The only statement among the choices provided that is false is: "The subclavian vein is contained within the carotid triangle." This statement is false because the subclavian vein in its entirety runs inferiorly to the boundaries of the carotid triangle.

The boundaries of the carotid triangle are as follows:

Superior: Posterior belly of the digastric muscle

Inferior: Superior belly of the omohyoid muscle

Lateral: Medial border of the sternocleidomastoid muscle

Each of the boundaries were stated correctly within the given answer choices. In addition, the internal jugular vein, is correctly stated as being present in the carotid triangle. Also contained in the carotid triangle are the common carotid artery, the internal jugular vein, the vagus nerve, and the hypoglossal nerve.

The tongue has a complicated innervation and is innervated by five cranial nerves. The innervation can be divided into motor and sensory innervations. In regards to motor innervation the palatoglossus is innervated by cranial nerve (CN) X (vagus nerve), while all other muscles of the tongue are innervated by CN XII (hypoglossal nerve). Sensory innervation is a bit more complicated. CN IX (glossopharyngeal nerve) is responsible for general and special sense (taste) of the posterior one-third of the tongue. CN VII (chorda tympani from the facial nerve) is responsible for special sensory (taste) of the anterior two-thirds of the tongue, while the mandibular branch of CN V (lingual nerve of the mandibular branch of trigeminal nerve) allows for general sensory of the anterior two-thirds of the tongue. 

The transverse fascia is a thin aponeurotic membrane that lies between the transverse abdominal muscle and the parietal peritoneum. Superficial to the transverse abdominal muscle is the internal oblique, with the external oblique superficial to the internal oblique. Sitting on top of the abdominal musculature is a layer of superficial fat followed by skin

Parietal peritoneum, extraperitoneal fat, transversesalis fascia, transversus abdominus, internal oblique, external oblique, superficial fat, skin

(Note: rectus abdominus lies within the aponeurosis of internal oblique).

From superficial to deep, the layers of abdominal wall structures above the arcuate line are in the following order: external oblique muscle, internal oblique muscle, transversus abdominis muscle, transversalis fascia, peritoneum.

Below the arcuate line, the only change is that internal oblique and the transversus abdominis aponeuroses join together and then travel superficial to the rectus muscle. 

The masseter is a muscle of mastication. It helps with food digestion rather than facial expression. 

The splenius capitus muscle will be stretched most effectively by rotation of the head and neck. The splenius capitus is a broad, strap like muscle found at the posterior neck. It attaches at the base of the skull and inserts at the vertebrae of the cervical and upper thoracic spine. It is involved in head extension, in addition to lateral flexion and rotation of the cervical spine. 

The rectus abdominis muscle originates from the pubic crest and pubic symphysis and inserts into the cartilage of the fifth to seventh ribs and the xiphoid process. It functions as a flexor of the vertebral column, especially in the lumbar region and is capable of compressing the abdomen to aid in urination, defecation, forced exhalation, and childbirth.

The external oblique muscle bilaterally compresses the abdomen and flexes the vertebral column. Unilaterally it can laterally flex the vertebral column, particularly in the lumbar region, as well as rotate the column.

The internal oblique muscle normally has its origin from the iliac crest, inguinal ligament, and thoracolumbar fascia. Its insertion is into the cartilage of the last three or four ribs as well as the transverse processes of the first four lumbar vertebrae.

The transversus abdominis muscle originates from the iliac crest, inguinal ligament, lumbar fascia, and cartilages of the inferior six ribs. It inserts into the xiphoid process, linea alba, and pubis. It functions as a compressor of the abdomen.