Chapter 14 MCQ + Short essay

c

b

(1) d

(2) c

(3) f

(4) b

(5) e

(6) a

(1) f

(2) i

(3) b

(4) g, h, j

(5) e

(6) i

(7) i

(8) k

(9) j

(10) c, d, f, k

(11) c

c

c

c

Short essay:

11. In the sensory receptors called “encapsulated nerve endings,” what is the “capsule” made of?

The capsule is made of connective tissue (layers of flattened cells/collagen) surrounding the nerve ending.

Short essay:

12. (a) Describe the roots to and the composition of a spinal nerve.
    (b) Are dorsal and ventral roots in the CNS or the PNS?
    (c) Name the branches of a spinal nerve (other than the rami communicates), and identify what the basic region of the body each branch supplies.

(a) Roots & Composition

A spinal nerve is formed by two roots:

• Dorsal root — carries sensory (afferent) fibers; has the dorsal root ganglion (cell bodies of sensory neurons)

• Ventral root — carries motor (efferent) fibers

They merge to form the spinal nerve → making it mixed (both sensory & motor).

(b) CNS or PNS?

Both roots are PNS — they emerge outside the spinal cord proper.

(c) Branches (Rami) of a Spinal Nerve

Branch	Region Supplied
Dorsal ramus	Posterior body wall (back muscles & skin)
Ventral ramus	Anterior & lateral body wall, and limbs
Meningeal branch	Meninges & vertebrae

Tip: Ventral rami form the major nerve plexuses (brachial, lumbar, etc.) — commonly tested!

Short essay:

13. (a) Define nerve plexus.
    (b) List the spinal nerves of origin of the four major nerve plexuses, and name the general body regions served by each plexus.

Nerve Plexuses:

(a) Definition

A nerve plexus is a network of interweaving ventral rami of spinal nerves, allowing fibers from multiple spinal levels to be redistributed into peripheral nerves.

(b) Four Major Plexuses:

Plexus	Spinal Origin	Region Served
Cervical	C1–C4	Neck, back of head, diaphragm (via phrenic nerve)
Brachial	C5–T1	Shoulder & upper limb
Lumbar	L1–L4	Anterior & medial thigh, groin
Sacral	L4–S4	Posterior thigh, leg, foot, pelvis

Note: Lumbar & Sacral are sometimes combined and called the Lumbosacral plexus

Tip: The phrenic nerve (cervical plexus) is high-yield — it controls breathing, which is why high cervical injuries can be fatal.