Musculus pectoralis profundus
The deep ascending pectoral (pectoralis ascendens / deep pectoral) is one of the major muscles of the chest. It originates along the ventral sternum and deep pectoral fascia and inserts on the medial tuberosity and lesser tubercle of the humerus. Its actions are to retract (pull backward) and adduct (pull toward the midline) the forelimb. When the limb is weight-bearing, it also helps draw the trunk forward over the planted leg: an important contribution to propulsion. It lies deep to the more superficial pectoral muscles and is innervated by the caudal pectoral nerves (roughly C8–T1). Because it is well protected by other muscles, isolated injury is uncommon, but it can be involved in trauma to the chest or proximal forelimb.
Origin: Ventral sternum and deep pectoral fascia
Insertion: Medial tuberosity of the humerus and lesser tubercle
Action: Retracts and adducts the forelimb; draws trunk forward
Innervation: Caudal pectoral nerves (C8-T1)
Rarely a primary source of lameness. Contusions or strains can occur with falls or collisions. It is considered in the differential for proximal forelimb or pectoral-region pain.
## Overview Pectoral muscle strain is injury to the muscles between the forelimbs, often from wide-stance landings, slipping, or doing the splits. It produces a shortened forelimb stride, reluctance
## Overview A pectoral abscess is a collection of pus in the chest muscles between the forelimbs. The classic cause in the western United States is Corynebacterium pseudotuberculosis (pigeon fever),
Swelling, heat, or reluctance to move the front leg forward after a fall or collision into a solid object should be examined. Most soft-tissue bruising resolves with rest.
## Overview Pectoral muscle strain is injury to the muscles between the forelimbs, often from wide-stance landings, slipping, or doing the splits. It produces a shortened forelimb stride, reluctance to abduct the limb, swelling between the front legs, and a stiff gait. It is relatively common in eventers and trail horses on slippery ground. ## Causes Acute overload from abduction or slipping. ## Diagnosis Palpation of pain and swelling, and ultrasound if needed. ## Treatment Rest, anti-inflammatories, and gradual return to work. ## Recovery and Prognosis Good. ## Prevention Safe footing and progressive conditioning. Signs include: shortened stride in front; reluctance to abduct the forelimb; swelling between the front legs; pain on palpation; stiff gait
## Overview A pectoral abscess is a collection of pus in the chest muscles between the forelimbs. The classic cause in the western United States is Corynebacterium pseudotuberculosis (pigeon fever), producing large, painful swellings. Injection reactions can also cause abscesses. Horses show heat, pain, fever, and stiff forelimb movement. ## Causes Corynebacterium pseudotuberculosis or other bacteria introduced by wounds or injections. ## Diagnosis Clinical appearance, ultrasound, and culture of aspirated pus. ## Treatment Allow the abscess to mature, then lance and drain. Antibiotics are used in some cases. Hot packing helps maturation. ## Recovery and Prognosis Good for external abscesses once drained. ## Prevention Fly control and wound management in endemic areas. Signs include: hot painful swelling in the chest; reluctance to move the forelimbs; possible draining tract; fever; stiff gait
Rarely a primary source of lameness. Contusions or strains can occur with falls or collisions. It is considered in the differential for proximal forelimb or pectoral-region pain.
Swelling, heat, or reluctance to move the front leg forward after a fall or collision into a solid object should be examined. Most soft-tissue bruising resolves with rest.
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