Human Gross Anatomy for Occupational Therapists (PT 6703) Course Introduction

Introduction to Occupation-Based Anatomy

• Core Learning Objectives (Chapter 1)

  1. Foundational movements of the body.

  2. Directional terms.

  3. Planes and axes of movement.

• Anatomical Position and Directional Terms

  • Definition: The anatomical baseline used for all biomechanical and musculoskeletal concepts.

  • Proximal: Closer to the trunk or point of attachment.

  • Distal: Further from the trunk or point of attachment.

  • Medial: Toward the midline of the body.

  • Lateral: Away from the midline of the body.

  • Right/Left: Refers to the subject's right and left, not the observer's.

• Introductory Movements

  • Bending and Straightening: Flexion and Extension.

  • Side to Side Movement: Abduction and Adduction.

  • Rotational Movement: Mediated around a vertical axis.

• Planes of View and Axes of Movement

  • Planes:

    • Sagittal Plane: Divides the body into right and left halves.

    • Frontal (Coronal) Plane: Divides the body into anterior and posterior halves.

    • Transverse (Horizontal) Plane: Divides the body into superior and inferior halves.

  • Axes:

    • Vertical Axis: Runs superior to inferior (associated with rotation).

    • Sagittal Axis: Runs anterior to posterior.

    • Frontal Axis: Runs medial to lateral.

The Essential Nervous System

• Core Learning Objectives (Chapter 2)

  1. Basic divisions of the nervous system.

  2. Afferent (input) vs. Efferent (output) pathways.

  3. Anatomy of a peripheral nerve.

  4. Spinal nerve roots (Sensory vs. Motor functions; Plexi).

• Divisions of the Nervous System

  • Central Nervous System (CNS):

    • Brain: Receives and processes sensory information, plans and initiates motor responses, regulates body systems, analyzes information, and stores memories.

    • Spinal Cord: Conducts signals to and from the brain; controls certain reflexes.

  • Peripheral Nervous System (PNS):

    • Motor Neurons: Transmit efferent information from the CNS to muscles and glands.

    • Sensory Neurons: Transmit afferent information from sensory receptors to the CNS.

  • Somatic Nervous System: Controls voluntary muscle contraction and movement.

  • Autonomic Nervous System (ANS): Regulates involuntary body functions.

    • Sympathetic Nervous System: "Fight or flight."

    • Parasympathetic Nervous System: "Rest and digest."

• Neural Anatomy and Histology

  • Neuron Types: Multipolar (Motor neuron), Unipolar (Sensory neuron), Multipolar (Interneuron).

  • Nerve Fiber Layers:

    • Endoneurium: Wraps an individual neuron.

    • Perineurium: Sheathes a fascicle (group of neurons).

    • Epineurium: Surrounds the entire nerve.

• Spinal Nerve Distribution

  • Total pairs: $31$ pairs of spinal nerves.

  • Cervical: $8$ pairs ($C1-C8$). Note: $C1$ exits above the Atlas.

  • Thoracic: $12$ pairs ($T1-T12$).

  • Lumbar: $5$ pairs ($L1-L5$).

  • Sacral: $5$ pairs ($S1-S5$).

  • Coccygeal: $1$ pair.

  • Nerve Plexuses:

    • Cervical Plexus: $C1 - C5$.

    • Brachial Plexus: $C5 - T1$ (Innervates the upper extremity).

    • Lumbar Plexus: $L1 - L4$.

    • Sacral Plexus: $L4 - S4$ (Includes the Sciatic nerve).

Osteology of the Spine and Scapula

• The Vertebral Column

  • Curvatures:

    • Cervical Lordosis: Anterior convexity.

    • Thoracic Kyphosis: Posterior convexity.

    • Lumbar Lordosis: Anterior convexity.

    • Sacral Kyphosis: Posterior convexity.

  • Common Vertebral Features: Vertebral body, Pedicle, Lamina, Vertebral foramen (spinal cord passage), Transverse process, Spinous process, Superior and Inferior facets.

• Regional Vertebral Characteristics

  • Upper Cervical:

    • Atlas ($C1$): No vertebral body or spinous process; has superior facets for the occipital condyles. Forming the Atlanto-Occipital Joint ($10^{\circ}$ Flexion, $25^{\circ}$ Extension).

    • Axis ($C2$): Features the Odontoid process (Dens), which acts as a pivot for rotation. Forming the Atlanto-Axial Joint (Median and Lateral joints).

  • Thoracic Vertebrae:

    • Characteristics: Heart-shaped bodies and costal facets for rib articulation.

    • Costovertebral Joints: Articulations between the head of the rib and the superior/inferior costal facets (demifacets).

  • Lumbar Vertebrae:

    • Characteristics: Massive bodies to support weight; rectangular spinous processes.

    • Joints: Zygapophyseal (facet) joints allow for flexion and extension.

  • Sacrum and Coccyx: Fused vertebrae; features sacral foramina for nerve exit and the Sacroiliac (SI) joint.

• Ligaments of the Spine

  • Atlanto-Occipital/Axial Ligaments: Alar ligaments, Cruciform ligament (Superior longitudinal fibers, Transverse ligament of atlas, Inferior longitudinal fibers).

  • Long Ligaments: Anterior Longitudinal Ligament (ALL), Posterior Longitudinal Ligament (PLL), Nuchal ligament.

• The Scapulothoracic Joint

  • Osteology: Superior angle, Inferior angle, Medial (vertebral) border, Lateral (axillary) border, Spine of the scapula, Acromion.

  • Movements:

    • Elevation and Depression.

    • Adduction (Retraction) and Abduction (Protraction).

    • Upward Rotation and Downward Rotation.

Muscles of the Back (OINA-P Model)

• Study Model (OINA-P)

  • O: Origin.

  • I: Insertion.

  • N: Nerve (Innervation).

  • A: Action.

  • P: Palpation/Practical application.

• Layer 1: Superficial Axioscapular (Extrinsic) Muscles

  • Trapezius:

    • Parts: Upper (Descending), Middle (Transverse), Lower (Ascending) fibers.

    • Innervation: Spinal Accessory Nerve ($CN XI$) and sensory fibers from $C3 - C4$.

  • Levator Scapulae:

    • Origin: Transverse processes of $C1 - C4$.

    • Insertion: Superior angle of scapula.

  • Rhomboid Major and Minor:

    • Action: Adduction/Retraction of scapula.

  • Latissimus Dorsi ("False" Back Muscle $1$):

    • Innervation: Thoracodorsal nerve ($C6-C8$) from the posterior cord of the brachial plexus.

• Layer 2: Respiratory and Superficial Intrinsic Muscles

  • Serratus Posterior Superior and Inferior: Respiratory thorax muscles.

  • Splenius Capitis and Cervicis: Involved in head and neck extension and rotation.

• Layer 3: Intermediate Intrinsic Back Muscles (Erector Spinae)

  • Consists of three columns (Lateral to Medial: "I Love Spaghetti"):

    1. Iliocostalis (Lumborum, Thoracis, Cervicis).

    2. Longissimus (Thoracis, Cervicis, Capitis).

    3. Spinalis (Thoracis, Cervicis).

• Layer 4 & 5: Deep Intrinsic Muscles

  • Transversospinalis Group: Semispinalis, Multifidi, Rotatores.

  • Minor Deep Layer: Intertransversarii and Interspinales.