Miembro torácico

Anatomical References of the Thoracic Limb

Overview of Thoracic Limb Anatomy

• The thoracic limb's surface anatomical references are crucial for clinical practice, differing from the pelvic limb as it connects to the body via extrinsic muscles rather than direct articulation.

• Key muscles include the latissimus dorsi, trapezius (both thoracic and cervical), rhomboid, omotransversarius, brachiocephalicus, and pectoral muscles (superficial and deep).

Regions of the Thoracic Limb

• The thoracic limb is divided into several regions:

• Shoulder Region: Articulates with the scapula and humerus.

• Arm Region: Humerus serves as its bony base.

• Elbow Region: Involves humerus, ulna, and radius articulating together.

Detailed Anatomical Features

• The elbow joint features prominent structures like the olecranon tuberosity; flexion and extension movements are primarily facilitated by triceps and biceps muscles.

• The forearm consists of two bones: radius (cranially located) and ulna (caudally located).

Hand Structure in Canines

• The canine thoracic limb has three main regions in the hand:

• Carpal Region

• Metacarpal Region

• Digital Region: Contains four weight-bearing digits plus a rudimentary fifth digit.

Scapular Anatomy

• Dorsally, the scapula features a prominent spine leading to an acromion. Muscles such as supraspinatus and infraspinatus are situated around this area.

Humeral Anatomy

• Important landmarks on the humerus include:

• Greater tubercle

• Deltoid tuberosity where deltoid muscle attaches.

Muscle Topography in Arm

• The arm houses significant musculature including:

• Triceps brachii with palpable long and lateral heads.

• Biceps brachii located medially but less visible due to overlying pectorals.

Elbow Joint Mechanics

• Key reference points at the elbow include olecranon tuberosity with associated epicondyles. Movements involve flexion/extension primarily driven by triceps/biceps respectively.

Forearm Muscle Groups

• Distinct muscle groups exist within the forearm:

• Extensors positioned laterally responsible for extending carpus/digits.

• Flexors found medially aiding in flexing actions.

Tendon Structures in Forelimb

• Four primary extensor tendons reach towards digits:

• Extensor carpi radialis,

• Common digital extensor,

• Lateral digital extensor,

• Ulnar carpal extensor.

Anatomical Overview of the Carpal Region and Associated Structures

Carpal Bones and Their Relationships

• The medial styloid process is located distal to the radius, with carpal bones arranged in two rows. The accessory carpal bone is notably palpable and visible.

• The carpal tunnel houses flexor tendons, blood vessels, and nerves essential for hand functionality, particularly in the metacarpal region where four metacarpals support the fingers.

Metacarpals and Phalanges Structure

• Each finger has a proximal, middle, and distal phalanx that articulates with metacarpals through specific joints: metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP).

• The distal phalanx is anatomically modified into a claw shape; palmar pads are present for digital support.

Vascular and Nervous Anatomy of the Forelimb

• The cephalic vein runs superficially along the cranial forearm, commonly used for venipuncture in dogs due to its accessibility.

• A lateral cutaneous nerve accompanies the cephalic vein; improper puncture can lead to intense pain if this nerve is damaged.

Nerve Pathways and Potential Injuries

• The radial nerve branches off near the elbow area; injury can result from fractures leading to paralysis of extensor muscles causing hyperflexion of the limb.