Anatomy & Physiology Spinal Cord & Spinal Nerves Waggy Spinal Cord & Spinal Nerves Waggy

The Spinal Cord The spinal cord provides a vital link between the brain and the rest of the body first lumbar vertebra (L1)The spinal cord travels from the foramen magnum of the skull and ends with first lumbar vertebra (L1) cervical region, thoracic region, lumbar region, sacral region, and coccygeal regionThe spinal cord can be subdivided into five regions: cervical region, thoracic region, lumbar region, sacral region, and coccygeal region (which has only one pair of nerves). The spinal cord provides a vital link between the brain and the rest of the body first lumbar vertebra (L1)The spinal cord travels from the foramen magnum of the skull and ends with first lumbar vertebra (L1) cervical region, thoracic region, lumbar region, sacral region, and coccygeal regionThe spinal cord can be subdivided into five regions: cervical region, thoracic region, lumbar region, sacral region, and coccygeal region (which has only one pair of nerves).

Spinal Nerves  Thirty-one pairs of spinal nerves  Eight pair cervical, twelve pair thoracic, five pair lumbar, five pair sacral, one pair coccygeal  Thirty-one pairs of spinal nerves  Eight pair cervical, twelve pair thoracic, five pair lumbar, five pair sacral, one pair coccygeal

Dermatomal Map  Dermatomal map  Dermatomal map: skin area supplied with sensory innervation by spinal nerves  Spinal nerves indicated by capital letter and number  Dermatomal map  Dermatomal map: skin area supplied with sensory innervation by spinal nerves  Spinal nerves indicated by capital letter and number

Cervical Plexus  Cervical vertebrae (C1- C4)  Motor:  Motor: Innervates muscles of the neck (SCM, trapezius), laryngeal muscles  Sensory:  Sensory: Skin of upper chest, shoulder, neck, and ear  Phrenic nerve  Innervates diaphragm  Cervical vertebrae (C1- C4)  Motor:  Motor: Innervates muscles of the neck (SCM, trapezius), laryngeal muscles  Sensory:  Sensory: Skin of upper chest, shoulder, neck, and ear  Phrenic nerve  Innervates diaphragm

Brachial Plexus  Between C5-T1 vertebrae  Nerves found here:  1. Axillary  2. Radial  3. Musculocutaneous  4. Ulnar  5. Median  Between C5-T1 vertebrae  Nerves found here:  1. Axillary  2. Radial  3. Musculocutaneous  4. Ulnar  5. Median

1. Axillary Nerve  Motor:  Motor: Innervates deltoid (abducts arm)  Sensory:  Sensory: from skin of the lateral shoulder  Motor:  Motor: Innervates deltoid (abducts arm)  Sensory:  Sensory: from skin of the lateral shoulder

2. Radial Nerve  Motor:  Motor: Stimulates muscles of arm, forearm, and hand  Sensory:  Sensory: From skin on posterior surface of arm and forearm, lateral 2/3 of dorsum of hand  Motor:  Motor: Stimulates muscles of arm, forearm, and hand  Sensory:  Sensory: From skin on posterior surface of arm and forearm, lateral 2/3 of dorsum of hand

3. Musculocutaneous Nerve  Motor:  Motor: Stimulates anterior arm: (biceps brachii, biceps brachialis)  Causes flexion movements at shoulder and elbow  Sensory:  Sensory: skin of forearm  Motor:  Motor: Stimulates anterior arm: (biceps brachii, biceps brachialis)  Causes flexion movements at shoulder and elbow  Sensory:  Sensory: skin of forearm

4. Ulnar Nerve  Motor:  Motor: Stimulates muscles in forearm & hand  Results in wrist and finger flexion  Sensory:  Sensory: skin of hand, little finger, and ring finger  Most easily damaged  Hitting the “funny bone” excites it  Motor:  Motor: Stimulates muscles in forearm & hand  Results in wrist and finger flexion  Sensory:  Sensory: skin of hand, little finger, and ring finger  Most easily damaged  Hitting the “funny bone” excites it

5. Median Nerve  Motor:  Motor: Innervates most of the flexors muscles of the wrist and of thumb and first two fingers,  Causes flexion of the wrist and fingers and thumb  Sensory:  Sensory: skin of 2/3 palm, thumb, index and middle fingers  Motor:  Motor: Innervates most of the flexors muscles of the wrist and of thumb and first two fingers,  Causes flexion of the wrist and fingers and thumb  Sensory:  Sensory: skin of 2/3 palm, thumb, index and middle fingers

The Lumbosacral Plexus  Lumbar plexus:  Lumbar plexus: found at L1-L4  Sacral plexus:  Sacral plexus: found at L4-S4  Usually considered together because of their close relationship  Four major nerves exit and enter lower limb  1. Obturator  2. Femoral  3. Tibial  4. Common fibular (peroneal)  Lumbar plexus:  Lumbar plexus: found at L1-L4  Sacral plexus:  Sacral plexus: found at L4-S4  Usually considered together because of their close relationship  Four major nerves exit and enter lower limb  1. Obturator  2. Femoral  3. Tibial  4. Common fibular (peroneal)

1. Obturator Nerve  Motor:  Motor: Innervates adductor group and gracilis of thigh  Causes adduction of the thigh and knee  Sensory:  Sensory: skin of the superior medial side of thigh  Motor:  Motor: Innervates adductor group and gracilis of thigh  Causes adduction of the thigh and knee  Sensory:  Sensory: skin of the superior medial side of thigh

2. Femoral Nerve  Motor:  Motor: Innervates anterior muscles of thigh & flexors and adductors of hip  Quadriceps group  Cause extension of the knee  Pectineus and Iliopsoas  Cause flexion of the hip  Sensory:  Sensory: skin of the anterior and lateral thigh; medial surface of leg and foot  Motor:  Motor: Innervates anterior muscles of thigh & flexors and adductors of hip  Quadriceps group  Cause extension of the knee  Pectineus and Iliopsoas  Cause flexion of the hip  Sensory:  Sensory: skin of the anterior and lateral thigh; medial surface of leg and foot

3. Sciatic Nerve  Thickest and longest nerve of the body  Motor:  Motor: Innervates posterior thigh and entire lower leg  Composed of 2 nerves (tibial and common fibular (or peroneal) in a common sheath)  The 2 divisions diverge just above the knee.  Sensory:  Sensory: skin of calf and foot  Thickest and longest nerve of the body  Motor:  Motor: Innervates posterior thigh and entire lower leg  Composed of 2 nerves (tibial and common fibular (or peroneal) in a common sheath)  The 2 divisions diverge just above the knee.  Sensory:  Sensory: skin of calf and foot

4. Tibial Nerve Motor:Motor: Innervates muscles of posterior thigh (hamstrings), posterior leg (gastrocnemius) Branches in foot to form medial and lateral plantar nerves Sensory: Sensory: posterior calf and foot

5. Common Fibular (Peroneal) Nerve Motor: Motor: Innervates anterior and lateral muscles of the leg and foot Sensory: Sensory: From skin of the lateral and anterior leg and dorsum of the foot. Motor: Motor: Innervates anterior and lateral muscles of the leg and foot Sensory: Sensory: From skin of the lateral and anterior leg and dorsum of the foot.

Other Nerves of the Lumbosacral Plexus  Iliohypogastric nerve  Iliohypogastric nerve - Muscles of abdominal wall and pubic region  Genitofemoral nerve  Genitofemoral nerve - Skin of scrotum (males) and labia (females); inferior abdominal muscles  Pudendal nerve  Pudendal nerve - innervates muscles and skin of the perineum (region encompasssing external genitalia and anus); and is involved in voluntary control of urination; the “shameful” nerve  Iliohypogastric nerve  Iliohypogastric nerve - Muscles of abdominal wall and pubic region  Genitofemoral nerve  Genitofemoral nerve - Skin of scrotum (males) and labia (females); inferior abdominal muscles  Pudendal nerve  Pudendal nerve - innervates muscles and skin of the perineum (region encompasssing external genitalia and anus); and is involved in voluntary control of urination; the “shameful” nerve

Coccygeal Plexus  Found at S4-S5  coccygeal nerve  Motor:  Motor: Muscles of pelvic floor  Sensory:  Sensory: skin over coccyx  Found at S4-S5  coccygeal nerve  Motor:  Motor: Muscles of pelvic floor  Sensory:  Sensory: skin over coccyx

The End  Be sure to bring the notes taken from this presentation and your completed line drawings to class so you will be successful on the quiz! (hint, hint!)