(1)Appendicular Skeleton Lecture Notes

These flashcards cover key vocabulary related to the appendicular skeleton, including bones and joints of the forelimb and hindlimb.

Thoracic Limb (Front Limb)

The forelimb of vertebrates, emphasizing a skeletal sequence of:

• Scapula (Shoulder blade)

• Humerus (Brachium)

• Radius and Ulna (Antebrachium)

• Carpus (Wrist)

• Metacarpus (Hand/Palm area)

• Digits/Phalanges (Fingers/Toes)

Pelvic Limb (Hind Limb)

The hindlimb sequence responsible for propulsion, consisting of:

• Pelvic Girdle (Os coxae)

• Femur (Thigh bone)

• Patella (Kneecap)

• Tibia and Fibula (Crus)

• Tarsus (Hock/Ankle)

• Metatarsus (Foot area)

• Digits/Phalanges (Toes)

Scapula: Detailed Anatomy

A flat, triangular bone on the lateral thorax. Functional landmarks include:

• Spine of the Scapula: A prominent ridge dividing the lateral surface.
• Supraspinous and Infraspinous Fossae: Depressions for muscle origins.
• Glenoid Cavity: The concave surface that articulates with the head of the humerus to form the shoulder joint.

Humerus: Major Landmarks

The long bone of the brachium featuring:

• Head: Articulates with the scapula.
• Greater and Lesser Tubercles: Sites for muscle attachment (e.g., supraspinatus).
• Deltoid Tuberosity: A lateral roughened area for the deltoid muscle.
• Condyle: Includes the trochlea and capitulum for articulation with the radius and ulna.

Biceps vs. Triceps Brachii

1. Biceps brachii: Originates on the supraglenoid tubercle of the scapula and inserts on the radius/ulna; acts to flex the elbow joint.
2. Triceps brachii: The large muscle on the caudal aspect of the humerus; its long head originates on the scapula and inserts on the olecranon, acting to extend the elbow joint.

The Elbow Joint (Cubital Joint)

A composite synovial joint formed by the humerus, radius, and ulna. Key features include the anconeal process of the ulna, which fits into the olecranon fossa of the humerus during extension to provide joint stability.

Pelvic Girdle (Os Coxae)

Composed of three fused bones on each side:

1. Ilium: The largest, most cranial part forming the pelvic wing.
2. Ischium: The most caudal part, featuring the tuber ischiadicum (pin bone).
3. Pubis: Forms the cranial floor of the pelvic cavity.

Acetabulum: The Hip Socket

A deep, cup-shaped cavity formed by the junction of the ilium, ischium, and pubis. It receives the head of the femur to form the coxofemoral joint. It is characterized by the lunate surface (articular) and the acetabular fossa (non-articular).

Femur: Special Landmarks

The heaviest bone in the pelvic limb, it contains:

• Trochanter Major: A massive lateral prominence for the insertion of the gluteal muscles.
• Trochanter Minor: Medial site for the iliopsoas muscle.
• Trochlea: A cranial groove where the patella glides during movement.

Stifle Joint (Geno Joint)

The equivalent of the human knee, involving the femur, patella, and tibia. It is held together by the Cranial and Caudal Cruciate Ligaments, which prevent the tibia from sliding forward (cranial) or backward (caudal) relative to the femur.

Sesamoid Bones: Patella and Fabellae

1. Patella: The largest sesamoid bone, embedded in the quadriceps femoris tendon, protecting the joint and increasing leverage.
2. Fabellae: Small sesamoid bones (usually two) found in the tendons of the gastrocnemius muscle in carnivores, located caudal to the femoral condyles.

Tarsal Joint (Hock)

The complex joint of the hindlimb. In many species, it consists of three rows of tarsal bones. The Calcaneus is the largest bone, featuring the tuber calcis, which serves as the insertion point for the Common Calcaneal (Achilles) Tendon.

Equine Digital Anatomy (The Hoof)

Specialized terminology for the distal limb in horses:

• Fetlock: Metacarpophalangeal joint.
• Pastern: Proximal\ Interphalangeal joint.
• Coffin: Distal\ Interphalangeal joint.
• P3 (Distal Phalanx): Also known as the Coffin Bone or Pedal Bone, encased within the hoof.

Metacarpal and Metatarsal Bones

• Carnivores: Usually five bones (though the first is reduced).
• Equine: Three bones; the large 3rd Metacarpal (Cannon bone) and two Splint bones (2nd and 4th Metacarpals).
• Ruminants: The 3rd and 4th bones are fused into a single 'large metacarpal' bone.

Fossa, Trochanter, and Tuberosity

• Fossa: A shallow depression often used for muscle origin (e.g., infraspinous fossa).
• Trochanter: Large, blunt processes found specifically on the femur (e.g., Greater Trochanter).
• Tuberosity: A smaller, rough projection or protuberance for muscle or ligament attachment (e.g., Deltoid tuberosity).