Senses

Spinal cord function

Transmits sensory and motor information between the brain and body and serves as a reflex center.

Epidural space

Space outside the dura mater containing fat and blood vessels.

Spinal dura mater

Outermost meningeal layer surrounding the spinal cord.

Arachnoid mater

Middle meningeal layer surrounding the spinal cord.

Subarachnoid space

Space between the arachnoid and pia mater containing cerebrospinal fluid (CSF).

Pia mater

Innermost meningeal layer that tightly covers the spinal cord.

Cervical enlargement

Enlarged region of the spinal cord that gives rise to nerves supplying the upper limbs.

Lumbar enlargement

Enlarged region of the spinal cord that gives rise to nerves supplying the lower limbs.

Conus medullaris

Tapered end of the spinal cord.

Cauda equina

Bundle of spinal nerves extending below the conus medullaris.

Gray matter

Contains neuron cell bodies.

Posterior (dorsal) horn

Receives sensory information.

Anterior (ventral) horn

Contains motor neuron cell bodies.

Lateral horn

Contains autonomic neuron cell bodies.

White matter

Contains ascending and descending myelinated tracts.

Dorsal ramus

Supplies the muscles and skin of the back.

Ventral ramus

Supplies the anterior trunk and limbs.

Cervical plexus function

Supplies the neck and diaphragm.

Phrenic nerve

Innervates the diaphragm for breathing.

Brachial plexus function

Supplies the shoulder, arm, forearm, and hand.

Axillary nerve

Deltoid and teres minor muscles; shoulder movement.

Radial nerve

Extensor muscles of the arm and forearm.

Median nerve

Most forearm flexors and thumb muscles.

Musculocutaneous nerve

Anterior arm muscles (biceps, brachialis).

Ulnar nerve

Intrinsic hand muscles and some forearm muscles.

Sacral plexus function

Supplies the pelvis, buttocks, and lower limb.

Sciatic nerve

Largest nerve in the body; supplies the posterior thigh and most of the lower leg.

Common fibular nerve

Anterior and lateral leg; dorsiflexion and eversion.

Tibial nerve

Posterior leg; plantar flexion.

Gluteal nerve

Supplies the gluteal muscles.

Palpebra

Eyelid; protects the eye.

Superior rectus

Elevates the eye.

Inferior rectus

Depresses the eye.

Medial rectus

Moves the eye medially.

Lateral rectus

Moves the eye laterally.

Superior oblique

Depresses and rotates the eye.

Inferior oblique

Elevates and rotates the eye.

Trochlea

Pulley-like structure for the superior oblique muscle.

Lacrimal gland

Produces tears.

Lacrimal duct

Drains tears into the nasal cavity.

Sclera

White outer layer that protects the eye.

Cornea

Clear front of the eye that refracts light.

Choroid

Vascular layer that nourishes the retina.

Tapetum lucidum

Reflective layer found in many animals, not humans.

Ciliary body

Controls lens shape and produces aqueous humor.

Iris

Colored portion of the eye that controls pupil size.

Pupil

Opening that allows light into the eye.

Retina

Contains photoreceptors that detect light.

Rods

Photoreceptors responsible for night and peripheral vision.

Cones

Photoreceptors responsible for color and detailed vision.

Optic disc

Blind spot where the optic nerve exits.

Fovea centralis

Area of sharpest vision with the highest concentration of cones.

Optic nerve

Carries visual information to the brain.

Optic chiasma

Location where optic nerve fibers partially cross.

Aqueous humor

Fluid in the anterior chamber that nourishes the cornea and lens.