Overview
This lecture introduces key concepts about the nervous system, vertebral column, and superficial back muscles, including their anatomy, function, and clinical relevance.
Course Introduction and Logistics
- Lectures are asynchronous and posted online; labs are held in-person on Fridays.
- Access to the dissection lab is available and should be utilized for study.
- Reading the course handbook and checking Canvas for announcements is required.
- Attendance is compulsory; certificate of compliance must be signed before the first practical.
- Email is the best way to contact staff; follow lab rules regarding attire and behavior.
Lab Rules and Safety
- Wear scrubs, closed shoes, gloves, and additional PPE as needed.
- No mobile phones, food, drink, or contact lenses in the dissection room (DR).
- Keep workstations tidy, do not move tissue, and wash hands/tools after sessions.
Organization of the Nervous System
- The nervous system communicates signals from both inside and outside the body.
- Sensory input is received and decisions for action are made, some voluntary, some automatic (e.g., heart rate).
- Ganglia are clusters of neuron cell bodies positioned near the spinal cord or affected organ.
- Spinal nerves form from posterior (dorsal) and anterior (ventral) roots, splitting into primary rami.
Dermatomes and Myotomes
- Dermatome: Skin area supplied by a single spinal nerve or cord level.
- Myotome: Skeletal muscle region innervated by a single spinal nerve or cord level.
- Herpes Zoster can affect dermatomes, causing a characteristic rash.
Vertebral Column & Surface Anatomy
- Vertebral column supports, enables movement, and protects vital structures.
- Key surface landmarks include the acromion, scapular spine, iliac crest, and vertebral levels (C2-S2).
- Common spinal curvatures: kyphosis, lordosis, scoliosis.
- Movements include forward/backward flexion and lateral tilting.
Muscles of the Back
- Extrinsic muscles: originate from the ventral body, include superficial and intermediate groups.
- Superficial extrinsic muscles connect to the appendicular skeleton; intermediate attach to ribs (respiratory function).
- Intrinsic muscles originate and remain on the dorsum (deep, involved in spine/head movement).
- Scapulothoracic movements occur without a true joint.
Superficial Extrinsic Back Muscles
- Trapezius: elevates, retracts, and depresses scapula; innervated by spinal accessory nerve (CN XI) and C3-4.
- Latissimus dorsi: extends, adducts, and medially rotates the arm; innervated by thoracodorsal nerve (C6-8).
- Rhomboid major/minor: retract and elevate the scapula; innervated by dorsal scapular nerve (C4-5).
- Levator scapulae: elevates scapula; innervated by cervical nerves (C3-4) and dorsal scapular nerve (C5).
Triangles of the Back
- Triangle of Auscultation: boundaries are trapezius (superior), latissimus dorsi (inferior), rhomboid major (lateral); floor is the 6th intercostal space.
- Lumbar Triangle: boundaries are latissimus dorsi (medial), external oblique (lateral), iliac crest (inferior); floor is internal oblique.
Key Terms & Definitions
- Dermatome — Skin region innervated by a single spinal nerve.
- Myotome — Muscle group innervated by a single spinal nerve.
- Ganglion — Cluster of neuronal cell bodies in the nervous system.
- Scapulothoracic Movement — Movement of the scapula held by muscles, not a joint.
- Triangle of Auscultation — Area with thin muscle cover for listening to lung sounds.
- Lumbar Triangle — Anatomical region with clinical significance for hernia site.
Action Items / Next Steps
- Read the course handbook and review lecture slides.
- Attend lab sessions and adhere strictly to lab safety protocols.
- Sign and submit the certificate of compliance before the first practical session.