Anatomy & Physiology: Skin, Skeletal, and Muscular System Study Guide

Integumentary System

Structure of the Skin

The skin is the largest organ of the body and consists of multiple layers that provide protection, sensation, and regulation of body temperature.

• Epidermis: The outermost layer, composed mainly of keratinized stratified squamous epithelium. Provides a waterproof barrier and creates our skin tone.

• Dermis: The middle layer, containing connective tissue, blood vessels, nerve endings, hair follicles, and glands.

• Hypodermis (Subcutaneous Layer): The deepest layer, consisting of fat and connective tissue that insulates the body and absorbs shock.

Key Functions:

• Protection against pathogens and physical injury

• Regulation of body temperature

• Sensation (touch, pain, temperature)

• Excretion of waste products through sweat

• Synthesis of vitamin D

Example: The skin's response to injury involves a sequence of healing processes, including inflammation, tissue formation, and remodeling.

Skeletal System

Vertebral Column

The vertebral column, or spine, is a bony structure composed of individual vertebrae stacked on top of each other, providing support and protection for the spinal cord.

• Cervical Vertebrae: 7 vertebrae in the neck region

• Thoracic Vertebrae: 12 vertebrae in the upper and mid-back

• Lumbar Vertebrae: 5 vertebrae in the lower back

• Sacrum: 5 fused vertebrae forming the back of the pelvis

• Coccyx: 3-5 fused vertebrae forming the tailbone

Functions:

• Protects the spinal cord

• Supports the head and body

• Provides attachment points for ribs and muscles

Pelvic Girdle and Sacrum

The pelvic girdle consists of the sacrum and the two hip bones (ilium, ischium, and pubis). The sacrum is a triangular bone at the base of the spine, formed by the fusion of five sacral vertebrae.

• Sacrum: Connects the spine to the hip bones and forms the posterior wall of the pelvis.

• Function: Supports the weight of the upper body when sitting and standing.

Scapula and Clavicle

The scapula (shoulder blade) and clavicle (collarbone) are part of the pectoral girdle, which connects the upper limb to the trunk.

• Scapula: A flat, triangular bone providing attachment for several muscles of the shoulder and upper arm.

• Clavicle: A long bone that serves as a strut between the shoulder blade and the sternum.

Muscular System

Major Muscles of the Back and Shoulder

The back and shoulder muscles are responsible for movements of the upper limb and stabilization of the shoulder joint.

• Trapezius: A large, triangular muscle extending over the back of the neck and shoulders. Responsible for moving, rotating, and stabilizing the scapula.

• Latissimus Dorsi: A broad muscle of the lower back that extends, adducts, and medially rotates the arm.

• Deltoid: A thick, triangular muscle covering the shoulder joint, responsible for arm abduction.

• Rhomboids: Muscles located between the spine and the scapula, retracting the scapula.

Muscles of the Upper Limb

The upper limb muscles facilitate movement of the arm, forearm, and hand.

• Biceps Brachii: Located in the anterior compartment of the upper arm; flexes the elbow and supinates the forearm.

• Triceps Brachii: Located in the posterior compartment of the upper arm; extends the elbow.

• Brachialis: Lies underneath the biceps and also flexes the elbow.

Muscle Attachments and Actions

Muscles attach to bones via tendons and produce movement by contracting and pulling on the bones.

• Origin: The fixed attachment point of a muscle.

• Insertion: The movable attachment point of a muscle.

• Action: The specific movement produced by muscle contraction (e.g., flexion, extension, abduction).

Summary Table: Major Bones and Muscles Identified

Structure	Location	Function
Vertebral Column	Back	Support, protection of spinal cord
Sacrum	Base of spine	Connects spine to pelvis
Scapula	Shoulder	Muscle attachment, shoulder movement
Trapezius	Upper back	Moves and stabilizes scapula
Latissimus Dorsi	Lower back	Arm movement
Biceps Brachii	Upper arm (anterior)	Elbow flexion, forearm supination
Triceps Brachii	Upper arm (posterior)	Elbow extension

Additional info:

• Some images appear to be from practical lab exams, where students are asked to identify bones, muscles, and anatomical features.

• Muscle and bone identification is a common component of Anatomy & Physiology courses, especially in lab settings.