Extrinsic muscles forelimb Flashcards
Superficial Pectoral m. (Descending and Transverse)
Origin, Insertion, Action, Innervation
Descending superficial to the transverse, smaller, and crosses obliquely.
ORIGIN: The first 2 sternebrae (some of 3rd) and fibrous raphe of adjacent muscle
INSERTION: THe whole crest of the greater tubercle of the humerus
ACTION: To adduct the limb when non-weight bearing, and prevent abduction when weight-bearing
INNVERVATION: Ventral branch of spinal nerves C7 and C8.
Deep Pectoral m. (Ascending)
Origin, Insertion, Action, Innervation
ORIGIN: The ventral part of sternum and fibrous raphe, deep abdominal fascia near xiphoid cartilage
INSERTION: Muscular, tendinous part of lesser tubercle, and aponeurosis of greater tubercle (caudal to brachial fascia)
ACTION: When limb is advanced and in fixed supporting position: to pull the trunk cranially and extend the shoulder joint
- When non-weight bearing: draw limb caudally and flex shoulder.
- To adduct limb
INNERVATION: Caudal Pectoral Nerves (C8, T1)
Brachiocephalicus m.
Cleidobrachialis and cleidocephalicsu (subdivisions)
Origin, Insertion, Action, Innervation
Clavicular Intersection
Compound muscle with one end attaching to the distal 1/3 of the humerus, crosses cranial surface of the shoulder, divides into two parts and attaches at the neck. Clavicular intersection (where the muscle crosses the shoulder) is the surface on which the vestigial clavicle is connected.
Cleidocephalicus:
ORIGIN: clavicular intersection (tendon)
INSERTION: Divides into pars mastoideus which attaches to the mastoid process of the skull and the par cervicalis which is interposed between the sternocephalicus (occipitalis) cranially and the trapezius caudally)
Cleidobrachialis:
ORIGIN: clavicular intersection
INSERTION: distal 1/3 of humerus (between biceps brachii and brachialis
ACTION: To advance the limb, extend the shoulder joint, and to draw the head and neck to the side
INNERVATION: Accessory nerve and ventral branches of spinal nerves
Omotransversarius m.
Insertion, Action, Innervation
Deep to the cleidocephalicus, strap like muscle. Superficial lymph nodes are located under this muscle and cranial to the scapula
INSERTION: transverse process or wing of Atlas
ACTION: To advance the limb, or flex the neck laterally
INNERVATION: Accessory nerve
Trapezius m. (subdivisions)
Where does it attach to the scapula?
Action, Innervation, Insertion
Divided into cervical and thoracic parts, separated by an apopneurosis. Extends from the median raphe of the neck and supraspinous ligament.
INSERTION: the spine of the scapula
ACTION: to elevate and abduct the forelimb
INNERVATION: Accessory nerve
Rhomboideus m. (know all parts)
Action, Innervation
Lies beneath trapezius and holds the dorsal border of the spine of the scapula close to the body. Consists of capitus, cervisism and thoracis.
Capitis: attaches the craniodorsal border of the scapula to the unchallenged crest of occipital bone
Cervicis: median raphe of neck to dorsal border of scapula
Thoracis: connects spines on first 7 thoracic vertebrae to dorsal border of scapula
ACTION: to elevate the forelimb and draw the scapula against the trunk
INNERVATION: Ventral branches of cervical and thoracic spinal nerves
Latissimus Dorsi m.
Origin, Insertion, Action, Innervation
ORIGIN: the thoracolumbar fascia from spinous processes of lumbar and last 7-8 thoracic vertebrae, 2-3 ribs muscular attachment
INSERTION: the tuberosity for teres major and teres major tendon
ACTION: to draw the free limb caudally as in diggin and to flex the shoulder joint
INNERVATION: Thoracodorsal nerve (C7, C8, T1)
Thoracolumbar fascia
Linea Alba
Deep fascia of the trunk, arises from supraspinous ligament and spines of thoracic and lumbar vertebrae, ribs, and abdomen. Fuses with opposite fascia along the ventral midline along fibrous raphe called the linea alba. This fascia serves as an attachment site for many muscles.
Serratus Ventralis (2 parts) m.
All parts, Origin, Insertion, Action, Innervation
Continuous, large, fan-shaped muscle that passes from cervical vertebrae and ribs to the dorsomedial aspect of the scapula. Acts as a sling to support the body between limbs.
2 Parts: cervicis and thoracis
ORIGIN: The transverse processes of last five cervical vertebra and first 7-8 ribs
INSERTION: The dorsomedial third of the scapula (serrated face)
ACTION: To support the trunk and depress the scapula
INNERVATION: Ventral branches of cervical spinal nerves and the long thoracic nerve. (C7)
Sternocephalicus m.
Action, Innervation
ACTION: To draw the head and neck to the side
INNERVATION: Accessory nerve and ventral branches of cervical spinal nerves
Sternohyoideus m.
Action, Innervation
Lies on the trachea, covered caudally by the sternocephalicus m.
ACTION: To pull the tongue and larynx caudally
INNERVATION: Ventral branches of cervical spinal nerves
Sternothyroideus m.
Covered at origin by sternohyoideus m.
ACTION: To pull the tongue and larynx caudally (same as sternothyroideus)
INNERVATION: Ventral branches of cervical spinal nerves AND HYPOGLOSSAL nerve
Carotid Sheath
Deep fascia that covers the common carotid artery, vagosympathetic trunk, internal jugular vein, and tracheal lymphatic trunk.
The Median Raphe of the neck
A longitudinal fibrous septum between right and left epaxial muscles, dorsal to unchallenged ligament. Serves as the attachment for many cervical muscles.
Cutaneous Trunci m.
A thin sheet of muscle that covers most of the dorsal, lateral, and ventral walls of the thorax and abdomen. No direct bony attachments. More closely associated with the skin, rather than underlying structures. Attaches to superficial fascia of trunk and skin.
ACTION: Responsible for twitching of the skin.
INNERVATION: Lateral thoracic nerve
