprascapular nerve.
- subscapularis: originates from the subscapular fossa and inserts on the lesser tubercle of the humerus. It adducts, extends and medially stabilises the shoulder joint and is innervated y the subscapular nerve.
- teres major: originates from the caudal angle and adjacent caudal border of the scapula and inserts on the teres major tuberosity of the humerus. it flexes the shoulder and rotates it medially, innervated by the axillary nerve.
- corachobrachialis: originates from teh coracoid process of the scapula and inserts to the crest of the elsser tubercle of the humerus, proximal to teh teres major tuberosity. It adducts, extends and stabilises the houlder joint and is innervated by the musculocutaneous nerve.
- tensor fasciae antebrachii: originates from teh fascia covering the lateral side of the latissims dorsi and inserts at the olecranon to extend the elbow, innervated by the radial nerve.
- triceps brachii: contains 4 parts (in the dog, varies between predator/prey species) a long head, lateral, accessory and medial head, they are all innervated by the radial nerve and all extend the elbow. The long head originates at the caudal border of the scapula and inserts at the olecranon tuber, the lateral head originates at the tricipital line of the humerus and inserts at the olecranon tuber, the accessory head originates at the neck of the humerus and inserts at the olecranon tuber while the medial head originates from the crest of the lesser tubercle near the teres major tuberosity and inserts at the olecranon.
- anconeus: originates from the lateral supracondylar crest and lateral and medial epicondyles of the humerus and inserts at the lateral surfaces of the proximal end of the ulna. This muscle extends the elbow and is innervated by theradial nerve.
- biceps brachii: originates from the supraglenoid tubercle and inserts at the ulnar and radial tuberosities. Flexes the elbow and extends the shoulder, innervated by musculocutaneous nerve.
- brachialis: originates from teh proximal third fo the lateral surface of the humerus and inserts at the ulnar and radial tuberosities. It flexes the elbow and is innervated by the musculocutaneous nerve.
Distal Limb
- extensor carpi radialis: originates from the lateral suprcondylarcrest inserts ont eh small tuberosities of the bases of metacarpals II and III. Extends the carpus and is innervated by the radial nerve.
- common digital extensor: originates from the alteral epicondyle of the humeru and inserts on the extensor processes of the stal phalanges of digits 2, 3, 4 and 5. Extends the joints of the 4 principal digits and the carpus and is innervated by the radial nerve.
- lateral digital extensor: originates from the lateral epicondyle fo the humerus and inserts on the proximal ends of the phalanges of digits 3,4 and five and extends the carpus and aforementioned digts and is innervated by the radial nerve.
- ulnaris lateralis: originates on teh lateral epicondyle of the humerus and inserts on the lateral aspect of the proximal end of metacarpal 5 and accessory carpal bone. It abducts the carpal joint and supports the carpus when extended to support weight and is innervated by radial nerve.
- supinator: Inserts on the lateral epicondyle of the humerus and insert on the cranial surface of the proximal fourth of the radius.It rotates the forearm laterally (supination) and is innervated by the radial nerve.
- abductor digit I longus: originates on the lateral border and cranial surface of the body of the ulna; the interosseous membrane and inserts on the proximal end of metacarpal I. it abducts the first digit or pollex and extends the carpal joints, innervated by the radial nerve.
- pronator teres: Originates on teh medial epicondyle of the humerus and inserts ont eh medial border of the radius and allows medial rotation (pronation) and is innervated by the median nerve.
- flexor carpi radialis: originates from teh medial epicondyle of the humerus and the medial border of the radius inserting on teh palmar side of the base of metacarpals Ii and III. It allows flexion of the carpus and is innervated by the median nerve.
- flexor carpi ulnaris: has two heads, ulnar and humeral. The ulnar head originates from the caudal border and medial surface of the olecranon and th humeral head originates from the medial epicondyle of the humerus. They both insert at the accessory carpal bone and function to flex the carpus being innervated by the ulnar nerve
- superficial digital flexor: originates from the medial epicondyle of the humerusand inserts ont eh palmar surface of the base of the middle phalanges of digits II, II IV, and V.
- deep digital flexor: has 3 heads; ulnar, radial and humeral. The ulnar head originates from the proximal 3/4 of the caudal border of the ulna, the radial head originates from the mdidle third of the medail border of the radius and the humeral head originates from the medial epicondyle of the humerus.
- pronator quadratus: fills the space between the radius and ulna and so is attached to apposed surfaces of these bones allowing pronation fo the paw and innervtaed by the median nerve.
Learn More:
WikiVet: Forelimb
WikiVet: Canine Forelimb
WikiVet: Bovine Forelimb
Anatomy Revision Kit
Colorado State University: Virtual Canine Anatomy
Real 3D anatomy: Dog Skeleton
Interactive Drawings for Veterinary Anatomy
Interactive Equine Anatomy
Interactive Canine Anatomy
Veterinary Anatomy Concept Checkers
Knowledge Testing
1. describe the following actions and list a muscle for each: abduction, adduction, protraction, retraction, flexion, extension, pronation, supination.
2. Name the joints and joint types int the forelimb.
Concept Testing
1.Discuss the evolutionary influences that have adapted the extrinsic structures of the forelimb in the animals we see about us today.
2. Relate the presence or absence of a clavicle in the forelimb girdle to its potential life style.
3. The superficial pectoral m is a protractor, a retractor and an adductor of the forelimb. Rationalise this statement.
4. The concepts of “effective centre of pivot” and “cranio-caudal movement of the centre of pivot” are very important in our cursorial animals. Discuss how the adaptations seen in cursorial animals that lead to change of muscular organisation in this region makes these concepts important. Consequently how are these movements controlled and managed during loaded (stance phase) and unloaded (swing phase) motion?
5. The scapular is in constant movement relative to the trunk during locomotion. Discuss the consequences for other structures which traverse the space between the base of the neck & chest wall out onto the forearm. Outline the organisation of these structures which prevents them being damaged by this activity.
6. Why are the retractors so much bigger muscles than the protractors? - relate to function